Plant biodiversity and soils in the Jebel Marra region of Darfur, Sudan

مقال فى مجلة

2020

K., Hegazy, A. . 2020

Jebel Marra, a volcanic complex in western Sudan, is an important
site of early settled agriculture, with high plant diversity, supported
by orographic rainfall. Vegetation types were examined in relation to
habitat, altitude, soils, and land management. In 52 sites, 274 species,
predominantly Fabaceae and Poaceae, were recorded (with 17
new records). Sites were clustered using TWINSPAN, and Detrended
Correspondence Analysis (DCA), generating eight vegetation types,
six new since the 1970s. Changes in the dominant species show that
the savanna has become sparser, with annuals displacing perennials.
Soils were mostly “sandy clay loams,” so vegetation types did not
directly correspond to soil types, although Type VIII vegetation grew
in soils with a higher clay content. The sand fraction that predominated
in soils of all other vegetation types was, mainly (87%) “soft”
or aeolian sand. Canonical Correspondence Analysis (CCA) separated
communities and species along a first axis, associated with finer soil
textures, higher Fe, and lower elevations. The second axis was positively
associated with elevated phosphorus, and negatively with
sandy loams. CCA showed that rainfall alone was less pertinent than
soil texture, which determines plant-available water capacity. The
region’s vegetation was not uniformly diverse; instead, a mosaic of
patches of diverse terrain, associated with different vegetation
“types,” collectively generates a diverse flora. Besides climate change,
overgrazing and increasing human pressures due to conflict, local
population growth and an influx of refugees place these (already
stressed) plant resources at risk. Our survey provides a baseline to
track changes and develop adaptive management strategies.

• مجلة/صحيفة: Arid Land Research and Management