TY - JOUR A1 - Metz, Johannes A1 - von Oppen, Jonathan A1 - Tielbörger, Katja T1 - Parental environmental effects due to contrasting watering adapt competitive ability, but not drought tolerance, in offspring of a semi-arid annual Brassicaceae JF - The journal of ecology N2 - Parental effects (PE) can be adaptive and improve offspring performance when parents and offspring experience similar environmental conditions. However, it is unknown whether adaptive PE exist also in habitats where such similarity is unlikely due to strong temporal variation. In particular, we do not know whether PE can adapt offspring to fluctuating levels of neighbour competition in such habitats. Here, we tested for adaptive PE in terms of two key environmental factors in a semi-arid annual system, competition and drought. While rainfall was stochastic in the study site, the competitive environment was partly predictable: higher plant densities followed after favourable (rainy) years due to high seed production. We therefore expected PE to adapt the offspring's competitive ability to these (predictable) fluctuations in plant densities, rather than to adapt the offspring's drought tolerance to the (unpredictable) occurrence of intensified drought. Parental plants of Biscutella didyma, an annual Brassicaceae, were raised under favourable watering and under drought conditions. Offspring performance was then tested under a full-factorial combination of two neighbour regimes and six watering levels in the glasshouse. Offspring of parents grown under favourable conditions were stronger competitors. This was associated with a small shift in phenology but not with higher parental seed provisioning. Offspring from parents grown under drought showed no improved drought tolerance. Moreover, no PE were detectable when offspring were grown without neighbours. Our results suggest a novel path of adaptive PE: higher competitive ability was induced in offspring that were more likely to experience high neighbour densities. Together with the lack of adaptive PE towards drought tolerance, this emphasizes that a correlation between parental and offspring environment is crucial for adaptive PE to evolve. Our results also call for the inclusion of competitive effects in future PE studies.Synthesis. This study demonstrates the important role of adaptive PE for plant fitness (regarding competition) but also their limits (regarding drought) in temporally variable environments, based on the predictability of the respective environmental factor. KW - annual plants KW - Biscutella didyma KW - competition KW - dryland ecosystems KW - maternal environmental effects KW - phenology KW - plant population and community dynamics KW - plant-plant interactions KW - transgenerational plasticity KW - water stress Y1 - 2015 U6 - https://doi.org/10.1111/1365-2745.12411 SN - 0022-0477 SN - 1365-2745 VL - 103 IS - 4 SP - 990 EP - 997 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Köchy, Martin A1 - Tielbörger, Katja T1 - Hydrothermal time model of germination : parameters for 36 Mediterranean annual species based on a simplified approach N2 - Germination rates and germination fractions of seeds can be predicted well by the hydrothermal time (HTT) model. Its four parameters hydrothermal time, minimum soil temperature, minimum soil moisture, and variation of minimum soil moisture, however, must be determined by lengthy germination experiments at combinations of several levels of soil temperature and moisture. For some applications of the HTT model it is more important to have approximate estimates for many species rather than exact values for only a few species. We suggest that minimum temperature and variation of minimum moisture can be estimated from literature data and expert knowledge. This allows to derive hydrothermal time and minimum moisture from existing data from germination experiments with one level of temperature and moisture. We applied our approach to a germination experiment comparing germination fractions of wild annual species along an aridity gradient in Israel. Using this simplified approach we estimated hydrothermal time and minimum moisture of 36 species. Comparison with exact data for three species shows that our method is a simple but effective method for obtaining parameters for the HTT model. Hydrothermal time and minimum moisture supposedly indicate climate related germination strategies. We tested whether these two parameters varied with the climate at the site where the seeds had been collected. We found no consistent variation with climate across species, suggesting that variation is more strongly controlled by site-specific factors.Abstract auch auf deutsch vorhanden:Keimungsgeschwindigkeit und Anteil gekeimter Samen lassen sich gut mit dem Hydrothermalzeit-Modell bestimmen. Dessen vier Parameter Hydrothermalzeit, Mindesttemperatur, Mindestbodenfeuchte und Streuung der Mindestbodenfeuchte müssen jedoch durch aufwendige Keimungsversuche bei Kombinationen von mehreren Temperatur- und Feuchtigkeitsstufen bestimmt werden. Für manche Anwendungen des Hydrothermalzeit-Modells sind aber ungefähre Werte für viele Arten wichtiger als genaue Werte