Data from: Consumer control as a common driver of coastal vegetation worldwide

Rapid, global anthropogenic alteration of food webs in ecosystems necessitates a better understanding of how consumers regulate natural communities. We provide a global synthesis of consumer control of vegetation in coastal wetlands, where the domineering role of physical factors such as nutrient and salinity, rather than consumers, has been emphasized for decades. Using a dataset of 1748 measures of consumer effects reported in 443 experiments/observations on all continents except the Antarctica, we examine the generality of consumer control in salt marshes and mangroves globally. Our analyses show that salt marsh herbivores, including insects, snails, crabs, waterfowl, small mammals, and livestock, generally and often strongly suppress plant survival, aboveground biomass, and height, while their effects on plant density, belowground biomass, reproduction, and cover are more variable. These effects occur in forbs, grasses, and shrubs, and in both seedlings and adult plants. Herbivores additionally affect plant nutrient stoichiometry, and mediate plant interactions, though their effects on plant diversity are less consistent. Higher trophic levels also affect plants, as predators facilitate plant growth through trophic cascades that suppress grazer abundance and grazing rate. In mangroves, there are also signs of consumer control, though the relatively few studies available have often focused on mangrove propagules and seedlings rather than adults. Our analyses further reveal that the strength of consumer control is regulated by many physical factors. Nutrient, disturbance, and flooding, for example, amplify the negative effects of herbivores. Along latitudinal gradients, increased temperature enhances the negative effects of ectothermic herbivores, but has no effect on those of endothermic herbivores. Consumer control of coastal plants is also apparent across study methodologies: in field and laboratory settings, in observational studies, in consumer exclusion and addition experiments, in natural and transplanted plants, and in experiments of various durations. The role of consumer control in coastal vegetation worldwide highlights the need to better recognize and theoretically conceptualize both top-down and bottom-up forcing and their interactions in coastal wetlands. Improved understanding and conservation of coastal wetlands will only occur if we incorporate what the science has revealed: trophic feedbacks are an important and pervasive determinant of coastal plant communities.

全球范围内由人类活动快速扰动的生态系统食物网结构改变，使得学界亟需深入厘清消费者（consumer）对自然群落的调控机制。本研究针对海岸湿地植被的消费者调控效应开展全球综合分析——数十年来，学界长期强调营养盐、盐度等物理因素的主导作用，而非消费者的调控功能。本研究整合了除南极洲以外所有大洲的443项实验与观测研究中的1748条消费者效应观测数据，以此检验全球盐沼（salt marsh）与红树林（mangrove）生态系统中消费者调控效应的普遍性。分析结果显示，盐沼植食动物（herbivore）涵盖昆虫、螺类、蟹类、水禽、小型哺乳类与家畜，总体上往往会显著抑制植物的存活、地上生物量与株高；而其对植物密度、地下生物量、繁殖能力与盖度的效应则更为多变。此类效应可见于双子叶草本（forb）、禾草与灌木，同时对幼苗与成株均产生影响。植食动物还会影响植物的营养化学计量比（nutrient stoichiometry），并调控植物间的种间相互作用，不过其对植物多样性的效应并不稳定。更高营养级的生物同样会对植物产生影响：捕食者（predator）可通过营养级联（trophic cascade）效应抑制植食者的种群数量与取食强度，从而促进植物生长。在红树林生态系统中，同样存在消费者调控的迹象，但现有相关研究数量较少，且多聚焦于红树林繁殖体（propagule）与幼苗，而非成株。本研究进一步揭示，消费者调控效应的强度受多种物理因素调控：例如营养盐、干扰与淹水会加剧植食动物的负面效应。在纬度梯度上，温度升高会强化变温植食动物（ectothermic herbivore）的负面效应，但对恒温植食动物（endothermic herbivore）的效应无显著影响。不同研究方法下均能观测到海岸植物的消费者调控效应：包括野外与实验室环境、观测性研究、消费者排除与添加实验、原生植物与移栽植物，以及不同持续时长的实验。全球海岸植被的消费者调控效应表明，我们亟需更好地认知并从理论上阐释海岸湿地中的下行调控（top-down）与上行调控（bottom-up）效应及其交互作用。只有将科学研究揭示的核心结论——营养级反馈是海岸植物群落的重要且普遍的决定因素——纳入研究与保护实践，才能推动对海岸湿地的深入理解与有效保护。