Abstract

Land sparing is the formal strategy to conserve biodiversity in southern Patagonia, with few natural reserves mainly implemented by national and provincial governments. However, these reserves are almost uniquely located near the front line with Chile or in the seacoasts, prioritizing preservation of aesthetical valuable landscapes over other conservation values. Here we discuss the potential utility of land sharing strategy (Lindenmayer et al., 2012) using retention approach to improve biodiversity conservation in different ecosystem types. We exemplified its potentiality and need through vascular plants as used as biodiversity indicators in Tierra del Fuego Island (Argentina). We use vegetation data (richness and cover) of 230 vascular plant species observed in 559 permanent plots belonging to the PEBANPA network (Peri et al., 2016), which were analysed by multivariate ordination and grouping techniques. We studied four zones along latitudinal- longitudinal gradients (North-West, South-West, North-East and South-East), six ecosystems types (grasslands, peat-bogs, shrublands, N. pumilio, N. antarctica and N. betuloides forests), and three management conditions in two forest types: harvesting impacted aggregated and dispersed retention vs. primary unmanaged stands in N. pumilio forests (see more details in Martínez Pastur et al., 2009); and livestock grazing impacted young secondary structures and edges over grasslands vs. primary closed canopy stands in N. antarctica forests. When vascular plant assemblages of different ecosystem types among zones along latitudinal and longitudinal gradients were compared, we found significant differences among NW, NE and SW groups for N. pumilio and N. antarctica forests, and between SW and SE groups for N. betuloides forests. Therefore, location of protected areas in one zone (e.g. National Park in the SW), did not ensure protection of particular understory of the three forest types in other zones. On the other hand, although ecosystem types share plant species, assemblages were significantly different among almost all in all zones. Then, exclusion of some ecosystem from harvesting, livestock or other impacts to does not guarantee the conservation of all the species. Finally, we found that vascular plant assemblages remained more similar to primary forests in aggregated than in dispersed retention for N. pumilio harvested forests, meanwhile livestock greatly impacted over secondary structures and edges of N. antarctica forests. We conclude that retention approach in every ecosystem should be implemented at low spatial scales (e.g. paddocks) by private or public land-owners to improve the conservation of not evenly distributed biodiversity at both medium and large scale.