Trong nhiều lĩnh vực của suy thoái Andes con người, do chăn thả, hỏa hoạn, và khai thác rừng đã dẫn đến sự thay thế của rừng tự nhiên của vùng đồng cỏ (Kappelle và Brown, 2001). Tuy nhiên, trong một số lĩnh vực, xu hướng này bắt đầu trở lại do các quá trình khác nhau kinh tế xã hội, bao gồm cả di cư nông thôn, những thay đổi kinh tế theo hướng thấp hơn phụ thuộc vào tài nguyên thiên nhiên, và các quyết định quản lý loại trừ một số khu vực sản xuất cho mục. | Part IV Effects of Grazing on Mountain Forests Copyright 2006 Taylor Francis Group LLC 19 Patterns of Forest Recovery in Grazing Fields in the Subtropical Mountains of Northwest Argentina Julietta Carilla H. Ricardo Grau and Agustina Malizia INTRODUCTION In many areas of the Andes anthropogenic degradation due to grazing fire and forest exploitation led to the replacement of native forest by grasslands Kappelle and Brown 2001 . However in some areas this tendency began to revert due to different socioeconomic processes including rural emigration economic changes toward a lower dependence on natural resources and management decisions that excluded some productive areas for conservation purposes Aide and Grau 2004 . These areas of secondary forest succession provide opportunities for ecological restoration by allowing the recovery of biodiversity associated with forests. In addition recovering forests provide ecological services such as the production of timber and the sequestration of atmospheric carbon Silver et al. 2000 . To evaluate the conservationist and economic values of these secondary forests it is necessary to understand the floristic tendencies during secondary succession and the recovery rates of biodiversity composition and biomass parameters. Patterns of secondary forest succession are influenced by the preabandonment conditions previous land use vegetation structure and microenvironmental characteristics the availability of propagules in the early stages of succession and the interactions inter- or intraspecific between secondary forest trees Pickett et al. 1987 . For example in many temperate forests those forests monodominated by pioneer species have slow growth rates due to intensive intraspecific competition self-thinning phase until large trees die releasing resources and providing opportunities for new recruitment and faster growth of the surviving trees Oliver and Larson 1996 . The upper-montane forest of northwestern Argentina is characterized
