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Plieninger T.,Berlin Brandenburg Academy of science and Humanities | Plieninger T.,Humboldt University of Berlin | Rolo V.,University of Extremadura | Moreno G.,University of Extremadura
Ecosystems | Year: 2010

In Central-Western Spain, forests and woodlands composed of Quercus sp. support outstanding levels of biodiversity, but there is increasing concern about their long-term persistence due to a lack of regeneration. We hypothesize that this regenerative lack is operating on a large geographic scale; that there are differences in the abundance of regeneration between three oak species; that oak regeneration is governed mainly by forest management and structure; and that shrubs act as important physical protectors of seedlings and saplings. We analyzed whether densities of oak seedlings and saplings in several size classes were related to stand-structure, understory, and physiographic variables potentially affecting regeneration. Data collected at a regional level (1 km × 1 km grid) by the Spanish Forest Inventory were evaluated from 2,816 plots. Results revealed that regeneration failure was common for all size categories, from small seedlings to large saplings, and for the three oak species studied, especially the evergreens. Of the Quercus ilex, Q. suber, and Q. pyrenaica plots studied, 49%, 62%, and 20% were lacking any small seedlings, and 82%, 96%, and 56% did not have any large saplings, respectively. Regeneration was positively correlated with tree cover and density, especially of small and medium-sized trees, and negatively correlated with the presence of large trees, indicating that regeneration failure is mostly associated with more open, uniform, and/or aged woodlands. Regeneration densities of Q. ilex and Q. suber were positively correlated with all understory variables, suggesting that the presence of pioneer shrubs represent a major safe site for early tree recruitment, independent from specific shrub species. © 2010 Springer Science+Business Media, LLC. Source

Schaich H.,Albert Ludwigs University of Freiburg | Plieninger T.,Berlin Brandenburg Academy of science and Humanities | Plieninger T.,Copenhagen University
Forest Ecology and Management | Year: 2013

In European cultural landscapes, forest area is subdivided into a mosaic of stands of different ownership types and sizes. Differences in ownership and different goals of the owners have a potentially decisive influence on the provision of forest ecosystem services and the implementation of instruments for the conservation of biodiversity. This study hypothesizes that forest ownership is an indirect determinant of forest management approaches and is thereby relevant for biodiversity conservation and carbon sequestration. We compared structure and species composition of forest stands in clusters of different ownership types, namely state-owned, municipal and small-scale private forests, in southwestern Germany. Although close-to-nature management has been practiced in public forests for some time, our study demonstrates that tree species diversity does not vary significantly between ownership types but is correlated with biogeographical factors. However, small-scale private forests comprise significantly higher levels of structural diversity, more dead wood and greater carbon storage capacity than both categories of public forests. This is contrary to other studies, where publicly owned lands were found to host higher biodiversity, and differs from the global trend, where continued fragmentation of private lands threatens forest sustainability. The importance of small-scale private forests, e.g. for the conservation of old-growth and dead wood dependent species, seems due to less intensive and more diverse forest management. The role of such forests for biodiversity conservation and carbon regulation may be jeopardized through forest conversion and wood mobilization initiatives accompanying rising natural resource prices. To safeguard forest biodiversity and ecosystem services, ownership-specific incentive schemes should be coordinated and refined. In public forests, close-to-nature management approaches should be complemented with binding goals aimed at promoting old-growth forest attributes and allowing site-specific variation in management practices. To conserve diversity in small-scale private forests, financial incentives and remuneration schemes for the provisioning of forest biodiversity and ecosystem services should be developed. Moreover, consulting and the provision of information on sustainable forest and conservation management should be intensified. © 2013 Elsevier B.V. Source

Plieninger T.,Berlin Brandenburg Academy of science and Humanities | Plieninger T.,Humboldt University of Berlin
Applied Geography | Year: 2012

