N. Zeng et Jd. Neelin, The role of vegetation-climate interaction and interannual variability in shaping the African savanna, J CLIMATE, 13(15), 2000, pp. 2665-2670
Using a coupled atmosphere-land-vegetation model of intermediate complexity
, the authors explore how vegetation-climate interaction and internal clima
te variability might influence the vegetation distribution in Africa. When
the model is forced by observed climatological sea surface temperature (SST
), positive feedbacks from vegetation changes tend to increase the spatial
gradient between desert regions and forest regions at the expense of savann
a regions. When interannual variation of SST is included. the climate varia
bility tends to reduce rainfall and vegetation in the wetter regions and to
increase them in the drier regions along this gradient, resulting in a smo
other desert-forest transition. This effect is most dramatically demonstrat
ed in a model parameter regime for which multiple equilibria (either a dese
rtlike or a forestlike Sahel) can exist when strong vegetation -climate fee
dbacks are allowed. However, the presence of a variable SST drives the dese
rtlike state and the forestlike state toward an intermediate grasslike stat
e, because of nonlinearities in the coupled system. Both vegetation and int
erannual variability thus play active roles in shaping the subtropical sava
nna ecosystem.