für wenige Arten. Wenn die Mindesttemperatur und die Streuung der Mindestfeuchte aus Veröffentlichungen und Expertenwissen geschätzt würde, können die Hydrothermalzeit und Mindestbodenfeuchte aus vorhandenen Daten von Keimungsversuchen mit nur einer Temperatur- und Feuchtigkeitsstufe berechnet werden. Wir haben unseren Ansatz auf einen Keimungsversuch zum Vergleich der Keimungsquote wilder einjähriger Arten entlang eines Trockenheitsgradienten in Israel angewendet. Mit diesem Ansatz bestimmten wir die Hydrothermalzeit und Mindestfeuchtigkeit von 36 Arten. Der Vergleich mit genauen Werten für drei Arten zeigt, dass mit unserem Ansatz Hydrothermalzeit-Parameter einfach und effektiv bestimmt werden können. Hydrothermalzeit und Mindestfeuchtigkeit sollten auch bestimmte klimabedingte Keimungsstrategien anzeigen. Deshalb testeten wir, ob diese zwei Parameter mit dem Klima am Ursprungsort der Samen zusammenhängen. Wir fanden jedoch keinen für alle Arten übereinstimmenden Zusammenhang, so dass die Unterschiede vermutlich stärker durch standörtliche als durch klimatische Ursachen hervorgerufen werden. Y1 - 2007 UR - http://www.sciencedirect.com/science/journal/14391791 U6 - https://doi.org/10.1016/j.baae.2006.04.002 SN - 1439-1791 ER - TY - JOUR A1 - Schiffers, Katja A1 - Schurr, Frank Martin A1 - Tielbörger, Katja A1 - Urbach, Carsten A1 - Moloney, Kirk A. A1 - Jeltsch, Florian T1 - Dealing with virtual aggregation : a new index for analysing heterogeneous point patterns Y1 - 2008 UR - http://www3.interscience.wiley.com/journal/117966123/home U6 - https://doi.org/10.1111/j.0906-7590.2008.05374.x SN - 0906-7590 ER - TY - JOUR A1 - Schiffers, Katja A1 - Tielbörger, Katja T1 - Ontogenetic shifts in interactions among annual plants N2 - 1.Interactions among plants are key processes that strongly influence the structure and dynamics of plant populations and communities. However, most empirical studies of plant-plant inter­actions failed to repeatedly measure the plants? response to neighboring individuals and thereby neglected possible changes in interactions through­out the life history of the plants.2.Here, we tested the hypo­thesis that competition between annual species intensifies from early to late life history stages. To test this hypothesis, we sequentially measured interactions at different levels of water stress. 3.For this purpose, we con­ducted neighbor-removal experiments in three study sites located along a climatic gradient in Israel. The two annual species Biscutella didyma and Hymenocarpos circinnatus were used as target plants. They grew with and without neighbors in their natural habitats. Five response variables, according to the consecutive life-history stages, (seedling survival, juvenile biomass, adult survival, number of seeds and final biomass) were recorded through­out the whole growing season. 4.The results suggest that direction and inten­sity of inter­actions varied consider­ably between environ­ments and life stages. On average, growth-related response variables indicated higher competition intensity at the productive end of the climatic gradient, while survival indicated either facilitation at the dry end or no trend along the gradient. 5.Considering the temporal aspect, moderate facili­tation short after germi­nation shifted to strong compe­tition at the end of the growing season. 6.Our results highlight that the outcome of experi­mental studies on plant-plant inter­actions may not only depend on the environ­mental productivity but even more on the life stage at which a target plant is found. Y1 - 2006 UR - http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2006.01097.x/pdf U6 - https://doi.org/10.1111/j.1365-2745.2006.01097.x ER - TY - JOUR A1 - Brose, Ulrich A1 - Tielbörger, Katja T1 - Subtle differences in environmental stress along a flooding gradient affect the importance of inter-specific competition in an annual plant community N2 - Empirical evidence suggests that the direction and intensity of plant-plant interactions may depend on the favourability of the environment. Previous studies have mainly focused on steep gradients of environmental stress or disturbance, while the interplay of competition and environment has not been tested for subtle environmental differences. Here, we present results from a study on plant communities of temporary wetlands in East-German farmland. Due to yearly ploughing in autumn, the vegetation is composed of annual species. Flooding does not affect adult plants and the elevation on the gradient expresses differences in the length of the growing season rather than in disturbance intensity or severe environmental stress. We tested whether such subtle differences in environmental stress may affect the importance of interspecific competition by the dominant species. Two treatments were applied at two elevations: removal of the dominant species (Matricaria maritima ssp. inodora) and reciprocal transplants of the seed-bank of the two elevations. At both elevations, removal of Matricaria inodora led to an increase in total species richness and number of wetland species, but the effects were substantially stronger at high elevations. Removal and the