1,721,161 research outputs found
Können wir die Bewirtschaftung großer Ölpalmenplantagen so verbessern, dass sie weniger umweltschädlich ist?
No full textDie hohe Produktivität von Ölpalmen ist oft mit schädlichen Umweltauswirkungen verbunden. In einem groß angelegten Feldexperiment haben wir Optionen zur Anpassung der Bewirtschaftung getestet, damit der Ertrag hoch bleibt, aber die Umweltauswirkungen geringer sind. Unsere Ergebnisse zeigen, dass die mechanische Unkrautbekämpfung in Kombination mit einem geringeren Düngemitteleinsatz eine vertretbare Bewirtschaftungsoption ist, die die Umweltbilanz verbessert und sogar den Gewinn erhöht
Regional variation in soil carbon and δ13 C in forests and pastures of northeastern Costa Rica
No full textRecent studies suggest that the direction and magnitude of changes in soil organic carbon (soil C) pools following forest-to-pasture conversion in the tropics are dependent upon initial soil conditions and local factors (e.g. pre-conversion soil C content, soil texture, vegetation productivity, and management practices). The goal of this study was to understand how landscape-scale variation in soil-forming factors influenced the response of soil C pools to forest clearing and pasture establishment in northeastern Costa Rica. We measured soil C and its stable isotopic composition in 24 paired pasture and reference forest sites distributed over large gradients of edaphic characteristics and slope throughout a 1400 km2 region. We used the large difference in stable C isotopic signatures of C3 vegetation (rain forest) versus C4 vegetation (pasture grasses) as a tracer of soil C dynamics. Soil C pools to 30 cm depth ranged from 26% lower to 23% higher in pastures compared to paired forests. The presence of non-crystalline clays and percent slope explained between 27 and 37% of the variation in the direction and magnitude of the changes in soil C storage following pasture establishment. Stable carbon isotopes (δ13C) in the top soil (0–10 cm) showed a rapid incorporation of pasture-derived C following pasture establishment, but the vegetation in these pastures never became pure C4 communities. The amount of forest-derived soil C in pasture topsoils (0–10 cm) was negatively correlated to both pasture age and the concentrations of non-crystalline iron oxides. Together these results imply that site factors such as soil mineralogy are an important control over soil C storage and turnover in this region
The role of dissolved organic carbon, dissolved organic nitrogen, and dissolved inorganic nitrogen in a tropical wet forest ecosystem
No full textAlthough tropical wet forests play an important role in the global carbon (C) and nitrogen (N) cycles, little is known about the origin, composition, and fate of dissolved organic C (DOC) and N (DON) in these ecosystems. We quantified and characterized fluxes of DOC, DON, and dissolved inorganic N (DIN) in throughfall, litter leachate, and soil solution of an old-growth tropical wet forest to assess their contribution to C stabilization (DOC) and to N export (DON and DIN) from this ecosystem. We found that the forest canopy was a major source of DOC (232 kg C ha–1 y–1). Dissolved organic C fluxes decreased with soil depth from 277 kg C ha–1 y–1 below the litter layer to around 50 kg C kg C ha–1 y–1 between 0.75 and 3.5m depth. Laboratory experiments to quantify biodegradable DOC and DON and to estimate the DOC sorption capacity of the soil, combined with chemical analyses of DOC, revealed that sorption was the dominant process controlling the observed DOC profiles in the soil. This sorption of DOC by the soil matrix has probably led to large soil organic C stores, especially below the rooting zone. Dissolved N fluxes in all strata were dominated by mineral N (mainly NO3−). The dominance of NO3– relative to the total amount nitrate of N leaching from the soil shows that NO3– is dominant not only in forest ecosystems receiving large anthropogenic nitrogen inputs but also in this old-growth forest ecosystem, which is not N-limited.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000230804500001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=6e41486220adb198d0efde5a3b153e7dVoR - Version of Recor
Tree-microbial biomass competition for nutrients in a temperate deciduous forest, central Germany
No full textAims Our goals were (1) to determine whether tree species diversity affects nutrient (N, P and K) cycling, and (2) to assess whether there is competition for these nutrients between microbial biomass and trees. Methods We measured nutrient resorption efficiency by trees, nutrient contents in leaf litterfall, decomposition rates of leaf litter, nutrient turnover in decomposing leaf litter, and plant-available nutrients in the soil in mono-species stands of beech, oak, hornbeam and lime and in mixed-species stands, each consisting of three of these species. Results Cycling of nutrients through leaf litter input and decomposition were influenced by the types of tree species and not simply by tree species diversity. Trees and microbial biomass were competing strongly for P, less for K and only marginally for N. Such competition was most pronounced in mono-species stands of beech and oak, which had low nutrient turnover in their slow decomposing leaf litter, and less in mono-species stands of hornbeam and lime, which had high nutrient turnover in their fast decomposing leaf litter. Conclusions The low soil P and K availability in beech stands, which limit the growth of beech at Hainich, Germany, were alleviated by mixing beech with hornbeam and lime. These species-specific effects on nutrient cycling and soil nutrient availability can aid forest management in improving productivity and soil fertility
Tree species diversity effects on productivity, soil nutrient availability and nutrient response efficiency in a temperate deciduous forest
No full textThere are contrasting reports whether and how tree diversity influences stand productivity in temperate deciduous forests. Tree species diversity may increase stand productivity in temperate forests through complementary resource use and/or facilitation if the resource considered limits productivity. In unpolluted temperate forests, net primary production is typically limited by nitrogen (N). However, in many parts of Europe high N deposition has alleviated N limitation and there is some evidence that phosphorus (P) and/or potassium (K) limitation has become more widespread. Here, we report on a study where we investigated whether complementarity and/or facilitation increase productivity in a typical German deciduous forest with tree species of beech (Fagus sylvatica), oak (Quercus petraea and Quercus robur), hornbeam (Carpinus betulus) and lime (Tilia cordata and Tilia platyphyllus). We measured biomass production and availability of soil N, P, K, calcium (Ca) and magnesium (Mg) in stands of single species (mono-species stands) and in stands with different combinations of three of the tree species above (mix-species stands). We used nutrient response efficiency (NRE) to evaluate whether a specific nutrient limits tree growth. At a stand level, above-ground net primary productivity did not differ between mono- and mix-species stands. At a tree level, using a neighborhood approach, relative growth rates of beech trees in mono-species stands were smaller than when they were in mix with lime and hornbeam whereas growth of lime trees in mono-species stands was larger than in mix with beech and oak. The NRE curve for beech showed that beech trees in mix-species stands had optimal P and K response efficiencies whereas beech trees in mono-species stands showed P and K limitations. The NRE curve for oak with exchangeable soil K showed that K levels were beyond the optimum NRE and thus K was not limiting oak growth. NRE curves for hornbeam and lime showed no significant relationships with any of the soil nutrients. Hence, nutrient limitation was species-dependent. Our results showed that using both NRE and a neighborhood approach are useful tools in quantifying the effects of individual tree species on a species’ productivity between mono- and mix-species stands. Such tools provide important basis for improving management of typical mix-species, temperate forests
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