TreeDazzled

Response of boreal plant communities to variations in previous fire-free interval

Johnstone, Jill F

Johnstone, Jill F.; Univ Saskatchewan, Dept Biol, Saskatoon, SK S7N 5E2, Canada

15 (4) : 497-508 2006

The present study used overlapping burn scars from natural wildfires to examine the effects of changes in the fire-free interval on early successional plant communities in boreal forests of central Yukon Territory, Canada. Data on plant community composition and residual organic material were collected in the first decade of post-fire regeneration in two study areas with recent fire overlap. Sites with a shorter fire-free interval had reduced loads of deadwood and shallower organic layers after the most recent fire. Multivariate analysis of species cover indicated that sites in and out of the burn overlap zones also supported distinct plant communities. Differences in the plant communities were associated with a greater abundance of woody deciduous species, such as Populus tremuloides, Salix spp., and Shepherdia canadensis, at sites that had recently re-burned. Sites that burned after a longer interval had higher moss cover and greater abundance of Picea mariana, Calamagrostis canadensis, and Ribes glandulosum in one study area, and Epilobium angustifolium in the second area. Ordinations of species cover indicated that plant community patterns were most strongly associated with gradients related to fire history and topography. In general, shorter fire-free intervals reduced pools of residual plant material and favored dominance of resprouting, woody deciduous species.

Tags: Terrestrial Ecology

G-435 and ARS 96-138, pink-fruited blueberry selections

Ehlenfeldt, Mark K; Finn, Chad E

Ehlenfeldt, Mark K. ; USDA ARS, Marucci Ctr Blueberry and Cranberry Res and Extens, 125A Lake Oswego Rd, Chatsworth, NJ 08019 USA

42 (1) : 172-173 FEB 2007

G-435 and ARS 96-138 are two pink-fruited blueberry selections developed by the Agricultural Research Service of the U.S. Department of Agriculture. G-435, a tetraploid, is predominantly Vaccinium corymbosum L. (highbush blueberry) with a mixture of other Vaccinium species germplasm in its ancestry. It has been evaluated in New Jersey and Michigan. ARS 96-138 is a hexaploid that is half V. ashei Reade (rabbiteye blueberry) and half synthetically derived, hexaploid, highbush-type germplasm. It has been evaluated in New Jersey and Oregon. ARS 96-138 was partially derived from a pink-fruited sibling of G-435; thus, the two selections are related, although they possess different ploidy levels. They are released as germplasm for further evaluation, breeding, and possible commercialization. They represent a novel fruit color in blueberry that is of interest to the landscape nursery business.

Tags: Horticulture

Litter and dead wood dynamics in ponderosa pine forests along a 160-year chronosequence

Hall, S A, Burke, I C, and Hobbs, N T

Hall, S. A. ; Nature Conservancy, N Cent Washington Field Off, 6 Yakima St,Suite 1A, Wenatchee, WA 98801 USA

16 (6) : 2344-2355 DEC 2006

Disturbances such as fire play a key role in controlling ecosystem structure. In fire-prone forests, organic detritus comprises a large pool of carbon and can control the frequency and intensity of fire. The ponderosa pine forests of the Colorado Front Range, USA, where fire has been suppressed for a century, provide an ideal system for studying the long-term dynamics of detrital pools. Our objectives were (1) to quantify the long-term temporal dynamics of detrital pools; and (2) to determine to what extent present stand structure, topography, and soils constrain these dynamics. We collected data on downed dead wood, litter, duff (partially decomposed litter on the forest floor), stand structure, topographic position, and soils for 31 sites along a 160-year chronosequence. We developed a compartment model and parameterized it to describe the temporal trends in the detrital pools. We then developed four sets of statistical models, quantifying the hypothesized relationship between pool size and (1) stand structure, (2) topography, (3) soils variables, and (4) time since fire. We contrasted how much support each hypothesis had in the data using Akaike's Information Criterion (AIC).Time since fire explained 39-80% of the variability in dead wood of different size classes. Pool size increased to a peak as material killed by the fire fell, then decomposed rapidly to a minimum (61-85 years after fire for the different pools). It then increased, presumably as new detritus was produced by the regenerating stand. Litter was most strongly related to canopy cover (r(2) = 77%), suggesting that litter fall, rather than decomposition, controls its dynamics. The temporal dynamics of duff were the hardest to predict. Detrital pool sizes were more strongly related to time since fire than to environmental variables. Woody debris peak-to-minimum time was 46-67 years, overlapping the range of historical fire return intervals (I to > 100 years). Fires may therefore have burned under a wide range of fuel conditions, supporting the hypothesis that this region's fire regime was mixed severity.

Tags: Biochemistry and Molecular Biophysics, Terrestrial Ecology

Potential of starch as a cheap gelling agent in plant tissue culture media

Cheema, Harvinder K; Patial, Anil

Cheema, Harvinder K. ; Panjab Univ, Dept Bot, Chandigarh 160014, India

55 (1-4) : 215-218 2005

In spite of its higher cost, agar is still used as most frequent gelling agent in commercialisation of plant tissue culture. The potential of tissue culture medium gelled with starch of two different varieties to support seed germination of Glycine max L. and morphogenetic response of various explants (shoot tip, leaf and root) was studied. Explants were obtained from one week old Glycine max L. plants raised in vitro. By analysing various responses, it was found that although there was no significant difference between the two gelling agents (agar and starch) in response to seed germination, yet the starch gelled medium was not found appropriate to replace agar for morphogenetic responses of various explants in culture.

Tags: Biochemistry and Molecular Biophysics, Methods and Techniques, Development, Agronomy

Reflectance seasonality and its relation to the canopy leaf area index in an eastern Siberian larch forest: Multi-satellite data and radiative transfer analyses

Kobayashi, Hideki, Suzuki, Rikie, and Kobayashi, Shiho

Kobayashi, Hideki ; JAMSTEC, FRCGC, Ecosyst Change Res Program, Kanazawa Ku, 3173-25 Showamachi, Yokohama, Kanagawa 2360001, Japan

106 (2) : 238-252 JAN 30 2007

Reliable monitoring of seasonality in the forest canopy leaf area index (LAI) in Siberian forests is required to advance the understanding of climate-forest interactions under global environmental change and to develop a forest phenology model within ecosystem modeling. Here, we compare multisatellite (AVHRR, MODIS, and SPOT/VEGETATION) reflectance, normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and LAI with aircraft-based spectral reflectance data and field-measured forest data acquired from April to June in 2000 in a larch forest near Yakutsk, Russia. Field data in a 30 x 30-m study site and aircraft data observed around the field site were used. Larch is a dominant forest type in eastern Siberia, but comparison studies that consider multi-satellite data, aircraft-based reflectance, and field-based measurement data are rarely conducted. Three-dimensional canopy radiative transfer calculations, which are based on Antyufeev and Marshak's [Antyufeev, VS., & Marshak, AL. (1990). Monte Carlo method and transport equation in plant canopies, Remote Sensing of Environment, 31, 183-19 1] Monte Carlo photon transport method combined with North's [North, P.R. (1996). Three-dimensional forest light interaction model using a Monte Carlo method, IEEE Transactions on Geoscience and Remote Sensing, 34(4), 946-956] geometric-optical hybrid forest canopy scene, helped elucidate the relationship between canopy reflectance and forest structural parameters, including several forest floor conditions. Aircraft-based spectral measurements and the spectral response functions of all satellite sensors confirmed that biases in reflectance seasonality caused by differences in spectral response functions among sensors were small. However, some reflectance biases occur among the near infrared (NIR) reflectance data from satellite products; these biases were potentially caused by absolute calibration errors or cloud/cloud shadow contamination. In addition, reflectance seasonality in AVHRR-based NIR data was very small compared to other datasets, which was partially due to the spring-to-summer increase in the amount of atmospheric water vapor. Radiative transfer simulations suggest that bi-directional reflectance effects were small for the study site and observation period; however, changes in tree density and forest floor conditions affect the absolute value of NIR reflectance, even if the canopy leaf area condition does not change. Reliable monitoring of canopy LAI is achieved by minimizing these effects through the use of NIR reflectance difference, i.e., the difference in reflectance on the observation day from the reflectance on a snow-free/pre-foliation day. This may yield useful and robust parameters for multi-satellite monitoring of the larch canopy LAI with less error from intersensor biases and forest structure/floor differences. Further validation with field data and combined use of other index (e.g. normalized difference water index, NDWI) data will enable an extension of these findings to all Siberian deciduous forests. (c) 2006 Elsevier Inc. All rights reserved.

