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*Effects of logging on the lowland tropical rain forest in Peninsular Malaysia
 
*Effects of logging on the lowland tropical rain forest in Peninsular Malaysia
 
Toshinori Okuda (Graduate School of Integrated Sciences for Life, Hiroshima University), co-authored with; Toshiro Yamada, Tetsuro Hosaka, Masahiro Miyasaku, Mazlan Hashim, Alvin Lau Meng Shin, Saw Leng Guan, Ken Shima, Toshihiro Yamada, Kaoru Niiyama, Yoshiko Kosugi, Tsuyoshi Yoneda, Eng Seng Quah
 
Toshinori Okuda (Graduate School of Integrated Sciences for Life, Hiroshima University), co-authored with; Toshiro Yamada, Tetsuro Hosaka, Masahiro Miyasaku, Mazlan Hashim, Alvin Lau Meng Shin, Saw Leng Guan, Ken Shima, Toshihiro Yamada, Kaoru Niiyama, Yoshiko Kosugi, Tsuyoshi Yoneda, Eng Seng Quah
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Recent rapid increases in ambient CO2 are largely attributed to deforestation in tropics. However, the carbon emissions from terrestrial ecosystem are mostly based on the area-wise statistics of “forest land” which is defined as an area with minimum crown coverage >10%, while extensive biomass (more than 50%) has been removed through “forest degradation” processes resulted from the over-harvesting in legitimated logging regime or illegal logging. Therefore, if the carbon losses accompanied by the forest degradation had been added on the forest statistics, actual carbon losses and emissions could have been larger than those were reported. Therefore, recovery process accompanied after forest degradation needs to be thoroughly monitored and reviewed in order to evaluate long term NET carbon losses.  
 
Recent rapid increases in ambient CO2 are largely attributed to deforestation in tropics. However, the carbon emissions from terrestrial ecosystem are mostly based on the area-wise statistics of “forest land” which is defined as an area with minimum crown coverage >10%, while extensive biomass (more than 50%) has been removed through “forest degradation” processes resulted from the over-harvesting in legitimated logging regime or illegal logging. Therefore, if the carbon losses accompanied by the forest degradation had been added on the forest statistics, actual carbon losses and emissions could have been larger than those were reported. Therefore, recovery process accompanied after forest degradation needs to be thoroughly monitored and reviewed in order to evaluate long term NET carbon losses.  
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In these respects and backgrounds, we studied biomass and canopy structural changes in a lowland tropical rain forest in the Pasoh Forest Reserve (PFR) of Peninsular Malaysia after selective logging in 1950s, and found that total aboveground biomass (AGB) has not fully recovered yet to the level observed in a primary forest plot within PFR. On this site, we also conducted canopy height mapping using an airborne light detection (LiDAR) in 2003 and 2011, and found that the average canopy height in the logged forest was still lower than that in the primary forest. The coefficient of variation of canopy height was also lower in the logged forest plot, suggesting that the highly heterogeneous features in canopy surface height commonly seen in the pristine old growth forest, known as typical features tropical rain forest, has not fully recovered yet. These studies suggest delay of recovery process, not only in AGB but in forest structures will possibly result in underestimate of the carbon emission from forest sectors, and “forest degradation” needs to be thoroughly studied and should be incorporated properly into the climate mitigation measures.
 
In these respects and backgrounds, we studied biomass and canopy structural changes in a lowland tropical rain forest in the Pasoh Forest Reserve (PFR) of Peninsular Malaysia after selective logging in 1950s, and found that total aboveground biomass (AGB) has not fully recovered yet to the level observed in a primary forest plot within PFR. On this site, we also conducted canopy height mapping using an airborne light detection (LiDAR) in 2003 and 2011, and found that the average canopy height in the logged forest was still lower than that in the primary forest. The coefficient of variation of canopy height was also lower in the logged forest plot, suggesting that the highly heterogeneous features in canopy surface height commonly seen in the pristine old growth forest, known as typical features tropical rain forest, has not fully recovered yet. These studies suggest delay of recovery process, not only in AGB but in forest structures will possibly result in underestimate of the carbon emission from forest sectors, and “forest degradation” needs to be thoroughly studied and should be incorporated properly into the climate mitigation measures.
  

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