elevation on the flooding gradient significantly influenced the plant community composition. In particular, the weed communities became more similar to the wetland communities after the removal. Transplanted weed species did not emerge at low elevations. While two of four target species had significantly higher densities after the removal at high elevations, none of them was influenced by removal at low elevations. This indicates that, consistent with previous studies from other habitat types, competition by the dominant species was more intense under conditions of low environmental stress. The overall results suggest that both flooding as well as interspecific competition are important in structuring the plant communities along the freshwater gradient studied Y1 - 2005 SN - 1385-0237 ER - TY - JOUR A1 - Deutschewitz, Kirstin A1 - Tielbörger, Katja A1 - Lausch, Angela T1 - Erklärt strukturelle Diversität der Landschaft das Verbreitungsmuster von fremdländischen Pflanzenarten? N2 - Recently, much ecological research has focused on predicting invasions of alien species in order to prevent potentially negative effects of such invasions. In this study, we utilize novel methods of landscape ecology for testing the hypothesis that increasing structural diversity correlates with an increasing number of alien plant species. Our overall findings support this hypothesis and suggest that in the studied area (RB Dessau, Sachsen Anhalt, Germany), species richness of neophytes is positively correlated with the diversity in land-use types and structures. However, this relationship between structural diversity and species diversity applied for native spe-cies, too. Furthermore, our results support findings of previous studies which show that neophytes occur mainly in artificially or naturally disturbed areas. Our overall findings highlight the use of landscape-scale ecological methods for studying plant distribution patterns. Y1 - 2003 ER - TY - JOUR A1 - Tschöpe, Okka A1 - Tielbörger, Katja T1 - The role of successional stage and small-scale disturbance for establishment of pioneer grass Corynephorus canescens N2 - Question Which mechanisms promote the maintenance of the protected pioneer grass Corynephorus canescens in a mosaic landscape? Which are the interactive effects of small-scale disturbances, successional stage and year-to-year variation on early establishment probabilities of C. canescens? Location Brandenburg, NE Germany. Methods We measured emergence and survival rates over 3 yr in a sowing-experiment conducted in three successional stages (C. canescens- dominated site, ruderal forb site and pioneer forest) under two different regimes of mechanical ground disturbance (disturbed versus undisturbed control). Results Overall, disturbance led to higher emergence in a humid year and to lower emergence in a very dry year. Apparently, when soil moisture was sufficient, the main factor limiting C. canescens' establishment was competition, while in the dry year, water became the limiting factor. Survival rates were not affected by disturbance. In humid years, C. canescens emerged in higher numbers in open successional stages while in the dry year, emergence rates were higher in late stages, suggesting an important role of late successional stages for the persistence of C. canescens. Conclusions Our results suggest that small-scale disturbances can promote germination of C. canescens. However, disturbances should be carefully planned. The optimal strategy for promoting C. canescens is to apply disturbances just before seed dispersal and not during dry years. At the landscape scale, a mosaic of different vegetation types is beneficial for the protected pioneer grass as facilitation by late-successional species may be an important mechanism for the persistence of C. canescens, especially in dry years. Y1 - 2010 UR - http://onlinelibrary.wiley.com/doi/10.1111/j.1654-109X.2009.01072.x/full U6 - https://doi.org/10.1111/j.1654-109X.2009.01072.x SN - 1402-2001 ER - TY - JOUR A1 - Moloney, Kirk A. A1 - Holzapfel, Claus A1 - Tielbörger, Katja A1 - Jeltsch, Florian A1 - Schurr, Frank Martin T1 - Rethinking the common garden in invasion research N2 - In common garden experiments, a number of genotypes are raised in a common environment in order to quantify the genetic component of phenotypic variation. Common gardens are thus ideally suited for disentangling how genetic and environmental factors contribute to the success of invasive species in their new non-native range. Although common garden experiments are increasingly employed in the study of invasive species, there has been little discussion about how these experiments should be designed for greatest utility. We argue that this has delayed progress in developing a general theory of invasion biology. We suggest a minimum optimal design (MOD) for common garden studies that target the ecological and evolutionary processes leading to phenotypic differentiation between native and invasive ranges. This involves four elements: (A) multiple, strategically sited garden locations, involving at the very least four gardens (2 in the native range and 2 in the invaded range); (B) careful consideration of the genetic design of the experiment; (C) standardization of experimental protocols across all gardens; and (D) care to ensure the biosafety of the experiment. Our understanding of the evolutionary ecology of biological invasions will be greatly enhanced by common garden studies, if and only if they are designed in a more systematic fashion, incorporating at the very least the MOD suggested here. