Suspended Dead Wood Decomposes Slowly in the Tropics, with Microbial Decay Greater than Termite Decay
Suspended Dead Wood Decomposes Slowly in the Tropics, with Microbial Decay Greater than Termite Decay
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DOI：
10.1007/s10021-018-0331-4
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发表时间：
2019-01
期刊：
影响因子：
3.7
通讯作者：
S. Law;P. Eggleton;H. Griffiths;L. Ashton;C. Parr
中科院分区：
文献类型：
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作者：
S. Law;P. Eggleton;H. Griffiths;L. Ashton;C. Parr
粗木屑（CWD）是森林生态系统中重要的碳库，它以落落、直立和悬浮的形式存在于各地层中。然而，与温带森林相比，热带森林中CWD的分解研究相对较少，特别是对悬浮CWD的研究基本上没有尝试过。白蚁是热带生态系统中重要的分解者，但其相对于微生物分解者的作用以及CWD垂直位置的重要性却很少被考虑。我们首次研究了大型无脊椎动物（主要是白蚁）和微生物对热带低地雨林悬浮物和地面放置（掉落）CWD腐烂的相对贡献。我们设置有白蚁接触和没有白蚁接触的木饵（辐射松），并在1年后测量木材质量损失。地面CWD检测的质量损失是悬浮CWD检测的四倍多。白蚁分解呈垂直分层，白蚁对地面CWD分解的相对贡献较大，对悬浮CWD分解的贡献可忽略不计。相反，微生物对分解的影响较低，且没有垂直分层。尽管我们的结果支持温带研究的发现，即CWD的分解取决于其物理位置，但我们表明，在热带雨林中，这主要是由于森林地面上的白蚁分解更大。悬浮的CWD仍然是一个重要的碳汇，因为微生物腐烂缓慢，直到它落到森林地面，白蚁更容易接近。
Coarse woody debris (CWD) is an important pool of carbon in forest ecosystems and is present in all strata as fallen, standing or suspended CWD. However, there are relatively few decomposition studies of CWD in tropical forests compared with temperate forests, and research on suspended CWD in particular has largely not been attempted. Termites are important decomposers in tropical ecosystems yet their role relative to microbial decomposers and the importance of the vertical location of CWD has rarely been considered. For the first time, we examined the relative contribution of macro-invertebrates (predominantly termites) and microbes to the decay of suspended and ground-placed (fallen) CWD in lowland, tropical rainforest. We set up wood baits (Pinus radiata) with and without termite access, and measured wood mass loss after 1 year. Mass loss of ground-placed CWD assays was over four times greater than suspended CWD assays. Termite decomposition was vertically stratified with termites having a large relative contribution to the decomposition of ground-placed CWD and a negligible contribution to the decomposition of suspended CWD. In contrast, the effect of microbes on decomposition was low and not vertically stratified. Although our results support the findings of temperate studies in that decomposition of CWD is dependent on its physical location, we show that in tropical rainforests this is predominantly due to greater termite decomposition on the forest floor. Suspended CWD remains an important carbon sink due to slow microbial decay until it falls to the forest floor where it is more accessible to termites.