1. The successional dynamics of forests—from canopy openings to regeneration, maturation, and decay—influence the amount and heterogeneity of resources available for forest-dwelling organisms. ...Conservation has largely focused only on selected stages of forest succession (e.g., late-seral stages). However, to develop comprehensive conservation strategies and to understand the impact of forest management on biodiversity, a quantitative understanding of how different trophic groups vary over the course of succession is needed. 2. We classified mixed mountain forests in Central Europe into nine successional stages using airborne LiDAR. We analysed α- and β-diversity of six trophic groups encompassing approximately 3,000 species from three kingdoms. We quantified the effect of successional stage on the number of species with and without controlling for species abundances and tested whether the data fit the more-individuals hypothesis or the habitat heterogeneity hypothesis. Furthermore, we analysed the similarity of assemblages along successional development. 3. The abundance of producers, first-order consumers, and saprotrophic species showed a U-shaped response to forest succession. The number of species of producer and consumer groups generally followed this U-shaped pattern. In contrast to our expectation, the number of saprotrophic species did not change along succession. When we controlled for the effect of abundance, the number of producer and saproxylic beetle species increased linearly with forest succession, whereas the U-shaped response of the number of consumer species persisted. The analysis of assemblages indicated a large contribution of succession-mediated β-diversity to regional γ-diversity. 4. Synthesis and applications. Depending on the species group, our data supported both the more-individuals hypothesis and the habitat heterogeneity hypothesis. Our results highlight the strong influence of forest succession on biodiversity and underline the importance of controlling for successional dynamics when assessing successional stages with highest diversity (early and late successional stages) are currently strongly underrepresented in the forests of Central Europe. We thus recommend that conservation strategies aim at a more balanced representation of all successional stages.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
1. Dead wood is a habitat for numerous fungal species, many of which are important agents of decomposition. Previous studies suggested that wood-inhabiting fungal communities are affected by climate, ...availability of dead wood in the surrounding landscape and characteristics of the colonized dead-wood object (e.g. host tree species). These findings indicate that different filters structure fungal communities at different scales, but how these factors individually drive fungal fruiting diversity on dead-wood objects is unknown. 2. We conducted an orthogonal experiment comprising 180 plots (0.1 ha) in a random block design and measured fungal fruit body richness and community composition on 720 dead-wood objects over the first 4 years of succession. The experiment allowed us to disentangle the effects of the host (beech and fir; logs and branches) and the environment (microclimate: sunny and shady plots; local dead wood: amount and heterogeneity of dead wood added to plot). 3. Variance partitioning revealed that the host was more important than the environment for the diversity of wood-inhabiting fungi. A more detailed model revealed that host tree species had the highest independent effect on richness and community composition of fruiting species of fungi. Host size had significant but low independent effects on richness and community composition of fruiting species. Canopy openness significantly affected the community composition of fruiting species. By contrast, neither local amount nor heterogeneity of dead wood significantly affected the fungal diversity measures. 4. Synthesis. Our study identified host tree species as a more important driver of the diversity of wood-inhabiting fungi than the environment, which suggests a hostcentred filter of this diversity in the early phase of the decomposition process. For the conservation of wood-inhabiting fungi, a high variety of host species in various microclimates is more important than the availability of dead wood at the stand level.
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BFBNIB, FZAB, GIS, IJS, INZLJ, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZRSKP
Phenology, the seasonal timing of life events, is an essential component of diversity patterns. However, the mechanisms involved are complex and understudied. Body colour may be an important factor, ...because dark-bodied species absorb more solar radiation, which is predicted by the Thermal Melanism Hypothesis to enable them to thermoregulate successfully in cooler temperatures. Here we show that colour lightness of dragonfly assemblages varies in response to seasonal changes in solar radiation, with darker early- and late-season assemblages and lighter mid-season assemblages. This finding suggests a link between colour-based thermoregulation and insect phenology. We also show that the phenological pattern of dragonfly colour lightness advanced over the last decades. We suggest that changing seasonal temperature patterns due to global warming together with the static nature of solar radiation may drive dragonfly flight periods to suboptimal seasonal conditions. Our findings open a research avenue for a more mechanistic understanding of phenology and spatio-phenological impacts of climate warming on insects.
