Effects of forest management on structural features important for biodiversity in mixed-age hardwood forests in Australia's subtropics

Native forest management in subtropical South America: long-term effects of logging and multiple-use on forest structure and diversity

“…The scenario in the fragments agrees with claims that conventional logging constitutes unsustainable forest management (Bawa and Seidler 1998;Sist et al 1998;Eyre et al 2010;Putz et al 2001). It also warns against claims that timber logging (Sanquetta 1999;Rosot 2007) allied to forest multiple-use management by landowners (Rosot 2007) could be an effective way of conserving the Araucaria mixed forests.…”

“…In a longer time scale, logged fragments may suffer from hampered succession due to dispersal limitation (Barlow et al 2006) and pervasive edge effects (Broadbent et al 2008) that promote widespread and permanent tree canopy openings (Souza and Martins 2005), elevated tree mortality (Laurance et al 2002) and favored population growth of pioneer species (Dupuy and Chazdon 1998;Laurance et al 2006), among other changes. Pervasive edge effects in the study region have been found to contribute to forest degradation elsewhere and include cattle grazing and trampling (Eyre et al 2010;Souza et al 2010), fire, hunting, firewood extraction, and seed harvesting (Guerra et al 2002;Silveira et al 2007). As has been found in other ecoregions (Santos et al 2008;Pütz et al 2011), degradation was more pronounced in smaller fragments, which are more susceptible to edge effects (Broadbent et al 2008).…”

“…Our results indicate that Angiosperms, on the other hand, may be more prone to ecologicallybased management plans aiming at selective logging, as indicated by its resilience to disturbance as a group and the formerly heavily-logged Ocotea in particular. The ecological sustainability of such exploitation, however, is likely to rely on more careful and biodiversityoriented management (Bawa et al 1998;Putz et al 2001;Fonseca et al 2009), that should include: (a) reduced logging intensities (Sist et al 1998;Chapman et al 2000;Barlow et al 2006;Eyre et al 2010), possibly up to 15 % of each stand basal area (Sist and Nguyen-Thé 2002), (b) adoption of careful planning of logging strategies aiming at minimizing operational impacts during felling and yarding, like reduced-impact logging (Sist et al 1998), (c) adoption of rotation times longer (at least 55 years) than those employed in experimental A. angustifolia plantations (45 years, Guerra et al 2002) (Horne and Hickey 1991;Sist et al 1998;Kariuki et al 2006;Sebbenn et al 2008;Fonseca et al 2009;Eyre et al 2010), (d) setting aside at least 10 % or a minimum of 25 ha (Pütz et al 2011) of managed forests as unlogged refugia for species conservation and as colonist sources (Barlow et al 2006), (e) restriction of forest management to fragments larger than the prudential and tentative threshold size of 100 ha, (f) sustainable harvesting of non timber forest products (Guerra et al 2002;Silveira et al 2007), (g) development of locally based ecotourism, (h) the regulation and generalization of landowners payment for ecosystem services, (i) livestock exclusion from forest remnants, in order to allow the maintenance of understory biodiversity (Fonseca et al 2009) and overstory natural regeneration (Eyre et al 2010;Souza et al 2010), and (j) restrict human access other than touristic to managed forests in order to avoid associated degrading effects like hunting and fire (Toivonen et al 2011). Each of these points represents a research agenda of great conservation relevance in itself.…”

“…In tropical and subtropical regions, most of the literature has concentrated on small-scale and short-term logging impacts (e.g., Bawa and Seidler 1998;Panfil and Gullison 1998;Sist et al 1998;Sist and Nguyen-Thé 2002;Gerwing 2002). However, due to the long life spans of forest trees and landscape-scale spatial variations in forest structure and composition, forest resilience assessments need long-term and large-scale data, which are difficult to obtain and largely lacking for these regions (but see Kariuki et al 2006;Eyre et al 2010 for Australian and Asian studies). The relative effects of logging and chronic forest disturbance are even less studied, in spite of the fact that logging and forest degradation are closely related processes (Putz et al 2001;Gerwing 2002;Asner et al 2006;Broadbent et al 2008;Eyre et al 2010;Toivonen et al 2011).…”

“…30-40 years of post-harvesting undisturbed succession (Horne and Hickey 1991;Panfil and Gullison 1998;Gerwing 2002;Kariuki et al 2006). Fragmentation and chronic disturbance, however, degrade forest fragments and keep them at early successional stages (Putz et al 2001;Santos et al 2008;Pütz et al 2011), with higher tree density, reduced basal area and scarce or absent regeneration (Gerwing 2002;Laurance et al 2002;Souza and Martins 2005;Broadbent et al 2008;Santos et al 2008;Eyre et al 2010;Souza et al 2010;Pütz et al 2011;Toivonen et al 2011). Structure of recentlylogged forests is expected to lie in between that of control and fragments.…”