Key factors affecting the future provision of tree-based forest ecosystem goods and services

The continuous provisioning of forest ecosystem goods and services (EGS) is of considerable interest to society. To provide insights on how much EGS provision will change with a changing climate and which factors will influence this change the most, we simulated forest stands on six climatically different sites in Central Europe under several scenarios of species diversity, management, and climate change. We evaluated the influence of these factors on the provision of a range of tree-based EGS, represented by harvested basal area, total biomass, stand diversity, and productivity. The most influential factor was species diversity, with diverse forest stands showing a lower sensitivity to climate change than monocultures. Management mainly influenced biomass, with the most intensively managed stands retaining more of their original biomass than others. All three climate-change scenarios yielded very similar results. We showed that (1) only few factor combinations perform worse under climate-change conditions than others, (2) diversity aspects are important for adaptive management measures, but for some indicators, management may be more important than diversity, and (3) at locations subject to increasing drought, the future provision of EGS may decrease regardless of the factor combination. This quantitative evaluation of the influence of different factors on changes in the provision of forest EGS with climate change represents an important step towards the design of more focused adaptation strategies and highlights key factors that should be considered in simulation studies under climate chang

Key factors affecting the future provision of tree-based forest ecosystem goods and services

ISSN:0165-0009ISSN:1573-148

Wind disturbance in mountain forests: Simulating the impact of management strategies, seed supply, and ungulate browsing on forest succession

Fifteen years after the heavy storm "Vivian", it is still not clear how succession in subalpine forests that were affected by the storm will continue and when regrowing forests will provide effective protection from natural hazards such as avalanches. We used a simulation model to evaluate forest succession, forest structure and the protective effect in subalpine blowdown areas after 50 simulation years under different scenarios. The scenarios included the effects of different management strategies such as clearing the fallen logs or leaving the sites untouched ("uncleared"), variations in seed supply, and ungulate browsing. The simulation results indicated that forest structure was heterogeneous after 50 years, with a high amount of trees between 11 and 100 cm hei-ht, and a low amount of trees taller than I m. The number of trees > 5 m, which is important for the protective effect of a site, was lower at uncleared areas if the area was covered with high amounts of fallen logs, but diversity of microsites was higher than at cleared areas. We found that it is particularly important that abundant seed supply occurs within the first few years after the blowdown at cleared sites, because in later stages there was high competition by tall herbs, which prevented the establishment of tree regeneration. Larger time lags between seed years in the simulations led to retarded tree regeneration. Particularly at cleared sites, ungulate browsing retarded tree regeneration. In contrast, uncleared sites had a higher potential to recover from high browsing pressure due to a high amount of favourable microsites that are provided by decaying logs. These results of our model simulations may help understanding the dynamics of forest regeneration and providing perspectives for management after blowdown events. (C) 2007 Elsevier B.V. All rights reserved

Temporal stability in forest productivity increases with tree diversity due to asynchrony in species dynamics

International audienceTheory predicts a positive relationship between biodiversity and stability in ecosystem properties, while diversity is expected to have a negative impact on stability at the species level. We used virtual experiments based on a dynamic simulation model to test for the diversity–stability relationship and its underlying mechanisms in Central European forests. First our results show that variability in productivity between stands differing in species composition decreases as species richness and functional diversity increase. Second we show temporal stability increases with increasing diversity due to compensatory dynamics across species, supporting the biodiversity insurance hypothesis. We demonstrate that this pattern is mainly driven by the asynchrony of species responses to small disturbances rather than to environmental fluctuations, and is only weakly affected by the net biodiversity effect on productivity. Furthermore, our results suggest that compensatory dynamics between species may enhance ecosystem stability through an optimisation of canopy occupancy by coexisting species

Long-term response of forest productivity to climate change is mostly driven by change in tree species composition

