Peter Poschlod

New handbook for standardised measurement of plant functional traits worldwide

Plant functional traits are the features (morphological, physiological, phenological) that represent ecological strategies and determine how plants respond to environmental factors, affect other trophic levels and influence ecosystem properties. Variation in plant functional traits, and trait syndromes, has proven useful for tackling many important ecological questions at a range of scales, giving rise to a demand for standardised ways to measure ecologically meaningful plant traits. This line of research has been among the most fruitful avenues for understanding ecological and evolutionary patterns and processes. It also has the potential both to build a predictive set of local, regional and global relationships between plants and environment and to quantify a wide range of natural and human-driven processes, including changes in biodiversity, the impacts of species invasions, alterations in biogeochemical processes and vegetation–atmosphere interactions. The importance of these topics dictates the urgent need for more and better data, and increases the value of standardised protocols for quantifying trait variation of different species, in particular for traits with power to predict plant- and ecosystem-level processes, and for traits that can be measured relatively easily. Updated and expanded from the widely used previous version, this handbook retains the focus on clearly presented, widely applicable, step-by-step recipes, with a minimum of text on theory, and not only includes updated methods for the traits previously covered, but also introduces many new protocols for further traits. This new handbook has a better balance between whole-plant traits, leaf traits, root and stem traits and regenerative traits, and puts particular emphasis on traits important for predicting species’ effects on key ecosystem properties. We hope this new handbook becomes a standard companion in local and global efforts to learn about the responses and impacts of different plant species with respect to environmental changes in the present, past and future.

The historical and socioeconomic perspective of calcareous grasslands—lessons from the distant and recent past

Calcareous grasslands are one of the most species-rich habitats and a central issue in nature conservation management in Europe. Comparative vegetation ecological studies let us suppose that calcareous grasslands did not exist before the neolithic age except on small and isolated areas such as hilly domes or outcrops in the Jurassic mountains and, therefore, they are man-made. Species number increased from the neolithic age whereas calcareous grasslands only spread since the Roman Empire which is evident from palynological and macrofossil findings. A historical analysis of the more recent times showed that the maximum of spread was only between the fifteenth and twentieth century, the period of large sheep flock migrations and transhumance. However, there were many different types of land use beside grazing from which calcareous grasslands developed such as alternate husbandry and three field rotation system. Practices to establish calcareous grasslands included also the sowing of hayseed. During the twentieth century, the number and area of calcareous grasslands decreased tremendously due to abandonment and afforestation since hay making and especially traditional shepherding became more and more uneconomical. Today, calcareous grasslands are threatened. Conservation management such as mowing was not able to maintain species richness and characteristic species, especially indicators of land use history. An integrative approach combining historical and socio-economic issues is proposed to maintain and to redevelop calcareous grasslands in Europe.

Challenges for the conservation of calcareous grasslands in northwestern Europe : integrating the requirements of flora and fauna

The conservation of biological diversity requires an integrated approach covering the ecological demands of a multitude of species. Integration may be achieved by focusing on a careful selection of target species, which is rare in practice. Calcareous grasslands offer a case in point. Although they harbour a high diversity of both plant and insect species, in management the emphasis is placed on the flora. This results in an underestimation of, notably, the importance of structural heterogeneity in the vegetation. As an apparent consequence, conservation management in the Netherlands has been much more successful for the flora than for butterflies. In contrast, Germany shows promising efforts to integrate both plant and animal species in conservation management and landscape planning. The main constraints for a successfully integrated conservation management presently consist of a limited availability and exchange of information, and an insufficient organisation of research and management at an international level.

