Land use change and natural Araucaria forest degradation : northeastern misiones - Argentina

Originally, araucaria forest was characteristic of the northeast Misiones landscape, covering around 210.000 hectares. The broad variety of possible uses for araucarian timber, as well as a growing need for agricultural land, however, leads to the circumstance that since the middle of the past century these forests were strongly exploited and cleared. In only 50 years, of the original existence of A. angustifolia in the Province of Misiones, from about 500.000 individuals before de exploitation, a mere 5% were left in 1992. After the depletion of the araucaria stands a timber industry was established in the region. From this and with the local population's growth other valuable species were selectively logged and a fast expansion of the agricultural frontier and the encroachment farming into the forest took place. Despite their natural and economic value, until now the araucarian forests in the Province of Misiones have poorly been studied. The aims of this study was an evaluation of the actual state of the Araucaria forests, the land use/land cover change after deforestation and their impacts on soil resource in the Province of Misiones. Whit this goals, processes combining air photography interpretation, air and terrestrial recognition and multi-temporal satellite imagery analysis, with the support of geographic information systems (GIS) and the Universal Soil Loss Equation (USLE) model, were carried out. <br>Today, the A.angustifolia population is completely fragmented, mostly composed from isolated individuals or of very poor growth or ones overmature or ill, remaining less than 4% of its original existence. The average deforestation rate (by clear-cutting) between 1962 and 2001 was approx. 1908 ha year-1, while in the period between 1986 and 2001 of 3515 ha year-1. The loss of forest covers was between 1962 and 2001 about 19%, while the agricultural land nearly quadruplicated. In regard to the land degradation, the results revealed that the soil organic matter (SOM) content in the first 10 cm depth considerably decreased after deforestation, ranging from 4.2 % to 2.3 % at soils under forest cover and agricultural use, respectively. Significant differences were observed between bulk densities at all treatments (P < 0.001), and the infiltration rate was very variable in all groups of measurement. Results provided by running a soil erosion assessment model (USLE) in a GIS environment showed that there is a greater amount of hectare vulnerable to moderate, high or very high erosion under agricultural use, while soil losses are comparatively) under degraded forest, reforestations and capuera. The lowest soil losses are recorded in areas under dense forest. <br>The presented findings reveal that the survival of A. angustifolia depends on an urgent revision of the conservation policy as well as the regional agricultural and forest policies. Likewise, in the face of the ignorance observed in the rural population about management techniques and resource conservation, it is also indispensable to generate better futures information channels and appropriate technical advice in order to a better sustainable natural resources use. Based on the methodology developed in this study, a consistent monitoring program using satellite imagery has to be implemented to control the application of a revised conservation policy and, therefore, to ensure the protection of the Araucaria forests in the future.

Author dc:creator

• Rau, María Fabiana

Contributors dc:contributor

• Drescher, Axel W.

• Argentinien
• Provinz Misiones
• Landnutzungswandel, Landsat TM, Landsat ETM+, Araukarienwälder, GIS
• Land use change, deforestation, Araucaria angustifolia, erosion, USLE

Repository record source_url

https://freidok.uni-freiburg.de/data/2327

OAI identifier oai:identifier

oai:freidok.uni-freiburg.de:2327