Tags: Methods and Techniques, Climatology, Terrestrial Ecology

Tree rings and the aging of trees: A controversy in 19th century America

Briand, Christopher H, Brazer, Susan E, and Harter-Dennis, Jeannine M

Briand, Christopher H. ; Salisbury Univ, Dept Biol Sci, Salisbury, MD 21801 USA

62 (2) : 51-65 2006

During the late 19th Century there was considerable debate in the United States among members of the legal profession, the general public and even some scientists about the validity of using tree rings to determine tree age. In an earlier boundary dispute case in Maryland (1830) the Honorable Theodorick Bland rejected the use of tree rings to establish the date when a purported witness tree was marked with an identifying blaze. Bland did not believe that there was enough scientific evidence or legal precedent to support this idea. A review of the current scientific literature of the time, however, indicates that most scientists, especially in Europe, accepted that tree rings could be used to determine age. In the United States, however, this idea was debated, particularly in the late 19th Century, in both the popular press and scientific publications. The main argument of opponents such as A. L. Child was that the number of tree rings was often wildly in excess of the known age of the tree. These inconsistencies were likely because of the inexperience of the observer, mistaking earlywood and latewood for separate rings, and the presence of a small number of false rings, sometimes called secondary rings. The great ages reported for the giant sequoias may have also raised doubts among the public. Among scientists, however, the relationship between ring number and tree age and between ring width and climate became widely accepted. Several cases heard in both Federal and State Courts as well as Bernhard E. Fernow's Age of Trees and Time of Blazing Determined by Annual Rings laid to rest any doubt of the relationship between tree rings and age in temperate forests, i.e. one ring equals one year's growth, and showed that the date when a witness tree was blazed could be easily determined from a cross-section of the trunk.

Tags: Terrestrial Ecology

Growth reactions of sub-alpine norway spruce (picea abies (l.) karst.) following one-sided light exposure (case study at davos "lusiwald")

Braeker, Otto U; Baumann, Ernst

Braeker, Otto U. ; Swiss Fed Res Inst WSL, CH-8903 Birmensdorf, Switzerland

62 (2) : 67-73 2006

In 1982, several rectangular openings were cut in a 100 year old sub-alpine Norway spruce forest stand to initiate regeneration at the Lusiwald site at Davos, Switzerland. The openings on the steep, north-facing slope created rapid changes to the environment of the border trees. Growth reactions of these border trees were compared and analysed with reference trees from the adjacent closed canopy stand in 1997. The radial growth pattern of the two data sets differed within the 14-year period since the openings were cut; the border trees showed growth releases. The growth reaction at the stem base was larger than at breast height. Changes in wind exposure may have influenced border trees to adapt their root systems. Sub-alpine Norway spruce stands aged around 100 years, which are usually considered slow-growing on a north aspect, still seem capable of reacting to greater resource availability such as sudden light changes.

Tags: Development, Terrestrial Ecology

Effects of organic waste substrates on the growth of impatiens

Dede, Omer H, Koseoglu, Gulgun, Ozdemir, Sairn, and Celebi, Ahmet

Dede, Omer H. ; Sakarya Univ, Dept Environm Engn, TR-540187 Sakarya, Turkey

30 (5) : 375-381 2006

The use of peat and peat substitute organic wastes as substrates for container-grown flowers was studied. Peat, hazelnut husk, and maize straw were considered as support materials and MSWC (municipal solid waste compost) and poultry manure as fertilizer supplements. Eight substrates were prepared by combining each additive with peat, hazelnut husk, and maize straw. Hazelnut husk and maize straw substitution by 50% and compost and poultry manure addition by 25% in peat exhibited acceptable physical and chemical properties that are important for container substrates. Nitrogen provided by the compost and poultry manure influenced plant growth and flowering. The lowest rate of plant growth was obtained with commercial peat, while the highest was obtained with peat+maize straw+poultry manure. The presence of compost in the substrate produced fewer flowers per plant even though the plants had a similar vegetative frame, and fresh and dry mass. Higher electrical conductivity (EC) of the substrate and lower nitrogen content in peat+MSWC and peat+hazelnut husk+MSWC reduced the number of flowers per plant more than the control did. On the other hand, plants in commercial peat flowered abundantly at the beginning of season, while plants in the substrate with MSWC and poultry manure added flowered 1 or 2 weeks later and had a longer abundant flowering period. Our results suggest that it is possible to use organic materials, such as those we tested, as an alternative growing media component to peat.

Tags: Agrichemicals, Horticulture

Restoration of the urban forests of Tokyo and Hiroshima following World War II

Cheng, Sheauchi; McBride, Joe R

Cheng, Sheauchi ; USDA, Forest Serv, Pacific SW Res Stn, POB 245, Berkeley, CA 94701 USA

5 (4) : 155-168 2006

The urban forests of Tokyo and Hiroshima were devastated by American bombing during World War II. Approximately 160 km(2) of Tokyo were burned by more than 100 fire bombings, while an area of 12 km(2) was leveled and burned by one atomic bomb in Hiroshima. Tokyo's street tree population was reduced from 105,000 to approximately 42,000 by the end of the war. In the years immediately following the war, the street tree population dropped to 35,000 in Tokyo due to a combination of further tree mortality and the cutting of trees for fire wood. No estimates of pre-war street tree populations are available for Hiroshima. Examination of pre- and post-atomic bombing photographs of Hiroshima suggests an even higher percentage of the trees in the city were destroyed. Post-war reconstruction of the urban forests of each city developed along different pathways. Plans for the redevelopment of Tokyo were rejected by the general public who wanted a return to pre-war conditions. Few streets were widened to accommodate traffic and allow for new street tree planting. Plans for new parks were shelved or only partially achieved. Some streets were replanted by private citizens. Initial survival rates of replanting were low. Trees in Tokyo's municipal tree nurseries, which had not been converted to vegetable gardens during the war, were often larger than the optimal size for transplanting, but were used as no other trees were available. A more concerted effort to reconstruct the urban forest came following the 1959 decision to site the 1964 Olympic Games in Tokyo. Many streets were widened and planted with trees. New tree-lined boulevards were also created. In contrast, Hiroshima sponsored an international competition for the design of a Peace Park and a major tree-lined boulevard. Several wide streets were built with space for street trees. Major plans were also drawn to create greenways along the rivers and to build additional parks. Trees were initially donated by local farmers and nearby towns for planting the parks and the boulevard since municipal tree nurseries had been converted to vegetable gardens during the war. Survival rates were very low due to the rubble content of the soil and difficulties in watering the transplanted trees. Strong support from the mayors of Hiroshima contributed to the success of urban forest reconstruction in Hiroshima. The historical significance of the destruction caused by the first atomic bomb to be dropped on an urban area also contributed to Hiroshima citizens' will to reconstruct both the city and its urban forest. Species and location of trees determined the survival of trees after war in both cities. Species with strong resprouting ability and thick bark survived the bombing and fire. In Tokyo trees located in open areas avoided the fire, while in Hiroshima trees standing behind tall concrete buildings were shielded from radiation and the heat wave. In addition to the difficulties faced during the city-wide replanning process, constraints of urban forest recovery included severe financial restriction, short supply of proper large-sized trees for planting and lack of labor for planting and post-planting tree care. Hiroshima used public participation and community involvement to restore the urban greenery successfully and, until today, has maintained a program to conserve the trees that survived the atomic bomb. (c) 2006 Elsevier GmbH. All rights reserved.

Tags: Conservation, Terrestrial Ecology

The effect of shading of stock plants on rhizogenesis in stem cuttings of Berberis thunbergii 'Red Rocket'

Pacholczak, Andrzej, Szydlo, Wieslaw, and Lukaszewska, Aleksandra

Pacholczak, Andrzej ; Agr Univ Warsaw, Dept Ornamental Plants, Fac Hort and Landscape Architecture, Nowoursynowska 159, PL-02776 Warsaw, Poland

28 (6) : 567-575 2006

In order to improve vegetative propagation of Berberis thunbergii 'Red Rocket', stock plants were subjected to shading and IBA treatment, as well as to the application of two commercially available rooting powders. Spraying stock plants with IBA 24 hours prior to cutting harvest gave the effect comparable to the use of rooting powders. Reduction of light intensity by 50% and 96% of ambient prior to harvest of cuttings improved rooting. Positive effect of shading results in changes in shoot anatomy, i.e. a weaker sclerenchyma development. Enhanced rooting in cuttings from shoots grown under reduced light intensity was accompanied by a decrease in the concentration of soluble proteins and by an increase in total chlorophyll content while the concentration of total soluble sugars remained unaffected.

