Consumer control as a common driver of coastal vegetation worldwide

• Published in: Ecological Monographs
• Main Authors: He, Qiang, Silliman, Brian R.
• Other Authors: National Science Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2016
• Subjects: Antarc*; Antarctica
• Online Access: http://dx.doi.org/10.1002/ecm.1221; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fecm.1221; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ecm.1221; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ecm.1221; https://esajournals.onlinelibrary.wiley.com/doi/am-pdf/10.1002/ecm.1221; https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecm.1221

Abstract 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 data set of 1748 measures of consumer effects reported in 443 experiments/observations on all continents except 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 ...