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