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The interactive nutrient and water effects on vegetation biomass at two A frican savannah sites with different mean annual precipitation
Author(s) -
Wang Lixin,
Katjiua Mutjinde,
D'Odorico Paolo,
Okin Gregory S.
Publication year - 2012
Publication title -
african journal of ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.499
H-Index - 54
eISSN - 1365-2028
pISSN - 0141-6707
DOI - 10.1111/j.1365-2028.2012.01339.x
Subject(s) - nutrient , biomass (ecology) , environmental science , vegetation (pathology) , ecosystem , grazing , productivity , nutrient cycle , agronomy , ecology , precipitation , agroforestry , biology , geography , medicine , macroeconomics , pathology , meteorology , economics
Savannahs cover more than 40% of A frica and provide a variety of important ecosystem services. Their productivity is constrained by disturbance and limiting resources. In southern A frica, fine‐leaf savannahs typical of arid environments are known for being richer in nutrients than broad‐leaf mesic savannahs. However, despite numerous recent studies on the dynamics of southern A frican savannahs, the interplay between water and nutrient limitations remains poorly investigated in these systems. To better understand the interactions between water, nutrients ( N and P in this manuscript) and grazing on the productivity of grasses and trees in fine‐leaf savannah ecosystems, a fertilization experiment with controlled grazing was conducted at two sites with different mean annual rainfall in Namibia. The experiment demonstrated that the vegetation at the drier site may not be nutrient‐limited ( N , P or N + P ). At the wetter site, however, vegetation showed significant response to nutrient addition. Grasses exhibited N limitation and trees exhibited P limitation. This experiment also showed that grazing reduces the overall grass biomass, but may not modify the response to nutrient treatments. The results indicated a switch from water to nutrient limitation between dry and wet sites and demonstrated different tree and grass responses to nutrient additions.