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/14338319 U6 - https://doi.org/10.1016/j.ppees.2009.05.002 SN - 1433-8319 ER - TY - JOUR A1 - Beyer, Lothar A1 - Tielbörger, Katja A1 - Blume, Hans-Peter A1 - Pfisterer, Ulrich A1 - PingPank, K. A1 - Podlech, Dieter T1 - Geo-ecological soil features and the vegetation pattern of an arid dune area in the Northern Negev, Israel Y1 - 1998 ER - TY - JOUR A1 - Tielbörger, Katja T1 - The vegetation of linear desert dunes in the north-western Negev, Israel N2 - In 1992, the flora and vegetation of an area of linear sand dunes at Nizzana, western Negev desert, Israel, was investigated. Seven different plant communities were found and a vegetation map of the research area was produced. The plant communities were distinguished by only the dominating perennial species. Nevertheless, the results of the study indicate, that also annual species may be suitable as a tool to distinguish between desert plant communities. Y1 - 1997 ER - TY - JOUR A1 - Tielbörger, Katja A1 - Kadmon, Ronen T1 - Relationships between shrubs and annual communities in a sandy desert ecosystem : a three-year study N2 - A field study was designed to investigate the effect of shrubs on the dynamics and structure of annual plant communities in a sandy desert ecosystem. Densities of emerging and reproductive plants of all annual species were monitored in permanent quadrats located under shrubs and in open areas between shrubs during three successive years; a relatively dry one, a relatively wet one, and a very dry one. A total of 29 species were recorded in the study. Of these, 19 species did not show any evidence for differences in abundance between the two habitats. Nine species exhibited year-to-year variation in their responses to the shrub-opening gradient, being more common in a particular habitat during one year, and showing no response or even an opposite response during a different year. Only one species was consistently more abundant under shrubs throughout the whole study period, and no species was consistently more abundant in the openings. These findings contradict the hypothesis that annual species associated with desert shrub communities can be categorized into distinct groups based on their 'preference' for shrubs vs. openings. Ordination analyses of community-level patterns indicated that annual communities inhabiting the openings were more stable than those inhabiting the shrub habitat. The main lesson from this study is the importance of long-term observations in studies attempting to characterize community-level responses to environmental gradients. Y1 - 1997 ER - TY - JOUR A1 - Petru, Martina A1 - Tielbörger, Katja A1 - Belkin, Ruthie A1 - Sternberg, Marcelo A1 - Jeltsch, Florian T1 - Life history variation in an annual plant under two opposing environmental constraints along an aridity gradient N2 - Environmental gradients represent an ideal framework for studying adaptive variation in the life history of plant species. However, on very steep gradients, largely contrasting conditions at the two gradient ends often limit the distribution of the same species across the whole range of environmental conditions. Here, we study phenotypic variation in a winter annual crucifer Biscutella didyma persisting along a steep gradient of increasing rainfall in Israel. In particular, we explored whether the life history at the arid end of the gradient indicates adaptations to drought and unpredictable conditions, while adaptations to the highly competitive environment prevail at the mesic Mediterranean end. We examined several morphological and reproductive traits in four natural populations and in populations cultivated in standard common environment. Plants from arid environments were faster in phenological development, more branched in architecture and tended to maximize reproduction, while the Mediterranean plants invested mainly in vertical vegetative growth. Differences between cultivation and field in diaspore production were very large for arid populations as opposed to Mediterranean ones, indicating a larger potential to increase reproduction under favorable conditions. Our overall findings indicate two strongly opposing selective forces at the two extremes of the aridity gradient, which result in contrasting strategies within the studied annual plant species Y1 - 2006 UR - http://www3.interscience.wiley.com/journal/117966123/home U6 - https://doi.org/10.1111/j.2005.0906-7590.04310.x ER - TY - GEN A1 - Shi, Jun A1 - Jasmin Radha, Jasmin A1 - Tielbörger, Katja A1 - Verhoeven, Koen J. F. A1 - Macel, Mirka T1 - Costs and benefits of admixture between foreign genotypes and local populations in the field T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Admixture is the