1,721,024 research outputs found
Dataset_Ehbrecht et al_Recovery of forest structural complexity during secondary succession in a human-modified neotropical landscape
No full textThe dataset contains all variables used in Ehbrecht et al., "Recovery of forest structural complexity during secondary succession in a human-modified neotropical landscap
Ehbrecht et al_Global patterns and climatic controls of forest structural complexity (SSCI)
No full textThe dataset summarizes measured plot and aggregated site values of forest structural complexity (SSCI) for boreal, temperate, subtropical and tropical primary forests. Aggregated site values were used to model global patterns of potential forest structural complexity. The dataset includes modelled SSCI-values for a global sampling grid with 50 km distance between sample points (21,851 points with lat/long coordinates, biome, realm, ecoregion, annual precipitation, precipitation seasonality and SSCI)
Ehbrecht et al_Global patterns and climatic controls of forest structural complexity_Map of potential structural complexity across biomes
No full textEhbrecht et al. "Global patterns and climatic controls of forest structural complexity". Maps of modelled potential structural complexity and confidence intervals for the (sub-)tropical moist broadleaf forest, (sub-)tropical tree savanna and woodland, temperate broadleaf and mixed forest, temperate conifer forest, and boreal forest biome. Extent of model predictions is confined to ecoregions that were classified as forest or woodland according to Olson et al. (2001)
Effects of structural heterogeneity on the diurnal temperature range in temperate forest ecosystems
No full textThe microclimate in forest ecosystems can be altered by modifications of stand structure due to forest management or natural forest development. Current forest management practices in Central Europe and North America aim to promote structural heterogeneity and maintain forest canopy cover, which is known to be a major driver of forest microclimate. Here, we investigated the impacts of forest management and structural heterogeneity on the diurnal temperature range (DTR) in 128 managed forest stands in three climatically different locations (Swabian Alb, Hainich-Dün and Schorfheide-Chorin) in Central Europe. Increasing structural heterogeneity by promoting tree size diversity and differentiation increased vertical stratification and resulted in an impaired DTR during the vegetation period. Linear regression models with geographic location, elevation above sea level, canopy openness and measures of structural heterogeneity as explanatory variables explained 79.4–80.9% of variance in DTR. However, the overall effect of structural heterogeneity on DTR was small. Differences in DTR between plots of different main tree species could be attributed to differences in canopy openness and light transmission, whereas tree species diversity had no significant effect on DTR. Unmanaged forests were characterized by a significantly lower DTR than managed, even-aged forests. DTR in uneven-aged stands managed under single tree selection was comparable to unmanaged stands. Terrestrial laser scanning (TLS) derived measures of canopy openness and vertical structure allowed to explain 79.4% of variance in DTR considering geographic location and elevation, which can also be assessed by TLS with integrated GPS and an altimeter. We conclude that structural characteristics of forest stands other than canopy openness contribute marginally to variation in forest microclimate. However, the analyses of structure-microclimate analyses indicate that effects of stand structure on DTR might be more pronounced in regions with low precipitation during the vegetation period
Application of point cloud data to assess edge effects on rainforest structural characteristics in tropical Sumatra, Indonesia
No full textAbstract Context In forestry, edge zones created by forest degradation and fragmentation are more susceptible to disturbances and extreme weather events. The increase in light regime near the edge can greatly alter forest microclimate and forest structure in the long term. In this context, understanding edge effects and their impact on forest structure could help to identify risks, facilitate forest management decisions or prioritise areas for conservation. Objective In this paper, we focus on the application of airborne laser scanning (ALS) data to assess the impact of edge effects on forest structural metrics in degraded rainforests in Sumatra, Indonesia. Changes in structural heterogeneity with respect to distance from an edge were also quantified. Methods We used 22 ALS structural metrics extracted from 105 plots in secondary forests adjacent to oil palm plantations and analysed the change in canopy structure across edge-to-interior transects. In addition, 91 plots taken from less disturbed areas were used as reference for comparison with the near-to-edge plots. Results Our analysis found strong evidence of degradation in the secondary forests studied, with multiple edge interactions resulting in a non-diminishing effect even at long distances from the forest edge. On average, we observed a large decrease of about 40% in all metrics of canopy height and about 25% in some metrics of canopy structure across all distances from an edge when compared to the interior forest conditions. Thus, in our forests, canopy height and structure were more susceptible to edge effects than metrics related to canopy gaps. Finally, the degraded forest in our study exhibited lower structural complexity, both at patch and landscape levels, suggesting that disturbances can greatly alter structural complexity in tropical rainforests. Conclusion Our study confirms the potential of ALS-derived vegetation metrics to study and understand the effects of forest edges and the associated changes in structural complexity over large areas in tropical rainforests. The approach followed here is transferrable to similarly fragmented landscapes in the tropics.