Abstract

A. AVILA, Fabio; ANGEL, Sonia Patricia  and  LOPEZ C., René. Diversity and structure of an oak community in the Cachalú Biological Reserve, Encino (Santander-Colombia. Colomb. for. [online]. 2010, vol.13, n.1, pp.87-116. ISSN 0120-0739.

We analyzed diversity, structure and preliminary plant dynamics features (mortality and recruit ment) of a one ha permanent plot in an oak forest, at the Reserva Biológica Cachalú, at an altitude of between 2100 and 2200 m. The plot was established in 2007, when all plant individuals with dbh ≥ 10 cm (first category) were tagged, measured and plotted. All individuals 1 ≥ and < 10 cm dbh (second category) were sampled in an area of 0.2 ha within the plot. In the last census (July 2009), we found 453 individuals, 23 families, 26 genera and 34 species from the first Category and 624 individuals, 34 families, 60 genera and 80 species from the second. The species-area curve showed a value of R²= 0.97. According to the structure analysis, most of the individuals, mainly treelets, were accumulated in the first diameter, showing an up-turned “J” distribution, which illustrates early forest stages. Between the plot establishment and the first census (1.5 yr) the basal area of the first category decreased 1.61% while the second increased 36.6%. The most important species ac cording to IVI were Quercus humboldtii, Clusia schomburgkiana and Blakea cuatrecasii. Mortal ity and recruitment rates for the first category were 0.96% y 1%, respectively and in the second cate gory these values were 2.8% y 12.2% respectively. During 1.5 yr new gaps appeared within the plot, which is associated with the decrease in total basal area. Despite high similarity in species composi tion compared with other neotropical montane forests, the dynamics and structure of the community in the present study appear to be distinct.

Keywords : oak forest; diversity; vegetation structure; mortality and recruitment; long-term plots; Santander- Colombia.

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