Department of Physics, Chemistry and Biology (IFM)

The importance of gap size for structuring butterfly assemblages were analyzed and a simple regression analysis comparing the similarity of the traps according to a gradient of gap size showed a significant positive correlation between increasing diversity between traps and the increase of gap size. The amount of light has been shown to be an important component of the structure of tropical forests, affecting butterfly assemblages (Sparrow et al., 1994). The amount of sunlight reaching the ground is also an important factor affecting plant growth (Terborgh, 1992), and might play an indirect effect also on the quality of butterfly host plants (Blau, 1980) and quantity of resources (Checa et al., 2009).The butterfly assemblages occurring in the small gaps were more similar to the understory assemblages than the ones found in the big gaps.

The results of the PCA comparing the gaps show that the distribution of the nymphalid species is affected by several environmental variables. The vegetation structure, in terms of density, diameter and height, affects the butterfly species, and most of them present a strong association with the presence of the woody plants in gaps, and an avoidance of the vines. There were higher light levels in gaps with a large amount of woody plants. The gaps that were most species rich were also the most open ones, and contained only a few vines. The vines are fast growing species, covering the gaps quickly, and give a much denser habitat than woody plants. The presence of woody plants in the gaps probably indicates a younger gap, with a possibility of more resources for the butterfly assemblages.

Different nymphalid species were associated with small or big, dense and shady or clear and sun exposed gaps. Among them, Pseudobedis valentina and Nessea obrinius were found in small shaded gaps, known as understory species strongly correlated with undisturbed areas (DeVries et al., 1997). Panacea prola were associated with the small and open gaps, the gap species Adelpha jordani, Memphis glauce, Yphthimoides poltys, Tamenis laothoe, Bia actorion, and Zaretis isidora, related to large and clear gaps, and only a few species of Taygetis, T.angulosa, T.laches and T.sosis, were found mainly in large and dense gaps, in accordance with their biological characteristics as understory species.