Tags: Biochemistry and Molecular Biophysics, Horticulture

Crown architecture development in Salix 'Prairie Cascade', a pendulous willow

Remphrey, William R; Pearn, Linda P

Remphrey, William R. ; Univ Manitoba, Dept Plant Sci, Winnipeg, MB R3T 2N2, Canada

84 (10) : 1531-1541 OCT 2006

This paper presents a longitudinal quantitative architectural study of Salix 'Prairie Cascade', a hardy pendulous willow cultivar developed for the Canadian Prairies. Trees were propagated from cuttings in 1993 and detailed measurements were obtained on amount of extension growth, orientation of shoots with respect to gravity, and the fate of buds and shoots until 2000. Instead of the mixed axis model of Champagnat typically ascribed to weeping willows, upright main-stem axes were constructed by vigorous, mostly distal shoots that remained more or less upright. The pendulous habit was largely the result of lateral shoots that were initially upright or semi-pendulous, drooping under their own weight to become pendulous. The pendulous habit was exacerbated by the weight of foliage. Sylleptic shoots were frequently incorporated into the main-stem axes. From original 1993 shoots, 40% of the buds developed into sylleptic shoots compared with 29% that developed into proleptic shoots. Two orders of sylleptic branching were often produced in one year. Willow is known for branch shedding but only 7% of 'Prairie Cascade' shoots were shed in the first year; however, more than half were gone by the third year and most of those remaining were located on the upper half of parent shoots.

Tags: Development, Horticulture

Two threatened coexisting indigenous conifer species in the dry Afromontane forests of Ethiopia are associated with distinct arbuscular mycorrhizal fungal communities

Wubet, Tesfaye, Weiss, Michael, Kottke, Ingrid, and Oberwinkler, Franz

Wubet, Tesfaye ; Univ Tubingen, Morgenstelle 1, D-72076 Tubingen, Germany

84 (10) : 1617-1627 OCT 2006

The molecular diversity of arbuscular mycorrhizal (AM) fungi colonizing roots of Podocarpus falcatus (Thunb.) R.Br. (Podocarpaceae) in the dry Afromontane forests of Ethiopia was investigated. The nuclear gene coding for small subunit ribosomal RNA (nucSSU rDNA) was amplified from colonized roots of P. falcatus, cloned, and sequenced using AM fungal specific primers. Phylogenetic analyses revealed that the glomeromycetous sequences from mycorrhizae of P. falcatus belong to the Glomeraceae, Diversisporaceae, and Archaeosporaceae. Overall, 16 Glomus, three Diversispora, and one Archaeospora sequence types were identified. These sequence types were distinct and only distantly related to sequences from the available defined species. The composition of the AM fungal communities differed significantly between the two study sites. Comparison of the AM fungal community composition of P. falcatus with that of previously investigated Juniperus procera Hochst. ex Endl. (Cupressaceae), the only coexisting indigenous conifer tree species in the dry Afromontane forest ecosystem, yields that the two tree species are colonized by distinct AM fungal communities. This suggests that fungal communities are host plant specific in the natural stand conditions. Therefore, in the conservation of these endangered species and restoration of the degraded ecosystem, the use of appropriate mycorrhizal fungi should be taken into account in future projects.

Tags: Biogeography, Biochemistry and Molecular Biophysics, Horticulture

Structural and physiological plasticity in response to light and nutrients in five temperate deciduous woody species of contrasting shade tolerance

Portsmuth, A; Niinemets, U

Niinemets, U.; Univ Tartu, Dept Plant Physiol, Rii 23, EE-51010 Tartu, Estonia

21 (1) : 61-77 FEB 2007

1. Plants encounter a variety of light and nutrient availabilities during succession. However, there is an ongoing debate to which extent light-dependent structural and physiological plasticity is associated with species shade tolerance.2. Seedlings of five species, Betula pubescens Ehrh., B. pendula Roth, Populus tremula L., Quercus robur L. and Acer platanoides L. (from most intolerant to most shade-tolerant), were grown at four different light and nutrient availabilities to test the hypotheses that intolerant species have higher physiological and tolerant species higher structural plasticity to light and also that there is an overall increase in plasticity with increasing nutrient availability. Two replicate experiments in different years were conducted. Plasticity was characterized by four estimates: (1) the range of variation of the components of relative growth rate (RGR), leaf area ratio (LAR) and net assimilation rate (NAR) (RGR = LAR.NAR) at common RGR; (2) average standardized slopes of physiological (RGR, NAR, i.e. physiological plasticity, Pi(P)) and structural (LAR, leaf dry mass per unit area, biomass allocation traits, i.e. structural plasticity, Pi(S)) traits vs. irradiance relationships; (3) standardized difference of plant traits measured at low to medium irradiance; (4) coefficient of variation across different irradiance treatments.3. Plant growth was more strongly associated with NAR than with structural traits, but shade-intolerant species had a greater range of variation in both NAR and LAR at a common RGR. RGR, NAR and structural characteristics also responded more strongly to increases in irradiance in shade-intolerant species, but at low irradiance RGR and NAR were similar among all species. Owing to higher biomass fraction in leaves, the intolerant species produced less woody biomass. In nonfertilized plants, both Pi(P) and Pi(S) were negatively associated with shade tolerance. The plasticity was enhanced by nutrient addition, but the nutrient-dependent enhancement in plasticity was greater in more tolerant species. Therefore, differences in plasticity among species of varying tolerance were lower at higher nutrient availability.4. Our study does not support the hypothesis of a trade-off between structural and physiological plasticity. Shade-tolerant species are generally less plastic than intolerant species, but increases in nutrient availability during succession reduce the differences in plasticity. Despite similar RGR in low light, first-year seedlings of shade-tolerant species produce more woody biomass, favouring survival and growth in subsequent years.

Tags: Terrestrial Ecology

Influence of transplant spacing and planting date on fruit yield, plant status of tomato and population development of Meloidogyne incognita

Kumar, S; Khanna, A S

Kumar, S. ; Dr Yashwant Singh Parmar Univ Hort and Forestry, Dept Entomol and Apiculture, Solan 173230, HP, India

34 (2) : 135-140 DEC 2006

Field studies were conducted to evaluate the most suitable tomato transplant spacing and planting date at a field site infested with Meloidogyne incognita. Tomatoes were transplanted the 20(th) of each month from March through July and, on each date, transplants were spaced 35, 45 and 55 cm apart in 60-cm-wide rows. Initial population densities of M. incognita were determined prior to transplanting each month and populations per 200 cm(3) soils were: 212, 246, 321, 790, and 410 in March, April, May, June and July, respectively. Tomato plant growth and yield was greatest in the April and May plantings. Tomatoes transplanted in March were stunted due to high nematode multiplication on their roots. The tomatoes transplanted in July suffered nematode damage in the vegetative phase and the cool temperatures at fruiting reduced ripening. Highest yield and largest fruit size were attained at the in-row plant spacing of 45 cm.

Tags: Parasitology, Methods and Techniques

The likely impact of elevated [CO2], nitrogen deposition, increased temperature and management on carbon sequestration in temperate and boreal forest ecosystems: a literature review

Hyvonen, Riitta, Agren, Goran I, Linder, Sune, Persson, Tryggve, Cotrufo, M Francesca, Ekblad, Alf, Freeman, Michael, Grelle, Achim, Janssens, Ivan A, Jarvis, Paul G, Kellomaki, Seppo, Lindroth, Anders, Loustau, Denis, Lundmark, Tomas, Norby, Richard J, Oren, Ram, Pilegaard, Kim, Ryan, Michael G, Sigurdsson, Bjarni D, Stromgren, Monika, van Oijen, Marcel, and Wallin, Goran

Hyvonen, Riitta ; Swedish Univ Agr Sci, Dept Ecol and Environm Res, SLU, POB 7072, SE-75007 Uppsala, Sweden

173 (3) : 463-480 2007

Temperate and boreal forest ecosystems contain a large part of the carbon stored on land, in the form of both biomass and soil organic matter. Increasing atmospheric [CO2], increasing temperature, elevated nitrogen deposition and intensified management will change this C store. Well documented single-factor responses of net primary production are: higher photosynthetic rate (the main [CO2] response); increasing length of growing season (the main temperature response); and higher leaf-area index (the main N deposition and partly [CO2] response). Soil organic matter will increase with increasing litter input, although priming may decrease the soil C stock initially, but litter quality effects should be minimal (response to [CO2], N deposition, and temperature); will decrease because of increasing temperature; and will increase because of retardation of decomposition with N deposition, although the rate of decomposition of high-quality litter can be increased and that of low-quality litter decreased. Single-factor responses can be misleading because of interactions between factors, in particular those between N and other factors, and indirect effects such as increased N availability from temperature-induced decomposition. In the long term the strength of feedbacks, for example the increasing demand for N from increased growth, will dominate over short-term responses to single factors. However, management has considerable potential for controlling the C store.

