Ecology, Management and Utilization of Woody Plants on Rangelands
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Woody plant invasion has increased on grasslands and rangelands worldwide in the last century. Distribution and density of mesquite (Prosopis glandulosa) and juniper (Juniperus spp.) are increasing at rapid rates and occupy over 70 million acres in Texas and Oklahoma alone. These increases are attributed to suppression of naturally occurring prairie fires, accelerated seed distribution via livestock consumption and fecal deposition, reduced competition from grasses due to livestock overgrazing, and increased atmospheric CO2 concentrations that favors growth of C3 woody species over C4 grasses. These factors will continue to have an effect and there is good reason to anticipate that woody brush encroachment will continue to increase.Woody plant infestation reduces herbaceous production, which reduces forage for livestock and increases soil erosion potential. Woody encroachment may reduce off-site water yield for municipal and agricultural uses, although recent evidence disputes this. Recent data from our work suggests that woody plants like mesquite increase root growth in responses to extended drought in order to maintain canopy growth. We also have shown that mesquite above-ground biomass production continued unabated during the recent severe droughts of 2011 and 2012 in north Texas. These factors indicate that under more extreme climates that are forecast due to climate change that the competitive ability of woody plants such as mesquite may be even greater than before. In contrast to these negative effects, woody plant increases may be beneficial for wildlife habitat and ecosystem carbon sequestration, and may have potential for bioenergy uses.Woody Plant/Grass Relationships.........