1. Logging to "salvage" economic returns from forests affected by natural disturbances has become increasingly prevalent globally. Despite potential negative effects on biodiversity, salvage logging ...is often conducted, even in areas otherwise excluded from logging and reserved for nature conservation, inter alia because strategic priorities for post-disturbance management are widely lacking. 2. A review of the existing literature revealed that most studies investigating the effects of salvage logging on biodiversity have been conducted less than 5 years following natural disturbances, and focused on non-saproxylic organisms. 3. A meta-analysis across 24 species groups revealed that salvage logging significantly decreases numbers of species of eight taxonomic groups. Richness of dead wood dependent taxa (i.e. saproxylic organisms) decreased more strongly than richness of non-saproxylic taxa. In contrast, taxonomic groups typically associated with open habitats increased in the number of species after salvage logging. 4. By analysing 134 original species abundance matrices, we demonstrate that salvage logging significantly alters community composition in 7 of 17 species groups, particularly affecting saproxylic assemblages. 5. Synthesis and applications. Our results suggest that salvage logging is not consistent with the management objectives of protected areas. Substantial changes, such as the retention of dead wood in naturally disturbed forests, are needed to support biodiversity. Future research should investigate the amount and spatio-temporal distribution of retained dead wood needed to maintain all components of biodiversity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Secondary forests and plantations increasingly dominate the tropical wooded landscape in place of primary forests. The expected reduction of biodiversity and its impact on ecological functions ...provided by these secondary forests are of major concern to society and ecologists. The potential effect of biodiversity loss on ecosystem functioning depends largely on the associated loss in the functional diversity of animal and plant assemblages, i.e., the degree of functional redundancy among species. However, the relationship between species and functional diversity is still poorly documented for most ecosystems. Here, we analyze how changes in the species diversity of groundâforaging ant assemblages translate into changes of functional diversity along a successional gradient of secondary forests in the Atlantic Forest of Brazil. Our analysis uses continuous measures of functional diversity and is based on four functional traits related to resource use of ants: body size, relative eye size, relative leg length, and trophic position. We find a strong relationship between species and functional diversity, independent of the functional traits used, with no evidence for saturation in this relationship. Recovery of species richness and diversity of ant assemblages in tropical secondary forests was accompanied by a proportional increase of functional richness and diversity of assemblages. Moreover, our results indicate that the increase in functional diversity along the successional gradient of secondary forests is primarily driven by rare species, which are functionally unique. The observed loss of both species and functional diversity in secondary forests offers no reason to believe that the ecological functions provided by secondary forests are buffered against species loss through functional redundancy.
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The factors determining gradients of biodiversity are a fundamental yet unresolved topic in ecology. While diversity gradients have been analysed for numerous single taxa, progress towards general ...explanatory models has been hampered by limitations in the phylogenetic coverage of past studies. By parallel sampling of 25 major plant and animal taxa along a 3.7 km elevational gradient on Mt. Kilimanjaro, we quantify cross-taxon consensus in diversity gradients and evaluate predictors of diversity from single taxa to a multi-taxa community level. While single taxa show complex distribution patterns and respond to different environmental factors, scaling up diversity to the community level leads to an unambiguous support for temperature as the main predictor of species richness in both plants and animals. Our findings illuminate the influence of taxonomic coverage for models of diversity gradients and point to the importance of temperature for diversification and species coexistence in plant and animal communities.
With the aim of wood production with negligible negative effects on biodiversity and ecosystem processes, a silvicultural practice of selective logging with natural regeneration has been implemented ...in European beech forests (Fagus sylvatica) during the last decades. Despite this near-to-nature strategy, species richness of various taxa is lower in these forests than in unmanaged forests. To develop guidelines to minimize the fundamental weaknesses in the current practice, we linked functional traits of saproxylic beetle species to ecosystem characteristics. We used continental-scale data from 8 European countries and regional-scale data from a large forest in southern Germany and forest-stand variables that represented a gradient of intensity of forest use to evaluate the effect of current near-to-nature management strategies on the functional diversity of saproxylic beetles. Forest-stand variables did not have a statistically significant effect on overall functional diversity, but they did significantly affect community mean and diversity of single functional traits. As the amount of dead wood increased the composition of assemblages shifted toward dominance of larger species and species preferring dead wood of large diameter and in advanced stages of decay. The mean amount of dead wood across plots in which most species occurred was from 20 to 60 m
3
/ha. Species occurring in plots with mean dead wood >60 m
3
/ha were consistently those inhabiting dead wood of large diameter and in advanced stages of decay. On the basis of our results, to make current wood-production practices in beech forests throughout Europe more conservation oriented (i.e., promoting biodiversity and ecosystem functioning), we recommend increasing the amount of dead wood to >20 m
3
/ha; not removing dead wood of large diameter (50 cm) and allowing more dead wood in advanced stages of decomposition to develop; and designating strict forest reserves, with their exceptionally high amounts of dead wood, that would serve as refuges for and sources of saproxylic habitat specialists.
