Are Namibia's Grasslands Desertifying?

Functioning in Grasslands

Grasslands are the potential natural ecosystem type on approximately 25% (33x lo6 km2) of the land surface of the earth (Shantz 1954). Current estimates of the global extent of grasslands range from 16% (Whittaker and Likens 1973, 1975) to 30% (Ajtay et al. 1979). The difference between the estimates of the potential extent of grasslands and the current extent provides an indication of the degr...

49624 NZ Grasslands Association.pmd

Although plant roots take up nitrogen (N) both as ammonium (NH 4 ) and nitrate (NO 3 ) ions, under most soil conditions uptake of NO 3 dominates. Once absorbed by the plant roots, the NO 3 is reduced to NH 4 , which is subsequently assimilated into organic compounds. However, when the ra te of uptake exceeds the rate of NO 3 reduction, accumulation of NO 3 in plants occurs. Ruminant animals wit...

Grasslands and Savannas

Fine-scale community and genetic structure are tightly linked in species-rich grasslands.

Recent evidence indicates that grassland community structure and species diversity are influenced by genetic variation within species. We review what is known regarding the impact of intraspecific diversity on grassland community structure, using an ancient limestone pasture as a focal example. Two genotype-dependent effects appear to modify community structure in this system. First, the abunda...

Phylogenetically diverse grasslands are associated with pairwise interspecific processes that increase biomass.

Biodiversity is an important determinant of primary productivity in experimental ecosystems. We combine two streams of research on understanding the effects of biodiversity on ecosystem function: quantifying phylogenetic diversity as a predictor of biodiversity effects in species-rich systems and the contribution of pairwise interspecific interactions to ecosystem function. We developed a stati...