Collaborative Research: Continent-wide forest recruitment change: the interactions between climate, habitat, and consumers

北美森林的可持续性取决于树木的种子生产以及必须为下一代树木建立的幼苗。在北美的大部分地区，既不知道产生的种子的数量，也不知道有多少种子能存活下来成为成年树。种群在当前边界之外的扩散将受到树木的种子生产（繁殖力）、发芽和幼苗存活率的控制——树木产生种子并将其传播到种群未来可以生存的栖息地的能力。规划环境变化影响需要这些知识来预测树种迁徙及其对依赖森林作为栖息地和食物的鸟类和哺乳动物的影响。要了解这些森林增收反应，需要从目前在小块土地上监测种子、幼苗和消费者的方法转变为可以在生物地理尺度上实施的广泛抽样方法。本研究将大陆尺度树木繁殖力估算与新一代监测和综合方法相结合，以综合树木繁殖力、幼苗成功及其对动物消费者的影响。这项研究将量化整个非洲大陆目前的趋势，正在发生的森林变化，以及导致这些变化的栖息地变化。发展树木繁殖力和繁殖的生物地理网络将为未来森林的科学和管理提供所需的监测平台。更广泛的影响将集中在利益相关者的整合上，包括保护和管理规划，向联邦和州机构的利益相关者传递信息，以及公民科学推广。这项研究的成果将在未来几十年内立即应用于森林再生实践。机构和非政府组织的利益相关者将提供咨询意见并传播研究成果。新的分析工具将确定北美哪些地方的树木繁殖受到限制，其变化速度以及导致这种变化的原因。该项目重点关注三个采收阶段：种子供应（每棵树的种子质量）、幼苗建立（每棵种子质量的幼苗数量）和采收率（每棵幼苗的高级再生）。每个招募阶段都将与气候和栖息地变量以及脊椎动物对种子、水果和坚果的消费有关。广泛梯度采样（EGS）是将其与传统的米尺度密集监测采样（IMS）相结合，估算与生境或植物群落尺度相关的关键人口统计学速率的一种新方法。该项目将包括基于这种新方法的数据收集、繁殖力、树木补充和分布在不同气候和栖息地的脊椎动物（EGS）。研究小组将基于摄像机陷阱（snapshot USA、NEON和本研究）、现场陷阱（NEON站点）和鸟类点计数（BBS、NEON和eBird）在北美进行预测脊椎动物活动建模（PVM）。通过了解树木的补充和依赖它们的脊椎动物，本研究将i)确定受补充限制的物种，包括发生限制的栖息地和阶段，ii)量化与脊椎动物活动的关系，iii)评估符合数据的气候-脊椎动物相互作用变化的预测分布。在生物地理尺度上量化树木繁殖力和动物与消费者的关系，将为下一代理解环境变化对食物网的影响奠定基础。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The sustainability of North American forests depends on seed production by trees as well as seedlings that must establish for the next generation of trees. For most of North America, neither the amounts of seed that are produced, nor how much of that seed survives to become adult trees is known. Population spread beyond current frontiers will be governed by seed production of trees (fecundity), germination, and seedling survival—the capacity of trees to produce seed and disperse it to the habitats where populations can survive in the future. Planning for environmental change impacts requires this knowledge to anticipate tree species migrations and its impacts on the birds and mammals that depend on forests for habitat and food. Understanding these forest recruitment responses requires a methodological shift from the current method of monitoring of seeds, seedlings, and consumers on small plots to extensive sampling methods that can be implemented at biogeographic scales. This study combines continental scale tree fecundity estimates with a new generation of monitoring and synthesis methods for integrating tree fecundity, seedling success, and its impacts on animal consumers. This research will quantify current trends across the continent, the changes in forests that are happening now, and the habitat changes that are causing them. Development of a biogeographic network of tree fecundity and recruitment will provide the monitoring platform needed for science and management of future forests. Broader impacts will focus on stakeholder integration, including conservation and management planning, information transfer to stakeholders in federal and state agencies, and citizen science outreach. Products of the study will have immediate application to forest regeneration practices in the coming decades. Agency and NGO stakeholders will advise and disseminate products of the study. New analytical tools will identify where tree recruitment is limited in North America, its rate of change, and what’s causing it. The project focuses on three recruitment stages, seed supply (seed mass per tree abundance), seedling establishment (seedlings per seed mass), and recruitment rate (advanced regeneration per seedling). Each recruitment stage will be linked to climate and habitat variables and to the vertebrate consumers of seeds, fruits, and nuts. Extensive gradient sampling (EGS) is a new approach to estimate the key demographic rates that are relevant at the scale of habitats or plant communities, while combining it with traditional data already available from the meter-scale intensive monitoring sampling (IMS). The project will include data collection based on this new approach, (EGS) of fecundity, tree recruitment, and vertebrates distributed across climate and habitats. Predictive vertebrate modeling (PVM) of activity based on camera traps (snapshot USA, NEON, and this study), live trapping (NEON sites) and bird point counts (BBS, NEON, and eBird) across North America will be conducted by the research team. By understanding tree recruitment and the vertebrates that depend on them, this study will i) identify the species that are limited by recruitment, including the habitats and stages where limitation occurs, ii) quantify the relationship with vertebrate activity, and iii) evaluate predictive distributions of change that account for climate-vertebrate interactions fitted to data. Quantifying tree fecundity and animal-consumer relationships at biogeographic scales will provide a foundation for the next generation of efforts to understand food web implications of environmental change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.