hybridization between populations within one species. It can increase plant fitness and population viability by alleviating inbreeding depression and increasing genetic diversity. However, populations are often adapted to their local environments and admixture with distant populations could break down local adaptation by diluting the locally adapted genomes. Thus, admixed genotypes might be selected against and be outcompeted by locally adapted genotypes in the local environments. To investigate the costs and benefits of admixture, we compared the performance of admixed and within-population F1 and F2 generations of the European plant Lythrum salicaria in a reciprocal transplant experiment at three European field sites over a 2-year period. Despite strong differences between site and plant populations for most of the measured traits, including herbivory, we found limited evidence for local adaptation. The effects of admixture depended on experimental site and plant population, and were positive for some traits. Plant growth and fruit production of some populations increased in admixed offspring and this was strongest with larger parental distances. These effects were only detected in two of our three sites. Our results show that, in the absence of local adaptation, admixture may boost plant performance, and that this is particularly apparent in stressful environments. We suggest that admixture between foreign and local genotypes can potentially be considered in nature conservation to restore populations and/or increase population viability, especially in small inbred or maladapted populations. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 647 KW - heterosis KW - inbreeding depression KW - local adaptation KW - Lythrum salicaria KW - outbreeding depression Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-425034 SN - 1866-8372 IS - 647 ER - TY - JOUR A1 - Tielbörger, Katja A1 - Prasse, Rüdiger A1 - Bornkamm, Reinhard A1 - Kadmon, Ronen A1 - Tsoar, H. T1 - Sukzessionsprozesse in einem Sanddünengebiet nach Ausschluß von Beweidung Y1 - 2000 ER - TY - JOUR A1 - Tielbörger, Katja A1 - Kadmon, Ronen A1 - Müller, Monika A1 - Jeltsch, Florian T1 - Populationsdynamische Funktionen von Ausbreitung und Dormanz Y1 - 2000 ER - TY - JOUR A1 - Tielbörger, Katja A1 - Kadmon, Ronen A1 - Müller, Monika A1 - Jeltsch, Florian T1 - Raum-zeitliche Populationsdynamik von einjährigen Wüstenpflanzen Y1 - 2000 ER - TY - JOUR A1 - Tielbörger, Katja A1 - Kadmon, Ronen T1 - Temporal environmental variation tips the balance between facilitation and interference in desert plants N2 - Recently, numerous studies have pointed to the importance of positive interactions in natural communities. There is now a broad consensus that the balance between negative and positive interactions should shift along environmental gradients, with competition prevailing under environmentally benign conditions and positive interactions dominating under harsh conditions. A commonly cited example of the importance of facilitation in harsh environments is the preference of desert annual plants for the areas under the canopy of shrubs. The recognition of apparently positive effects of desert shrubs on annuals, however, has been mostly based on density measurements, while fitness parameters of the understory plants have been ignored. Also, the temporal consistency of such effects has not been previously tested. Based on conceptual ideas about the balance between interference and facilitation, we predicted that positive effects of the shrubs on the understory should dominate in dry years, while in favorable years, negative effects would be stronger. We tested our hypothesis by measuring the direction and magnitude of the shrub effect on demographic responses of four desert annual plant species during four consecutive seasons of differing rainfall. The results contradicted our initial hypothesis. Depending on the species, the effect of the shrubs shifted from either negative to neutral or from neutral to positive with increasing annual rainfall. However, this trend was stronger for the effect of shrubs on plant reproductive success than on their densities. Our data highlight the importance of measuring fitness parameters in studies of plant-plant interactions. We suggest that the negative effects of shrubs on plant fitness were due to rainfall interception, while positive effects were related to increased nutrient availability beneath shrubs. However, the mechanisms by which the shrubs and annuals interact can only be resolved using an experimental approach. Our results contradict previous hypotheses about the relative importance of positive and negative interactions along environmental gradients. A simple conceptual model summarizing the proposed role of rainfall in determining the direction of shrub effects on their understory annuals is presented. Y1 - 2000 ER - TY - JOUR A1 - Tielbörger, Katja A1 - Kadmon, Ronen T1 - Indirect effects in a desert plant community : is competition among annuals more intense under shrub canopies? N2 - An unresolved discussion in contemporary ecology deals with the relative importance of competition along environmental gradients. In