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Question: How does climate change influence plant species population dynamics, their time to extinction, and proportion of occupied habitats in a fragmented landscape? Location: Germany and Central European lowland. Methods: We apply a mechanistic general simulation model to test the response of plant functional types to direct and indirect effects of climate change. Three functional types were chosen to represent a set of well-studied perennial plant species: Juncus atratus, Gentiana pneumonanthe and Primula veris. We link local population dynamics within a heterogeneous, fragmented landscape context. "Species spheres", i.e. multi-dimensional parameter ranges rather than single parameter realizations, based on field and literature data served as proxy for life stage transition parameters. Four climatic scenarios summarizing different cumulative weather effects on demographic rates and different local disturbance frequencies were run. The model predicts "time to extinction" (TE) and "proportion of occupied habitat" (POH) as regional indicators for species extinction risk. Results: TE decreased for all species when weather conditions worsened, and even more so when the frequency of local destructive events additionally increased. However, management towards fewer disturbance events could buffer the negative effect of climate to some extent. The magnitude of these responses varied with species type. POH declined with an increase in bad weather as well as with increasing disturbance frequency. The better the climatic conditions, the less severe were disturbances on population performance. Conclusions: The "species spheres" proved to be a valuable approach for predictive trends. As climate change usually also implies destructive events such as land-use change, flooding or fire, our model on local and regional extinction risks can support conservation issues and management actions. © 2010 International Association for Vegetation Science.

Question: How does climate change influence plant species population dynamics, their time to extinction, and proportion of occupied habitats in a fragmented landscape? Location: Germany and Central European lowland. Methods: We apply a mechanistic general simulation model to test the response of plant functional types to direct and indirect effects of climate change. Three functional types were chosen to represent a set of well-studied perennial plant species: Juncus atratus, Gentiana pneumonanthe and Primula veris. We link local population dynamics within a heterogeneous, fragmented landscape context. "Species spheres", i.e. multi-dimensional parameter ranges rather than single parameter realizations, based on field and literature data served as proxy for life stage transition parameters. Four climatic scenarios summarizing different cumulative weather effects on demographic rates and different local disturbance frequencies were run. The model predicts "time to extinction" (TE) and "proportion of occupied habitat" (POH) as regional indicators for species extinction risk. Results: TE decreased for all species when weather conditions worsened, and even more so when the frequency of local destructive events additionally increased. However, management towards fewer disturbance events could buffer the negative effect of climate to some extent. The magnitude of these responses varied with species type. POH declined with an increase in bad weather as well as with increasing disturbance frequency. The better the climatic conditions, the less severe were disturbances on population performance. Conclusions: The "species spheres" proved to be a valuable approach for predictive trends. As climate change usually also implies destructive events such as land-use change, flooding or fire, our model on local and regional extinction risks can support conservation issues and management actions. © 2010 International Association for Vegetation Science.

Short-term field experiments are often used to predict and evaluate long-term management effects. Based on a mowing experiment in two calcareous fens near Lake Neuchatel, Switzerland, we investigated whether shea-term treatment effects (i.e. during the first four years) were confirmed by longterm results (13 - 14 yr). Plots were mown in summer or in winter or left unmown. The main long-term trends in overall species composition (based on percentage cover estimates) were already observable in the first four years: mown and unmown plots diverged, whereas summer-cut and winter-cut plots remained similar. At the individual species level, however, short-term and long-term treatment effects differed considerably: many species whose abundance seemed affected by treatments during the first four years showed no response in the long term, and vice versa. These discrepancies were similar when based on cover estimates or on counts of shoots. Species responses did actually depend on the time scale considered. Short-term and long-term treatment effects on species richness were similar (i.e. a decrease in unmown plots), although only long-term effects were significant. Treatment effects on the above-ground biomass varied considerably, and short-term trends (lower biomass in unmown plots) differed from long-term trends (higher biomass in unmown plots). Our sites showed little overall change in species composition during the period investigated, and treatment effects were low compared with other similar experiments. if study sites are less stable or treatment effects more drastic, a short-term evaluation is expected to be even less reliable. Knowledge on species dynamics at a site may help to choose the adequate spatial and temporal scale of investigation, and thus increase the efficiency of management experiments.