Tags: Bioenergetics, Soil Science, Climatology, Forestry

Snow-vegetation relations in a High Arctic ecosystem: Inter-annual variability inferred from new monitoring and modeling concepts

Buus-Hinkler, Jorgen, Hansen, Birger U, Tamstorf, Mikkel P, and Pedersen, Steen B

Buus-Hinkler, Jorgen ; Univ Copenhagen, Dept Geog, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark

105 (3) : 237-247 DEC 15 2006

For High Arctic ecosystems, snow is one of the most important climatic factors-affecting both length of the growing season, and primary plant production. To perform a retrospective analysis of inter-annual variability in snow distribution/amount and vegetative activity in a High Arctic ecosystem, these factors were investigated for the Zackenberg valley at 74.5 degrees N, 21 degrees.0W in Northeast Greenland. The analysis was based on recently introduced techniques that utilize Conventional- and Multispectral Digital Camera Images combined with Landsat TM/ETM+ and SPOT HRV satellite data. Since 1998 (and since 2002 multispectral) digital cameras have been installed on the Zackenberg mountain 500 in above the valley floor taking daily images of the valley automatically. The images taken by the cameras were transformed into digital orthophotos, which were then used to analyze snow cover and Normalized Difference Vegetation Index (NDVI). The snow cover and NDVI data were used to develop models to calculate end-of-winter snow accumulation, snow-cover-depletion, and net vegetative activity in 16 different melting (growing) seasons (1988-2004). At Zackenberg the end-of-winter snow accumulation shows significant inter-annual variability, whereas the end-of-winter snow cover distribution remains similar from year to year. A comparison between snow cover and NDVI distribution reveals that vegetative vigor in the Zackenberg area primarily is linked to the initiation time of the snow-free period rather than temperature. This indicates that in some Arctic regions increases in winter (snow)-precipitation might be as or even more crucial for the ecosystem, than the increased temperatures projected by the majority of General Circulation Models (GCMs). (c) 2006 Elsevier Inc. All rights reserved.

Tags: Biogeography, Models and Simulations, Climatology, Terrestrial Ecology

Germination ecology of eleven species of Geraniaceae and Malvaceae, with special reference to the effects of drying seeds

Van Assche, Jozef A; Vandelook, Filip E A

Van Assche, Jozef A. ; Katholieke Univ Leuven, Lab Plant Ecol, Kasteelpk Arenberg 31, B-3001 Louvain, Belgium

16 (4) : 283-290 DEC 2006

Germination and survival of water-impermeable seeds of 11 species of Geraniaceae and Malvaceae were monitored during dry storage and during burial in soil for up to 2.5 years. During dry storage, seeds of annual Geraniaceae became permeable and also lost their physiological dormancy. However, during burial in natural conditions, most seeds remained impermeable and viable, with no seasonal change in germination capacity. Germination in only one species (Geranium robertianum) was enhanced by daily alternating temperatures when seeds were exhumed in spring. Drying of exhumed seeds broke physical dormancy. Seeds of the perennial Geranium pratense gradually became permeable in a prolonged germination test of 31 weeks. Most seeds of Malva remained impermeable during dry storage. Buried seeds gradually germinated in situ, and exhumed seeds had a low germination capacity in all seasons. We concluded that dormancy of hard seeds in natural conditions may be broken by drying during summer, by specific temperature regimes or by gradual softening of the seed coat, ensuring the spread of germination over many seasons.

Tags: Development, Ecology

Evaluation of woody plant restoration in the Middle Rio Grande: Ten years after

Taylor, John P, Smith, Loren M, and Haukos, David A

Smith, Loren M. ; Texas Tech Univ, Wildlife and Fisheries Management Inst, Lubbock, TX 79409 USA

26 (4) : 1151-1160 DEC 2006

Native riparian cottonwood (Populus deltoides) dominated habitats are declining throughout the southwestern United States and being replaced by the exotic salt cedar (Tamarix ramosissima, T. chinensis) dominated systems. Restoration efforts have often involved removing salt cedar and simulating or restoring overbank flooding timed with seed rain of cottonwood and willow (Salix spp.). Success is then often assessed by examining seedling densities of the native species and their known competitive superiority over salt cedar at this stage. We measured plots in the Middle Rio Grande Valley, New Mexico, USA that had been cleared of salt cedar a decade earlier, compared the initial seedling community to the established community, and determined variables important in predicting establishment of cottonwood. During the decade since establishment, the proportion of cottonwood and seep willow (Baccharis glutinosa) increased, while salt cedar and coyote willow (S. exigua) decreased. Proportion of community foliar volume changed little for salt cedar (17.0 to 17.6%), while it increased for cottonwood (25.5 to 63.3%). Cottonwood dominated (> 70%) the overstory. Initially established woody stem density (all species) was the only predictor of the percent of cottonwood canopy cover a decade later as declining coyote willow allowed for greater cottonwood growth. No abiotic variables were important in predictions of subsequent cottonwood community establishment, probably because these variables were similar among sites in this active floodplain. High initial cottonwood and salt cedar seedling densities were related to lower cottonwood foliar volume and smaller individual tree diameters a decade later. Low initial densities of cottonwood allowed individuals to grow rapidly to a greater height, dominating the canopy. Restoration biologists should therefore consider areas that have low initial cottonwood seedling densities as potentially very successful if their goal is to produce a stand of large cottonwoods in a relatively short time.

Tags: Biogeography, Conservation, Terrestrial Ecology

Control and monitoring: control of Plum pox virus in the United Kingdom

Mumford, R A

Mumford, R. A.; Cent Sci Lab, York YO41 1LZ, N Yorkshire, UK

36 (2) : 315-318 AUG 2006

Plum pox virus (PPV) was first identified in the United Kingdom in 1965. Despite a rigorous eradication policy, the disease spread quickly and established itself in all the main plum-growing areas in England. In 1975, the policy was changed from a blanket eradication campaign to one of containment; retaining statutory control of PPV on propagation material but allowing the industry to control the disease in orchards. As part of the current containment campaign, annual surveys are carried out on propagation material. These surveys show that the incidence of PPV in this material is very low and that only the D-strain is present. The precise situation regarding PPV incidence in commercial orchards is unknown. Given the low incidence in propagation material, it is likely that PPV is uncommon in actively managed orchards. However, some infected orchards probably do still exist, especially older, unmanaged or abandoned ones. Overall, the history of PPV control in the UK is one of unsuccessful eradication but successful containment. The UK experience demonstrates that given the right combination of strain and host, alongside a regular testing regime, it is possible to control PPV through the establishment of a regulated certification scheme and the supply of virus-free planting material.

Tags: Infection, Methods and Techniques, Epidemiology

Estimating relative error in growth ring analyses of second-growth coast redwood (Sequoia sempervirens)

Waring, Kristen M; O'Hara, Kevin L

Waring, Kristen M. ; No Arizona Univ, Sch Forestry, POB 15018, Flagstaff, AZ 86011 USA

36 (9) : 2216-2222 SEP 2006

Coast redwood (Sequoia sempervirens (D. Don) Endl.) grows in the coastal zone of north-central California and southern Oregon in pure and mixed-species forests. Redwood has long been recognized to exhibit unusual patterns within the annual growth rings typical of temperate forest trees, including partial and missing rings and ring-width anomalies. However, these patterns have not been quantified beyond a few suppressed trees. This study quantified the variation in ring counts occurring in 22 second-growth redwood trees from different canopy classes. Ring counts from cross sections taken at sample points along each tree bole revealed missing or incomplete rings in all sample trees and 70% of the cross sections. Ring counts along multiple radii were used to calculate probability of obtaining a maximum ring count along one radius. This probability was lowest at the tree base (0.25) and breast height (0.30) and highest near the top of the tree (0.90). Because of the high amount of variation present in ring counts at breast height, care should be taken when drawing conclusions regarding stand ages from increment cores. Increment cores should be taken from the longest axis of the tree and coring at tree base can be abandoned as cores are not likely to have higher ring counts than breast height cores.