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Georg-August-Universität Göttingen http://dx.doi.org/10.13039/50110000338
African Mahogany (Khaya anthotheca) negative distance-dependent recruitment in a Ugandan rainforest and implications for restoration
No full textAssessing different components of three-dimensional forest structure with single-scan terrestrial laser scanning: A case study
No full textEfficient quantification of the three-dimensional forest structure is of increasing importance for our understanding of forest functions and services, but it remains challenging with conventional methods. We used a single-scan ground-based laser approach in stands with a known difference in management history and associated differences in structures. The data were used to test whether the measurement approach could distinguish various structural measures among the stands, including overall density, vertical structure, competitive conditions for regeneration, horizontal visibility, and three-dimensional structural variability. In general, our data reflected known differences in stand structure. However, in some cases the different measures showed contradicting results, highlighting the limited information represented in each measure when considered in isolation. At the same time, our results suggested that all components of stand structure do not develop in sync. The variability of horizontal and vertical structural heterogeneity appears to be a good indicator of structural elements, typically found in old-growth forests, i.e., spatially homogenous (scale independent) horizontal structural variability in combination with a scale-dependent vertical structural variability. In addition, our results provided information with direct management implications. For example, gap creation, a prominent practice in restoration treatments in the region, increased spatial variability, but the hard edges and removal of all trees inside the gap, are not reflecting structural conditions found in our old-growth stand. In summary, our results suggest that this new technology can efficiently provide objective and holistic inventories of stand structures. However, more work is needed to fully understand the implications of the novel structural measures for ecosystem processes and services. (C) 2016 Published by Elsevier B.V
Impacts of forest management on stand and landscape-level microclimate heterogeneity of European beech forests
No full textAbstract Context Forest microclimate influences biodiversity and plays a crucial role in regulating forest ecosystem functions. It is modified by forest management as a result of changes in forest structure due to tree harvesting and thinning. Objectives Here, we investigate the impacts of even-aged and uneven-aged forest management on stand- and landscape-level heterogeneity of forest microclimates, in comparison with unmanaged, old-growth European beech forest. Methods We combined stand structural and topographical indices derived from airborne laser scanning with climate observations from 23 meteorological stations at permanent forest plots within the Hainich region, Germany. Based on a multiple linear regression model, we spatially interpolated the diurnal temperature range (DTR) as an indicator of forest microclimate across a 4338 ha section of the forest with 50 m spatial resolution. Microclimate heterogeneity was measured as α-, β-, and γ-diversity of thermal niches (i.e. DTR classes). Results Even-aged forests showed a higher γ-diversity of microclimates than uneven-aged and unmanaged forests. This was mainly due to a higher β-diversity resulting from the spatial coexistence of different forest developmental stages within the landscape. The greater structural complexity at the stand-level in uneven-aged stands did not increase α-diversity of microclimates. Predicted DTR was significantly lower and spatially more homogenous in unmanaged forest compared to both types of managed forest. Conclusion If forest management aims at creating a wide range of habitats with different microclimates within a landscape, spatially co-existing types of differently managed and unmanaged forests should be considered, instead of focusing on a specific type of management, or setting aside forest reserves only.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Georg-August-Universität Göttingen 50110000338
From tree to stand-level structural complexity — Which properties make a forest stand complex?
No full textEffective number of layers: A new measure for quantifying three-dimensional stand structure based on sampling with terrestrial LiDAR
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