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Ernst Detlef Schulze

Other affiliations: University of Idaho, University of Utah, University of Würzburg  ...read more
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.


Papers
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Journal ArticleDOI
01 Oct 1980-Planta
TL;DR: The water relations of leaves of Tradescantia virginiana were studied using the miniaturized pressure probe and results would indicate a relationship between guard cell volume and ε which would be inverse to that for plant cells known in the literature.
Abstract: The water relations of leaves of Tradescantia virginiana were studied using the miniaturized pressure probe (Husken, E. Steudle, Zimmermann, 1978 Plant Physiol. 61, 158–163). Under well-watered conditions cell turgor pressures, Po, ranged from 2 to 8 bar in epidermal cells. In subsidiary cells Po was about 1.5 to 4.5 bar and in mesophyll cells about 2 to 3.5 bar. From the turgor pressure, relaxation induced in individual cells by changing the turgor pressure directly by means of the pressure probe, the half-time of water exchange was measured to be between 3 and 100 s for the epidermal, subsidiary, and mesophyll cells. The volumetric elastic modulus, e, of individual cells was determined by changing the cell volume by a defined amount and simultaneously measuring the corresponding change in cell turgor pressure. The values for the elastic modulus for epidermal, subsidiary, and mesophyll cells are in the range of 40 to 240 bar, 30 to 200 bar, and 6 to 14 bar, respectively. Using these values, the hydraulic conductivity, Lp, for the epidermal, subsidiary, and mesophyll cells is calculated from the turgor pressure relaxation process (on the basis of the thermodynamics of irreversible processes) to be between 1 and 55·10-7 cm s-1 bar-1. The data for the volumetric elastic modulus of epidermal and subsidiary cells indicate that the corresponding elastic modulus for the guard cells should be considerably lower due to the large volume changes of these cells during opening or closing. Recalculation of experimental data obtained by K. Raschke (1979, Encycl. Plant Physiol. N.S., vol. 7, pp 383–441) on epidermal strips of Vicia faba indicates that the elastic modulus of guard cells of V. faba is in the order of 40–80 bar for closed stomata. However, with increasing stomatal opening, i.e., increasing guard cell volume, e decreases. Therefore, in our opinion Raschke's results would indicate a relationship between guard cell volume and e which would be inverse to that for plant cells known in the literature. e assumes values between 20–40 bar when the guard cell colume is soubled.

57 citations

Journal ArticleDOI
TL;DR: The use of the δ 15N technique for studying nutrition of carnivorous species and the ecological significance of insect feeding of different growth forms of Drosera growing in a large range of habitats is discussed.
Abstract: Plants of Drosera species, neighbouring noncarnivorous plants, and arthropods on or near each Drosera sp. were collected at 11 contrasting habitat locations in SW Australia. At three of the sites clones of the rare glandless mutant form of D. erythrorhiza were collected alongside fully glandular counterparts. The δ 15N value (15N/14N natural isotope composition) of insect-free leaf and stem fractions was measured, and the data then used to estimate proportional dependence on insect N (%NdI) for the respective species and growth forms of Drosera. The data indicated lower %NdI values for rosette than for self-supporting erect or for climbing vine species. The latter two groups showed an average %NdI value close to 50%. The %NdI increased with length and biomass of climbing but not erect forms of Drosera. δ 15N values of stems were positively correlated with corresponding values for leaves of Drosera. Leaf material was on average significantly more 15N enriched than stems, possibly due to delayed transport of recent insect-derived N, or to discrimination against 15N in transfer from leaf to the rest of the plant. The comparison of δ 15N values of insects and arthropod prey, glandless and glandular plants of D. erythrorhiza indicated %NdI values of 14.3, 12.2 and 32.2 at the respective sites, while matching comparisons based on δ 15N of insect, reference plants and glandular plants proved less definitive, with only one site recording a positive %NdI (value of 10.4%) despite evidence at all sites of feeding on insects by the glandular plants. The use of the δ 15N technique for studying nutrition of carnivorous species and the ecological significance of insect feeding of different growth forms of Drosera growing in a large range of habitats is discussed.

