Immediate effects of thinning with a small patch clearcut on understory light environments in a Cryptomeria japonica plantation in central Taiwan

Jyh Min Chiang, Kuo Chuan Lin, Jeen Liang Hwong, Hsueh Ching Wang, Teng Chiu Lin

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Thinning is an important forest management practice; however, its effects on the microenvironment have rarely been investigated in tropical and subtropical ecosystems. We examined the effect of 25% (25 of 100 10 × 10 m subplots were clearcut) and 50% (1/2 of the subplots were cut) thinning on understory light environments characterized using hemispherical photography at a Cryptomeria japonica plantation, Taiwan's most common plantation species. Thinning had a greater effect on the variability than on the availability of understory light, with the former increasing 40 and 120% under 25 and 50% thinning intensities, respectively, and the variance increasing 2.4∼9.9-fold. The > 40% increase in understory light availability following 25% thinning was much greater than the 25% increase in light at a forest in northeastern Taiwan following the 1996 category-3 typhoon Herb, which decreased variability of understory light. Typhoons are the most important natural disturbance in Taiwan. Thus, mechanical thinning at intensities > 25% increases light availability and variability to levels that rarely exist following typhoon disturbance. In addition, mechanical thinning of 0.01-ha patches as applied in this study led to an understory light environment that was decoupled from the pre-thinning condition. In contrast, typhoon disturbances are typically more evenly spread, resulting in positively correlated pre- and post-typhoon light environments. Long-term monitoring is required to understand differences in successional trajectories following mechanical thinning and typhoon disturbance.

Original languageEnglish
Pages (from-to)319-331
Number of pages13
JournalTaiwan Journal of Forest Science
Issue number4
Publication statusPublished - 2012 Dec 1



  • Gap
  • Hemispherical photography
  • Light environment
  • Thinning

ASJC Scopus subject areas

  • Forestry

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