Agriculture adjustment, land cover re-distribution and rural population dynamics in a subtropical watershed

NANNI, A. SOFÍA; GRAU, H. RICARDO

Berlin

Congreso; Global Land Project 2nd Open Science Meeting; 2014

Global Land Project, Amsterdam/Berlin/Sao Paulo

Patterns of land use and land cover change are usually grouped into one of two categories defined by the dominant trend: (1) deforestation resulting from expanding agriculture and (2) forest expansion, usually related to the abandonment of marginal lands. At regional scale, however, both processes can occur simultaneously even in the absence of net change. Given the focus on net change, such redistribution of agricultural and natural and seminatural lands, has been generally overlooked. The interaction between agriculture modernization, human demography and complex topographic gradients of northwestern Argentina has resulted in processes of both forest recovery and deforestation; thus providing the opportunity to analyze patterns and driving forces of land cover redistribution. We analyzed 20 years (1986-2006) of land cover change in a subtropical watershed in relation to topographic and demographic variables. Although net forest change represented less than 1%, complex forest dynamics emerged when moist and dry forests were considered separately, as the expansion of moist forests over grasslands offset dry forests conversion to crops and pastures in lowlands. There was a consistent geographic segregation of deforestation and forest recovery, with forests expanding over steep highlands and agriculture expanding over lowland irrigated areas. Demographic trends explained 25% of land cover change: forest cover change was negatively correlated with population increase and, more importantly, with local rural immigration. Highland forest expansion and lowland deforestation respectively imply conservation opportunities for humid montane forests and the environmental services they provide (e.g. watershed conservation) and threats for the conservation of dry forests and its biodiversity. The presentation will contribute to the session by exemplifying the importance of land use re-distribution (rather than net change) as a framework for analyzing land use transitions, with relevant environmental consequences at regional scale.