The Lawn is Buzzing: Increasing insect biodiversity in urban greenspaces through low-intensity mowing

Data and code to reproduce statistical modelling, figures and tables from: The Lawn is Buzzing: Increasing insect biodiversity in urban greenspaces through low-intensity mowing Abstract Greenspaces have become the anvil where stewards and practitioners are forging innovative, evidence-based actions to meet biodiversity targets in urban environments, catalysing a wave of co-designed research/practice projects aimed at assessing the ecological changes brought about by urban greening and generating the evidence that biodiversity objectives are being met. Their full potential often remains unrealised due to entrenched management practices, as best exemplified by high-intensity mowing, which has given rise to the most ubiquitous greenspaces feature worldwide: the turfgrass lawn. Lawns are notoriously deficient at supporting insect communities due to their simplified vegetation structure and low plant diversity, and the compounded effect of frequent mowing on forb growth, which limits their capacity to come into flower and supply floral resources to pollinators and other flower visitors. Addressing these shortcomings can be readily achieved by reducing mowing intensity, resulting in greater vegetation height, flower cover and plant diversity – effectively transforming lawns into a more complex grassland-type ecosystem. This approach is particularly enticing to practitioners pursuing positive, cost-effective biodiversity outcomes while upholding their commitment to core ecological restoration and biodiversity conservation projects. Here, we demonstrate how transitioning a lawn from high- to low-intensity mowing regimes led to pronounced increases in the number of indigenous insect species, evident both for the whole community and on assemblages of functionally similar species, including detritivores, herbivores, predators, parasitoids and pollinators. We further identify a positive effect of vegetation height on the community and species-specific probabilities of occurrence of indigenous species, which was consistently strong for detritivores, herbivores and parasitoids. We also show that the number of indigenous species associated with our low-intensity mowing treatment markedly exceeded that of 43 high-intensity mowed lawns previously surveyed throughout the study area, and that the effect of vegetation height across our field experiment gradient was substantially stronger than that of the existing high-intensity lawns gradient. Our findings provide compelling evidence that reducing lawn mowing intensity yields positive ecological outcomes for functionally diverse indigenous insect communities, charting a course for stakeholders tasked with demonstrating how evidence-based greening actions can be a sound investment to meet local, regional and global biodiversity targets. Keywords: Co-design, Detritivores, Flower-visitors, Functional assemblages, Greening, Hierarchical community models, Nature in cities, Parasitoids, Pollinators, Predators, Urban ecology, Urban environments本数据集可用于复现论文《草坪嗡鸣：通过低强度刈割提升城市绿地昆虫生物多样性》中的统计建模、图表与表格所需的数据与代码。 摘要： 城市绿地已成为管理者与实践者打造创新循证举措以达成城市生物多样性目标的实践平台，催生了一系列协同设计（co-design）的研究与实践项目，旨在评估城市绿化带来的生态变化，并验证生物多样性目标的实现情况。由于根深蒂固的管理模式，其潜力往往难以充分发挥，其中以高强度刈割最为典型——这种管理方式催生了全球最普及的绿地景观类型：草皮草坪。众所周知，草坪因植被结构单一、植物多样性低下，加之频繁刈割对非禾本科草本植物生长的叠加影响，限制了其开花能力，无法为传粉昆虫及其他访花者提供花资源，因此难以支撑昆虫群落存续。通过降低刈割强度即可轻松解决这些弊端，可提升植被高度、花覆盖度与植物多样性，本质上将草坪转化为结构更复杂的草地型生态系统。该方案对追求兼具效益与成本优势的生物多样性成果的实践者极具吸引力，同时也契合其生态修复与生物多样性保护的核心使命。 本研究表明，将草坪从高强度刈割模式转换为低强度刈割模式后，本土昆虫物种种数显著增加，这一现象在整个昆虫群落以及食腐动物（detritivores）、植食性昆虫（herbivores）、捕食性昆虫（predators）、寄生性天敌（parasitoids）与传粉昆虫（pollinators）等功能类群中均有体现。我们还发现，植被高度对昆虫群落及本土物种的发生概率存在正向影响，这一效应在食腐动物、植食性昆虫与寄生性天敌尤为显著。此外，本研究中的低强度刈割样地的本土物种种数显著高于研究区域内此前调查的43块高强度刈割草坪；同时，田间试验梯度下的植被高度效应也远强于现有高强度刈割草坪的梯度效应。本研究结果提供了有力证据，证明降低草坪刈割强度可为功能多样的本土昆虫群落带来积极生态效益，为相关利益相关者提供了实践路径，以证明循证绿化举措可作为一项合理投资，助力实现地方、区域乃至全球的生物多样性目标。 关键词：协同设计（co-design）、食腐动物（detritivores）、访花者（flower-visitors）、功能类群（functional assemblages）、城市绿化（greening）、层级群落模型（hierarchical community models）、城市自然（nature in cities）、寄生性天敌（parasitoids）、传粉昆虫（pollinators）、捕食性昆虫（predators）、城市生态学（urban ecology）、城市环境（urban environments）