Elaboração de um modelo de produção de bolota em Herdade do Baixo Alentejo

Mestrado em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia

Montado is an agro-silvopastoral system characterized for having high biodiversity, for being a privileged space for multifunctional management and also for being the best land use option in poor soils of the Iberian Peninsula. Many authors consider this system to be at least 4500 years old, having nevertheless been simplified in its structure and transformed in the present extensive system. In the interior areas, where the risk of desertification is high, Holm Oak is the best adapted species and has been since ancient times valued for its high acorn production which in turn is used mainly by pig livestock’s. The most important characteristic of the Iberian Black Swine lies on the grazing system, which is influenced mainly by the abundance of acorns, quality of the grasses and availability of water. The production of acorn is the main source of food for the livestock and wild game. However, little is known of the factors that determine the production of acorn. Although the importance of oaks in the mediterranean region, there has been few works on the production of acorn of Holm Oak. A better knowledge of these factors is essential not only for a better management but also for the conservation of this system. The aim of this work was to develop a model for acorn production based on parameters both of the individual tree as of the stand, and in order to achieve this purpose it was selected an area of montado to collect acorn. On the first part of the study it was collected information of the different factors that influence acorn production. For the field work it was chosen an area integrated in the Experimental Centre of Baixo Alentejo, which is managed by the Regional Department of Agriculture of Alentejo and covers an area of 1.480 hectares. This centre has been used for the experimentation, development and demonstration of new technologies in the agro-pastoral and forest sector. It was chosen stands of montado of different density and measured the dendrometric parameters of the trees and collected the acorn. The information was analysed both at the stand level as at the individual tree level. Three models were produced, one of the total weight of acorn of the stand, another of the medium weight of acorn of the stand and the third of the individual tree production. . The conclusions obtained should be considered provisional, namely due to the low adjustment of the models. Some considerations must be made regarding the results obtained: - the data is only from one year, which was a very low productive year; - the data is only from a restricted area; - acorn production has a great variability dependent on the year - it was not taken in consideration other factors such as soil and climate;- the variables have the same weight----------------------------------------O montado é um sistema que se caracteriza por apresentar uma elevada biodiversidade, sendo um espaço privilegiado para a multifuncionalidade, além de se constituir como uma das melhores formas de valorização económica dos solos na região Alentejo. A produção de bolota é a principal fonte de alimento no inverno tanto para o gado como para a vida selvagem. O melhor conhecimento dos factores que influenciam a produção de bolota contribuirá para um melhor aproveitamento do recurso, ao mesmo tempo que servirá para assegurar à perpetuidade os montados e permitirá conservar a sua diversidade. Pretendeu-se com este trabalho desenvolver um modelo de produção de bolota relacionado com características do povoamento e de variáveis dendrométricas das árvores e que pudesse contribuir para informações mais precisas sobre a quantidade de bolota disponível. Foram produzidos três modelos de produção, um para o peso total a nível da parcela, outro do peso médio da parcela e outro a nível individual. Trata-se de conclusões que são provisórias, nomeadamente pelo facto dos modelos se revelarem de fraca ajustabilidade. Do ponto de vista produtivo, a variável que interessaria maximizar nos modelos para a predição do peso seria a produção por área (hectare).