Tags: Methods and Techniques, Development, Forestry

Is long primary growth associated with stem sinuosity in Douglas-fir?

Gartner, Barbara L; Johnson, G R

Gartner, Barbara L. ; Oregon State Univ, Dept Wood Sci and Engn, Corvallis, OR 97331 USA

36 (9) : 2351-2356 SEP 2006

Stem sinuosity is a highly visible stem-form trait in the leaders of fast-growing Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) trees, yet its cause is unknown. We tested the hypotheses that sinuous stems have longer expanses of primary growth than nonsinuous stems (putting the leader at higher risk for curvature, induction of compression wood formation, and possibly overcorrection) and higher leader angle using 4- to 5-year-old saplings in raised beds. As hypothesized, sinuous stems had longer expanses of primary growth than did nonsinuous stems (13.5 vs. 12.3 cm, respectively). However, for the dates for which growth (length/day, primary growth, secondary growth, and total growth) differed significantly among sinuosity class, sinuosity class only explained 15%-21% of the variation in growth rate. There were no significant differences in leader angle for saplings of the three sinuosity classes. Contingency tables indicated some consistency in the category of sinuosity to which we assigned the stems in 2001 and 2002 (chi(2) = 11.2, p < 0.004). When we used a more quantitative measure, the ratio of stem length/stem distance, there was a tendency toward a significant relationship between the two years (r = 0.272, p = 0.0893). These data suggest that, counter to expectation, the rate of stem growth was not a large factor in determining whether leaders become sinuous for this population of trees.

Tags: Development, Forestry

Species richness and stand stability in conifer forests of the Sierra Nevada

DeClerck, Fabrice A J, Barbour, Michael G, and Sawyer, John O

DeClerck, Fabrice A. J. ; Dept Agr and Agroforestry, CATIE 7170, Turrialba, Costa Rica

87 (11) : 2787-2799 NOV 2006

Theoretical and empirical studies have long suggested that stability and complexity are intimately related, but evidence from long-lived systems at large scales is lacking. Stability can either be driven by complex species interactions, or it can be driven by the presence/absence and abundance of a species best able to perform a specific ecosystem function. We use 64 years of stand productivity measures in forest systems composed of four dominant conifer tree species to contrast the effect of species richness and abundance on three stability measures. To perform this contrast, we measured the annual growth increments of > 900 trees in mixed and pure forest stands to test three hypotheses: increased species richness will (1) decrease stand variance, (2) increase stand resistance to drought events, and (3) increase stand resilience to drought events. In each case, the alternate hypothesis was that species richness had no effect, but that species composition and abundance within a stand drove variance, resistance, and resilience. In pure stands, the four species demonstrated significant differences in productivity, and in their resistance and resilience to drought events. The two pine species were the most drought resistant and resilient, whereas mountain hemlock was the least resistant and resilient, and red fir was intermediate. For community measures we found a moderately significant (P = 0.08) increase in the community coefficient of variation and a significant (P = 0.03) increase in resilience with increased species richness, but no significant relationship between species richness and community resistance, though the variance in community resistance to drought decreased with species richness. Community resistance to drought was significantly (P = 0.001) correlated to the relative abundance of lodgepole pine, the most resistant species. We propose that resistance is driven by competition for a single limiting resource, with negative diversity effects. In contrast resilience measures the capacity of communities to partition resources in the absence of a single limiting resource, demonstrating positive diversity effects.

Tags: Terrestrial Ecology, Biodiversity

Genetic variation in wood stiffness and strength properties of hybrid larch (Larix gmelinii var. japonica x L kaempferi)

Fujimoto, Takaaki, Akutsu, Hisashi, Nei, Miki, Kita, Kazuhito, Kuromaru, Makoto, and Oda, Kazuyuki

Fujimoto, Takaaki ; Hokkaido Forest Prod Res Inst, 1-10 Nishikagura, Asahikawa, Hokkaido 0710198, Japan

11 (5) : 343-349 OCT 2006

Genetic parameters for wood stiffness and strength properties were estimated in a 29-year-old hybrid larch stand (Larix gmelinii var. japonica x Larix kaempferi). The study included 19 full-sib larch families from Hokkaido, northern Japan. Implications of these genetic parameters in wood quality improvement are subsequently discussed. Traits included in the analyses were the dynamic modulus of elasticity of green logs (E-log), the modulus of elasticity (MOE), the modulus of rupture (MOR), compression strength parallel to the grain (CS) in small clear specimens, wood density (DEN), and diameter at breast height (DBH). DEN had the lowest coefficients of variation and MOE the highest. The narrow-sense heritability estimates of E-log, MOE, MOR, and CS were 0.61, 0.44, 0.60, and 0.43, respectively, and those of DEN and all mechanical properties increased from an inner to outer position within the stem. E-log and DEN had high positive phenotypic (0.52-0.83) and genetic (0.70-0.92) correlations with MOE, MOR, and CS. The mechanical properties of the inner position of the stem had rather high phenotypic and genetic correlations with those of the outer position and overall mean. The predicted gains in wood stiffness (Elog and MOE) were higher than those of the strength properties (MOR and CS). The predicted correlated responses in MOE, MOR, and CS when selecting for E-log and DEN were 72.6%-97.8% of a gain achievable from direct selection of these traits. DBH showed an insignificant correlation with all mechanical properties, although selection of this trait had a slightly negative effect on the mechanical properties.

Tags: Biogeography, Population Genetics, Genetics, Forestry

Blackberry, black raspberry, blueberry, cranberry, red raspberry, and strawberry extracts inhibit growth and stimulate apoptosis of human cancer cells in vitro

Seeram, Navindra P, Adams, Lynn S, Zhang, Yanjun, Lee, Rupo, Sand, Daniel, Scheuller, Henry S, and Heber, David

Seeram, Navindra P. ; David Geffen Sch Med, Ctr Human Nutr, 900 Veteran Ave, Los Angeles, CA USA

54 (25) : 9329-9339 DEC 13 2006

Berry fruits are widely consumed in our diet and have attracted much attention due to their potential human health benefits. Berries contain a diverse range of phytochemicals with biological properties such as antioxidant, anticancer, anti-neurodegerative, and anti-inflammatory activities. In the current study, extracts of six popularly consumed berries-blackberry, black raspberry, blueberry, cranberry, red raspberry and strawberry-were evaluated for their phenolic constituents using high performance liquid chromatography with ultraviolet (HPLC-UV) and electrospray ionization mass spectrometry (LC-ESI-MS) detection. The major classes of berry phenolics were anthocyanins, flavonols, flavanols, ellagitannins, gallotannins, proanthocyanidins, and phenolic acids. The berry extracts were evaluated for their ability to inhibit the growth of human oral (KB, CAL-27), breast (MCF-7), colon (HT-29, HCT116), and prostate (LNCaP) tumor cell lines at concentrations ranging from 25 to 200 Ag/mL. With increasing concentration of berry extract, increasing inhibition of cell proliferation in all of the cell lines were observed, with different degrees of potency between cell lines. The berry extracts were also evaluated for their ability to stimulate apoptosis of the COX-2 expressing colon cancer cell line, HT-29. Black raspberry and strawberry extracts showed the most significant pro-apoptotic effects against this cell line. The data provided by the current study and from other laboratories warrants further investigation into the chemopreventive and chemotherapeutic effects of berries using in vivo models.

