Impacts of selective logging on spatial structure of tree species composition in Bornean tropical rain forests

ABSTRACT

We studied the impacts of selective logging on the spatial structure of tree species composition in the tropical rain forest of Sabah, Malaysia. We established 50 20-m radius plots (0.12 ha in area) across primary to highly degraded forests in each of two logging concessions with distances in between any two plots ranging from 0.2 to 40 km. In addition, we established one 100 × 200-m plot in each of primary, reduced-impact logged, and conventionally logged forest in other two logging concessions, and each plot was divided into 40 × 30-m quadrats (0.12 ha in area) for the further analysis of the spatial structure at the scale of less than 200 m. A decline of species-compositional similarity with increasing in-between distance was found in primary and moderately logged forest at both larger and smaller than 0.2-km scale. Such a spatial structure could not be detected in heavily logged forests at both scales. The heavily logged forests were rather characterized by mosaics of remnant stands and regenerating patches of pioneer species, leading to a high spatial variance of species composition without the distance-dependent spatial structure. Accordingly, high-impact conventional logging damages the distance-dependent spatial structure of species composition in canopy tree communities by creating random vegetation patches, while reduced-impact logging can maintain the spatial structure.

KEYWORDS:

• Borneo
• conventional logging
• reduced-impact logging
• sustainable forest management
• tree community composition

Acknowledgments

We acknowledge kind assistance from the KTS Plantation Sdn. Bhd., the Sapulut Forest Development Sdn. Bhd., and Forest Research Centre, Sabah Forestry Department. We thank M. Postar, D. Joel, and J. Jemson for tree species identification; J. B. Sampurai, J. Mandek, R. Ajon and many other staff of the FMUs for assisting field inventory; R. Aoyagi, S. Fujiki, A. Langner, and A. Tanaka for helpful discussion, and P. Lagan for generous support in every aspect.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for the article can be accessed here.

Additional information

Funding

This study was supported by JSPS KAKENHI Grant Numbers JP17K15289 and JP19K06128 to NI the Global Environment Research Fund (F-071, D-1006 and 1-1403) of the Ministry of the Environment, Japan to KK.