Climate change affects ecosystem functioning directly through impacts on plant physiology, resulting in changes of global productivity. However, climate change has also an indirect impact on ecosystems, through changes in the composition and diversity of plant communities. The relative importance of these direct and indirect effects has not been evaluated within a same generic approach yet. Here we took advantage of a novel approach for disentangling these two effects in European temperate forests across a large climatic gradient, through a large simulation-based study using a forest succession model. We first showed that if productivity positively correlates with realized tree species richness under a changed climate, indirect effects appear pivotal to understand the magnitude of climate change impacts on forest productivity. We further detailed how warmer and drier conditions may affect the diversity-productivity relationships (DPRs) of temperate forests in the long term, mostly through effects on species recruitment, ultimately enhancing or preventing complementarity in resource use. Furthermore, losing key species reduced the strength of DPRs more severely in environments that are becoming climatically harsher. By disentangling direct and indirect effects of climate change on ecosystem functioning, these findings explain why high-diversity forests are expected to be more resilient to climate change

Vegetation and disturbance history of the Bavarian Forest National Park, Germany

National parks are supposed to protect large-scale ecological processes, along with species and ecosystems. Detailed knowledge about past vegetation and disturbance regimes therefore forms an important basis for appropriate management. In the Bavarian Forest National Park in SE Germany, we therefore studied fossil pollen, spores and macrofossils from lake Rachelsee, a nearby mire, and Stangenfilz mire, all lying at higher elevations. Results indicate that deciduous forest on lower slopes (ca. 500–1,000 m a.s.l.) were first affected by humans in Neolithic times ca. 4500 bc with marked declines of Tilia, Ulmus and Fraxinus. High-montane mixed forests (1,000–1,450 m a.s.l.) were in a near-natural state consisting of Picea, Abies and Fagus in comparable proportions up to ca. 500 bc (a natural baseline condition), after which they were impacted by forest grazing and/or logging, starting between early-Roman times to early-Medieval times depending on location. Abies especially declined markedly. Forest partially recovered during the migration period fifth-eighth century ad, especially Carpinus, but not Abies. Subsequently, deforestation increased at lower elevation for food production, and forest grazing and wood extraction at higher elevation led to a further strong decline of Abies around ad 1000 near Rachelsee. After that, nutrient levels increased continually at all elevations, and a forest fire occurred in the 13th century near Stangenfilz. During the 19th century, forests around Rachelsee recovered partially whereas overgrazing of Stangenfilz resulted in a hiatus. Forests declined further in the 20th century around the study sites, but after ca. ad 1960 less so around Rachelsee thanks to local conservation measures. Historically recorded large-scale bark-beetle infestations following heavy storms, such as in the ad 1870s and 1980s, hardly left traces in the pollen data. From a palaeoecological perspective the Park’s no-intervention management strategy is well-suited to facilitate recovery of original forest functioning and diversity, as it is slowly leading to renewal of natural mixed forest of Abies, Picea and Fagus. This development may have considerable influence on the future disturbance regime, and the insights obtained will be important for the park management

Long-term response of forest productivity to climate change is mostly driven by change in tree species composition

Climate change affects ecosystem functioning directly through impacts on plant physiology, resulting in changes of global productivity. However, climate change has also an indirect impact on ecosystems, through changes in the composition and diversity of plant communities. The relative importance of these direct and indirect effects has not been evaluated within a same generic approach yet. Here we took advantage of a novel approach for disentangling these two effects in European temperate forests across a large climatic gradient, through a large simulation-based study using a forest succession model. We first showed that if productivity positively correlates with realized tree species richness under a changed climate, indirect effects appear pivotal to understand the magnitude of climate change impacts on forest productivity. We further detailed how warmer and drier conditions may affect the diversity-productivity relationships (DPRs) of temperate forests in the long term, mostly through effects on species recruitment, ultimately enhancing or preventing complementarity in resource use. Furthermore, losing key species reduced the strength of DPRs more severely in environments that are becoming climatically harsher. By disentangling direct and indirect effects of climate change on ecosystem functioning, these findings explain why high-diversity forests are expected to be more resilient to climate change