Micro-sítio como filtro para o estabelecimento de regenerantes arbóreos em áreas restauradas / Microsites as filters for tree species establishment under restoration plantings

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

20/12/2011

RESUMO

The characteristics of the natural regeneration of restoration plantings understory express the main indicators of success of ecological restoration projects, in which the absence of regeneration indicates a bottleneck for the perpetuation of forest communities inserted into highly fragmented landscapes. Nevertheless, adverse conditions of the micro-site of regeneration in restoration plantings may hamper the colonization of the understory by native species, which in turn collapse its perpetuation along the time. We sought to evaluate if, or how, the physical-chemical conditions of the micro-site of regeneration of restoration plantings with different ages can limit native tree species establishment and therefore, the dynamic of forest restoration. The study was developed in three areas under restoration with different ages (10, 22 and 55 years). The physical-chemical characterization of the micro-site of regeneration of the study areas was carried out by evaluating the soil compression level, porosity, humidity, organic matter and nutrients content and granulometry, as well as litter dry mass and canopy cover. In each area, we set 10 experimental blocks, each one consisting of four 1 m x 1 m plots, in which nine tree species were sown. In each plot we established three treatments: A) direct seeding in the natural condition of the area, without any alteration in the characteristics of the micro-site (indigenous leaf litter), B) direct seeding on the leaf litter and soil transplanted from a native forest (allochthonous leaf litter), C) direct seeding on grounded and composted sugarcane bagasse and D) control (no seeding). Seedling emergence and mortality were observed through six months. An increase on the canopy cover and soil porosity, humidity, clay and organic matter content were observed in the oldest areas, as well as a decrease in soil compression. Seedling emergence did not differ among the studied areas; however, seedling survival was significantly lower in the oldest reforestation, with 55 years. A positive correlation was observed between seedling mortality with the increase of canopy cover and soil organic matter content. Seedling emergence and survival were statistically higher in the treatment A (indigenous leaf litter). Thus, although the micro-site conditions for seedling establishment become even more similar to reference ecosystems as restoration planting evolve, it also becomes more restrictive. In addition, seedling establishment was favored in the conditions of local substrate of restoration plantings, without evidence of limitation for the progress of secondary succession. Consequently, dispersal limitation may play a higher influence in this condition for the advance of restoration process.

ASSUNTO(S)

ecossistemas florestais establishment limitation forest restoration mata atântica natural regeneration plântulas regeneração natural restauração florestal seedling establishment site of establishment

ACESSO AO ARTIGO

Documentos Relacionados