Organisms as Ecosystem Engineers

In this Project

My collaborative research involves empirical studies on the effects of engineers, the development of concepts and models of ecosystem engineering, syntheses of the existing literature, and forging connections between ecosystem engineering and other disciplines (geomorphology, evolutionary biology, environmental management). Research in this area is helping us understand how species – including humans as ecosystem engineers – can affect the abundance and diversity of species and the functioning of ecosystems.

Many organisms build, modify or destroy physical structures in the environment. For example, both beavers and the Army Corps of Engineers build dams. Beaver dams and many other physical structures have important ecological effects on other species because these structures create habitat, control the amount of abiotic resources that other species can use, and can ameliorate or exacerbate abiotic conditions that affect organisms. Rock-eating snails in the Negev Desert control the amount of soil for plants. Desert Isopods control soil erosion and remove salts that decrease soil fertility for plants. Desert porcupines dig pits that trap water and seeds, making an ideal place for annual plants to grow. There are hundreds of other examples of organisms physically modifying the environment in all sorts of ecosystems. And yet, in general we know far less about these engineers and their ecological effects than we know about the effects of predation or competition for resources among organisms. How and why do engineers have effects? How important are these effects? How similar are different engineers? How can we quantify, compare and model engineering effects?


General pathways of physical ecosystem engineering (modified from Gutiérrez & Jones, 2008)

oak
Secondary oak (Quercus rubra) forest near Millbrook, NY, USA (Changes microclimate; affects soil biogeochemistry and understory species).
cordgrass
Smooth cordgrass, Spartina alterniflora, in a tidal marsh in the La Plata estuary near Playa Peninos, Uruguay (Attenuates storm surges, increases sedimentation, and retains organic matter; affects biogeochemistry and creates protected habitat for other species).
reefs
Reefs of tube-building polychaetes, Ficopomatus enigmaticus, an exotic species in Mar Chiquita coastal lagoon, Argentina (Reef in foreground is ca. 3 meters across. Alters hydrodynamics, increases sedimentation; provides shelter for many invertebrates).
riparian forest
Riparian forest area transformed by the dam building activity of beaver, Castor canadensis, in Tierra del Fuego, Chile, where it is an exotic species (Alters hydrology, sedimentation, light levels; affects biogeochemistry and species habitats).
atta sexdens
Mound of leaf-cutting ant, Atta sexdens, in the “blanqueal” area near Fray Bentos, Uruguay (Brings saline soil at depth to surface, eliminating most vegetation on mound).
The Southwestern Atlantic burrowing crab, Neohelice (Chasmagnathus) granulata, in Mar Chiquita coastal lagoon, Argentina (buries litter in excavation mounds; prevents litter export as a nutrient subsidy to adjacent estuary).
oak
cordgrass
reefs
riparian forest
atta sexdens

Cary Institute of Ecosystem Studies | Millbrook, New York 12545 | Tel (845) 677-5343

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