Small-scale plant species distribution in snowbeds and its sensitivity to climate change

Alpine snowbeds are characterized by a long-lasting snow cover and low soil temperature during the growing season. Both these key abiotic factors controlling plant life in snowbeds are sensitive to anthropogenic climate change and will alter the environmental conditions in snowbeds to a considerable extent until the end of this century. In order to name winners and losers of climate change among the plant species inhabiting snowbeds, we analyzed the small-scale species distribution along the snowmelt and soil temperature gradients within alpine snowbeds in the Swiss Alps. The results show that the date of snowmelt and soil temperature were relevant abiotic factors for small-scale vegetation patterns within alpine snowbed communities. Species richness in snowbeds was reduced to about 50% along the environmental gradients towards later snowmelt date or lower daily maximum temperature. Furthermore, the occurrence pattern of the species along the snowmelt gradient allowed the establishment of five species categories with different predictions of their distribution in a warmer world. The dominants increased their relative cover with later snowmelt date and will, therefore, lose abundance due to climate change, but resist complete disappearance from the snowbeds. The indifferents and the transients increased in species number and relative cover with higher temperature and will profit from climate warming. The snowbed specialists will be the most suffering species due to the loss of their habitats as a consequence of earlier snowmelt dates in the future and will be replaced by the avoiders of late-snowmelt sites. These forthcoming profiteers will take advantage from an increasing number of suitable habitats due to an earlier start of the growing season and increased temperature. Therefore, the characteristic snowbed vegetation will change to a vegetation unit dominated by alpine grassland species. The study highlights the vulnerability of the established snowbed vegetation to climate change and requires further studies particularly about the role of biotic interactions in the predicted invasion and replacement proces

Nitrogen fixation by common beans in crop mixtures is influenced by growth rate of associated species

Background: Legumes can fx atmospheric nitrogen (N) and facilitate N availability to their companion plants in crop mixtures. However, biological nitrogen fxation (BNF) of legumes in intercrops varies largely with the identity of the legume species. The aim of our study was to understand whether BNF and concentration of plant nutrients by common bean is infuenced by the identity of the companion plant species in crop mixtures. In this greenhouse pot study, common beans were cultivated with another legume (chickpea) and a cereal (Sorghum). We compared BNF, crop biomass and nutrient assimilation of all plant species grown in monocultures with plants grown in crop mixtures. Results: We found beans to exhibit low levels of BNF, and to potentially compete with other species for available soil N in crop mixtures. The BNF of chickpeas however, was enhanced when grown in mixtures. Furthermore, biomass, phosphorous and potassium values of chickpea and Sorghum plants were higher in monocultures, compared to in mixtures with beans; suggesting competitive efects of beans on these plants. Concentration of calcium, magnesium and zinc in beans was higher when grown with chickpeas than with Sorghum. Conclusions: It is generally assumed that legumes beneft their companion plant species. Our study highlights the contrary and shows that the specifc benefts of cereal-legume mixtures are dependent on the growth rate of the species concerned. We further highlight that the potential of legume-legume mixtures is currently undervalued and may play a strong role in increasing N use efciency of intercrop based systems

Findings Related to Cerebrospinal Fluid and Central Nervous System Disorders in Small Ruminants—A Retrospective Study on Sheep and Goats

Background: Small ruminants often suffer from central nervous system (CNS) disorders, and cerebrospinal fluid (CSF) analysis can be used as a diagnostic tool in this regard. In small animals and cattle, specific CSF patterns have been defined for specific disease categories. No data exist regarding CSF results obtained from small ruminants and their association with certain CNS diseases. Objectives: The objective of this study was to retrospectively investigate CSF findings obtained from sheep and goats and to identify possible CSF patterns associated with disease categories. Methods: CSF samples and medical records from 44 sheep and 27 goats were included in this study. All animals were presented to the Veterinary Teaching Hospital Zurich of the Veterinary Teaching Hospital Zurich of the Vetsuisse Faculty of the University of Zurich between 2003 and 2016 and had either a confirmed CNS diagnosis or showed CSF changes without a specific CNS diagnosis. Results: Mixed mononuclear pleocytosis was the most common CSF pattern in sheep (25%), followed by monocytic pleocytosis (21%). Lymphocytic pleocytosis was most frequently found in goats (37%). In 75% of sheep and 56% of goats, infectious CNS diseases were diagnosed, with listeriosis being the most common infectious disease in both species, followed by parasitic disorders (nematodiasis and coenurosis). Conclusions: The cytologic CSF patterns in small ruminants are mainly based on the increased presence of monocytic and lymphocytic cells with variable quantitative expression, whereas neutrophilic pleocytosis and cytoalbuminologic dissociation were rare findings. Infectious diseases of bacterial origin were the most common underlying causes for CSF alterations in sheep and goats, followed by parasitic disorders. The pleocytosis type is not helpful for differentiating disease types

The shift from plant-plant facilitation to competition under severe water deficit is spatially explicit

