Leaf breakdown is a primary process of nutrient cycling and energy flow, contributing to the functioning of aquatic ecosystems. In the present study, leaves of Baccharis platypoda and Coccoloba cereifera were incubated in a high-altitude stream in a rupestrian field. Two hypotheses were tested: i) intrinsic factors (quality of detritus) are more important than extrinsic factors (decomposer communities) in decomposition; and ii) low detritus quality hinders microbial colonization, thereby altering the composition and structure of the associated invertebrate community and slowing leaf breakdown. The breakdown coefficients of B. platypoda and C. cereifera leaves were low (k = -0.0019 day -1 and k = -0.0008 day -1 , respectively) and the proportions of structural compounds were high, delaying the remobilization of energy and nutrients into the aquatic ecosystem. Fungal biomass was higher at the end of the experiment, suggesting favorable conditions for colonization. The densities of invertebrates associated with the detritus increased coincident with the peak concentration of ergosterol, with the trophic groups collector-gatherer and scraper having the highest densities. The distribution of these groups was likely related to the growth of biofilm on the surface of the litters. As described for tropical streams, shredders had the lowest densities of any invertebrate group, suggesting a reduced participation of these invertebrates in leaf processing. The results suggest that slow decomposing species are important to both invertebrates and microorganisms as substrates and sources of particulate organic matter. The low palatability and nutritional quality of the detritus in the present study, associated with low dissolved nutrient concentrations in water, delayed the leaf conditioning process by microorganisms. Decomposition rates and invertebrate participation were reduced as a result, leading to major physical decomposition. Headwater tropical streams have chemically diverse detrital resources, and the intrinsic factors of litter may play key roles in the decomposition process.
展开▼
机译：叶片分解是养分循环和能量流的主要过程，有助于水生生态系统的功能。在本研究中，将白菜叶和小球藻的叶在菜田中的高海拔流中培育。测试了两个假设：i）在分解中，内在因素（碎屑的质量）比外在因素（分解者群落）更重要; ii）碎屑质量低会阻碍微生物定植，从而改变相关无脊椎动物群落的组成和结构，并减缓叶片破裂。 B. platypoda和C. cereifera叶片的分解系数很低（分别为k = -0.0019 day -1和k = -0.0008 day -1），结构化合物的比例很高，从而延迟了能量和养分的迁移。水生生态系统。在实验结束时，真菌的生物量更高，这为定殖提供了有利条件。与碎屑相关的无脊椎动物的密度随着麦角固醇的峰值浓度增加而增加，其中营养族的收集器-收集器和刮具的密度最高。这些组的分布可能与垫料表面生物膜的生长有关。如对热带溪流所述，切碎机的密度在所有无脊椎动物中是最低的，这表明这些无脊椎动物参与叶片加工的程度有所降低。结果表明，缓慢分解的物种对于无脊椎动物和微生物都非常重要，因为它们是颗粒状有机物的基质和来源。在本研究中，碎屑的适口性和营养品质低，与水中溶解的营养素浓度低相关，从而延迟了微生物对叶片的调节过程。结果，分解率和无脊椎动物的参与度降低，导致严重的身体分解。上游源头的热带河流具有化学上多种多样的碎屑资源，垃圾的内在因素可能在分解过程中起关键作用。
展开▼