Tags: Biochemistry and Molecular Biophysics, Tumor Biology, Pharmacognosy

Chitin-supplemented foliar application of chitinolytic Bacillus cereus reduces severity of Botrytis gray mold disease in chickpea under controlled conditions

Kishore, G K; Pande, S

Kishore, G. K. ; Agr and Agri Food Canada, Saskatoon Res Ctr, Plant Gene Resources Canada, 108 Sci Pl, Saskatoon, SK S7N 0X2, Canada

44 (1) : 98-105 JAN 2007

Aim: To identify and evaluate chitinolytic bacteria for control of Botrytis gray mold (BGM), a devastating disease in chickpea.Methods and Results: Two antifungal bacterial isolates, chitinolytic Bacillus cereus CRS 7 and nonchitinolytic Pseudomonas fluorescens CRS 31, from the rhizosphere of chickpea, were applied as a prophylactic foliar spray and evaluated for control of BGM. In a controlled environment, the two isolates reduced the severity of BGM on the susceptible cv. JG 62 to 6.0 and 5.6, respectively, compared with 9.0 in the control, measured on a 1-9 rating scale. Supplementation of the foliar application of CRS 7 with 0.5% and 1.0% colloidal chitin reduced BGM severity to 4.4 and 4.1 respectively, while chitin-supplemented application of CRS 31 was similar to CRS 31 applied alone. Partially purified 47-kDa chitinase from the cell-free culture filtrate of CRS 7 at 20 and 40 mu g protein ml(-1) (enzyme activity 3.1 units ml(-1)) inhibited the germination and lysed the conidia of Botrytis cinerea, and as a prophylactic foliar spray reduced BGM severity to 5.4 and 4.8, respectively.Conclusion: Chitin supplementation improved the biocontrol of the foliar disease BGM by chitinolytic bacterium. Disease control with partially purified chitinase of CRS 7 supported the major role of chitinolysis in improved control of BGM.Significance and Impact of the study: Enhanced control of BGM by chitin-supplemented application of CRS 7 is of significant in view of the frequent inconsistency in biocontrol of foliar diseases. This study supports further attempts on chitinolysis-based biocontrol methods for foliar disease biocontrol.

Tags: Infection, Pesticides, Horticulture

Acclimation of Arabidopsis thaliana to long-term CO2 enrichment and nitrogen supply is basically a matter of growth rate adjustment

Tocquin, Pierre, Ormenese, Sandra, Pieltain, Alexandra, Detry, Nathalie, Bernier, Georges, and Perilleux, Claire

Tocquin, Pierre ; Univ Liege, Dept Life Sci, Lab Plant Physiol, Sart Tilman B22, B-4000 Liege, Belgium

128 (4) : 677-688 DEC 2006

The long-term response of Arabidopsis thaliana to increasing CO2 was evaluated in plants grown in 800 mu l 1(-1) CO2 from sowing and maintained, in hydroponics, on three nitrogen supplies: "low," "medium" and "high." The global response to high CO2 and N-supply was evaluated by measuring growth parameters in parallel with photosynthetic activity, leaf carbohydrates, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) messenger RNA and protein, stomatal conductance (g(s)) and density. CO2 enrichment was found to stimulate biomass production, whatever the N-supply. This stimulation was transient on low N-supply and persisted throughout the whole vegetative growth only in high N-supply. Acclimation on low N-high CO2 was not associated with carbohydrate accumulation or with a strong reduction in Rubisco amount or activity. At high N-supply, growth stimulation by high CO2 was mainly because of the acceleration of leaf production and expansion while other parameters such as specific leaf area, root/shoot ratio and g, appeared to be correlated with total leaf area. Our results thus suggest that, in strictly controlled and stable growing conditions, acclimation of A. thaliana to longterm CO2 enrichment is mostly controlled by growth rate adjustment.

Tags: Molecular Genetics, Development, Bioenergetics, Chemical Coordination and Homeostasis

Unfertilized ovary: a novel explant for coconut (Cocos nucifera L.) somatic embryogenesis

Perera, Prasanthi I P, Hocher, Valerie, Verdeil, Jean Luc, Doulbeau, Sylvie, Yakandawala, Deepthi M D, and Weerakoon, L Kaushalya

Perera, Prasanthi I. P. ; Coconut Res Inst, Tissue Culture Div, Lunuwila 61150, Sri Lanka

26 (1) : 21-28 JAN 2007

Unfertilized ovaries isolated from immature female flowers of coconut (Cocos nucifera L.) were tested as a source of explants for callogenesis and somatic embryogenesis. The correct developmental stage of ovary explants and suitable in vitro culture conditions for consistent callus production were identified. The concentration of 2,4-dichlorophenoxyacetic acid (2,4-D) and activated charcoal was found to be critical for callogenesis. When cultured in a medium containing 100 mu M 2,4-D and 0.1% activated charcoal, ovary explants gave rise to 41% callusing. Embryogenic calli were sub-cultured into somatic embryogenesis induction medium containing 5 mu M abscisic acid, followed by plant regeneration medium (with 5 mu M 6-benzylaminopurine). Many of the somatic embryos formed were complete with shoot and root poles and upon germination they gave rise to normal shoots. However, some abnormal developments were also observed. Flow cytometric analysis revealed that all the calli tested were diploid. Through histological studies, it was possible to study the sequence of the events that take place during somatic embryogenesis including orientation, polarization and elongation of the embryos.

Tags: Biochemistry and Molecular Biophysics, Development, Reproductive System

Secondary dispersal of bigcone Douglas-fir (Pseudotsuga macrocarpa) seeds

Vander Wall, Stephen B, Borchert, Mark I, and Gworek, Jennifer R

Vander Wall, Stephen B. ; Univ Nevada, Dept Biol, Reno, NV 89557 USA

30 (1) : 100-106 JUL-AUG 2006

Large-seeded pines (Pinus spp.) are known to be dispersed by seed-caching corvids (i.e. jays and nutcrackers) and rodents (e.g. chipmunks and mice), with a concomitant decrease in seed dispersability by wind. We tested the idea that seeds of bigcone Douglas-fir (Pseudotsuga macrocarpa), which are winged but larger than the seeds of other members of Pseudotsuga, are dispersed by a combination of wind and seed-caching rodents. We compared characteristics of seeds from P. macrocarpa in southern California (mean seed mass 132.6 mg) to seeds of a population of Pseudotsuga menziesii (Douglas-fir) in northern California (24.8 mg). We also tested whether rodents would cache seeds of P. macrocarpa. Seeds of P. macrocarpa had greater wing loadings (1.37 mg/mm(2)) and descent velocities (2.47 m/s) than those of P. menziesii (0.52 mg/mm(2) and 1.28 m/s, respectively). These data indicate that the wind dispersability of P. macrocarpa is likely to be less than that of P. menziesii, but this loss of wind dispersability is partially compensated for by secondary dispersal of seeds by rodents, which readily gathered and cached the larger seeds of P macrocarpa up to 34 in from source trees. Large seed size confers several advantages to P. macrocarpa, most importantly attracting seed-caching animals that effectively bury seeds. (c) 2006 Elsevier SAS. All rights reserved.

Tags: Terrestrial Ecology

An integrated plan towards management of Chestnut blight on a national scale

Diamandis, S; Perlerou, C

Diamandis, S. ; NAGREF, Forest Res Inst, Thessaloniki 57006, Greece

20 (1) : 50-54 2006

Chestnut blight caused by Cryphonectria parasifica (Murr.) can be controlled by transmissible hypovirulence. Relatively recent research has shown that cytoplasmic double stranded RNA (dsRNA) viruses, when present in the fungus, can convert it from virulent to hypovirulent. Transmission of viruses by mycelial anastomosis from hypovirulent to virulent strains is feasible only if the two strains fall in the same type of vegetative compatibility (vc type). Such transmissible hypovirulence has been used in practice to control chestnut blight satisfactorily in several countries. Chestnut blight is a rapid spreading disease. Only simultaneous intervention over a large area, or even better on a national scale, can be effective. An integrated work plan towards blight management of chestnut blight should include: i) application of biological control by using transmissible hypovirulence and ii) silvicultural/horticultural measures towards reducing the disease potential. For the application of biological control, it is essential to conduct a survey and identify the vc types of Cryphonectria parasitica occurring in the country concerned and compose studies for each major chestnut area stating the vc types, their distribution, severity of infection, etc. After having evaluated the severity of infection, coppice stands or orchards should be assigned to three disease categories: Least concerned (LC) with disease severity 0-10%; Unstable (U) with disease severity 11-40%; Critical (C) with disease severity over 50%. Silvicultural/horticultural measures should be applied according to disease category and should include clear felling of stands or orchards in critical condition and salvage thinning or pruning in unstable stands or orchards, respectively. Hypovirulence may appear naturally in old-infection chestnut areas. Before introducing hypovirulence, the decision maker should consider the rate of loss, the history of the disease in the particular country and the availability of the necessary funds.

