Relationship between huisache (Acacia farnesiana) canopy cover and understory forage characteristics in Texas coastal prairies



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Huisache (Acacia farnesiana) is a leguminous tree that has become a significant pest in the Gulf Coast Prairies and South Texas Plains regions of Texas. This plant establishes and invades quickly due to prolific seed production and its ability to resprout and has become a significant portion of the overstory canopy in many pastures in the region, but little research has been conducted regarding the effect of huisache canopy cover on understory forage nutritive value. I established an ongoing study at 3 different ranches in the coastal prairies of Texas, located in Victoria, Refugio, Goliad, San Patricio, and Bee counties. We measured total overstory canopy cover (by species), bulk understory forage nutritive value, and total forage production on nineteen 300-foot transects across the study area. We then used simple linear regression to test the relationship between forage nutritive and production variables and the independent variables of huisache or mesquite canopy cover, huisache plus mesquite canopy cover, and total canopy cover. Additionally, I conducted a greenhouse study in order to examine the effect of huisache canopy cover on grass growth, applying three light levels to simulate different levels of huisache canopy over two grass species: Virginia Wildrye (Elymus virginicus) and little bluestem (Schizachyrium scoparium). This study was analyzed via standard least squares comparing the effect of different light levels on plant height and growth stages. Results of this study confirmed that as huisache and other brush canopy increases, total forage production decreases and it causes shifts in species composition. In addition, canopy cover may have an impact on various nutrients.



Huisache, Forage