Comportamento de espécies arbóreas nativas implantadas em áreas com diferentes graus de sucessão no reservatório Iraí – PR

Abstract

Forests destruction is growing on a alarming rate. It is estimated that each year 15.4 million hectares of tropical forests are being destroyed or seriously damaged. Therefore, starting from the 90’s, a large increase of initiatives aiming recovery of degraded areas started to be driven by society awareness and new legal requirements (Forest Code, law 4771/65). As a result, recovery programmes are creating demands for new studies which generate needs for new technical/scientific knowledge improvements. The present work aimed to focus on silvicultural, morph-anatomical and physiological aspects of four native forest species (Schinus terebinthifolius; Mimosa scabrella; Podocarpus lambertii and Luehea divaricata) implanted into two different areas with different succession degrees of revegetation on Iraí’s Reservoir margins, at Curitiba metropolitan region. Height and diameter measurements were taken at 6, 12, 18 and 24 months to support this study, finding in the end the species survival rate. With 18 months, leaves of S. terebinthifolius, M. scabrella, P.lambertii were collected in order to check morph-anatomy, and at the same period physiological data from S. terebinthifolius and M. scabrella were also gathered. These data were submitted to t teste. S. terebinthifolius test, presenting as a result a height superiority of individuals up to 18 months on regenerating forest. On 24 months, figures were quite similar, survival rate was up to 81,37% for regenerating forest and 68,15% on open fields. In respect to morpho-anatomical data, S. terebinthifolius made a significant difference to the leaf area and specific leaf area, being higher for individuals on regenerating forest; cuticle thickness, palisade parenchyma and total limb thickness were significantly higher for individuals on open fields. Physiological data showed significant difference to transpiration rate only, being higher in regenerating forest. For both areas, M. scabrella was the specie with worst survival rate, only 13.54% on open field and 21.18% on regenerating forest remained planted after 24 months. For morphological parameters, M. scabrella made a great difference just for specific leaf area being bigger for regenerating forest. In respect to anatomical parameters, only adaxial skin thickness and palisade parenchyma showed significant differences. Adaxial epidermis was greater in the area of regenerating forest, while the palisade parenchyma was higher in the open field one. Physiological data showed a significant difference on transpiration rate being bigger on open fields, as stomatal conductance being higher in regenerating forest. P. lambertii always had better growth rates, both in height and diameter measurements, in open field and made significant difference on leaf areas, being higher for individuals of regenerating forest. For stomatal density, cuticle thickness, palisade parenchyma, spongy parenchyma, total thickness, height and diameter were significantly higher for individuals on open fields. Up to 18 months, L. divaricata showed no significant difference between open fields and regenerating forests, although on 24 months height was greater on regenerating forest area in relation to open fields. Diameter was greater for open fields on 24 months though. Thus, among the studied species, S. terebinthifolius is the specie with greater plasticity. The second kind with better survival rate and growth was P. lambertii, which also presented some plasticity. L. divaricata though should be prioritized in plantations offering a better shading condition and M. scabrella is recommended only in high densities, since mortality rates can be very expressive.