The Effects of Drought on Plant Communities in the Desert Rangelands of Tunisia
Plant communities of the Dahar plateau are characteristic of the Tunisian desert both in structure and in dynamics. Although a number of plant communities can be differentiated, four major vegetation types are often distinguished that differ in plant spec
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Abstract
Plant communities of the Dahar plateau are characteristic of the Tunisian desert both in structure and in dynamics. Although a number of plant communities can be differentiated, four major vegetation types are often distinguished that differ in plant species cover and composition, as well as other factors, such as soil types and elevation. Among the abiotic factors which affect the vegetation structure and diversity of plants, climate is probably the most relevant. The desert vegetation in southern Tunisia is in a state of change and the most debilitating risk is that of drought in these desert areas. Under protection from grazing the dynamic nature of this vegetation is affected by such conditions such as drought. Precipitation probably explains part of the vegetation response to drought. The effects of drought stress on vegetation were tested for four plant communities who are Stipagrostis pungens, Anthyllis sericea, Helianthemum kahiricum, and Hammada schmittiana. Patterns of plant response to drought differed among the four vegetation types considered. Vegetation cover, species richness, and diversity were used for the characterization of the considered vegetation. Main results show that plant cover, richness, and diversity change with vegetation type and rainfall variations. Vegetation cover on H. kahiricum steppe is more affected by drought than the other steppes. Plant diversity is affected by drought in all plant community and mainly on the A. sericea and H. kahiricum steppes. Keywords
Drought stress Plant communities Management Desert rangeland
Introduction M. Gamoun (*) J. Zammouri Laboratory of Range Ecology, Arid Regions Institute (IRA), Medenine 4119, Tunisia +216 97 277 824 e-mail: [email protected]
Desert lands throughout the world are often degraded or increasingly at risk of degradation. These lands, including those at the border of arid
R.K. Gaur and P. Sharma (eds.), Approaches to Plant Stress and their Management, DOI 10.1007/978-81-322-1620-9_11, # Springer India 2014
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regions, commonly exhibit accelerated soil erosion, losses of productivity, and impaired economic potential to support human populations. Desertification involves human and environmental drivers of change but is a regional symptom that emerges from degradation at finer spatial scales (Reynolds and Stafford 2002). Desertification does not describe cyclic phenomena, as when decadal variations of precipitation lead to periods of drought and to losses of vegetation cover that are fully restored when rains return (Tucker et al. 1994). Natural disturbances and often previously unappreciated human disturbances became a serious challenge to traditional succession beginning as early as the 1940s (e.g., Stearns 1949; Raup 1957), but really solidifying in 1970s. The increasing recognition of the pervasiveness of disturbances (White 1979) led to idea that ecological systems consisted of patches of different times since the last disturbance. Dynamic changes in vegetation level are controlled by the balanc
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