Relación entre la composición florística y los nutrientes del suelo en comunidades de palmas del Chocó biogeográfico en Colombia y Ecuador

Abstract

We studied the floristic composition of palm communities and their relation with soil nutrients in two localities of the Chocó biogeographic region to undestand (1) How soil nutrients vary between the two localities? (2) What is the relationship between soil nutrients and palm floristic composition? (3) What are the most important nutrients that explain the variation in floristic composition of palm communities? (4) How the abundance of the most abundant understory and canopy palm species varies along the concentration gradient of the most important nutrients? We established 20 transects (5 x 500 m) and identified all palm individuals of all growth stages. Soil samples were taken at each transect at the beginning, middle and end. Macronutrients (Al, Ca, Mg, K, P) were extracted with the Mehlich-III technique and their concentrations were analyzed by inductively coupled plasma emission spectrometry (ICP-OES). The concentration of nutrients was related to the floristic composition using Mantel, partial Mantel tests, linear regressions and non-metric multidimensional scaling. We found a total of 9158 individuals and 33 species of palms in the 5 ha covered by our transects. Species composition had a positive and significant correlation with soil nutrients (rM = 0.63-0.69) and with geographical distance between transects (rM= 0.71-0.75), whereas the soil nutrients were highly correlated with geographical distance (rM = 0.72). We found a small yet significant relationship between soil fertility and the abundance of undestorey palms, but no relationship with canopy palms. Our results demonstrate for the first time that soils play an important role in the composition of palm communities at local scales in the Chocó region, and that infertile and phosphorus-rich soils have the highest palm diversity.