Demography and population growth rate of the tree Prosopis flexuosa with contrasting grazing regimes in the Central Monte Desert

ASCHERO, V.; MORRIS, W.F.; VÁZQUEZ, D.P.; ALVAREZ J.A.; VILLAGRA,P.E.

FOREST ECOLOGY AND MANAGEMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 369 p. 184 - 190

0378-1127

One of the most important current challenges for ecologists is to evaluate how human-induced changesin ecosystems would impact viability of populations. Demographic response to anthropogenic impactcould help us to understand how to manage those impacts. Using demographic techniques and populationprojection models, here we assess if demography and population dynamics of the tree Prosopisflexuosa change in cattle grazed areas compared to ungrazed areas in the Central Monte desert,Mendoza, Argentina. To this end, we quantified vital rates and constructed a population projection matrixmodel to compare the deterministic population growth rate (lambda) between grazed and ungrazed areas. Wealso estimated elasticities of vital rates to evaluate their potential importance for future changes in k andperformed a life table response experiment (LTRE) to identify the life cycle transitions that contribute themost to the observed differences in k between the two treatments. Although we found differences indemographic processes, such as lower seed production and higher probability of reversion to smaller sizeclasses in young individuals when cattle were present, our results indicate that cattle grazing had nosignificant effect on k for this species. According to the elasticity analysis, survival of large trees is themain driver of the population growth rate (lambda) of P. flexuosa, and the vital rates related to tree reproduction,such as seed production and germination, have a poor contribution to k. Therefore, limitations ofactivities that can affect survival of large trees should be considered as part of the conservation strategyfor this species. Our study provides a compilation of demographic information that can be useful to setpolicies connecting the conservation objectives for this woodlands with that of ranch managers of thearea.