Characterizing the emergence timing of weed species and determining implications for greater weed success in the context of climate change

杂草是农业中危害最大的一类有害生物。杂草萌发是杂草种子萌发和出苗的成功过程。我的研究项目的目的是确定杂草为什么会在杂草发生时发生招聘，并探索招聘物候对杂草的形成、竞争力和持久性的影响，目的是减少杂草对农业的影响。招募时间是除草剂成功与否的主要决定因素。招聘物候的种内异质性也很重要，因为它可以成为适应包括气候变化在内的环境变化的生态战略。尽管它在这些方面至关重要，但我们对杂草招募时机的机制仍知之甚少。通过我的发现计划研究，到目前为止，我们在两个关键领域取得了进展，实现了我的长期研究目标，即能够预测气候变化对农业生态系统中杂草的侵入性、适合性和范围的影响。1)种子休眠和持久性：我们已经证明，缺乏种子休眠和种子持久性可以对招募物候产生实质性的影响。2)开花物候：我们已经证明，除了种子深度(和微场地条件)之外，开花物候还可以显著影响杂草的招募物候。我们使用兼性冬季年生植物(FWA)作为模式物种，并与加拿大灯盏花一起，首次证实开花和种子棚物候、播种深度和天气模式(驱动开花物候)都是驱动杂草补充物候的重要因素，气候变化可能显著影响杂草的开花物候和随后的幼苗补充物候。对杂草的了解仍然有限，a)开花物候的变化如何以及在多大程度上影响随后的生殖物候，以及开花物候在决定补充时间方面所起的作用，b)开花物候和气候变化对种子环境的影响程度，以及c)对杂草适合性的影响。在气候变化的背景下尤其如此，因为影响杂草招募的关键因素(即温度和降水模式)正在发生变化。我的发现研究计划的目标是描述杂草物种的招募物候特征，并确定在气候变化的背景下杂草取得更大成功的含义。在接下来的5年里，我将通过以下方式实现这一目标：1)在前所未有的广泛农业生态和气候范围内建立田间试验，以收集关于杂草开花和种子棚物候、招募物候和杂草表现的独特数据，以及2)使用这些数据来驱动确定性模型，以预测气候变化对杂草竞争力和入侵的影响。

Weeds are the most harmful category of pests in agriculture. Weed recruitment is the successful seed germination and seedling emergence of weeds. The purpose of my research program is to determine why weeds recruit when they do and to explore the implications of recruitment phenology on weed establishment, competitiveness and persistence with an aim to reducing the impact of weeds on agriculture. Time of recruitment is a prime determinant of weed success. Intra-specific heterogeneity in recruitment phenology is also important because it can be an ecological strategy for adapting to environmental change including climate change. Despite its fundamental importance in these respects, our understanding of the mechanisms of weed recruitment timing remain poorly understood. Through my discovery program research we have, to-date, made progress in two key areas toward my long-term research goal of being able to predict the impact of climate change on the invasiveness, fitness and range of weeds in agro-ecosystems. 1) Seed dormancy and persistence: we have shown that a lack of seed dormancy and seed persistence can substantively affect recruitment phenology. 2) Flowering phenology: we have shown that in addition to seed depth (and microsite conditions), flowering phenology can significantly affect weed recruitment phenology. We use facultative winter annuals (FWA) as model species and with Canada fleabane, we were the first to confirm that flowering and seed shed phenology, seeding depth and weather patterns (driving flowering phenology) are all significant factors driving the recruitment phenology of weeds and that climate change could significantly impact flowering phenology and subsequent seedling recruitment phenology for weeds. There remains a limited understanding for weeds of a) how and to what extent changes in flowering phenology influence subsequent reproductive phenology and the role that flowering phenology plays in determining time of recruitment, b) the extent to which seed environment is impacted by changes in flowering phenology and climate change and c) the implications for weed fitness. This is especially true in the context of climate change where the key factors affecting weed recruitment (i.e. temperature and precipitation patterns), are changing. The objective of my discovery research program is to characterize the recruitment phenology of weed species and to determine the implications for greater weed success in the context of climate change. Over the next 5 years I will pursue this objective by 1) establishing field experiments across an unprecedented broad agro-ecological and climatic range to collect unique data on weed flowering and seed shed phenology and recruitment phenology and weed performance, and 2) using this data to drive deterministic models for predicting the impact of climate change on the weed competitiveness and invasiveness.