The University of Arizona

Above-ground biomass yields at different densities of honey mesquite.

J.D. Laxson, W.H. Schacht, M.K. Owens

Abstract


Dense stands of honey mesquite (Prosopis glandulosa Torr. var. glandulosa) negatively impact livestock handling and herbaceus forage production; however, very little information is available on the effect of stand density on biomass production of herbage and wood. Our study compared above-ground yields of herbage and wood in undisturbed, cleared, and 3 levels of thinned (100, 300, and 900 stems ha-1) stands of mesquite. Total removal of the mesquite canopy resulted in a 45% increase in herbaceous standing crop compared to the control in the first 2 years post-clearing. Herbage yields for the thinning treatments were intermediate although herbage yields for the 900 stems ha-1 (2,017 kg ha-1) treatment was similar (P>0.1) to the control (1,849 kg ha-1) and lower (p<0.1) than the cleared treatment (2,684 kg ha-1). Total wood production was significantly (p<0.1) lower for the 3 thinned treatments (481 to 1,214 kg ha-1 yr-1) than the control (8,128 kg ha-1 yr-1) because of the higher stem density for the control (>7,500 stems ha-1). Growth rates of individual mesquite stems were 2- to 3-fold greater (p<0.1) for the l00 and 300 stem ha-1 stands than for the higher- density stands during the relatively wet growing season of 1992. Under the drier 1993 conditions, however, growth rates were similar (P>0.1) for all treatments. Results indicated that severe thinning to less than 900 stems ha-1 increased the amount of available forage and positively influenced the potential growth rates of the remaining mesquite stems.

Keywords


thinning;agroforestry;stand density;Prosopis glandulosa var. glandulosa;multiple land use;rain;biomass production;semiarid zones;Texas;biomass

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