Evaluation of natural regeneration in disturbed springs in Lavras, MG

Abstract

Este trabalho teve como objetivo avaliar a din\ue2mica da regenera\ue7\ue3o natural em duas nascentes em processo de recupera\ue7\ue3o no munic\uedpio de Lavras, MG. Para tanto, foram realizados dois invent\ue1rios ap\uf3s o isolamento das \ue1reas, nos per\uedodos de Agosto/2005 (18 meses) e Abril/2006 (24 meses). Foram alocadas no total 122 parcelas de 5 75 m (25 m2), sendo 76 na nascente 1 e 46 parcelas na nascente 2. As parcelas foram distribu\ueddas de forma sistem\ue1tica ao longo de toda a \ue1rea das nascentes. Todos os indiv\uedduos com altura superior a 0,10 m e DAP (di\ue2metro a altura do peito) < 5 cm, foram identificados, tendo seus di\ue2metros e alturas mensuradas. Foram avaliadas a composi\ue7\ue3o flor\uedstica, a estrutura, e a din\ue2mica da regenera\ue7\ue3o natural. Foram amostrados no total 524 indiv\uedduos pertencentes a 24 fam\uedlias e 55 esp\ue9cies. A fam\uedlia Asteraceae se destacou em n\ufamero de esp\ue9cies na nascente 1 e as fam\uedlias Fabaceae Faboideae, Myrtaceae e Solanaceae na nascente 2. As esp\ue9cies Baccharis dracunculifolia e Vernonia ferruginea apresentaram os maiores \uedndices de regenera\ue7\ue3o natural, na nascente 1, enquanto que as esp\ue9cies Vernonia polyanthes e Nectandra nitidula se destacaram na nascente 2. O maior \uedndice de diversidade foi registrado para a nascente 2 na segunda avalia\ue7\ue3o, aumentando de 3,324 (primeira avalia\ue7\ue3o) para 3,384 (segunda avalia\ue7\ue3o). O \uedndice de similaridade flor\uedstica encontrado entre as duas nascentes, foi de 20,0 e 18,5% para as avalia\ue7\uf5es 1 e 2 respectivamente. Durante o per\uedodo de monitoramento, verificou-se um aumento significativo de 33,33 e 15,8% no n\ufamero de indiv\uedduos amostrados nas nascentes 1 e 2 respectivamente. O m\ue9todo da regenera\ue7\ue3o natural apresenta grande potencial para a recupera\ue7\ue3o da vegeta\ue7\ue3o no entorno das duas nascentes, sendo necess\ue1ria, no entanto, a ado\ue7\ue3o de t\ue9cnicas de controle do capim Brachiaria sp.This work aimed at evaluating the natural regeneration dynamics in two springs in process of recovery in Lavras-MG, surrounded in December/2003. To do that, two springs were carried out from August/2005 (18 months) to April/2006 (24 months). 122 plots in the total of 5 x 5m (25m2) were plotted, being 76 plots in spring 1 and 46 plots in spring 2. The plots were distributed systematically throughout all the area of the springs. All individuals with height larger than 0.10 m and DBH lower than 5 cm were identified, having their diameters and height measured. Floristic composition, structural analyses and natural regeneration dynamics were studied. In the total, 524 individuals from 24 family and 55 species were sampled. The Asteraceae family was distinguished in species number in spring 1 and the families Fabaceae Faboideae, Myrtaceae and Solanaceae in spring 2. The species Baccharis dracunculifolia and Vernonia ferruginea presented the highest natural regeneration indexes in spring 1, while the species Vernonia polyanthes and Nectandra nitidula in spring 2. The higher diversity index was registered for the spring 2 in the second evaluation, having an increase from 3,324 (first evaluation) to 3,384 (second evaluation). The floristic similarity index registered between the springs was of 20.0% and 18.5% for the evaluations 1 and 2, respectively. During the time of monitoring, it was verified a significant increase of 33.33% and 15.8% in individuals number sampled in springs 1 and 2, respectively. The natural regeneration method presents potential for the recovering of the vegetation of the two springs; however, it is necessary the adoption of control techniques of Brachiaria sp. grass