Ecología de una población herbácea (Carex remota L.) asociada a regatas de un bosque templado no gestionado

Abstract

Our main objective is to describe the spatial behavior of several microclimatic conditions and how they affect the structure of a riparian plant population. Riparian zones provide space for high biological diversity compared with adjacent upland forest because of their special microclimatic conditions. The study site is in an old-growth temperate forest in the Cuenca del Suspiro, Bertiz Natural Park of the north of Navarra (Spain). Our first objective it to explain spatio-temporal soil moisture gradient generated from the stream edges, and explain how it affect to the presence of a riparian species. Our second objective is to understand the dependence on abiotic factors and the biotic process of the development of Carex remota L. population. Soil moisture showed a sigmoid trend and allowed us to define the limits of a wet riparian zone at 1.25 m of distance from and 0.55 m in elevation above stream banks. Elevation above stream banks is more influential than distance in defining the limits of the riparian zone. Riparian zone values of soil moisture are high and constant even at the end of a dry period due to the continuous water flow. These high and constant soil moisture values allow the establishment and development of a riparian plant species. With the approach of point processes we were able to simulate separately and jointly the effect of a homogeneous or heterogeneous habitat and the absence or presence of some biotic processes, as seed dispersal and/or density-dependent interactions. The result of the bivariate function analysis suggested a weak positive relation between adults and seedlings that survived the first summer. Models from three censuses showed a decreasing degree of clustering from seedlings to adults. The new Matern Cluster process allowed the quantification of the different sources of variation driving the spatial distribution of Carex remota population studied. Besides, the results showed that the importance of the main factors that explain the population structure changes along the development of Carex stages. Compared to seedlings, the adults pattern showed an increasing dependence of abiotic factors.