Abstract:
During the last decades a need for more agricultural land was to be recognized in Ecuador. Reasons for this need were a rapidly growing population and a non sustainable use of land which caused degradation and abandonment of large territories. As a result labile ecosystems like the Ecuadorian montane rain forest were anthropogenically disturbed and cultivated. The aim of this study was to investigate the effect of anthropogenic disturbances on landscape structure and to describe the actually existing mosaic of disturbed and undisturbed patches. Another intention was to identify the driving forces of landscape structure and its dynamics. A 25 km long and 4 km wide area in the south of the Ecuadorian Andes was choosen as study site. Altitude ranges from 1050 to 2600 m above sea level and can be regarded as a location where naturally a montane cloud forest would be growing. The land use of the complete area was mapped firstly. To gain a deeper insight into land use practices and techniques, 12 farms were selected and investigated more intensively. Maps were drawn of every farm by viewing the patches from the other side of the valley. Where a rapid change in land use was recognized, boundaries were marked. Afterwards every patch was examined and data on position within the landscape, structure and cultivation were recorded. Following interviews with each owner served for gaining more knowledge about land use practices and the socio economical background of the family. During investigation of the patches two different scales were taken into consideration: the scale of the stand and the landscape scale, respectively. Based on the parameters which referred to the stand a cluster analysis was applied to all the patches. It resulted in the distinction of 14 structural patch types which then were interrelated with different landscape parameters. The landscape of the region is very heterogeneous and rich in structural elements. The primary forest which once covered all of the area was cultivated and changed into cropland and mainly pasture. Although it is now pushed back on sites which are unfavourable for agriculture, the forest still builds the matrix for the embedded fields. The patches have different persistences and also differ in form and size. By comparing all farms one can recognize that there is a regularity in the arrangement of the different structural units. Based on the collected data and maps a scheme was drawn which shows this regular arrangement. Another scheme, which elucidates the temporal sequence between different patch types, was developed by comparing the information of the farmers with field-hints indicating former land use. Due to the low level of mechanization agriculture of the study site is still being very traditional. The extreme inclinations as well as the very low income rate of the farmers do not allow to buy machines which could facilitate the distinct working operations. Rather irregularly than geometrically shaped patch forms and rather gradual than distinct boundaries are the result. Some of the farmers are using fire to clear the forest or the already existing pastures, which causes a rapid decline of nutrients during the following weeks. Undemanding species like bracken (Pteridium aquilinum (L.) Kuhn) are now able to invade the fields and compete with crops and pasture for left nutrients. Clearing even extremely inclined slopes and thereby causing soil erosion increases the effect of degradation. Because of not using fertilizers or taking measures against soil erosion the farmer is compelled to abandon degraded and unproductive sites and replace them by clearing more forest. As a consequence the loss of montane cloud forest continues. To oppose this prospect a modification of non sustainable land use practices regarding the needs and knowledge of the Ecuadorian population has to be implemented. More scientific investigation could contribute to this aim.
