STRUCTURE AND FLORISTIC COMPOSITION OF A SHRUB UNDER PINUS RADIATA D.DON PLANTATION IN CENTRAL CHILE

Abstract

The structure and floristic composition of an understory under a Pinus radiata D. Don plantation in the coastal area of the central Chilean Maule Region(35°27'43.3" S; 72°23'56" W) is documented. Based on nine vegetation samples the vascular flora was inventoried determining species richness, frequency, cover-abundance, and values of importance as well as phytogeographic origin and life forms. The vascular flora comprises 48 taxa with a high representation of native and endemic species (19 each), including Adesmia bijuga Phil. (Fabaceae) as an endemic to the coastal mountain range of Maule Region and only 11 exotic species. The studied shrub community shows a vertical organization in layers of which the herbaceous ground layer shows the highest diversity, whereas Pinus radiata, Adesmia bijuga, and Escallonia pulverulenta Pers. show highest frequency levels. All Raunkiaer life forms are represented, being phanerophytes and hemicryptophytes the dominant life forms. The exotic species Aira caryophyllea L. and Pinus radiata have the highest importance values. We interpret the shrub community structure to be variable and complex due to the artificiallity of the vegetation composition of a planted P. radiata stand that replaced the native vegetation. Adesmia bijuga shows that the vital cycle could help to its conservation in situ under the canopy, but in a regime of risk threats its survival. In spite of little representativeness in the area the specie is outside the regional units of the SNASPE and is not considered in the Chilean Red Data Book.