Majdi Nabil, Traunspurger Walter, Garrigue Joseph, Larrieu Laurent
Massane Forest Reserve, Banyuls-sur-Mer, France.
Toulouse University, LRSV, UMR 5546 UPS/CNRS/INPT, Auzeville-Tolosane, France.
Oecologia. 2025 Aug 21;207(9):148. doi: 10.1007/s00442-025-05774-5.
Microscopic soil invertebrates are known to play an important role in forest ecosystems through their interactions with the rhizosphere and belowground food webs. However, little is known about the abundance, diversity, distribution, and ecological roles of micro-invertebrates above the forest floor, particularly within tree-related microhabitats (TreMs). In this study, we sampled 18 distinct types of TreMs in the UNESCO World Heritage old-growth beech forest of La Massane, located in the southeastern Pyrenees. We extracted and counted various groups of micro-invertebrates (nematodes, tardigrades, rotifers, and mites) associated with these TreMs, and identified nematodes to the species level. Additionally, we measured the stable isotopic signatures of carbon and nitrogen in various resources and invertebrate groups to reveal the structure of TreM-associated food webs in unprecedented detail. TreMs emerged as hotspots of both abundance (averaging 195 individuals per gram of dry TreM substrate) and diversity (98 nematode morphospecies across 20 families). We found significant differences among TreM types in terms of community composition and food web structure, revealing distinct species assemblages and trophic pathways. These differences could be linked to factors such as the stage of wood decomposition, occupation by larger animals (e.g., insects, birds), and the position of TreMs within trees. Our findings suggest that micro-invertebrates serve as valuable ecological indicators, adding a new layer of biodiversity and functional understanding to TreM typology. This, in turn, supports more comprehensive strategies for nature conservation and forest management.
已知微观土壤无脊椎动物通过与根际和地下食物网的相互作用在森林生态系统中发挥重要作用。然而，对于森林地面以上的微型无脊椎动物的丰度、多样性、分布和生态作用，尤其是在与树木相关的微生境（TreMs）中的情况，人们了解甚少。在本研究中，我们在位于比利牛斯山脉东南部的联合国教科文组织世界遗产地拉马萨讷老龄山毛榉林中，对18种不同类型的TreMs进行了采样。我们提取并计数了与这些TreMs相关的各类微型无脊椎动物（线虫、缓步动物、轮虫和螨类），并将线虫鉴定到物种水平。此外，我们测量了各种资源和无脊椎动物群体中碳和氮的稳定同位素特征，以前所未有的详细程度揭示与TreMs相关的食物网结构。TreMs成为丰度（平均每克干燥的TreM基质中有195个个体）和多样性（来自20个科的98种线虫形态种）的热点区域。我们发现不同类型的TreMs在群落组成和食物网结构方面存在显著差异，揭示了不同的物种组合和营养途径。这些差异可能与木材分解阶段、大型动物（如昆虫、鸟类）的占据以及TreMs在树木中的位置等因素有关。我们的研究结果表明，微型无脊椎动物是有价值的生态指标，为TreM类型学增添了新的生物多样性和功能理解层面。这反过来又支持了更全面的自然保护和森林管理策略。