This study explores the potential of historical maps to detect, measure and monitor changes of trees outside forests. The main goal is to assess local-level changes of scattered trees and orchards and their land-use determinants in two areas in Southern Germany between 1901/1905 and 2009. Firstly, overall landscape changes are recorded. Secondly, the spatial-temporal trajectories of scattered trees and their land-use determinants are identified. Thirdly, changes in quantity and fragmentation patterns of traditional orchards are analyzed in their relationship to overall land-cover change. The results confirm major losses in scattered trees, mainly due to urbanization, agricultural intensification, and land abandonment. They further reveal that, while orchards have persisted in total area, they have undergone critical changes toward a simplified landscape structure and loss of the traditional land-use mosaic, which is a characterizing feature of high nature value landscapes. Multi-temporal assessment showed that most trends have been continuous and did not change directions over time, but rather accelerated during periods of rapid change (most dramatically in the 1950-1990 period). The case of orchards and scattered trees illustrates a major problem of cultural landscapes in Europe: Semi-natural landscape features of high nature value are threatened by both intensification and abandonment of land uses. This makes their conservation a potentially costly enterprise, as both opportunity costs for lost alternative land uses and for conservation management costs arise. © 2011 Elsevier Ltd. Source

Germer S.,Berlin Brandenburg Academy of science and Humanities | Werther L.,University of Potsdam | Elsenbeer H.,University of Potsdam
Journal of Hydrology | Year: 2010

Stemflow was monitored on event-basis in an undisturbed open tropical rainforest with a large number of palm trees located in the southwestern Amazon basin of Brazil. We estimated stemflow of 24 trees with a diameter at breast height (DBH) over 5cm and of 16 juvenile and eight aborescent babassu palms (Orbignya phalerata Mart.). To obtain within-event stemflow variability we monitored stemflow of one additional aborescent babassu palm with a tipping-bucket rain gauge at 5-min intervals. Total stemflow of the forest accounted for 8.0±1.8% (S.E.) of incident rainfall and reached the forest floor over an area corresponding to the total basal area that sums up to only 0.3% of the plot area. The most influential predictive variables for stemflow generation were DBH and rainfall amount. The stemflow parameter 'funneling ratio', which is normalized for DBH and rainfall amount, was particularly useful to highlight the relevance of small trees (DBH≤10cm) for stemflow generation. Small trees and babassu palms had significantly higher funneling ratios than larger trees (median funneling ratios: 15-27 and 1-2, respectively). The maximum 5-min stemflow intensity (1232mmh-1) was 15-fold that of rainfall. High funneling ratios of small trees and babassu palms suggest that high stemflow intensities are the rule rather than the exception. Therefore, we expect small trees and babassu palms to influence hydrologic processes as subsurface flow, saturation overland flow or groundwater recharge. Consequently, stemflow studies should include all DBH classes and species with exceptionally high funneling ratios. For modeling purposes, stemflow should be estimated and not just assumed if study sites have a large number of palms or of small trees. © 2010 Elsevier B.V. Source

Germer S.,Berlin Brandenburg Academy of science and Humanities | Neill C.,The Ecosystems Center | Krusche A.V.,University of Sao Paulo | Elsenbeer H.,University of Potsdam
Journal of Hydrology | Year: 2010

Soil compaction that follows the clearing of tropical forest for cattle pasture is associated with lower soil hydraulic conductivity and increased frequency and volume of overland flow. We investigated the frequency of perched water tables, overland flow and stormflow in an Amazon forest and in an adjacent 25-year-old pasture cleared from the same forest. We compared the results with the frequencies of these phenomena estimated from comparisons of rainfall intensity and soil hydraulic conductivity. The frequency of perched water tables based on rainfall intensity and soil hydraulic conductivity was expected to double in pasture compared with forest. This corresponded closely with an approximate doubling of the frequency of stormflow and overland flow in pasture. In contrast, the stormflow volume in pasture increased 17-fold. This disproportional increase of stormflow resulted from overland flow generation over large areas of pasture, while overland flow generation in the forest was spatially limited and was observed only very near the stream channel. In both catchments, stormflow was generated by saturation excess because of perched water tables and near-surface groundwater levels. Stormflow was occasionally generated in the forest by rapid return flow from macropores, while slow return flow from a continuous perched water table was more common in the pasture. These results suggest that deforestation for pasture alters fundamental mechanisms of stormflow generation and may increase runoff volumes over wide regions of Amazonia. © 2009 Elsevier B.V. All rights reserved. Source

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