Data from: Macro-detritivores assist resolving the dryland decomposition conundrum by engineering an underworld heaven for decomposers

Litter decomposition in most terrestrial ecosystems is regulated by moisture-dependent microorganism activity, among other things. Decomposition models typically underestimate rates of plant litter decomposition in drylands, suggesting the existence of additional drivers of decomposition. Attempts to reveal these drivers have predominantly focused on abiotic degradation agents, alternative moisture sources, and soil-litter mixing. The role of burrowing animals in promoting decomposition has received less attention despite greatly contributing to plant litter transfer from the harsh desert surface to the moister and nutrient-rich environment belowground. Our goal was to explore how macro-detritivore burrows affect plant litter mineralization dynamics. We introduced 13C-labeled litter belowground into (1) desert isopod (Hemilepistus reaumuri) burrows and (2) artificial burrows, and aboveground on top of (3) isopod fecal pellet mounds and (4) bare soil crust. We compared the litter mass loss between the four treatments and used cavity ring-down spectroscopy to reveal the in situ mineralization dynamics. No litter mineralization was evident during the dry summer months both above- and belowground. Following rain events, mineralization rates spiked in all four micro-environments, quickly diminishing aboveground while slowly waning belowground. Total litter mass loss was twofold higher below- than aboveground and was significantly higher in isopod burrows compared to artificial burrows. Our findings demonstrate that burrowing macro-detritivores promote litter decomposition in deserts by transferring organic matter to their burrows where favorable climatic conditions and a nutrient-enriched environment foster microbial activity. Thus, attempts to resolve the dryland decomposition conundrum should not be limited to exploring factors that allow decomposition under harsh desert surface climatic conditions, but focus on the role that animals play in facilitating decomposer-friendly environments to which they translocate plant litter.

绝大多数陆地生态系统中的植物枯落物分解，除其他调控因素外，主要受依赖水分的微生物活性调控。当前主流的分解模型往往低估干旱区植物枯落物的分解速率，暗示枯落物分解存在额外驱动因子。目前为揭示此类驱动因子所开展的研究，主要聚焦于非生物降解因子、替代水源以及土壤与枯落物的混合过程。然而，打洞动物对分解过程的促进作用却未得到足够重视——尽管它们可将原本位于严酷荒漠地表的枯落物转运至湿度更高、养分更丰富的地下环境，极大推动了枯落物分解进程。本研究旨在探究大型碎屑食性动物的洞穴如何影响植物枯落物的原位矿化动态。我们将13C标记枯落物（13C-labeled litter）布设为四组处理：(1) 置入沙漠等足虫（Hemilepistus reaumuri）洞穴中；(2) 置入人工洞穴内；(3) 放置于等足虫粪球堆表层；(4) 放置于裸土结壳表层。我们对比了四组处理下的枯落物质量损失率，并采用腔环衰荡光谱法（Cavity Ring-down Spectroscopy）解析原位矿化动态。实验结果显示：干旱夏季期间，地表与地下生境均未观测到明显的枯落物矿化现象。降雨事件发生后，四种微环境中的矿化速率均出现显著峰值；地表生境的矿化速率快速回落，而地下生境的矿化速率则缓慢衰减。地下生境的总枯落物质量损失率为地表生境的两倍，且沙漠等足虫洞穴中的损失率显著高于人工洞穴。本研究表明，打洞的大型碎屑食性动物可通过将有机质转运至自身洞穴——该环境具备更适宜的气候条件与养分富集的微环境，可促进微生物活性——从而推动荒漠地区的枯落物分解。因此，破解干旱区枯落物分解难题的研究不应仅局限于探索严酷荒漠地表气候条件下的分解驱动因子，还应关注动物在构建利于分解者的微环境并转运植物枯落物过程中所发挥的关键作用。