The stress-gradient hypothesis predicts a higher frequency of facilitative interactions as resource limitation increases. Under severe resource limitation, it has been suggested that facilitation may revert to competition, and identifying the presence as well as determining the magnitude of this shift is important for predicting the effect of climate change on biodiversity and plant community dynamics. In this study, we perform a meta-analysis to compare temporal differences of species diversity and productivity under a nurse plant (Retama sphaerocarpa) with varying annual rainfall quantity to test the effect of water limitation on facilitation. Furthermore, we assess spatial differences in the herbaceous community under nurse plants in situ during a year with below-average rainfall. We found evidence that severe rainfall deficit reduced species diversity and plant productivity under nurse plants relative to open areas. Our results indicate that the switch from facilitation to competition in response to rainfall quantity is nonlinear. The magnitude of this switch depended on the aspect around the nurse plant. Hotter south aspects under nurse plants resulted in negative effects on beneficiary species, while the north aspect still showed facilitation. Combined, these results emphasize the importance of spatial heterogeneity under nurse plants for mediating species loss under reduced precipitation, as predicted by future climate change scenarios. However, the decreased water availability expected under climate change will likely reduce overall facilitation and limit the role of nurse plants as refugia, amplifying biodiversity loss

Facilitation and sustainable agriculture: a mechanistic approach to reconciling crop production and conservation

Summary Food security is currently considered a major global problem. However, increasing intensity of food production in agricultural systems has driven reductions in farmland biodiversity. A major challenge is to enable biodiversity conservation whilst addressing the problem of food security. Here we describe how facilitative plant-plant interactions in crop systems could be used to help strike this balance. An obvious example is that of intercropping systems, where combinations of crop species can – under some circumstances – deliver reduced inputs of agrochemicals (fertilisers, pesticides) per unit yield, with potential knock-on benefits for biodiversity conservation. Other facilitative processes can also play a role in biodiversity conservation. Increased intra-specific crop genetic diversity can help protect crops from pests and diseases. Although overlooked in facilitation research, we argue that the mechanisms operate in a manner which is directly analogous to associational defence against herbivores, a process well-recognised in the facilitation literature. As with intercropping, the benefits to nature conservation arise from reduced pesticide use per unit harvested crop. Crops may have facilitative effects on some arable weed species, particularly those that are currently considered rare in intensive farming systems. Work is in its early stages to understand the underlying mechanisms, but it appears that crops might create niche space to which some weed species are adapted. Increasing plant species diversity through niche space creation may then have cascading benefits for other components of farmland biodiversity. Our new understanding of facilitative processes arising from work on crop systems has lessons for the study of facilitative interactions in natural and semi-natural communities. We argue that, although easier to identify and quantify in crop systems, some of these facilitative processes have to date been overlooked in studies of non-crop systems, and certainly deserve further consideration. Finally we discuss what steps may be needed to move from our understanding of the role of facilitation to the development of new agricultural practice. In some cases the challenge may be one of encouraging uptake of existing practices, and in others more research is needed to understand how new ecological understanding might deliver more sustainable agricultural practice

Legume Shrubs Are More Nitrogen-Homeostatic than Non-legume Shrubs

Legumes are characterized as keeping stable nutrient supply under nutrient-limited conditions. However, few studies examined the legumes' stoichiometric advantages over other plants across various taxa in natural ecosystems. We explored differences in nitrogen (N) and phosphorus (P) stoichiometry of different tissue types (leaf, stem, and root) between N2-fixing legume shrubs and non-N2-fixing shrubs from 299 broadleaved deciduous shrubland sites in northern China. After excluding effects of taxonomy and environmental variables, these two functional groups differed considerably in nutrient regulation. N concentrations and N:P ratios were higher in legume shrubs than in non-N2-fixing shrubs. N concentrations were positively correlated between the plants and soil for non-N2-fixing shrubs, but not for legume shrubs, indicating a stronger stoichiometric homeostasis in legume shrubs than in non-N2-fixing shrubs. N concentrations were positively correlated among three tissue types for non-N2-fixing shrubs, but not between leaves and non-leaf tissues for legume shrubs, demonstrating that N concentrations were more dependent among tissues for non-N2-fixing shrubs than for legume shrubs. N and P concentrations were correlated within all tissues for both functional groups, but the regression slopes were flatter for legume shrubs than non-N2-fixing shrubs, implying that legume shrubs were more P limited than non-N2-fixing shrubs. These results address significant differences in stoichiometry between legume shrubs and non-N2-fixing shrubs, and indicate the influence of symbiotic nitrogen fixation (SNF) on plant stoichiometry. Overall, N2-fixing legume shrubs are higher and more stoichiometrically homeostatic in N concentrations. However, due to excess uptake of N, legumes may suffer from potential P limitation. With their N advantage, legume shrubs could be good nurse plants in restoration sites with degraded soil, but their P supply should be taken care of during management according to our results

Increasing water availability and facilitation weaken biodiversity-biomass relationships in shrublands