57 citations

Book ChapterDOI
01 Jan 2005
TL;DR: Schlapfer et al. as discussed by the authors investigated the relationship between biodiversity and ecosystem functioning in the tropics of Costa Rica and found that low and intermediate levels of diversity are the part of the gradient where most effects are expected to occur, according to local deterministic processes involving species interactions.
Abstract: Despite of the tremendous increase in knowledge about the relationship between biodiversity and ecosystem functioning during the last decade (Scherer-Lorenzen et al., Chap. 1, this Vol.), it should be noted that most of the studies were conducted with model systems, which – for very practical reasons – were small-statured, short-lived and even-aged, mainly herbaceous assemblages or microbial microcosms (e.g., Tilman et al. 1997b; Hector et al. 1999; Petchey et al. 2002; for an overview, see Schlapfer and Schmid 1999; Schmid et al. 2002). Experiments in forest ecosystems have been almost absent, with the exception of studies manipulating diversity of consumers or decomposers in the soil (e.g., Mikola and Setala 1998; Laakso and Setala 1999; see Scheu, Chap. 11, this Vol.). A manipulation of the producer level, i.e., trees, is obviously a difficult and long-lasting task and only recently attempts in this direction have been made (Scherer-Lorenzen et al., Chap. 16, this Vol.). The experiment by Ewel and colleagues in the tropics of Costa Rica (Berish and Ewel 1988; Ewel et al. 1991) has often been mentioned as the first manipulative diversity experiment indicating diversity effects on biogeochemistry (Vitousek and Hooper 1993). However, this experiment was designed to explore the possibilities of developing sustainable agroecosystems for the humid tropics, mimicking structural diversity of successional communities, and not to study the interaction of species richness and ecosystem functioning per se. Clear effects on soil chemistry were detectable between maize monocultures and highly-diverse (>100 species) treatments consisting of herbaceous and woody plants. Low and intermediate levels of diversity were lacking, which should be the part of the gradient where most effects are expected to occur, according to local deterministic processes involving species interactions (see below). Positive effects at such intermediate levels of tree species richness have been reported from afforestation experiments in Costa Rica, for example (Byard et al. 1996; Montagnini 2000). In contrast, mixture experiments from forestry

57 citations

01 Jan 1976
TL;DR: The present study investigates the physioIogical bases of species which compose the typical vegetation types of the Northern Namib: the savannas, the subtropical grasslands and the succulent deserts.
Abstract: The present study investigates the physioIogical bases of species which compose the typical vegetation types of the Northern Namib: the savannas, the subtropical grasslands and the succulent deserts. The relative role in terms of vegetation cover and species diversity of the various pathways of photosynthetic production is determined and the environmental factors responsible for the distribution of the various metabolic types is discussed.

55 citations

Journal ArticleDOI
TL;DR: In apricot, the stomatal response to changes in temperature and water-vapor concentration difference between leaf and air significantly determined the rates of gas exchange during the day (parts I and II), and the T/P-ratio changed considerably during the year.
Abstract: Measurements of CO2 and water vapor exchange were performed on Prunus armeniaca L. with humidity- and temperature-controlled chambers under the climatic conditions of a desert habitat. In apricot, the stomatal response to changes in temperature and water-vapor concentration difference between leaf and air (WD) significantly determined the rates of gas exchange during the day (parts I and II). The effect of climate-controlled stomatal response on the transpiration/net photosynthesis (T/P)-ratio was analyzed and simulated using experiments conducted at constant temperature and/or humidity conditions for input parameters. The measured values of the T/P-ratio at naturally varying conditions of humidity and temperature were compared with calculated results of a model in which it was assumed, (1) that stomata and photosynthetic activity are not affected by air humidity and temperature, (2) that the stomata only respond with a constant photosynthetic activity to changes in WD, and (3) that the stomata respond to both, leaf temperature and air humidity with a constant photosynthetic activity. These simulations facilitated an analysis of the naturally observed changes in the T/P-ratio.The calculated T/P-ratios were very small if the simulation assumed that stomata only respond to WD at a constant photosynthetic activity. These low predicted values of the T/P-ratio were not obtained under natural conditions, since an increase in WD during the day was correlated with a temperature rise which tended to open stomata and change the photosynthetic activity. Humidity induced stomatal closure did appear to substantially reduce T/P-ratios.The measured T/P-ratio changed considerably during the year. The lowest T/P-ratios were obtained in the middle of the dry season at a time when stomata responded strongly to air humidity and when optimum of photosynthesis was reached at high temperatures. The daily average T/P-ratio calculated from the daily sum of P and T showed little change during the seasons. A high T/P-ratio was also observed at reduced rates of gas exchange. The T/P-ratios of apricot were compared with different species in different environments.

55 citations


Cited by
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Journal ArticleDOI
TL;DR: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols used xiii 1.
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

14,171 citations

Journal ArticleDOI
TL;DR: 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.
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.

6,891 citations

Journal ArticleDOI
08 Aug 2002-Nature
TL;DR: 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.
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.

6,569 citations

Journal ArticleDOI
22 Apr 2004-Nature
TL;DR: 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.
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.

6,360 citations

Journal ArticleDOI
01 Jan 1989
TL;DR: In this article, the physical and enzymatic bases of carbone isotope discrimination during photosynthesis were discussed, noting how knowledge of discrimination can be used to provide additional insight into photosynthetic metabolism and the environmental influences on that process.
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

6,246 citations