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害虫。杂草补强是指杂草种子的成功萌发和出苗。我的研究计划的目的是确定为什么杂草会招生，并探索招生物候对杂草建立、竞争力和持久性的影响，目的是减少杂草对农业的影响。招聘时间是成功与否的主要决定因素。招募物候的种内异质性也很重要，因为它可以作为适应包括气候变化在内的环境变化的生态策略。尽管它在这些方面具有根本的重要性，但我们对杂草招募时间机制的理解仍然知之甚少。通过我的发现项目研究，到目前为止，我们在两个关键领域取得了进展，朝着我的长期研究目标——能够预测气候变化对农业生态系统中杂草的入侵性、适应性和范围的影响——取得了进展。1)种子休眠和持续：我们已经证明，缺乏种子休眠和持续会实质性地影响招募物候。2)开花物候：我们已经证明，除了种子深度（和微地条件）外，开花物候对杂草招募物候有显著影响。我们使用兼性冬季一年生植物（FWA）作为模式物种，并以加拿大fleabane为研究对象，首次证实了开花和种子棚物候、播种深度和天气模式（驱动开花物候）都是杂草招募物候的重要因素，并且气候变化可能显著影响杂草的开花物候和随后的幼苗招募物候。对杂草的认识仍然有限：a)开花物候变化如何以及在多大程度上影响随后的生殖物候变化，以及开花物候变化在决定招募时间方面的作用；b)种子环境受开花物候变化和气候变化的影响程度；c)对杂草适合度的影响。在气候变化的背景下尤其如此，因为影响杂草生长的关键因素（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，并确定在气候变化背景下杂草成功的影响。在接下来的5年里，我将通过以下方式实现这一目标：1)在前所未有的广泛的农业生态和气候范围内建立田间实验，收集有关杂草开花和种子棚物候学、招募物候学和杂草性能的独特数据；2)利用这些数据驱动确定性模型，预测气候变化对杂草竞争力和入侵性的影响。

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.