Con el objeto de producir madera con efectos negativos insignificantes sobre la biodiversidad y los procesos del ecosistema, durante las últimas décadas se ha implementado una práctica silvícola de tala selectiva con regeneración natural en bosques europeos de haya (Fagus sylvatica). No obstante esta estrategia casi natural, la riqueza de especies de varios taxa es menor en estos bosques que en bosques no manejados. Para desarrollar directrices para minimizar las debilidades fundamentales en la práctica actual, relacionamos atributos funcionales de especies de escarabajos saproxílicos con las características del ecosistema. Utilizamos datos a escala continental de 8 países europeos y datos a escala regional de un bosque extenso en el sur de Alemania y variables de bosques que representaron un gradiente de intensidad del uso de bosques para evaluar el efecto de las estrategias de manejo casi naturales sobre la diversidad funcional de los escarabajos saproxílicos. Las variables de bosques no tuvieron un efecto significativo sobre la diversidad funcional total, pero afectaron significativamente la media y diversidad de atributos funcionales individuales. A medida que incrementó la cantidad de madera muerta, la composición de los ensambles cambió hacia dominancia de especies mayores y de especies que prefieren madera muerta de mayor diámetro y con estadios avanzados de descomposición. La cantidad promedio de madera muerta en las parcelas en donde ocurrió la mayor parte de las especies fue de 20 - 60 m
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/ha, Las especies que ocurrieron en parcelas con un promedio de madera muerta >60 m
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/ha consistentemente fueron las que habitan en madera muerta de diámetro grande y con estadios avanzados de descomposición. Con base en nuestros resultados, para que las prácticas de producción de madera en bosques de haya en Europa están más orientadas a la conservación (i.e., promuevan el funcionamiento de la biodiversidad y del ecosistema), recomendamos incrementar la cantidad de madera muerta a >20 m
3
/ha; no remover la madera muerta de diámetro mayor a 50 cm y permitiendo más madera muerta en etapas de descomposición avanzadas; y diseñar reservas forestales estrictas, con sus cantidades de madera muerta excepcionalmente altas, que podrían funcionar como refugios para y como fuentes de especialistas de hábitats saproxílicos.
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1. Wood-decaying fungi are crucial for the functioning of forest ecosystems. We tested the hypotheses that on coarse woody debris (CWD), the abundance, diversity and composition of fungi depend more ...on the amount of available resource than on macro- or microclimate, and that on fine woody debris (FWD) more on the microclimate because of the rapid desiccation of thin woody debris. 2. We sampled 7183 dead wood objects with 10 818 fungal samples on 290 plots along four transects, from 650 to 1450 m a.s.l., in the Bavarian Forest National Park, Germany, Overall, we recorded 263 species (54 only on FWD and 71 only on CWD). 3. For each plot, we characterized the macroclimate using field data and a terrain model. Microclimate variables were extracted from remote-sensing and ground surveys. Resource availability was characterized by measuring the amount, tree species composition, diameter and rotting stage of all dead wood objects. We extracted principal components from each of the three data sets for further analyses. 4. The number of species found per sampled surface area of woody debris indicated that the fungal community on FWD needs a much lower surface area than that on CWD; FWD probably provides more niches per unit surface area than CWD. The abundance of fungi (and therefore also species density) living on FWD and CWD as well as the fungal community composition on CWD were clearly driven by variables characterizing the amount and diversity of the resource. In general, the surface area was the most important factor for abundance of species. In contrast, the community composition on FWD was better predicted by variables characterizing the microclimate. 5. Synthesis. Our results supported the hypotheses that the amount of available resources is more important than macroclimate for fungi living on CWD, and microclimate is more important for fungi living on FWD. Therefore, both dead wood removal and silviculture, which, like logging, open the canopy and increases sunlight exposure, will strongly affect the diversity of wood-decaying fungi in forests. For the conservation of this important group of organisms in forests, silvicultural strategies are more important than climate.
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Whether diversity and composition of avian communities is determined primarily by responses of species to the floristic composition or to the structural characteristics of habitats has been an ...ongoing debate, at least since the publication of MacArthur and MacArthur (1961). This debate, however, has been hampered by two problems: 1) it is notoriously time consuming to measure the physiognomy of habitat, particularly in forests, and 2) rigorous statistical methods to predict the composition of bird assemblages from assemblages of plants have not been available. Here we use airborne laser scanning (lidar) to measure the habitat (vegetation) structure of a montane forest across large spatial extents with a very fine grain. Furthermore, we use predictive co-correspondence and canonical correspondence analyses to predict the composition of bird communities from the composition and structure of another community (i.e. plants). By using these new techniques, we show that the physiognomy of the vegetation is a significantly more powerful predictor of the composition of bird assemblages than plant species composition in the field and as well in the shrub/tree layer, both on a level of
p
<
0.001. Our results demonstrate that ecologists should consider remote sensing as a tool to improve the understanding of the variation of bird assemblages in space and time. Particularly in complex habitats, such as forests, lidar is a valuable and comparatively inexpensive tool to characterize the structure of the canopy even across large and rough terrain.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Small-scale studies have shown that colour lightness variation can have important physiological implications in ectotherms, with darker species having greater heating rates, as well as protection ...against pathogens and photooxidative damage. Using data for 41% (3059) of all known frog and toad species (Anura) from across the world, we reveal ubiquitous and strong clines of decreasing colour lightness towards colder regions and regions with higher pathogen pressure and UVB radiation. The relative importance of pathogen resistance is higher in the tropics and that of thermoregulation is higher in temperate regions. The results suggest that these functions influence colour lightness evolution in anurans and filtered for more similarly coloured species under climatic extremes, while their concurrent importance resulted in high within-assemblage variation in productive regions. Our findings indicate three important functions of colour lightness in anurans - thermoregulation, pathogen and UVB protection - and broaden support for colour lightness-environment relationships in ectotherms.
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