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Desert Grasslands, KIRK ANDERSON, GARDENS COLLECTION MANAGER


Equids’ Home on the Range


Desert Grasslands – areas where grasses are adapted to growing in semi-arid and arid climes – are home to a rich collection of birds, mammals, reptiles and insects. T ey represent an ecological niche that sustains the remaining populations of the world’s wild equids: on the steppes of Mongolia, on the savannahs of South Africa and in the scrublands of northern Kenya and Somalia.


Desert grasslands tend to be complex mosaics of grasses, shrubs, small trees, succulents and forbs rather than the pure grass seas reminiscent of the American Midwest. T ese regions support an unbelievable diversity of life above and especially below the ground. T eir soils teem with microscopic organisms invisible to the naked eye. Bacteria, fungi, protozoans, nematodes and mites all play a role in determining soil vitality. Termites and ants aid water infi ltration and alter soil texture by constructing labyrinths of tunnels for foraging and nesting. Subterranean termites are largely responsible for the recycling of nutrients locked up in dead vegetation and animal dung, while harvester ants aff ect plant composition through seed collecting.


12 www.LivingDesert.org


Desert grasslands at one time were considered a climax plant community – one that over time and through successive generations has achieved optimum adaptive stability within its environment. On the contrary, research has revealed that desert grasslands can be relatively unstable. T eir tenuous existence can literally be aff ected by a change in the winds, and altered rainfall patterns can swing the odds in favor of one plant form over another. Ninety - fi ve percent of desert grasses have evolved a method of photosynthesis (called C4 carbon fi xation) that is more effi cient in hot and arid environments than the more common C3 carbon fi xation used by most other plants.


Fluctuating populations of herbivores (plant eaters) and their predators can have a dramatic impact on plant distribution in desert grasslands. Effi cient granivores (seed eaters) like kangaroo rats, mice, ants and certain bird species can harvest nearly all the grass seed set in a given season, tilting the scales in favor of shrub development. T e grass’s unique morphology allows it to survive repeated grazing by herbivores, including wild and domestic ungulates, rabbits and rodents.


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