Management Effects on Tree Species Diversity and Dipterocarp Regeneration

Abstract

Unregulated selective logging has been common throughout the Southeast Asian tropical rain forests. Such logging usually damages more than 50 % of the original forest biomass and causes soil disturbances by the use of heavy machinery (Cannon et al. 1994; Pinard and Putz 1996; Bertault and Sist 1997; Sist et al. 1998). To mitigate the deleterious logging impacts, reduced-impact logging has been applied in some tropical production forests (Kleine and Heuveldop 1993; Lagan et al. 2007; Putz et al. 2008a). Reduced-impact logging is a modification of selective logging that is intended to minimize collateral damage to the residual stands. Such methods include pre-harvest inventory, mapping of all canopy trees, directional felling, liana cutting, and planning of skid trails, log decks, and roads (see Chap. 1). In comparison with unregulated conventional logging, reduced-impact logging is beneficial in maintaining not only future crop trees (Rockwell et al. 2007; Pena-Claros et al. 2008) and forest biomass (Johns et al. 1996; Pinard and Putz 1996; Bertault and Sist 1997; Sist et al. 1998; Putz et al. 2008b; Imai et al. 2009), but also biological diversity, such as dung beetles (Davis 2000), flying insects (Akutsu et al. 2007), soil fauna (see Chap. 4 by Hasegawa et al., this volume), and forest-dwelling vertebrates (see Chap. 5 by Samejima et al., this volume). Many other taxa, such as ants, arachnids, bats, birds, fishes, and animals, also are not adversely affected by reduced-impact logging (Azevedo-Ramos et al. 2006; Wunderle et al. 2006; Castro-Arellano et al. 2007; Felton et al. 2008; Presley et al. 2008; Dias et al. 2010; Bicknell and Peres 2010). However, the effects of reduced-impact logging on tree species diversity of tropical rain forests remain largely unknown, despite that the diversity of trees is fundamental to the structure and functions of the forests. The diversity of trees may also determine the diversity of other taxonomic groups because trees provide resources and habitat structures for dependent species. The aim of this study is to examine the effects of reduced-impact logging versus conventional logging on tree species diversity and composition in the lowland tropical rain forests in Deramakot and Tangkulap.