Predação de mudas de castanheira em área sob restauração florestal na Amazônia.

Abstract

The use ofbrazil nut {Bertholletia excelsa Bonpl). forest restoration and recovery ofdegraded areas in the Amazon. has beenpromising due to its favorable silvicultural characteristics and the socioeconomic benefits that the species can bring. However. when used in abandoned pasture areas. their survival rate can be strongly threatened by the predation of rodents in disturbed areas. Faced with this problem for the forest restoration with this species in pasture areas. it is necessary to carry out management studies that aim to reduce the damages caused by these mammals and consequently increase survival rates. In this way. the objective of this work was to evaluate the predation of brown tree seedlings by rodents in abandoned pasture under forest restoration process and its relationship with silvicultural treatments. Three treatments were performed: treatment 1 - with physical silvicultural Ircalmcnls; treatment 2 - with physical and chemical silvicultural treatments; treatment 3 - with physical and chemical silvicultural Ircalmcnls and use of seedlings. Each treatment had 8 replicates with 40 seedlings each. totaling 320 seedlings per treatment distributed in the spacing of 12m x 12m. The monitoring was carried out in 2016 and 2017. in which the number of plants killed by wild rodents and other factors were identified and counted in the worksheet Data were submitted to normality tests and Kruskal-Wallis test at 1% probability. to compare means between areas. There were significant differences between ali Ircalmcnls. Rodent mortality in treatment 1 was 29.69% and by other factors it reached 27.81%. In Ircalmcnls 2 and 3 there was no attack of rodents. being the mortality by other factors of 4.37% and 16.56%. respectively. It was found that the high rate of predation in treatment 1 is directly associated with the presence of fast-growing exotic grasses, which provided shelter and protection for rodent feeding at lower risks of being hunted by other animais. The presence of these grasses may reduce seedling survival rates, both as a shelter for rodents. and to limit seedlings' access to light. water and nutrients. The incorporation of chemical weeding to the silvicultural Ircalmcnls for grass conlrol. provided better conditions for seedling survival. reducing the rates of predationby rodents. It is recommended that in pasture areas under restoration with chestnut trees. adequate conlrol of the grass in the initial years should be carried out with the use of semi-mechanized weeding and chemical (herbicide). or that the use of older seedlings with lignified endospermbe adopted. to avoid the attack of rodents and to reduce the competition with the seedlings.