Quantifying the functional importance of ants in savanna ecosystems

量化蚂蚁在稀树草原生态系统中的功能重要性

• 批准号: 1950032
• 金额: --
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1950032
• 关键词: Quantifying; functional; importance; ants; savanna

Ants (Hymenoptera: Formicidae) are the dominant invertebrate group in the tropics and mediate a range of ecosystem processes and perform a wide variety of functions, but few studies have quantified their importance in ecosystems at large scales. In savannas, ants may constitute up to 70% of ground-active invertebrates, yet the role they play in structuring these ecosystems is largely unknown. It is thought that ants affect ecological processes on a number of levels. At basal levels, ants affect soil structure and nutrients through their nest-building and scavenging behaviours. At higher trophic levels, ants exert top-down control on invertebrates via predation, including regulating termites which may indirectly alter basal processes such as decomposition rates and soil bioturbation. Through their regulation of herbivorous invertebrates, ants may indirectly limit invertebrate herbivory which may have consequences for plant growth and survivorship. This project will utilise an ant-suppression treatment to exclude ants and measure the changes that occur in the ecosystem in their absence. There are four control plots and four ant-suppression plots. The suppression treatment targets ants without affecting the other invertebrates in the community. This study will determine the extent to which ants affect savanna ecosystem functioning through direct and indirect control of a range of ecosystem processes. Aim: To quantify the roles of ants in mediating ecosystem functioning in savannas.Objectives: To quantify the effect of ants on the following ecosystem processes:1. Soil nutrients, carbon storage and heterogeneity We will measure the impact of ants on soil properties by analysing soil pH, and concentrations of carbon and other organic soil nutrients associated with soil fertility (pH, P, Ca, Mg, K, Na, N). The structure of the soil will also be analysed. 2. Food resource distributionWe will quantify how much resource redistribution in the savanna can be attributed to ants, and whether vertebrates or non-ant invertebrates compensate in the removal of food resources when ants are excluded from the ecosystem. Bait removal by ants, vertebrates and non-ant invertebrates will be quantified through a combination of ant-suppression treatment and vertebrate-exclusion cages. 3. Termite activity, soil bioturbation and decompositionWe will quantify the impact of ants on termite activity by measuring termite consumption of cellulose baits on all plots every 4 weeks. At various time points over the course of a year, we will measure the amount of termite-mediated decomposition of wood blocks, and we will measure termite soil bioturbation under transects, in all experimental plots. 4. Invertebrate community regulationWe will assess the degree to which ants regulate and structure the invertebrate community by sampling invertebrates from different strata (soil, ground, grass, arboreal) and comparing community composition in the treatment and control plots, 5. Tree growth and herbivoryWe will determine the impact of ants on rates invertebrate-mediated herbivory on seedlings of two native tree species, Terminalia sericea and Acacia exuvialis, and on rates of survivorship and growth in all experimental plots over the course of two years. Invertebrate-mediated herbivory on adult T. sericea trees will also be measured.Through these experiments we aim to shed light on the many roles ants play in savanna ecosystems. We hope to highlight the importance of ants in structuring tropical systems and emphasise that ant diversity is key to healthy ecosystem functioning in the tropics.

蚂蚁（Hyattera：蚁科（Formicidae）是热带地区的主要无脊椎动物类群，介导一系列生态系统过程并发挥各种功能，但很少有研究量化它们在大尺度生态系统中的重要性。在热带稀树草原中，蚂蚁可能占地面活动无脊椎动物的70%，但它们在构建这些生态系统中所扮演的角色在很大程度上是未知的。人们认为蚂蚁在许多层面上影响生态过程。在基层，蚂蚁通过筑巢和清除行为影响土壤结构和养分。在较高的营养水平上，蚂蚁通过捕食对无脊椎动物施加自上而下的控制，包括调节白蚁，这可能间接改变分解率和土壤生物扰动等基础过程。通过调节食草无脊椎动物，蚂蚁可以间接限制无脊椎动物的食草行为，这可能对植物的生长和生存产生影响。该项目将利用抑制蚂蚁的方法来排除蚂蚁，并测量在没有蚂蚁的情况下生态系统中发生的变化。有四个对照区和四个蚂蚁抑制区。抑制处理针对蚂蚁，而不影响群落中的其他无脊椎动物。这项研究将确定蚂蚁通过直接和间接控制一系列生态系统过程来影响稀树草原生态系统功能的程度。目的：目的：量化蚂蚁对以下生态系统过程的影响：1。土壤养分、碳储量和异质性我们将通过分析土壤pH值、碳浓度和与土壤肥力相关的其他有机土壤养分（pH、P、Ca、Mg、K、Na、N）来衡量蚂蚁对土壤性质的影响。还将分析土壤的结构。2.食物资源分布我们将量化热带稀树草原中有多少资源重新分配可以归因于蚂蚁，以及当蚂蚁被排除在生态系统之外时，脊椎动物或非蚂蚁无脊椎动物是否会补偿食物资源的损失。蚂蚁、脊椎动物和非蚂蚁无脊椎动物的诱饵去除将通过蚂蚁抑制处理和脊椎动物排除笼的组合进行量化。3.白蚁活动，土壤生物扰动和分解我们将量化蚂蚁对白蚁活动的影响，测量白蚁消耗的纤维素诱饵在所有地块每4周。在一年中的不同时间点，我们将测量白蚁介导的木块分解量，并在所有实验地块中测量横断面下的白蚁土壤生物扰动。4.无脊椎动物群落调节我们将评估蚂蚁调节和构建无脊椎动物群落的程度，方法是从不同地层（土壤、地面、草地、乔木）取样无脊椎动物，并比较处理区和对照区的群落组成。树木生长和草食我们将确定蚂蚁对无脊椎动物介导的草食率的影响，对两个本地树种，Terminalia sericea和Acacia exuvialis的幼苗，以及在两年的时间里，所有实验地块的存活率和生长率。无脊椎动物介导的草食性对成虫T.通过这些实验，我们的目标是阐明蚂蚁在热带稀树草原生态系统中扮演的许多角色。我们希望强调蚂蚁在构建热带系统中的重要性，并强调蚂蚁多样性是热带健康生态系统功能的关键。