Allelopathy can play an important role in structuring plant communities, but allelopathic effects are often difficult to detect because many methods used to test for allelopathy can be confounded by experimental artifacts. The use of activated carbon, a technique for neutralizing allelopathic compounds, is now employed in tests for allelopathy; however, this technique also could produce large e...

The nitrogen and phosphorus supply in a lowland rain forest with a nutrient-rich soil was investigated by means of the leaf N/P quotient. It was hypothesised a high N and P supply to the forest ecosystem with a N and P rich soil. Total N and extractable P were determined in the surface (10 cm) soil of three plots of the forest. Total N was analysed by the Kjeldahl method, and P was extracted wi...

1. Globally, both climatic patterns and nitrogen deposition rates show directional changes over time. It is uncertain how woody seedlings, which coexist with herbaceous plants in savannas, respond to concurrent changes in water and nutrient availability. 2. We investigated competition effects between herbaceous vegetation and tree seedlings ( Colophospermum mopane ) under changed water and nutr...

Nutrient availability regulates the responses of high-latitude ecosystems to climate change but nitrogen, phosphorus and sulfur biogeochemistry, especially, phosphorus and sulfur cycles, are poorly understood in Alpine tundra ecosystem. This study examines the cycling of nutrients in a 302-year-old Alpine tundra ecosystem in which litter has accumulated through compartment methods. Samples of t...

Livestock waste composts with minimum inorganic fertilizer as a soil amendment in low-input intensive farming are a feasible agricultural practice to improve soil fertility and productivity and to mitigate soil degradation. The key benefits of the practice rely on the activities of soil microorganisms. However, the role of different livestock composts [composted cattle manure (CCM) vs. composte...

We identi®ed and measured changes in soil characteristics, nutrient availability and microbial activity to a gradient of grazing intensity in the Chaco region of northwestern Argentina (248 430 S and 638 170 W). Three sites were selected for comparison: 1. highly restored (no grazing for 20 years); 2. moderately restored (eight years of restoration); and 3. highly degraded (a typical Chaco camp...

Understanding the factors shaping species distribution patterns along tropical rainfall gradients is necessary to predict the consequences of climate change for tropical tree communities. Direct effects of water availability exclude wet forest species from dry forests, but the exclusion of dry forest species from wet forests remains unexplained. We tested the hypothesis that high light and nutr...

than other regions of the world (Mitchell et al., 1990; Maxwell, 1992). Summer air temperatures in northern To investigate the interactions among mineral N, C availability, Alaska are predicted to increase 3 to 68C over current microbial biomass, and respiration in arctic soils, we sampled soils five times during a growing season from a toposequence on a slope levels, whereas precipitation duri...