印度西高止山北卡納達區內，不同人為干擾壓力下熱帶雨林之地上部生物量與碳存量動態

Above – Ground Standing Biomass and Carbon Stock Dynamics under a Varied Degree of Anthropogenic Pressure in Tropical Rain Forests of Uttara Kannada District, Western Ghats, India

在印度南部西高止山北卡納達區內，我們從1984到2009年間，以25年的時距監測六個面積一公頃的永久森林樣區，用以瞭解在不同人為干擾壓力下森林地上部的現存生物量與碳存量動態。結果發現，在25年過後，每公頃樹木總損失株數可從97棵到761棵（23.95-60.7%）。其中，人為砍除的株數從每公頃42棵到559棵（5.5-55.17%），自然死亡的株數則從每公頃55棵到370棵（5.52-38.38%）。其中，有兩個樣區因為死亡個體過多，而造成整體植物底面積減少（-1.81 m2/ha及-1.73 m2/ha）。另外四個樣區的植物底面積及整體生物量，則因為存活個體的生長，而呈現增加（底面積0.98 to 22.19 m2/ha;生物量6.40 to 144.67 t/ha）。樹木新增株數範圍，則從每公頃214棵到1,840棵，這比其中四個樣區因為死亡而損失的植株數還要多，顯示樣區在植株密度上具有快速恢復的能力。在第25年時，樣區新增率為28.34- 85.06%，佔樣區植物底面積的1.20-18.47%，以及1.0 -14.67%的地上部生物量及碳存量，使得我們調查的所有六個樣區都是碳匯。綜合言之，在北卡納達區內森林，碳的累積率約為1.13 t C /ha /yr，其中有0.58±1.18 t C /ha/yr是由存活個體貢獻，0.55±0.33 t C/ha/year則是由新增個體所貢獻。因此，這片森林碳吸存的潛力，可以在適當的經營及復育策略下提升，使得西高止山地區成為碳匯。所以在計畫及經營森林時，為促使森林中的碳存量增加，必須加以考慮新增個體在森林動態中扮演的角色。

Above-ground standing biomass and carbon-stock dynamics were monitored for 25 years (from 1984 to 2009) in six 1-ha permanent forest sites subjected to different levels of anthropogenic pressure in tropical rain forests of Uttara Kannada district,Western Ghats, south India. Over the years, total loss of trees ranged from 97 to 761 (23.95- 60 .7%) trees/ha, removal of trees by people ranged from 42 to 559 (5.5-55.17%) trees/ha and number of trees dead ranged from 55-370 (5.52-38.38%) trees/ha, leading to reduction in basal area in two sites (-1.81 m2/ha, and -1.73 m2/ha). In four sites, basal area increased from 0.98 to 22.19 m2/ha, because of compensatory growth of surviving trees and added above-ground standing biomass ranging from 6.40 to 144.67 t/ha. Tree recruitment ranged from 214 to 1,840 trees/ha and it was more than the number of trees lost in four sites, indicating faster recovery of tree density. In the 25th year, recruits formed 28.34 - 85.06% of the stand tree density and shared 1.20-18.47% of the stand basal area and accounted for 1.0-14.67% of the above-ground standing biomass and carbon stock, making all six sites as C-sinks. In general, the rate of carbon accumulation in forests of Uttara Kannada district was 1.13 t C /ha /yr , of which, 0.58 ± 1.18 t C /ha/year was contributed by surviving trees and 0.55 ± 0.33 t C/ha/year was added by recruits. With proper management strategies, the C-sequestration potential in the forests can be elevated and by reforesting degraded area, the carbon sink can be enhanced in the Western Ghats region. Role of recruits in forest dynamics must be considered while planning and management of forests to enhance carbon stocks.