https://www.wsl.ch/staff/niklaus.zimmermann/papers/ecomod135_147.pdf

Predictive habitat distribution models in ecology

Statistics for Spatial Data.

Publisher Summary This chapter reviews the rates at which Coarse Woody Debris (CWD) is added and removed from ecosystems, the biomass found in streams and forests, and many functions that CWD serves. CWD is an important component of temperate stream and forest ecosystems and is added to the ecosystem by numerous mechanisms, including wind, fire, insect attack, pathogens, competition, and geomorphic processes. Many factors control the rate at which CWD decomposes, including temperature, moisture, the internal gas composition of CWD, substrate quality, the size of the CWD, and the types of organisms involved. The mass of CWD in an ecosystem ideally represents the balance between addition and loss. In reality, slow decomposition rates and erratic variations in input of CWD cause the CWD mass to deviate markedly from steady-state projections. Many differences correspond to forest type, with deciduous-dominated systems having generally lower biomass than conifer-dominated systems. Stream size also influences CWD mass in lotic ecosystems, while successional stage dramatically influences CWD mass in boat aquatic and terrestrial settings. This chapter reviews many of these functions and concludes that CWD is an important functional component of stream and forest ecosystems. Better scientific understanding of these functions and the natural factors influencing CWD dynamics should lead to more enlightened management practices.

Ecology of Coarse Woody Debris in Temperate Ecosystems

I. CONTEXT * The Ecosystem Concept * Earth's Climate System * Geology and Soils * II. MECHANISMS * Terrestrial Water and Energy Balance * Carbon Input to Terrestrial Ecosystems * Terrestrial Production Processes * Terrestrial Decomposition * Terrestrial Plant Nutrient Use * Terrestrial Nutrient Cycling * Aquatic Carbon and Nutrient Cycling * Trophic Dynamics * Community Effects on Ecosystem Processes * III. PATTERNS * Temporal Dynamics * Landscape Heterogeneity and Ecosystem Dynamics * IV. INTEGRATION * Global Biogeochemical Cycles * Managing and Sustaining Ecosystem * Abbreviations * Glossary * References

Principles of Terrestrial Ecosystem Ecology

▪ Abstract The use of stable isotope techniques in plant ecological research has grown steadily during the past two decades. This trend will continue as investigators realize that stable isotopes can serve as valuable nonradioactive tracers and nondestructive integrators of how plants today and in the past have interacted with and responded to their abiotic and biotic environments. At the center of nearly all plant ecological research which has made use of stable isotope methods are the notions of interactions and the resources that mediate or influence them. Our review, therefore, highlights recent advances in plant ecology that have embraced these notions, particularly at different spatial and temporal scales. Specifically, we review how isotope measurements associated with the critical plant resources carbon, water, and nitrogen have helped deepen our understanding of plant-resource acquisition, plant interactions with other organisms, and the role of plants in ecosystem studies. Where possible we also...

Stable Isotopes in Plant Ecology

Modeling individual tree mortality for Austrian forest species

Knievel (1973) developed a method for evaluating the ratio of live root material to dead based on the relationship between that ratio and triphenyltetrazolium chloride (TTC) reduction per gram of root tissue. The method allows the processing of quantities of roots in bulk but has only been tested on white, nonwoody roots. A procedure very similar to Knievel's was tested on woody roots obtained from a mature white oak (Quercus alba L.) stand. Extractants from live and from dead roots both produced stains whose spectrophotometric absorbance at 480 The authors are, respectively, Environmental Scientist, Tennessee Valley Authority, Division of Air and Water Resources, TVA/ORNL Watershed Study Program, Building 1505, ORNL, Oak Ridge, TN 37830, and Professor, School of Forestry, Fisheries, and Wildlife, 1-31 Agriculture Building, University of Missouri, Columbia, Mo. 65211. Contribution from the Missouri Agricultural Experiment Station--Journal Series Number 9567. Manuscript received 19 July 1983. VOLUME 30, NUMBER 4, 1984 / 965

Height Growth and Site Index Curves for Inland Douglas-fir Based on Stem Analysis Data and Forest Habitat Type

Simulation of forest tree mortality

The CO2 concentration of the atmosphere has increased by almost 30% in the past two centuries, with most of the increase (>5 Pa) during the past 60 years. Controlled environment studies of crop plants dependent on the C3 photosynthetic pathway indicate that an increase of this magnitude would enhance net photosynthesis, reduce stomatal conductance, and increase the difference in CO2 concentration across the stomata, i.e., CO2 concentration outside the leaf to that within (c
a-c
i). Here we report evidence, based on stable isotope composition of tree rings from three species of field-grown, native conifer trees, that the trees have indeed responded. However, rather than increasing c
a-c
i, intercellular CO2 concentrations have shifted upward to match the rise in atmospheric concentrations, holding c
a-c
i constant. No differences were detected among Douglas-fir (Pseudotsuga menziesii), ponderosa pine (Pinus ponderosa), or western white pine (Pinus monticola). The values of c
a-c
i were inferred from stable carbon isotope ratio (δ13C) of tree ring holocellulose adjusted for the 0.6–2.6‰ difference between holocellulose and whole sapwood. The cellulose extraction removed contaminants deposited in the tree ring after it formed and the adjustment corrected for the enrichment of cellulose relative to whole tissue. The whole sapwood values were then adjusted for bublished estimates of past atmospheric δ13CO2 and CO2 concentrations. To avoid confounding tree age with CO2, cellulose deposited by saplings in the 1980s was compared to cellulose deposited in the inner rings of nature trees when the mature trees were saplings, between 1910–1929 and 1941–1970; thus saplings were compared to saplings. In a separate analysis, the juvenile effect, which describes the tendency for δ13C to increase in the first decades of a tree's life, was quantified independent of source CO2 effects. This study provides evidence that conifers have undergone adjustments in the intercellular CO2 concentration that have maintained c
a-c
i constant. Based on these results and others, we suggest that c
a-c
i, which has also been referred to as the intrinsic water-use efficiency, should be considered a homeostatic gas-exchange set point for these conifer species.

Robert A. Monserud

Papers

Modeling individual tree mortality for Austrian forest species

Height Growth and Site Index Curves for Inland Douglas-fir Based on Stem Analysis Data and Forest Habitat Type

Simulation of forest tree mortality

Homeostatic gas-exchange parameters inferred from 13C/12C in tree rings of conifers.

A crown ratio model for Austrian forests