Introduction

chileHabitat fragmentation and forest loss have been recognized as a major threat to ecosystems worldwide (Armenteras et al., 2003; Dale and Pearson, 1997; Iida and Nakashizuka, 1995; Noss, 2001). These two processes may have negative effects on biodiversity, by increasing isolation of habitats (Debinski and Holt, 2000), endangering species, and modifying species’ population dynamics (Watson et al., 2004).

Fragmentation may also have negative effects on species richness by reducing the probability of successful dispersal and establishment (Gigord et al., 1999) as well as by reducing the capacity of a patch of habitat to sustain a resident population (Iida and Nakashizuka, 1995). For example, fragmentation of Maulino temperate forest in central Chile has affected the abundance of bird richness (Vergara and Simonetti, 2004) and regeneration of shade-tolerant species (Bustamante and Castor, 1998), and has also favoured the invasion of alien species (Bustamante et al., 2003). The ecological consequences of fragmentation can differ depending on the pattern or spatial configuration imposed on a landscape and how this varies both temporally and spatially (Armenteras et al., 2003; Ite and Adams, 1998).

Some studies have shown that the spatial configuration of the landscape and community structure may significantly affect species richness at different scales (Steiner and Ko¨hler, 2003). Other authors emphasise the need to incorporate the spatial configuration and connectivity attributes at a landscape level in order to protect the ecological integrity of species assemblages (Herrmann et al., 2005; Piessens et al., 2005). The temporal evaluation of forest change based on satellite imagery linked to fragmentation analysis is becoming a valuable set of techniques for assessing the degree of threat to ecosystems (Armenteras et al., 2003; Franklin, 2001; Imbernon and Branthomme, 2001; Luque, 2000; Sader et al., 2001).

A number of deforestation studies have been conducted in tropical forests (Imbernon and Branthomme, 2001; Sader et al., 2001; Skole and Tucker, 1993; Steininger et al., 2001; Turner and Corlett, 1996) and, in particular, in the Amazon, which is now considered as the most studied region in the world by some researchers (Jorge and Garcia, 1997; Laurance, 1999; Laurance et al., 2000; Pedlowski et al., 1997; Ranta et al., 1998; Sierra, 2000). Conversely, few studies of deforestation and fragmentation have been reported for temperate forests (Staus et al., 2002), particularly in the southern hemisphere.

Chile has the largest temperate forest area in South America and more than half of the total area of temperate forests in the southern hemisphere (Donoso, 1993). Most of these forests are distributed along the Coastal and the Andean Range of Chile from 35 to 56 S and extend to a total of 13.4 million ha in the country (Conaf et al., 1999a). The temperate forest of Chile has been classified a biodiversity hotspot for conservation (Myers et al., 2000) and has also been included among the most threatened eco-regions in the world in the Global 200 initiative launched by WWF and the World Bank (Dinerstein et al., 1995).

In these forests, a 34% of the plant genera are endemic (90% monotypic) (Armesto et al., 1997). However, Chile’s temperate forests are being harvested to supply the increasing global demand for wood and paper products. A substantial amount of forest has also been lost due to the conversion of native forests to pasturelands, human-set fires, high grading (selective felling) and other logging practices (Lara et al., 2000). Although some of the ecological consequences of forest fragmentation have been studied in Chile (Bustamante and Grez, 1995; Donoso et al., 2003; Vergara and Simonetti, 2004; Willson et al., 1994), integrated spatial and temporal analyses have not been conducted. Although some attempts have been made in Chile to estimate the rate of deforestation (Lara et al., 1989; Olivares, 2000) or to assess land cover change (Conaf et al., 1999b; Sandoval, 2001), these have been undertaken at local scales, over short time intervals (no more than 10 years), or using different types of data to compare forest cover over time, which confers some methodological limitations. Longterm analyses of the spatial patterns of deforestation and fragmentation of temperate forest ecosystems at the landscape scale have not yet been reported either in Chile or elsewhere in the southern hemisphere.

The purpose of this study is to contribute to the understanding of the patterns of deforestation and fragmentation in the temperate forests of Chile at the landscape level. In particular, we examined the patterns of land-cover change and the changes in the spatial configuration in the Maulino temperate forest over time and space by using satellite scenes acquired at different time intervals. In this study, we hypothesised that there has been a substantial loss of native forest as a result of an increase in area of exotic-species plantations. Also, we anticipated that this forest loss was related to fragmentation of Maulino forests due to changes in the spatial configuration in terms of size, shape and degree of isolation of forest patches. This work is the first step to understand the potential ecological effects of fragmentation and the proximate drivers and causes of deforestation, which will be addressed in other studies.

source: Rapid deforestation and fragmentation of Chilean Temperate Forests
by Cristian Echeverria a,b, * ,1 , David Coomes a , Javier Salas c , Jose´ Marı´a Rey-Benayas d , Antonio Lara b , Adrian Newton