Tags: Infection, Horticulture

Seed germination characteristics of Phragmites communis: Effects of temperature and salinity

Gorai, Mustapha, Vadel, Ahmedou M, and Neffati, Mohamed

Gorai, Mustapha ; Inst Reg Arides, Lab Ecol Pastrol, Medenine 4119, Tunisia

139 (1) : 78-86 2006

Phragmites communis Trin. has a wide ecological and geographical amplitude in Tunisia and grows under a variety of environmental conditions. A laboratory experiment was performed to evaluate the effect of temperature and salinity on the germination of P communis. The germination response of the seeds in darkness were determined over a wide range of temperatures (between 5 degrees C and 40 degrees C) and salinity (between 0 mM and 500 mM NaCl). We analysed the responses of seeds to salinity at the optimum germination temperature. Temperatures between 10 degrees C and 30 degrees C appeared favourable for the germination of this species. The optimum temperature was 20 degrees C. To assess the effect of temperature on germination rates, the reciprocal of time to 50% germination was calculated and regressed against temperature. Based on the regression, the minimum temperature beyond which no germination is expected was 6.7 degrees C. Salt stress decreased both the germination percentage and germination speed (increase of the mean time-to-germination, MTG). The ability of R communis to maintain a germination capacity in hypersaline conditions (400 mM) showed that this species can germinate on salt-soils.

Tags: Systematics and Taxonomy

Microsite differentiation among conifer species during seedling establishment at alpine treeline

Maher, Eliza L; Germino, Matthew J

Germino, Matthew J.; Idaho State Univ, Dept Biol Sci, POB 8007, Pocatello, ID 83209 USA

13 (3) : 334-341 2006

Tree establishment is a potentially important factor affecting tree populations in alpine-treeline ecotones. Patterns of seedling establishment of Abies lasiocarpa, Punts albicaulis, and Picea engelmannii were evaluated relative to neighbouring trees and herbs over two years and three treelines of the Rocky Mountains, USA. The greatest mortality rates were observed in seedlings that had just emerged from seed and were in their first year of growth and in seedlings that had the least amount of cover provided by trees or other landscape features, that block exposure to the sky. Although herb cover promoted survivorship in microsites that were not near trees, no seedlings were detected at or above the upper limit of the treeline ecotone. Microsite tree cover was greatest for A. lasiocarpa and least for P albicaulis seedlings, which matches predictions based on their relative photosynthetic tolerances to the bright sunlight and frequent frost that occur in exposed microsites. Interspecific differences in seedling requirements for neighbouring plant cover likely contribute to the apparent coexistence and possible interdependency of these conifers along a continuum of colonization and succession within treelines.

Tags: Ecology

In vitro binding of bile acids by blueberries (Vaccinium spp.), plums (Prunus spp.), prunes (Prunus spp.), strawberries (Fragaria X ananassa), cherries (Malpighia punicifolia), cranberries (Vaccinium macrocarpon) and apples (Malus sylvestris)

Kahlon, T S; Smith, G E

Kahlon, T. S. ; USDA, ARS, Western Reg Res Ctr, 800 Buchanan St, Albany, CA 94710 USA

100 (3) : 1182-1187 2007

The in vitro binding of bile acids by blueberries (Vaccinium spp.), plums (Prunus spp.), prunes (Primus spp.), strawberries (Fragaria X ananassa), cherries (Malpighia punicifolia) cranberries (Vaccinium macrocarpon) and apples (Malus sylvestris) was determined using a mixture of bile acids secreted in human bile at a duodenal physiological pH of 6.3. Six treatments and two blank incubations were conducted to testing various fresh raw fruits on an equal dry matter basis. Considering cholestyramine (bile acid binding, cholesterol lowering drug) as 100% bound, the relative in vitro bile acid binding on dry matter (DM), total dietary fiber (TDF) and total polysaccharides (PCH) basis was for blueberries 7%, 47% and 25%; plums 6%, 53% and 50%; prunes 5%, 50% and 14%; strawberries 5%, 23% and 15%; cherries 5%, 37% and 5%; cranberries 4%, 12% and 7%; and apple 1%, 7% and 5%, respectively. Bile acid binding on DM basis for blueberries was significantly (P <= 0.05) higher than all the fruits tested. The bile acid binding for plums was similar to that for prunes and strawberries and significantly higher than cherries, cranberries and apples. Binding values for cherries and cranberries were significantly higher than those for apples. These results point to the relative health promoting potential of blueberries > plums = prunes = strawberries = cherries = cranberries > apples as indicated by their bile acid binding on DM basis. The variability in bile acid binding between the fruits tested maybe related to their phytonutrients (antioxidants, polyphenols, hydroxycinnamic acids, flavonoids, anthocyanins, flavonols, proanthocyanidins, catechins), structure, hydrophobicity of undigested fractions, anionic or cationic nature of the metabolites produced during digestion or their interaction with active binding sites. Inclusion of blueberries, plums, prunes, strawberries, cherries and cranberries in our daily diet as health promoting fruits should be encouraged. Animal studies are planned to validate in vitro bile acid binding of fruits observed herein to their potential of atherosclerosis amelioration (lipid and lipoprotein lowering) and cancer prevention (excretion of toxic metabolites). Published by Elsevier Ltd.

Tags: Biochemistry and Molecular Biophysics

Using compost from urban solid waste to prevent erosion in road embankments

Osorio, Francisco; de Ona, Juan

Osorio, Francisco ; Univ Granada, Dept Civil Engn, Campus Fuentenueva S-N, E-18071 Granada, Spain

41 (10) : 2311-2327 OCT 2006

This paper describes how compost, a by-product generated by solid waste treatment plants, can be usefully applied to road embankments to prevent erosion. Our study analyzed this process in terms of the following variables: (1) location and orientation; (2) embankment slope; (3) soil and compost characteristics; (4) compost dosage; (5) vegetation species; (6) plot dimensions; and (7) planting method. The results obtained focus on the vegetation survival rate, plant growth and germination; colonization of other species; cover crop for plots; and erosion estimation. It was found that when greater quantities of compost were added to embankments, soil loss was decreased. The addition of this material also produced a marked increase in plant growth, the survival rate of manually planted vegetation, the colonization of other species, as well as the cover crop. However, we observed that compost seemed to hinder the germination of hydroseeded species, whereas colonizing plants germinated more quickly. The side slope was not found to be a significant factor for manually planted species, but turned out to be crucial for hydroseeded varieties.

Tags: Methods and Techniques, Terrestrial Ecology, Bioprocess Engineering

Farmers' use of wild relative and sexual reproduction in a vegetatively propagated crop. The case of yam in Benin

Scarcelli, N, Tostain, S, Vigouroux, Y, Agbangla, C, Dainou, O, and Pham, J -L

Scarcelli, N. ; IRD, UMR 1097, Equipe DYNADIV, BP 64501, F-34394 Montpellier 5, France

15 (9) : 2421-2431 AUG 2006

The impact of traditional farmers' management on genetic diversity of vegetatively propagated crops is poorly documented. In this study, we analysed the impact of ennoblement of spontaneous yams, an original traditional farmers' practice, on the genetic diversity of yam (Dioscorea sp.) in Benin. We used 11 microsatellite markers on yam tubers from a small village in northern Benin and demonstrated that wild x cultivated hybrids are spontaneously formed. Many of the spontaneous yams collected by farmers from surrounding savannah areas for ennoblement were shown to be of wild and hybrid genotypes. Moreover, we demonstrated that some yam varieties have a wild or hybrid signature. Lastly, we performed a broader ranging genetic analysis on yam material from throughout Benin and showed that this practice is used in different ecological and ethno-linguistic regions. Through this practice, farmers create new varieties with new genetic combinations via sexual reproduction of wild and cultivated yams. This system, whereby a sexual cycle and asexual propagation are mixed, ensures potential large-scale cultivation of the best genotypes while preserving the potential for future adaptation.

