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91.
Effects of atmospheric and climate change at the timberline of the Central European Alps 总被引:1,自引:0,他引:1
Gerhard Wieser Rainer Matyssek Roland Luzian Peter Zwerger Peter Pindur Walter Oberhuber Andreas Gruber 《Annals of Forest Science》2009,66(4):402-402
92.
Andreas Gruber Jolanda Zimmermann Gerhard Wieser Walter Oberhuber 《Annals of Forest Science》2009,66(5):503-503
93.
Mariangela N. Fotelli Michael Nahm Kalliopi Radoglou Heinz Rennenberg George Halyvopoulos Andreas Matzarakis 《Forest Ecology and Management》2009
Due to its wide European distribution and its drought-susceptibility, beech (Fagus sylvatica L.) received intensive attention recently in the light of global warming. Contrary to central European beech ecosystems, little is known about the ecophysiology of beech at its south-eastern European distribution limit. Here we tested whether climatic fluctuations during a three-year period affected the ecophysiology of a beech site in Greece. Attention was paid at comparing our findings to the intense effects the 2003 extreme drought had on beech forests in central Europe. 相似文献
94.
One of the first steps in estimating the potential for reducing emissions from deforestation and forest degradation (REDD) initiatives is the proper estimation of the carbon components. There are still considerable uncertainties about carbon stocks in tropical rain forest, coming essentially from poor knowledge of the quantity and spatial distribution of forest biomass at the landscape level. 相似文献
95.
Anne C. Lang Werner Härdtle Helge Bruelheide Christian Geißler Karin Nadrowski Andreas Schuldt Mingjian Yu Goddert von Oheimb 《Forest Ecology and Management》2010
Trees are able to respond to their local biotic and abiotic environment with morphological adjustments which improve resource acquisition and, thus, growth. In forests, light is broadly recognised as one of the major factors determining growth, and morphological responses comprise changes in crown architecture and stem stature. On sloping terrain, the interplay of phototropism and gravitropism may further affect morphological growth characteristics. However, different tree species are expected to show species-specific responses. In this study, we analysed three growth characteristics of tree individuals belonging to four species of two functional groups (evergreen: Schima superba, Castanopsis eyrei, deciduous: Quercus serrata var. brevipetiolata, Castanea henryi) in a species-rich Chinese subtropical forest. Crown projection area, relative crown displacement and stem inclination were related to biotic (local species richness, functional richness, competition, stand age) and abiotic (slope aspect and inclination, soil depth) variables in the local neighbourhood of the tree individuals. We hypothesised that (i) there are species-specific differences in the morphological response of crown architecture and stem stature and (ii) that crown size and asymmetry as well as stem inclination are influenced by both, biotic and abiotic factors. In contrast to our expectations we were unable to reveal any species-specific differences in any of the three growth characteristics. The results of mixed effects models showed that crown area was mainly affected by the target tree's dbh and biotic variables related to neighbours (competition, functional diversity), whereas stem inclination was mainly influenced by slope. Relative crown displacement was influenced by both, biotic and abiotic variables. We conclude that growth responses resulting in crown displacement and stem inclination seem to be an important mechanism to ameliorate foraging for light in our study area, but that these responses appear to be species-independent. The interplay of stem inclination and crown displacement allows for a plastic response of tree individuals in biotically and abiotically heterogeneous environments. Our results indicate that forest management in this region should focus on functionally diverse stands which are promoting crown area positively resulting in increased growth rates of individual trees. 相似文献
96.
Wildfire risk related to hazards on people and assets is expected to increase in the face of climate change, especially in fire-prone environments such as the M... 相似文献
97.
Jürg Andreas Stückelberger Hans Rudolf Heinimann Edouard Charles Burlet 《European Journal of Forest Research》2006,125(4):377-390
Cost estimation is probably the most decisive factor in the process of computer-aided, preliminary planning for low-volume road networks. However, the cost of construction is normally assumed to be route-independent for a specific project area, resulting in sub-optimal layouts. This is especially true for mountainous terrain and in areas with unstable subsoil. Here, we present a model for more accurately estimating spatial variability in road life-cycle costs, based on terrain surface properties as well as geological properties of the subsoil. This parametric model incorporates four structural components: embankment, retaining structures, pavement, and drainage and stream-crossing structures. It is linked to a geo-database that allows users to derive location-specific parameter values as input. In applying this model, we have demonstrated that variability in costs ranges widely for mountainous areas, with the most expensive construction being approximately five times greater there than on more favorable sites. This variability strongly affects the optimal layout of a road network. First, when location-specific slope gradients are considered, costs are reduced by about 17% from those calculated via currently available engineering practices; when both slope gradient and geotechnical formations are included, those costs are decreased by about 20%. Second, the length of the road network is increased by about 4% and 10% respectively, compared with current practices. 相似文献
98.