Experimental studies on the dispersal of plants and animals on sheep in calcareous grasslands

1. In June to September 1993 a transhumant flock of sheep on the Schwabische Alb was examined with respect to which plants and animals are transported on and in the wool of sheep within calcareous grasslands. Several factors possibly influencing the attachment and detachment of diaspores on fleeces were studied, as well as the distribution of diaspores on the various body-parts of a sheep. The effects of different modes of sheep locomotion on dispersal were examined with the help of a sheep dummy. In order to assess the retention time of diaspores and animals on sheep, some experiments with marked diaspores and animals were carried out on two tamed sheep. 2. In 16 intensive examinations of the fleece of a single sheep, over 8500 diaspores of 85 vascular plants species were found. The highest numbers of diaspores were attached at the breast and neck of the sheep. 3. Height of diaspore presentation, surface structure of diaspores and sheep locomotion were found to be the decisive factors for the reception and transport of diaspores in the wool. In addition, plant frequency and the length of the disseminating period are of importance. 4. Marked diaspores with both adhesive and smooth surfaces remained on the sheepskin for up to seven months, and can consequently be dispersed over the entire roaming area of the sheep. 5. Amongst the animals transported by sheep, only grasshoppers (13 species) were observed frequently on the flock of sheep. The period of time marked grasshoppers stayed on sheep ranged from I to 69min, with an average of 14 min. During this period sheep can cover distances of over 100m when grazing and well over 500m when roaming. 6. Our study indicates that the importance of the dispersal of diaspores, and especially animals, by animals has so far been largely underestimated. This is mostly due to the methods previously used to examine dispersal mechanisms. 7. Conservation management of rare and endangered species should consider the importance of sheep for maintaining the species richness of calcareous grasslands. It is likely that transhumant sheep farming is irreplaceable in the restoration of grasslands threatened by fallow and woody successional stages. Moreover, traditional shepherding facilitates the exchange of individuals of both plants and animals between isolated patches. That is, sheep are able to maintain dynamic processes even in our greatly fragmented landscape; this is probably essential to long-term population viability of many species.

Conservation management of calcareous grasslands. Changes in plant species composition and response of functional traits during 25 years

Five management treatments have been applied to a calcareous grassland since 1974 to study their efficiency in maintaining high diversity of grassland species. The treatments were: continuing sheep grazing, mowing, mulching, burning and leaving fallow (unmanaged). After 25 years of management, the treatments mowing and mulching resulted in a species composition similar to that from grazing by sheep. Thus, mowing and mulching can be useful management alternatives to grazing. In contrast, both burning and leaving fallow considerably changed the species composition. The changes were similar in both treatments and neither can be recommended for management purposes. We also evaluated eight traits with assumed sensitivity to the treatments (life form, life cycle, growth form, runners, lateral spread, fecundity, seed mass, germination season). In 1999, all traits except life cycle were found to respond to the different treatments. Trait response is discussed in detail.

ASSESSMENT OF WIND DISPERSAL POTENTIAL IN PLANT SPECIES

Conventional plant dispersal classification systems use simple binary assignment schemes classifying each species as either being dispersed by means of a certain dispersal vector or not. However, because the dispersal potential ranges continually, this dichotomy appears to be rather artificial, and the existing systems may not be very useful for addressing ecological questions. To quantify gradual differences in the dispersal potential, we developed a system assessing wind dispersal potentials. Wind dispersal potential is defined as the proportion of diaspores exceeding a predefined reference distance under certain weather conditions, to acknowledge that wind dispersal potential is scale and context specific. The system is based on an independently validated simulation model of wind dispersal that was used to compute the proportion of diaspores exceeding predefined reference distances. On an ordinal scale, the proposed system allows one to assess the wind dispersal potential of any plant species with known falling velocity and release height of its diaspores without further computing. The system mainly relies on two traits characterizing the plant species (falling velocity and initial release height of the diaspores) and two context-specific parameters (reference distance and weather conditions). We examined how wind dispersal potential is sensitive to these factors and found that it was most sensitive to weather conditions and falling velocity. The species-specific traits interact with reference distance: the greater the reference distance and the lower the release height in relation, the more relevant a low falling velocity becomes for achieving a high wind dispersal potential. We subsequently applied the system to 335 plant species and found a considerable variation in their wind dispersal potentials. Many species commonly assumed to be wind dispersed exhibit only a low wind dispersal potential. Comparing the wind dispersal potentials to the morphology of the diaspores also reveals a considerable variation of the wind dispersal potential of species classified as the same morphological type. The results show that the conventional assignment of a plant species to a certain mode of dispersal, which is primarily based on the morphology of its diaspores, will often result in misleading conclusions regarding the dispersal potential of the respective species. Corresponding Editor: M. L. Cain.