Tags: Horticulture

High-throughput monolithic HPLC method for rapid vitamin C phenotyping of berry fruit

Walker, Paul G, Gordon, Sandra L, Brennan, Rex M, and Hancock, Robert D

Hancock, Robert D.; Scottish Crop Res Inst, Unit Plant Biochem, Dundee DD2 5DA, UK

17 (5) : 284-290 SEP 2006

A rapid method for the quantification Of L-ascorbic acid (1) in berry fruit by HPLC with photodiode array detection is presented. L-Ascorbic acid was resolved on a C,, monolithic column with aqueous buffer, after which the column was washed with acetonitrile to remove lipophilic compounds prior to re-equilibration for analysis of the next sample. Using the monolithic column format with high mobile phase flow rates, the entire separation, wash and re-equilibration were achieved in 3 min. With the exception of gooseberry (Ribes uva-crispa), for which an interfering compound co-eluted, concentrations of 1 could be determined in a wide range of berry fruits after extraction in metaphosphoric acid without further sample preparation. Using this extraction method, recoveries of I in excess of 85% were achieved. Fruit or juice extracts were stable in 5% metaphosphoric acid for at least 4 h and stability could be extended to longer than 150 h by the addition of the reducing agent tris(2-carboxethyl)phosphine hydrochloride. Following validation, the method was utilised for the phenotyping of fruit in a Scottish Crop Research Institute (SCRI) Ribes nigrum L. breeding population of 300 individuals. An improved extraction method allowed extraction, quantification of I and data analysis to be undertaken in less than one working week. Copyright (c) 2006 John Wiley & Sons, Ltd.

Tags: Methods and Techniques, Biochemistry and Molecular Biophysics

Forest-tundra larch forests and climatic trends

Kharuk, V I, Ranson, K J, Im, S T, and Naurzbaev, M M

Kharuk, V. I. ; Russian Acad Sci, Siberian Div, Sukachev Inst Forest, Krasnoyarsk 660036, Russia

37 (5) : 291-298 SEP-OCT 2006

Climate-related changes that occurred in the Ary-Mas larch forests (the world's northernmost forest range) in the last three decades of the 20th century have been analyzed. An analysis of remote-sensing images made by Landsat satellites in 1973 and 2000 has provided evidence for an increase in the closeness of larch forest canopy (by 65%) and the expansion of larch to the tundra (for 3-10 in per year) and to areas relatively poorly protected from wind due to topographic features (elevation, azimuth, and slope). It has also been shown that the radial tree increment correlates with summer temperatures (r = 0.65, tau = 0.39) and the amounts of precipitation in summer (r = -0.51, tau = 0-41) and winter (r = -0.70, tau = -0.48), decreases with an increase in the closeness of forest canopy (r = -0.52, p > 0.8; tau = -0.48, p > 0.95), and increases with an increase in the depth of soil thawing (r = 0.63, p > 0.9; tau = 0.46, p > 0.9). The density of undergrowth depends on temperatures in winter(tau = 0.53, p > 0.8) and summer (r = 0.98, p > 0.99, tau = 0.9, p > 0.99) and the date of the onset of the growing period (r = -0.60, p > 0.99; T = -0.4, p > 0.99) and negatively correlates with the amount of precipitation in summer (r = -0.56, p > 0.99, T = -0.38, p > 0.99).

Tags: Climatology, Forestry

Age determination of miombo species Brachystegia spiciformis (Leguminosae-Caesalpinoideae) in Zimbabwe using growth rings

Grundy, I M

Grundy, I. M.; Rutherglen Ctr, Dept Primary Ind, RMB 1145,Chiltern Valley Rd, Rutherglen, Vic 3685, Australia

(206) : 5-12 MAR 2006

The objective of this study was to determine whether Brachystegia spiciformis Benth. (Leguminosae Caesalpinoideae), one of the dominants of dry miombo woodland in Zimbabwe, forms annual growth rings. In the past the production of effective cutting rotations and sound management plans for native miombo woodland in southern Africa has been hindered by the difficulty in determining the ages of the trees, and therefore their growth rates, because it was assumed that tropical trees did not form annual rings. This research indicates that B. spiciformis does form annual rings, made up of xylem cells terminated (or marked) by a narrow band of marginal axial parenchyma cells, even in dry years. The rings may sometimes be associated with a darkening of the xylem due to the production of flatter and thicker fibres, but the darker bands are not always produced at the end of the growing season as they would be in temperate species and may also be present at the beginning of the new season. Only in particularly wet or dry years do the changes in the width of the annual rings correspond closely with fluctuations in mean annual rainfall. These results provide a means to estimate the age and annual increment of this species, which will enable woodland managers to predict future yields more accurately and monitor of the effects of management on tree growth.

Tags: Biogeography, Development, Forestry

Manipulating the postharvest period and its impact on vine productivity of Semillon grapevines

Holzapfel, Bruno P, Smith, Jason P, Mandel, Roger M, and Keller, Markus

Holzapfel, Bruno P. ; Charles Sturt Univ, Natl Wine and Grape Ind Ctr, Locked Bag 588, Wagga Wagga, NSW 2678, Australia

57 (2) : 148-157 2006

Trials were established in four Semillon hot-climate vineyards to determine the importance of the postharvest period for vines grown under different cropping levels and management practices. Two sites were chosen in high-yielding, furrow-irrigated vineyards in the Riverina region, and two in lower-yielding, drip-irrigated vineyards in the neighboring Hilltops region of New South Wales, Australia. Treatments were imposed over two consecutive seasons to alter either the length or the effectiveness of the postharvest period at each site. Complete defoliation at harvest to eliminate carbon assimilation during the postharvest period decreased yields by up to 21% relative to the control vines after one season and by 50% after two seasons of treatment. Extending the length of the postharvest period by early crop removal over two consecutive seasons increased yields by 48% when fruit was retained to commercial maturity in the third year. Vegetative growth responded similarly, and vine balance was not altered by any treatment. Berry sugar concentration at harvest was highest for previously defoliated vines and lowest for vines with an extended postharvest period. Treatments were less effective at the Hilltops vineyards, where lower yields and water availability may have reduced the importance of the postharvest period. Leaf damage or leaf spray applied after harvest did not impact vine productivity. Results suggest that adequate postharvest recovery is crucial for maintaining the productivity of high-yielding grapevines and that vineyards could be managed after harvest to manipulate vegetative growth and yield in the following season.

Tags: Foods, Economics

Viticultural performance of five Merlot clones in Oakville, Napa Valley

Benz, M Jason, Anderson, Michael M, Williams, Molly A, Barnhisel, Kristen, and Wolpert, James A

Wolpert, James A.; Univ Calif Davis, Dept Viticulture and Enol, Davis, CA 95616 USA

57 (2) : 233-237 2006

Five certified clones of Merlot from Foundation Plant Services (FPS), University of California, Davis, were evaluated for viticultural performance in Oakville, Napa Valley. Vine yield components (cluster number, cluster weight, clusters per shoot, berries per cluster, and berry weight), fruit composition (Brix, pH, titratable acidity), potassium (K) concentration, and vegetative growth parameters (pruning weight and shoot weight) were measured over five growing seasons, 1997 to 2001. Yield, berries per cluster, berry weight, and cluster weight varied significantly among clones, and all yield components varied significantly from season to season. FPS 8 yielded 35% less than clones FPS 1, 3, and 6. FPS 9 showed the most erratic yield pattern over seasons. The number of berries per cluster was primarily responsible for yield differences. Fruit composition parameters pH and K concentration varied significantly among clones, with FPS 8 having both the highest pH and K concentration. Brix concentration at harvest did not significantly differ among clones despite yield differences. Vegetative growth differed significantly among clone, with FPS 8 having the greatest pruning weight and FPS I the least. Yield to pruning weight ratios were lowest for FPS 8 and highest for FPS 1.

Tags: Botany

Interference to hardwood regeneration in northeastern North America: Ecological characteristics of American beech, striped maple, and hobblebush

Nyland, Ralph D, Bashant, Amy L, Bohn, Kimberly K, and Verostek, Jane M

Nyland, Ralph D. ; SUNY Coll Environm Sci and Forestry, Syracuse, NY 13210 USA

23 (1) : 53-61 MAR 2006

Several woody species may inhibit regeneration of desirable northern hardwoods. This includes a dense understory of American beech (Fagus grandifolia Ehrh.) that commonly occurs in stands infected with beech bark disease. Root injuries during logging and by natural causes also promote new stickers that, along with some stump sprouts, often maintain or increase the abundance of beech saplings. Additionally, browsing deer primarily bypass beech in favor of more palatable species. Where any of these factors has resulted in a dense understory of small beech, overstory; cutting will promote its development, increase ground-level shading, and lead to a site conversion to beech. Similarly, striped maple (Acer pensylvanicum L.) often interferes with hardwood regeneration after overstory cutting. This species persists in heavy shade, grows rapidly after release, and produces abundant seed. When dense, striped maple may interfere Milt the regeneration of other species. Hobblebush (Viburnum alnifolium Marsh.), a shrub, reproduces by rhizomes to form thickets when damaged during overstory cutting. Heavy shade by these thickets may prevent regeneration of trees. This review