Positive biodiversity–ecosystem‐functioning (BEF) relationships are commonly found in experimental and observational studies, but how they vary in different environmental contexts and under the influence of coexisting life forms is still controversial. Investigating these variations is important for making predictions regarding the dynamics of plant communities and carbon pools under global change. We conducted this study across 433 shrubland sites in northern China. We fitted structural equation models (SEMs) to analyze the variation in the species‐richness–biomass relationships of shrubs and herbs along a wetness gradient and general liner models (GLMs) to analyze how shrub or herb biomass affected the species‐richness–biomass relationship of the other life form. We found that the positive species‐richness–biomass relationships for both shrubs and herbs became weaker or even negative with higher water availability, likely indicating stronger interspecific competition within life forms under more benign conditions. After accounting for variation in environmental contexts using residual regression, we found that the benign effect of greater facilitation by a larger shrub biomass reduced the positive species‐richness–biomass relationships of herbs, causing them to become nonsignificant. Different levels of herb biomass, however, did not change the species‐richness–biomass relationship of shrubs, possibly because greater herb biomass did not alter the stress level for shrubs. We conclude that biodiversity in the studied plant communities is particularly important for plant biomass production under arid conditions and that it might be possible to use shrubs as nurse plants to facilitate understory herb establishment in ecological restoration

Objetivos ambientales de la agricultura española: recomendaciones científicas para su implementacion efectiva según la nueva política agraria común 2023-2030

[EN]: The next reform ofthe EU Common Agricultural Policy (CAP) for the period 2021-2027 (currently extended to 2023-2030) requires the approval by the European Commission of a Strategic Plan with environmental objectives for each Member State. Here we use the best available scientific evidence on the relationships between agricultural practices and biodiversity to delineate specific recommendations for the development of the Spanish Strategic Plan. Scientific evidence shows that Spain should (1) identify clear regional biodiversity targets and the landscape-level measures needed to achieve them; (2) define ambitious and complementary criteria across the three environmental instruments (enhanced conditionality, eco-schemes, and agri-environmental and climate measures) of the CAP’s Green Architecture, especially in simple and complex landscapes; (3) ensure that other CAP instruments (areas of nature constraints, organic farming and protection of endangered livestock breeds and crop varieties) really support biodiversity; (4) improve farmers’ knowledge and adjust measures to real world constraints; and (5) invest in biodiversity and ecosystem service monitoring in order to evaluate how the Plan achieves regional and national targets andto improve measures if targets are not met. We conclude that direct assessments of environmental objectives are technically and economi- cally feasible, can be attractive to farmers, and are socially fair and of great interest for improving the environmental effectiveness of CAP measures. The explicit and rigorous association of assessments and monitoring, relating specific environmental indicators to regional objectives, should be the main criterion for the approval of the Strategic Plan in an environmentally-focused CAP2023-2030.[ES]: La reforma de la Política Agraria Común (PAC) para el periodo 2021-2027 (extendido en la actualidad a 2023-2030) exige que la Comisión Europea apruebe un Plan Estratégico por cada Estado Miembro con claros objetivos ambientales. En este trabajo desarrollamos recomendaciones específicas para la elaboración del Plan Estratégico para los sistemas agrícolas españoles, basadas en la mejor evidencia científica disponible sobre las relaciones entre la gestión agrícola y los componentes de la biodiversidad. La evidencia científica muestra que España debe 1) identificar objetivos regionales claros relativos a la biodiversidad de los medios agrarios y las medidas a nivel paisajístico necesarias para alcanzarlas; 2) definir criterios ambiciosos y complementarios para los tres instrumentos ambientales (condicionalidad extendida, eco-esquemas y medidas agroambientales y climáticas) de la Arquitectura Verde de la PAC, especialmente en paisajes sencillos y complejos; 3) garantizar que otros instrumentos de la PAC (zonas desfavorecidas, agricultura ecológica y protección de razas ganaderas y variedades de cultivos en peligro de extinción) favorecen realmente la diversidad biológica; 4) mejorar el conocimiento de los agricultores y ajustar las medidas a las limitaciones del mundo real; y 5) invertir en seguimiento de la biodiversidad y sus servicios ecosistémicos asociados con el fin de evaluar si el Plan alcanza los objetivos regionales y nacionales y mejorarlos adaptativamente si no lo consigue. Concluimos que la evaluación directa de los objetivos ambientales es técnica y económicamente viable, puede ser atractiva para los agricultores, es socialmente justa y de gran utilidad en la mejora de la efectividad de las medidas de la PAC. Una combinación rigurosa de seguimiento y evaluación de medidas y objetivos adaptados regionalmente mediante indicadores ambientales directos y claros debería ser el criterio que guíe la aprobación del Plan Estratégico para una PAC 2023-2030 centrada en el medio ambiente y orientada a la conservación de la biodiversidad.Peer reviewe

The sensitivity of plant interactions and species distribution in alpine snowbeds to climate change

Resumen de Tesis Doctoral. Institute of Geography, University of Bern, Switzerland. December 2008. Supervision: Prof. Dr. Heinz Veit, Dr. Peter Kammer, Dr. Philippe Choler