Species survival in fragmented landscapes

Preface. Part I: Case Studies on Species Survival in Fragmented Landscapes. Part II: A Review of Species Survival in Fragmented Habitats: Theory and Approaches. Part III: The FIFB Project. FIFB: Conceptual Frame. FIFB: The Hilly Landscape of Halle - Main Study Area. FIFB: Survival of Plants in Fragmented Landscapes. FIFB: Survival of Vertebrates in Fragmented Landscapes. FIFB: Survival of Butterflies in Fragmented Landscapes. FIFB: Survival of Grasshoppers and Bush Crickets in Fragmented Landscapes. FIFB: Survival of Snails in Fragmented Landscapes. FIFB: Genetics, Habitat Models, and Implementation. Part IV: Summary Conclusions.

Plant functional trait responses to grassland succession over 25 years

Abstract Many grasslands and arable fields have been abandoned in Europe in the last decades. So far, however, ecologists have not been able to establish one general, unifying theory for successionally induced changes in species composition following abandonment. In fact, the course of succession seems to be unique for each site and year. Here we focused on the analysis of plant functional traits in order to detect general trends in trait responses to succession which would prove independent of site characteristics. We studied permanent plot series of 14 grassland sites in SW Germany that had been abandoned for 25 yr. Species composition as well as the course of succession varied significantly among the grasslands. Response to succession was analysed for the following traits: ‘plant height’, ‘canopy structure’, ‘specific leaf area’ (SLA), ‘storage organ’, ‘vegetative spread’, ‘plant persistence’, ‘seed bank longevity’, ‘start of flowering’, ‘duration of flowering’ and ‘seed mass’. We compared a univariate with a multivariate approach. In the univariate approach, attributes of each trait were analysed separately employing GLM whereas in the multivariate approach all traits were handled together in NMS. Both analyses indicated similar trait responses to succession. There was a significant increase in the proportion of species characterized by the following attributes: plant height > 0.6 m, leaves distributed regularly along the stem, vegetative spread > 100 mm, start of flowering later than May, duration of flowering 1–2 months and seeds of either low or high mass. Abbreviations: GLM = General Linear Model; NMS = Non-metric Multidimensional Scaling. Nomenclature: vegetation types according to Rennwald (2000).

Comparison of species composition between different grassland management treatments after 25 years

Abstract To identify management treatments suitable for the conservation of extensively managed grasslands, the ‘Fallow experiments in Baden‐Württemberg’ were set up in 1975. In this investigation, species composition of the grazing, mowing, mulching, controlled burning and unmanaged (succession) treatments were analysed after 25 yr of continuous management in Arrhenatherum elatius and Bromus erectus grasslands. Through ordination analyses it was found that species composition is strongly dependent on the management treatment. The first axis, identified by ordination analysis, essentially corresponded to a gradient of decreasing disturbance frequency. Controlled burning resulted in a unique species composition. Grazing, mowing and mulching twice a year were found to be most suitable for the conservation of unimproved, species‐rich grasslands. Nomenclature:Oberdorfer (1994).

BIOPOP - A DATABASE OF PLANT TRAITS AND INTERNET APPLICATION FOR NATURE CONSERVATION

In scientific literature there is a wealth of information about the ecological and life-history traits of plant species. This information would be very valuable for a functional analysis of the response of species and communities to environmental changes and subsequent vulnerability/viability analysis or predictive modelling. However, the information is scattered in a multiple of different sources. Researchers often are discouraged from searching all available information.We are compiling a database of plant traits of the flora of Germany. Our aim is to create a comprehensive, well documented database to be made freely accessible within FLORAWEB, an Internet portal of the German Federal Agency for Nature Conservation (BfN). An interactive user-interface will enable the data to be readily used for extracting biological risk factors and for decision-making in nature conservation.A further aim of the project is to develop an application to enable simple predictions of plant population responses to habitat conservation or restoration management.