Deliberatie transnationalism — Transnational governance,public participation and expert deliberation
Andreas Klinke 《Forest Policy and Economics》2009,11(5-6):348-356
Transboundary governance is increasingly characterized by the disentanglement from traditional state-centric institutions and the emergence of non-hierarchical and dialogue-oriented governance modes. Within the Great Lakes-regime between the USA and Canada, a form of transnational governance has been evolved, which produces democratic legitimacy and effectiveness through public participation and expert deliberation in argumentative procedures aiming at factual and common good oriented problem solving. The paper develops categories of participatory and deliberative democracy theory for transnational governance to conceptualize deliberative transnationalism and to identify and measure the deliberative quality in the Great Lakes-regime. Such categories are fair chances of access and influence in political processes, dialogue-oriented participation forms and collective problem solving capability. They serve as normative-analytical framework to appraise the potential of democratic legitimacy and effectiveness in transnational governance. 相似文献
99.
Plant species richness and diversity in urban and peri-urban gardens of Niamey,Niger 总被引:1,自引:0,他引:1
Hannah Bernholt Katja Kehlenbeck Jens Gebauer Andreas Buerkert 《Agroforestry Systems》2009,77(3):159-179
Urban and peri-urban agriculture (UPA) significantly contributes to food and nutritional security of urban dwellers in many
African countries. Economic and demographic pressures often lead to transformation of subsistence-oriented traditional homegardens
into commercial production units. Such transformation is claimed to result in decreasing plant diversity, particularly of
local species. A study was therefore undertaken in 51 gardens of Niamey, Niger, to assess the factors determining plant diversity
and the suitability of UPA for in situ conservation of plant genetic resources. In each garden, the number and abundance of
all human-used plant species were determined, and species density, Shannon index and Shannon evenness were calculated. In
the 51 surveyed gardens, a total of 116 plant species were cultivated, most of them for the production of fruits or vegetables.
Annual vegetables dominated, particularly exotic species grown for sale. In the cold season, an average of 14 species were
cultivated per garden, the Shannon index was 0.96 and evenness was 0.39. Commercial gardens had a species richness similar
to that of subsistence gardens, but a lower evenness (P < 0.005), caused by the dominance of a few vegetable species. Gardens of immigrants had a lower Shannon index than those
of members of the local Djerma ethnic group. Stepwise multiple regression analysis showed significant influence of various
variables on plant species richness and diversity parameters: garden size (richness and Shannon index), ethnicity of the gardener
(richness and evenness), gender of the gardener and cash-oriented production (evenness), household size (richness) and garden
possession status (Shannon index). Cluster analysis revealed the existence of five garden types. The highest species richness
and diversity, particularly of perennial and local species, was found in large, peri-urban, commercial gardens managed by
relatively wealthy, elderly gardeners with large families and a regular non-agricultural income. 相似文献
100.
Herb-layer diversity in deciduous forests: Raised by tree richness or beaten by beech? 总被引:3,自引:0,他引:3
Andreas Mlder Markus Bernhardt-Rmermann Wolfgang Schmidt 《Forest Ecology and Management》2008,256(3):272
Where natural production capacity permits, modern silvicultural management in Central Europe frequently aims at the development of mixed broadleaved stands, instead of pure European beech (Fagus sylvatica) stands. It is crucial to study the effects of these tree-layer diversity variations on herb-layer vegetation, since herb-layer vegetation contributes significantly to ecosystem functioning in forests. In Hainich National Park (Thuringia, Germany), we conducted observational research in deciduous stands to investigate whether herb-layer diversity was related to canopy-layer diversity, and to ascertain possible causal mechanisms. We found that herb-layer vegetation of deciduous forest stands rich in canopy species appeared to be more diverse than herb-layer vegetation of beech-dominated stands. We surmise that herbaceous understorey diversity was indirectly influenced by canopy tree species through the medium of the altered environmental factors soil pH and litter layer thickness. Apparently, lower beech proportion had a more profound effect than the number of secondary tree species. There were no correlations between herb-layer diversity and light transmissibility of the canopy layer, indicating that the light factor was not crucial for herb-layer diversity. At least for the Hainich research sites, our results indicated that small-scale light and soil heterogeneity is insignificant for herb-layer diversity. We found several herb-layer species whose occurrence was particularly correlated with tree-layer diversity and environmental factors. Remarkably, all species positively correlated with soil pH were important for the phytosociological classification of the research sites. Beech-dominated research sites showed high tree-layer volumes, whereas research sites with high tree-layer diversity tended to feature lower tree-layer volumes. These findings could be the result of differing former silvicultural systems and varying soil clay contents affecting tree species composition. In contrast, herb-layer biomass was positively correlated with tree-layer diversity. Herb-layer productivity might be promoted in more diverse research sites by increased nutrient supply and base saturation. It is also possible that greater beech proportion interfered with herb-layer productivity. However, herb-layer biomass was also positively correlated with herb-layer diversity. Hence, our study hints that positive diversity-functioning relationships might occur in the herb-layer of the deciduous forest under investigation. 相似文献