Yale University School of the Environment, New Haven, Connecticut, USA.
The New York Botanical Garden, The Bronx, New York, USA.
J Anim Ecol. 2023 Dec;92(12):2280-2296. doi: 10.1111/1365-2656.14002. Epub 2023 Sep 5.
Animals interact with and impact ecosystem biogeochemical cycling-processes known as zoogeochemistry. While the deposition of various animal materials (e.g. carcasses and faeces) has been shown to create nutrient hotspots and alter nutrient cycling and storage, the inputs from parturition (i.e. calving) have yet to be explored. We examine the effects of ungulate parturition, which often occurs synchronously during spring green-up and therefore aligns with increased plant nitrogen demand in temperate biomes. Impacts of zoogeochemical inputs are likely context-dependent, where differences in material quality, quantity and the system of deposition modulate their impacts. Plant mycorrhizal associations, especially, create different nutrient-availability contexts, which can modify the effects of nutrient inputs. We, therefore, hypothesize that mycorrhizal associations modulate the consequences of parturition on soil nutrient dynamics and nitrogen pools. We established experimental plots that explore the potential of two kinds of zoogeochemical inputs deposited at ungulate parturition (placenta and natal fluid) in forest microsites dominated by either ericoid mycorrhizal (ErM) or ectomycorrhizal (EcM) plants. We assess how these inputs affect rates of nutrient cycling and nitrogen content in various ecosystem pools, using isotope tracers to track the fate of nitrogen inputs into plant and soil pools. Parturition treatments accelerate nutrient cycling processes and increase nitrogen contents in the plant leaf, stem and fine root pools. The ecosystem context strongly modulates these effects. Microsites dominated by ErM plants mute parturition treatment impacts on most nutrient cycling processes and plant pools. Both plant-fungal associations are, however, equally efficient at retaining nitrogen, although retention of nitrogen in the parturition treatment plots was more than two times lower than in control plots. Our results highlight the potential importance of previously unexamined nitrogen inputs from animal inputs, such as those from parturition, in contributing to fine-scale heterogeneity in nutrient cycling and availability. Animal inputs should therefore be considered, along with their interactions with plant mycorrhizal associations, in terms of how zoogeochemical dynamics collectively affect nutrient heterogeneity in ecosystems.
动物与生态系统生物地球化学循环过程相互作用并产生影响，这些过程被称为动物地球化学。虽然各种动物物质（如尸体和粪便）的沉积已被证明会产生养分热点，并改变养分循环和储存，但分娩（即产犊）的输入尚未得到探索。我们研究了食草动物分娩的影响，食草动物分娩通常在春季植被变绿期间同步发生，因此与温带生物群落中植物氮需求的增加相一致。动物地球化学输入的影响可能取决于具体情况，其中物质质量、数量和沉积系统的差异会调节其影响。特别是植物菌根共生体，会创造出不同的养分可利用性环境，从而改变养分输入的影响。因此，我们假设菌根共生体调节了分娩对土壤养分动态和氮库的影响。我们建立了实验小区，以探索在以石南科菌根（ErM）或外生菌根（EcM）植物为主的森林微生境中，两种在食草动物分娩时沉积的动物地球化学输入（胎盘和羊水）的潜在影响。我们使用同位素示踪剂来追踪氮输入到植物和土壤库中的命运，以此来评估这些输入如何影响各种生态系统库中养分循环的速率和氮含量。分娩处理加速了养分循环过程，并增加了植物叶片、茎和细根库中的氮含量。生态系统背景强烈调节这些影响。以 ErM 植物为主的微生境会使分娩处理对大多数养分循环过程和植物库的影响减弱。然而，两种植物-真菌共生体在保留氮方面同样有效，尽管分娩处理小区中氮的保留量比对照小区低两倍多。我们的研究结果突出了以前未被检验的动物输入（如分娩输入）对养分循环和可用性的微观尺度异质性的潜在重要性。因此，在考虑动物地球化学动态如何共同影响生态系统中的养分异质性时，应将动物输入及其与植物菌根共生体的相互作用一起考虑。
