The amount of carbon stored in deadwood is equivalent to about 8 per cent of the global forest carbon stocks¹. The decomposition of deadwood is largely governed by climate^2,3,4,5 with decomposer groups—such as microorganisms and insects—contributing to variations in the decomposition rates^2,6,7. At the global scale, the contribution of insects to the decomposition of deadwood and carbon release remains poorly understood⁷. Here we present a field experiment of wood decomposition across 55 forest sites and 6 continents. We find that the deadwood decomposition rates increase with temperature, and the strongest temperature effect is found at high precipitation levels. Precipitation affects the decomposition rates negatively at low temperatures and positively at high temperatures. As a net effect—including the direct consumption by insects and indirect effects through interactions with microorganisms—insects accelerate the decomposition in tropical forests (3.9% median mass loss per year). In temperate and boreal forests, we find weak positive and negative effects with a median mass loss of 0.9 per cent and −0.1 per cent per year, respectively. Furthermore, we apply the experimentally derived decomposition function to a global map of deadwood carbon synthesized from empirical and remote-sensing data, obtaining an estimate of 10.9 ± 3.2 petagram of carbon per year released from deadwood globally, with 93 per cent originating from tropical forests. Globally, the net effect of insects may account for 29 per cent of the carbon flux from deadwood, which suggests a functional importance of insects in the decomposition of deadwood and the carbon cycle.

枯木中储存的碳量相当于全球森林碳储量的 8% 左右¹。枯木的分解主要受气候^2,3,4,5的影响，分解者群体（例如微生物和昆虫）会导致分解速率的变化^2,6,7。在全球范围内，昆虫对枯木分解和碳释放的贡献仍然知之甚少⁷. 在这里，我们在 55 个森林地点和 6 个大洲展示了木材分解的现场实验。我们发现枯木分解速率随温度增加而增加，并且在高降水量下发现最强的温度效应。沉淀在低温下对分解速率产生负面影响，在高温下对分解速率产生积极影响。作为一种净效应——包括昆虫的直接消耗和与微生物相互作用的间接影响——昆虫加速了热带森林的分解（每年平均质量损失 3.9%）。在温带和寒带森林中，我们发现微弱的正面和负面影响，平均质量损失分别为每年 0.9% 和 -0.1%。此外，我们将实验推导出的分解函数应用于根据经验和遥感数据合成的枯木碳全球地图，估计全球枯木每年释放 10.9 ± 3.2 拍克的碳，其中 93% 来自热带森林。在全球范围内，昆虫的净效应可能占死木碳通量的 29%，这表明昆虫在死木分解和碳循环中的功能重要性。