The Grassland Society of Southern Africa (GSSA) is involved and concerned with the science and practice of range and pasture management. This broad field involves primarily the use and conservation of natural resources. It encompasses applied fields such as livestock production, wildlife management, nature conservation, water catchment management and range and mine-dump rehabilitation. The disciplines include, amongst others, ecology, botany zoology, range and pasture science, animal science, soil science and genetics. This collection includes journal articles from the African Journal of Range and Forage Science as well as related articles and reports from throughout the Southern African region.
The organization of plant communities: negative plant-soil feedbacks and semiarid grasslands
Understanding how plant communities are organized requires uncovering the mechanism(s) regulating plant species coexistence and relative abundance. Negative soil feedbacks may affect plant communities by suppressing dominant species, causing rarity of most plants, or reducing the competitive abilities of all species. Here, three soil feedback experiments were used to differentiate the effects of soil feedbacks on mid- to late-successional and semiarid grasslands. Then I tested whether the direction and degree of soil feedback accounts for variation in relative abundance among species that coexist within each plant community. Negative soil feedbacks predominated across all species and sites and were individually discernible for 40% of plant species. Negative soil feedbacks affected rare to dominant plant species. Negative soil feedbacks, capable of having negative frequency-dependent effects, have the potential to act as a fundamental driver of species coexistence.
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