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Scale-dependent effects of plant and animal functional characteristics on nutrient cycling in pastures

植物和动物功能特征对牧场养分循环的规模依赖性影响

基本信息

批准号：
251283083
负责人：
Dr. Bettina Tonn
金额：
--
依托单位：
Abteilung Graslandwissenschaft
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/251283083?language=en
关键词：
Scale dependent effects plant animal

项目摘要

Both in low-input managed pastures and in natural ecosystems grazed by large herbivores, nutrients excreted in dung and urine of the grazing animals play an important part in the nutrient cycle. These nutrient flows involve spatial concentration and spatial separation of the main mineral nutrients at the scale of the excreta patch. Animal and plant functional characteristics influence the grain size and degree of this spatial heterogeneity, as well as the patch-scale responses of vegetation and grazing animal biomass intake to the nutrient input through excreta. While ecological research has strongly focused on large-scale effects of herbivory in terms of speed and stoichiometry of nutrient cycling, agricultural research has mostly regarded excreta-patch effects on a small scale and detached from the large-scale systems in which they occur. Plant and animal functional characteristics have important effects on nutrient cycling at the excreta-patch scale that have not yet been explicitly addressed in either ecological or agricultural research. The project intends to combine approaches and concepts from both ecological and agricultural research about herbivory effects on nutrient cycling. It will investigate how the effect of animal excreta on above-ground nutrient flows and on plant biomass nutrient stoichiometry is influenced by plant functional groups and grazing animal functional characteristics.The study system will be a long-term unfertilized grazing experiment with two experimental factors: sward type (diverse and grass-dominated) and grazing animal species (cattle and sheep, differing in body size, excreta patch size and grazing selectivity). Data will be gathered on three levels: paddock-scale and patch-scale data in the grazed system and patch-scale data under simulated grazing. At the paddock scale, biomass productivity and nutrient concentrations (nitrogen, phosphorus and potassium), biomass and mineral nutrient ingestion by the grazing animals and nutrient excretion in dung and urine will be quantified, and will be used to up-scale excreta patch effects to the paddock scale. At the patch scale, dung, urine and unaffected control patches will be marked in the grazed pasture to assess plant and herbivory responses to excreta patches. A cutting experiment with simulated dung and urine patches will be used to validate these data under controlled conditions and to extend observation period and measured parameters beyond the programme feasible under grazing. Process parameters such as defoliation interval and defoliation severity will be chosen to simulate those of the grazed study system.The project is expected to advance the basic knowledge about large-herbivore effects on nutrient cycling by addressing the small-scale heterogeneity of the quantitatively important nutrient flows through herbivore excreta and the functional characteristics of plants and herbivores that are process-relevant at this scale.

在低投入管理的牧场和大型食草动物放牧的自然生态系统中，放牧动物从粪便和尿液中排泄的营养物质在营养循环中发挥着重要作用。这些营养流涉及主要矿质营养物质在排泄物斑块尺度上的空间集中和空间分离。动植物功能特征影响这种空间异质性的颗粒大小和程度，以及植被和放牧动物的生物量对通过排泄物输入的养分的斑块尺度响应。虽然生态学研究主要集中在食草动物在养分循环的速度和化学计量方面的大范围影响，但农业研究大多着眼于小范围的排泄物-斑块效应，脱离了它们发生的大系统。植物和动物的功能特性对排泄物-斑块尺度上的养分循环具有重要影响，这在生态学或农业研究中尚未明确解决。该项目旨在结合生态和农业研究中关于草食对养分循环的影响的方法和概念。它将研究植物功能群和放牧动物的功能特性如何影响动物排泄物对地上营养流和植物生物量营养计量的影响。研究系统将是一个长期的无肥放牧实验，包括两个实验因素：草坪型(多样性和草本型)和放牧动物物种(牛和羊，体型不同，排泄物斑块大小和放牧选择性不同)。在三个水平上收集数据：放牧系统中围场尺度和斑块尺度的数据和模拟放牧下的斑块尺度数据。在围场尺度上，生物量生产力和养分浓度(氮、磷和钾)、放牧动物摄入的生物量和矿物质养分以及粪便和尿液中的养分排泄将被量化，并将被用于扩大围场尺度的排泄物斑块效应。在斑块尺度上，将在放牧草地上标记粪便、尿液和未受影响的对照斑块，以评估植物和草食对排泄物斑块的反应。将使用模拟粪便和尿斑的切割实验，在受控条件下验证这些数据，并将观察期和测量参数延长到放牧条件下可行的方案之外。将选择诸如落叶间隔和落叶严重程度等过程参数来模拟放牧研究系统的过程参数。该项目有望通过解决草食动物排泄物中数量上重要的营养物质流动的小规模异质性以及与该尺度上的过程相关的植物和草食动物的功能特征来促进关于大型草食动物对养分循环的影响的基本知识。