Research achievements of Jianfengling National Forest Ecological Station --Partial recovery of the secondary forests after half century logging in Hainan Island
Author:   Source: Research Institute of Tropical   Time: 2015-07-01

Under the support of the Jianfengling National Forest Ecological Station, Research Institute of Tropical Forestry (RITF), Chinese Academy of Forestry (CAF), one biodiversity monitoring and research platform was set up in 2014 by hard field works for six years. It is composed of one 60 ha permanent plots, 180 satellite quadrats and eleven 3000-10000 m2 permanent plots. Around eight billion data were recorded for all of these field investigations.

By analyzing the data from 164 25×25 m quadrats across a 160-km2 tropical rain forest landscape on Hainan Island, China, which had been clear-cut or selectively harvested and left to recover without management for up to 50 years. Species richness and species abundance distributions were compared among five successional categories to investigate changes in species richness and species abundance over time. Basal areas and three different species similarity indices were compared to reveal temporal changes in species composition and community structure. We found some crucial clues for the recovery of tropical secondary forests.

Species richness recovered faster than species composition and structure in both selectively logged and clear-cut forests. Both total number of species and number of rare species tended to increase from younger harvested forests through older harvested forests to old-growth intact forests. Within 20–40 years after harvest species composition of harvested forests tended towards that of old-growth forests, community similarity between harvested and old-growth forests decreased subsequently and basal area did not recover, given even a half-century of succession undisturbed by anthropogenic forces.

Shortly after harvest, pioneer species increased rapidly, but shade-tolerant species required much more time to recover to former abundances. The shift from pioneer species to shade-tolerant species indicates significant recovery of logged forests.

Selectively logged forests recovered more quickly and had higher conservation values than clear-cut forests.

These findings indicate that logged tropical forests only partially recovered the characteristics of pre-harvest, primary forest after a half-century of succession. Recovery of the original tree biodiversity on such post-harvest landscapes will be slow at best, if measured by species composition or stand structure. Our study amplifies the importance of conserving tropical forest integrity and developing harvest and management approaches that facilitate full recovery of logged tropical forests.

These findings supported the theory about how to manage tropical forests proposed by RITF, CAF, that is, 70% of the original forests should be conserved to facilitate the recovery of tropical secondary forests and the logged target trees should be selected carefully. This theory was also supported by the main achievements from the Second National Prize for Progress in Science and Technology achieved by RITF, CAF in 1999.

This paper was published in Journal of Applied Ecology and the editor and reviewers regarded that this paper illustrated the importance of reasonable management and protection of tropical primary forests. It is important for assessing the conservation effects of tropical natural forests and improving the natural protection and managements measures in China.

ReferenceHan Xu, Shirong Liu*, Yide Li, Runguo Zang*, Fangliang He and Spence John. 2015. Partial recovery of a tropical rain forest a half century after clear-cut and selective logging. Journal of Applied Ecology, 52(4): 1044-1052. DOI: 10.1111/1365-2664.12448.

Fig. 1. Species accumulation curves based on (a, b) number of sampling quadrats and (c, d) number of sampling stems using rarefaction method for old-growth forests (OG), older selectively logged forests (SLold), recently selectively logged forests (SLyoung), older clear-cut forests (CLold) and recently clear-cut forests (CLyoung).

Fig. 2. Basal areas at the breast height of selectively logged forests (SL) and clear-cut forests (CL) compared to old-growth forests (OG) along recovery times, with (a) d.b.h. 2_5 cm, (b) d.b.h. 40 cm, (c) d.b.h. 2_5 cm for eighteen pioneer species and (d) d.b.h. 2_5 cm for eighteen shade-tolerate species. Average value for each of the old-growth forest category is plotted as a straight line for comparison, respectively. Basal area unit: m2/625 m2.