deserts, local-scale differences in environmental productivity may be caused by the presence of shrubs, which represent a favorable habitat for annual populations within a nutrient-poor matrix. In this study, we attempted to test the hypothesis that facilitation of desert annuals by shrubs increase the intensity of competition among the annual plants. Such negative indirect effects have so far been ignored in studies about plant-plant interactions. We tested our hypothesis by measuring seedling survival and fecundity of four abundant annual plant species with and without neighbors in open areas and under shrub canopies in a sandy desert area. Our findings did not indicate indirect negative effects of shrubs on their understory annuals. Sensitivity to the presence of neighbors varied between species and surprisingly, the species with the smallest seeds was the only one which was not negatively affected by the presence of neighbors. In contrast to our hypothesis, there was no difference between the habitat types shrubs and openings in absolute and relative competition intensity. Our overall results suggest that negative indirect effects of shrubs are unimportant in determining demographic response of understory annual plants. Y1 - 2000 ER - TY - JOUR A1 - Kadmon, Ronen A1 - Tielbörger, Katja T1 - Testing for source-sink population dynamics : an experimental approach exemplified with desert annuals N2 - Theoretical models indicate that natural populations may be structured in such a way that many individuals occur in habitats where reproduction is insufficient to balance mortality. The persistence of such 'sink' populations depends on immigration from neighboring 'source' habitats where local reproduction exceeds mortality. While source-sink dynamics has become a fundamental concept in ecological theory, there has been virtually no experimental test for the existence of sources and sinks in natural populations. This paper reports the results of a four-year study that was designed to experimentally test for source-sink population dynamics in desert annual communities. Based on evidence from a variety of desert ecosystems indicating that patchiness caused by the presence of shrubs is important in structuring desert annual communities, we distinguished between two types of habitats: areas beneath the canopy of shrubs and the open areas between the shrubs. If, as suggested in previous studies, source-sink dynamics is important in structuring such annual communities, one would expect that removal of populations from one habitat leads to extinction of some species in the other habitat. We tested this prediction using removal experiments. Specifically, we monitored density responses of annual populations inhabiting open areas to the repeated removal of conspecific populations from the shrubs and vice versa. Four years after establishment of the experiment, none of the studied 34 species responded to the removal treatments with habitat-specific extinction. Only one species exhibited a significant habitat-specific decrease in density in response to the removal of conspecific populations from the other habitat. These findings contradict our expectations and point to the importance of applying an experimental approach in studies of source-sink dynamics. Y1 - 1999 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Tews, Jörg A1 - Brose, Ulrich A1 - Grimm, Volker A1 - Tielbörger, Katja A1 - Wichmann, Matthias A1 - Schwager, Monika T1 - Animal species diversity driven by habitat heterogeneity/diversity : the importance of keystone structures N2 - In a selected literature survey we reviewed studies on the habitat heterogeneity-animal species diversity relationship and evaluated whether there are uncertainties and biases in its empirical support. We reviewed 85 publications for the period 1960-2003. We screened each publication for terms that were used to define habitat heterogeneity, the animal species group and ecosystem studied, the definition of the structural variable, the measurement of vegetation structure and the temporal and spatial scale of the study. The majority of studies found a positive correlation between habitat heterogeneity/diversity and animal species diversity. However, empirical support for this relationship is drastically biased towards studies of vertebrates and habitats under anthropogenic influence. In this paper we show that ecological effects of habitat heterogeneity may vary considerably between species groups depending on whether structural attributes are perceived as heterogeneity or fragmentation. Possible effects may also vary relative to the structural variable measured. Based upon this, we introduce a classification framework that may be used for across-studies comparisons. Moreover, the effect of habitat heterogeneity for one species group may differ in relation to the spatial scale. In several studies, however, different species groups are closely linked to 'keystone structures' that determine animal species diversity by their presence. Detecting crucial keystone structures of the vegetation has profound implications for nature conservation and biodiversity management. Y1 - 2004 ER -