Avocado tree level survey and yield dataset

Ensuring the sustainability of crop production, whilst simultaneously taking actions to mitigate the environmental impacts of agriculture, is a current global priority. Given around 75% of global food crop yields benefit from pollination services provided by diverse wild and managed insect taxa, management strategies that support diverse communities of pollinator taxa are valuable to ensure ongoing pollination service provisioning and agricultural production. In addition to pollination, realised crop yields are also influenced by other biotic and abiotic factors which vary across different spatial and temporal scales. This thesis addresses three important aspects of crop pollination, namely the need to merge disparate research fields, the degree to which pollinator taxa service multiple crops and regions and how pollination interacts with crop tree physiological factors such as tree vigour. First, I reviewed the literature to evaluate the knowledge gaps concerning pollinator effectiveness and the utility of using remote sensing in crop pollination research. I conducted surveys and pollen deposition trials to identify pollinators in avocado, mango and macadamia crops in three geographically distinct growing regions in Australia across three years. Using single visit deposition rates, bipartite networks and spatial analyses I also investigated pollinator service provisioning and the land use types that influence pollinator communities in these crop and regions. Using hand pollination trials over two years I investigated the impact of supplemental cross pollination on the yield of avocado trees. My first review identified important research directions to account for pollination processes occurring at a community level including: plant-pollinator interactions, heterospecific pollen transfer and variation in pollination outcomes. My second review identified the areas in which remote sensing technologies can facilitate our understanding of interactions between pollinators, pollination services, environmental and plant physiological factors which affect final harvest measures. Using multi-crop, multi-year and multi-region crop-pollinator networks I demonstrated that shared wild pollinator taxa visit multiple crops across several regions. In particular, honey bees (A. mellifera) and two families of wild visitors, Syrphidae and Calliphoridae, are present across all regions and crops. Further, regional comparisons for both avocado and mango crops identified additional shared families that were locally abundant such as Coccinellidae and native Apidae. I found that the effect of additional cross pollination on trees of different vigour varied between individual orchard blocks and across years. General patterns relating to the impact of interaction between tree vigour and pollination on yield were discernible in this study, with lower and medium vigour trees responding more positively to supplemental pollination than high vigour trees. High variability in results and differences in effect response across orchard blocks highlight the need to investigate further factors at a tree and block scale, in future analyses. My research indicates that there is significant potential to identify shared pollinators that provide services across multiple crops. Pollination management strategies that are regionally specific and that include bee and non-bee taxa and co-flowering crop species are needed to ensure ongoing effective and resilient pollination services are delivered to crop systems. The merging of different research fields, such as remote sensing, pollinator ecology and precision agriculture offers exciting new approaches to facilitate our understanding of these complex crop-pollinator interactions.

保障作物生产的可持续性，同时采取行动减缓农业生产对环境造成的负面影响，是当前全球的核心要务。鉴于全球约75%的粮食作物产量得益于由多样野生与管理型昆虫类群（insect taxa）提供的授粉服务（pollination services），支持多样授粉者类群群落的管理策略，对于保障持续的授粉服务供给与农业生产至关重要。除授粉之外，实际作物产量还会受到其他生物与非生物因素的影响，这些因素随不同空间与时间尺度发生动态变化。

本研究围绕作物授粉的三个核心方向展开：一是整合不同研究领域的必要性，二是授粉者类群可为多种作物及区域提供服务的程度，三是授粉与作物树势（tree vigour）等树木生理因素的互作机制。

首先，本研究通过文献综述，评估了关于授粉者效能（pollinator effectiveness）以及遥感（remote sensing）在作物授粉研究中应用价值的知识空白。随后，本研究在三年时间内，对澳大利亚三个地理分隔的种植区域内的牛油果（avocado）、芒果（mango）与澳洲坚果（macadamia）作物开展了调查与花粉沉积试验（pollen deposition trials），以明确其中的授粉者类群。本研究还通过单花花粉沉积速率、二部图网络（bipartite networks）与空间分析手段，探究了上述作物与区域内的授粉服务供给情况，以及影响授粉者群落的土地利用类型。在两年时间内开展人工授粉试验（hand pollination trials），本研究探究了补充异花授粉对牛油果产量的影响。

首次文献综述明确了群落水平授粉过程的重点研究方向，包括：植物-授粉者互作（plant-pollinator interactions）、异种花粉传递（heterospecific pollen transfer）以及授粉结果的变异。第二次文献综述则梳理了遥感技术可助力我们理解授粉者、授粉服务、环境与植物生理因素之间互作关系的方向，而这些因素会最终影响最终收获产量。

本研究通过多作物、多年份、多区域的作物-授粉者网络分析，证明了共享的野生授粉者类群会造访多个区域内的多种作物。具体而言，西方蜜蜂（A. mellifera）以及野生访客类群中的食蚜蝇科（Syrphidae）与丽蝇科（Calliphoridae），在所有调研区域与作物中均有出现。此外，针对牛油果与芒果作物的区域对比分析还发现了其他局部丰度较高的共享类群，如瓢虫科（Coccinellidae）与本土蜜蜂科（Apidae）。

本研究发现，补充异花授粉对不同树势植株的影响，在各个果园区块之间以及不同年份之间均存在差异。本研究可提炼出树势与授粉互作对产量影响的通用规律：树势较弱与中等的植株对补充授粉的响应效果优于树势较强的植株。研究结果存在较高变异性，且不同果园区块的响应效果存在差异，这表明未来的分析中需要进一步探究植株与区块尺度下的相关影响因素。

本研究表明，挖掘可跨多种作物提供授粉服务的共享授粉者类群具有巨大潜力。为保障作物系统能够获得持续高效且具有韧性的授粉服务，需要制定区域特异性的授粉管理策略，涵盖蜂类与非蜂类类群以及同期开花的作物物种。整合遥感、授粉者生态学与精准农业等不同研究领域，可为我们理解这些复杂的作物-授粉者互作关系提供极具前景的新方法。