Ernst Detlef Schulze

Bio: Ernst Detlef Schulze is an academic researcher from Max Planck Society. The author has contributed to research in topics: Biodiversity & Ecosystem. The author has an hindex of 133, co-authored 670 publications receiving 69504 citations. Previous affiliations of Ernst Detlef Schulze include University of Idaho & University of Utah.

Carbohydrate partitioning in relation to whole plant production and water use of Vigna unguiculata (L.) Walp.

Abstract: Increases in plant biomass are mainly a balance between growth of new leaves and growth of new roots, the new leaves having positive feedback upon the production process and the new roots having positive feedback upon the plant water status. Control of both opposing processes with respect to biomass production may be considered optimal whenever biomass of the plant reaches a maximum without adversely affecting plant water status. This occurs only if all carbohydrates are partitioned into growth of new leaves, unless water uptake is insufficient to meet the additional evaporative demand created by the newly grown leaf area without decreasing the water status of the plant. It is shown by theoretical considerations based upon optimization theory, especially by application of the Pontryagin Maximum Principle, that in this case carbohydrate partitioning is dependent upon the transpiration rate per leaf weight and upon the efficiency of the root at taking up water. Growth of Vigna unguiculata at two levels of air humidity and two levels of water uptake rate by the root was consistent with such a carbohydrate partitioning pattern. Growth of total biomass and its components (leaves, stems, and roots), whole plant transpiration, and the pattern of carbon partitioning were predicted and explained by applying the foregoing principles of optimization in a heuristic model for vegetative growth of an annual.

Mistletoes: a hypothesis concerning morphological and chemical avoidance of herbivory.

Abstract: Leaves from many misletoe species in Australia strongly resemble those of their hosts. This cryptic mimicry has been hypothesized to be a means of reducing the likelihood of mistletoe herbivory by vertebrates. Leaf Kjeldahl nitrogen contents (a measure of reduced nitrogen and thus amines, amino acids and protein levels) of mistletoes and their hosts were measured on 48 mimetic and nonmimetic host-parasite pairs to evaluate hypotheses concerning the significance of crysis versus noncrypsis. The hypothesis that mistletoes mimicking host leaves should have higher leaf nitrogen levels than their hosts is supported; they may be gaining a selective advantage through crypsis (reduced herbivory). The second hypothesis that mistletoes which do not mimic their hosts should have lower leaf nitrogen levels than their hosts is also supported; they may be gaining a selective advantage through noncrypsis (reduced herbivory resulting from visual advertisement of their reduced nutritional status).

Equilibrium freezing of leaf water and extracellular ice formation in Afroalpine giant rosette plants

Abstract: The water potentials of frozen leaves of Afroalpine plants were measured psychrometrically in the field. Comparison of these potentials with the osmotic potentials of an expressed cellular sap and the water potentials of ice indicated almost ideal freezing behaviour and suggested equilibrium freezing. On the basis of the osmotic potentials of expressed cellular sap, the fractions of frozen cellular water which correspond to the measured water potentials of the frozen leaves could be determined (e.g. 74% at -3.0° C). The freezing points of leaves were found to be in the range between 0° C and -0.5° C, rendering evidence for freezing of almost pure water and thus confirming the conclusions drawn from the water-potential measurements. The leaves proved to be frost resistant down to temperatures between -5° C and -15° C, as depending on the species. They tolerated short supercooling periods which were necessary in order to start ice nucleation. Extracellular ice caps and ice crystals in the intercellular space were observed when cross sections of frozen leaves were investigated microscopically at subfreezing temperatures.

Resources, recruitment limitation and invader species identity determine pattern of spontaneous invasion in experimental grasslands.

Abstract: Summary 1 A number of experimental studies have supported the hypothesis that diversity increases invasion resistance, but several mechanisms were proposed to explain this relationship We studied spontaneous invasion in experimental grasslands varying in species richness (1–16 (60)) and plant functional group richness and identity (1–4; grasses, legumes, tall herbs small herbs) during the first 3 years after establishment on large-area plots of 20 × 20 m size 2 Invader species number, biomass and density decreased with increasing community species richness The identity of successful invaders changed through time as the relative importance of external invaders (= species not belonging to the experimental species pool) decreased, while internal invaders (= species belonging to the experimental species pool) became more important The presence of legumes increased, while the presence of grasses in the plant communities decreased density, biomass and species number of external invaders and biomass of internal invaders in the second and third year after establishment 3 Analyses of viable seeds in the topsoil, a higher invasion in communities with more potential invaders in adjacent plots and an edge effect with a higher invader density and species number at the margin of the plots suggested recruitment limitation of internal invader species in contrast to external invader species that were more strongly limited by community characteristics 4 Resource availability, in particular percentage cover of resident species, root length density and soil nitrate, and propagule availability had significant effects on invasibility However, statistical analyses revealed that these variables did not completely control for effects of community species richness and the presence of grasses and legumes respectively on invasion resistance 5 Separate analyses of frequent invader species showed that the invasion success of individual species varied in response to biodiversity and resource niches 6 Synthesis Our results confirm that a more complete use of available resources in plant communities of increasing species richness generally decreases invasibility However, the overall positive effects of biodiversity on invasion resistance are dependent on species identity of the invader species Thus, mechanisms at species level are important to understand community invasion resistance

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

Effects of biodiversity on ecosystem functioning: a consensus of current knowledge

Abstract: Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls. The scientific community has come to a broad consensus on many aspects of the re- lationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are struc- tured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain.

Agricultural sustainability and intensive production practices

Abstract: A doubling in global food demand projected for the next 50 years poses huge challenges for the sustainability both of food production and of terrestrial and aquatic ecosystems and the services they provide to society. Agriculturalists are the principal managers of global useable lands and will shape, perhaps irreversibly, the surface of the Earth in the coming decades. New incentives and policies for ensuring the sustainability of agriculture and ecosystem services will be crucial if we are to meet the demands of improving yields without compromising environmental integrity or public health.

The worldwide leaf economics spectrum

Abstract: Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.

Carbon Isotope Discrimination and Photosynthesis

Abstract: We discuss the physical and enzymatic bases of carbone isotope discrimination during photosynthesis, noting how knowledge of discrimination can be used to provide additional insight into photosynthetic metabolism and the environmental influences on that process