The vegetation of the Caatinga, present in the dry areas of the Brazilian Semi-arid region has been little studied, when it relates to population dynamics of their species. The objective of this study was to evaluate ...The vegetation of the Caatinga, present in the dry areas of the Brazilian Semi-arid region has been little studied, when it relates to population dynamics of their species. The objective of this study was to evaluate the mortality and recruitment rates of a Croton blanchetianus Baill. population in a two-year interval (January/2013 to January/2015), in area of caatinga in the semi-arid Paraiba. Monitoring of structural changes in the vegetation was carried out in 96 10 × 10 m contiguous plots. The phytosociological survey conducted in January 2013 sampled 1078 individuals of C. blanchetianus, occurring in the 96 plots studied. The years of 2012 and 2013 had rainfall below the annual average. Take into consideration the evaluation period;there was a high mortality rate (M = 47.33% year-1) and a low recruitment rate (R = 0.18% year-1) for the population of C. blanchetianus. The real gain (RG) of the population was significantly negative (-93.91% year-1) since the number of dead individuals was much higher than the recruited ones in the population. The highest height class, composed of individuals of 4.1 to 5.0 m height, was the most tolerant to water scarcity, resulting in 53.85% of surviving individuals. Therefore, the results demonstrated that periodic droughts compromise the recruitment, development, survival, and establishment of individuals in natural systems in the Brazilian semi-arid region.展开更多
文摘The vegetation of the Caatinga, present in the dry areas of the Brazilian Semi-arid region has been little studied, when it relates to population dynamics of their species. The objective of this study was to evaluate the mortality and recruitment rates of a Croton blanchetianus Baill. population in a two-year interval (January/2013 to January/2015), in area of caatinga in the semi-arid Paraiba. Monitoring of structural changes in the vegetation was carried out in 96 10 × 10 m contiguous plots. The phytosociological survey conducted in January 2013 sampled 1078 individuals of C. blanchetianus, occurring in the 96 plots studied. The years of 2012 and 2013 had rainfall below the annual average. Take into consideration the evaluation period;there was a high mortality rate (M = 47.33% year-1) and a low recruitment rate (R = 0.18% year-1) for the population of C. blanchetianus. The real gain (RG) of the population was significantly negative (-93.91% year-1) since the number of dead individuals was much higher than the recruited ones in the population. The highest height class, composed of individuals of 4.1 to 5.0 m height, was the most tolerant to water scarcity, resulting in 53.85% of surviving individuals. Therefore, the results demonstrated that periodic droughts compromise the recruitment, development, survival, and establishment of individuals in natural systems in the Brazilian semi-arid region.
