Concept Of Ecosystem Engineering Research Articles

Ecosystem engineers cause biodiversity spill-over: Beavers are associated with breeding bird assemblages on both wetlands and adjacent terrestrial habitats

The influence of ecosystem engineers on habitats and communities is commonly acknowledged in a site-bounded context, i.e. in places directly affected by the presence of the focal species. However, the spatial extent of the effects of such engineering is poorly understood, raising the question as to what impact they have on ecosystems situated beyond the species' direct influence. Beavers Castor spp., iconic ecosystem engineers, are capable of significantly transforming aquatic ecosystems. Their presence boosts biodiversity in adjacent aquatic and riparian habitats, but as a result of cascading processes, beavers may affect terrestrial habitats situated beyond the range of their immediate activity. Our study investigates the breeding bird assemblage along a spatial gradient from the water to the forest interior on central European watercourses modified and unmodified by beavers. The results show that beaver sites are characterized by a higher species richness and abundance of breeding birds than unmodified watercourses. Such sites also host a different species pool, as 27 % of the recorded bird species occurred exclusively on the beaver sites. The effect of the beaver's presence on the bird assemblage extended to adjacent terrestrial habitats located up to 100 m from the water's edge, where the species richness and abundance was higher and the species composition was substantially modified. We also found a positive correlation between the total area of beaver wetland and the numbers of bird species and individuals recorded. Our study adds to the general understanding of the spatial context of the ecosystem engineering concept, as the changes brought about by engineers have an influence beyond the area of their immediate occurrence. Our work also has implications for landscape planning and management, where existing beaver sites with terrestrial buffer zones may constitute a network of biodiversity hotspots.

A Review of Diopatra Ecology: Current Knowledge, Open Questions, and Future Threats for an Ecosystem Engineering Polychaete.

Simple SummaryMost of the world is ocean, and most of the ocean bottom is mud or sand. Understanding the ecology of sedimentary habitats is therefore important for understanding marine ecosystems writ large. Marine sediments are typically occupied by burrowing and tube-building animals that physically structure the habitat. In coastal sediments, an especially widespread example is the annelid worm Diopatra, which builds large tubes up to 2 m deep and 1 cm in diameter. These tubes have extensive physical effects on other organisms in the habitat, including commercially important fish and crustaceans. Diopatra are currently being impacted by climate change, species invasions, and (in some areas) the bait-digging industry. In this article, I review what we know about Diopatra ecology with an eye to identifying major open questions and future threats facing this important architect of coastal marine systems.A well-known example of marine ecosystem engineering is the annelid genus Diopatra, which builds large tubes in coastal sediments worldwide. Early studies of Diopatra were among the first to recognize the importance of facilitation in ecology, and Diopatra has become a key marine soft-sediment application of the ecosystem engineering concept. Here, I review our current knowledge of Diopatra ecology, including its natural history, ecosystem engineering effects, and trophic relationships. I particularly explore how human activities are influencing Diopatra in terms of climate change, bait fishing, and species invasions. Most of what we know about Diopatra ecology comes from focal studies of a few species in a few well-known regions. Further evaluating how our current understanding applies to other species and/or other regions will help to refine and deepen our understanding of structure and function in marine systems.

MENGENAL PEREKAYASA EKOSISTEM

UNDERSTANDING THE ECOSYSTEM ENGINEERS. Ecosystem engineers are organisms that can create, destroy or even maintain the sustainability of a particular habitat. The process of ecosystem engineering begins with structural changes in the environment and subsequently change the abiotic the biotic term or the existence of other organisms. Ecosystem engineers are divided into two, namely autogenic and allogenic engineers. Autogenic engineers change the habitat condition by shifting their body conditions, whereas allogenic engineers that can directly change habitat conditions. The impact of ecosystem engineers on the environment is determined by the magnitude and duration of structural changes made or abandoned by the ecosystem engineer. Understanding the concept of ecosystem engineering is useful as one of the efforts to restore habitat and conservation acts.

Large‐scale ecosystem engineering by flamingos and fiddler crabs on West‐African intertidal flats promote joint food availability

Although the ecosystem engineering concept is well established in ecology, cases of joint engineering by multiple species at large scales remain rare. Here, we combine observational studies and exclosure experiments to investigate how co‐occurring greater flamingos Phoenicopterus roseus and fiddler crabs Uca tangeri promote their own and each other's food availability by creating a spatially complex mosaic of depressions (bowls, gullies) and hummocks (plateaus, mounds) in the intertidal zone. This results in a mosaic of microhabitats with different tidal inundation regimes. These microhabitats are spatially organized with labyrinth‐like patterns in the high intertidal zone and spotted patterns in the lower intertidal, both of which likely arise from biophysical interactions between these organisms and hydrodynamic forces. We show that the resulting spatial complexity is vital for biofilm production. The depression microhabitats were wetter and richer in organic matter and biofilms compared with hummocks. Excluding flamingos and crabs resulted in an increase in biofilm biomass over the shorter term (six months), but a decrease over the longer term (after one year). Moreover, our results strongly suggest that these biogeomorphological microhabitats in the mosaics were maintained by the feeding activities of flamingos and to a lesser extent crabs. During a period of flamingo exclusion, all the spotted patterns filled up with sediment, while the exclusion of crabs led to gradual sediment accumulation in the labyrinth‐like patterns. Collectively, these findings provide empirical evidence for large‐scale joint promotion of food availability by multiple taxa in a marine ecosystem.

Author Correction: Ecosystem engineering as an energy transfer process: a simple agent-based model

original published online version of this article unfortunately contained a mistake. On page 2, line 7, in chapter The concept of ecosystem engineering as an energy transfer process.

Ecosystem engineering as an energy transfer process: a simple agent-based model

Ecosystem engineers are defined as organisms who modulate the availability of resources for themselves and other organisms by physically changing the environment. Ecosystem engineering is a well-recognised ecological interaction, but there is a limited number of general models due to the recent development of the field. Agent-based models are often used to study how organisms respond to changing environments and are suitable for modelling ecosystem engineering. To our knowledge, agent-based methodology has not yet been used to model ecosystem engineering. In this paper, we develop a simple agent-based population dynamics model of ecosystem engineering as an energy transfer process. We apply energy budget approach to conceptually explain how ecosystem engineers transfer energy to the environment and define various types of energy transfers relative to their effects on the engineers and other organisms. We simulate environments with various levels of resource abundance and compare the results of the model without ecosystem engineering agents to the model with ecosystem engineering agents. We find that in environments with higher levels of resources, the presence of ecosystem engineers increases the average carrying capacity and the strength of population fluctuations, while in environments with lower levels of resources, ecosystem engineering mitigates fluctuations, increases average carrying capacity and makes environments more resilient. Finally, we discuss about the further application of agent-based modelling for the theoretical and experimental development of the ecosystem engineering concept.

Habitat engineering by beaver benefits aquatic biodiversity and ecosystem processes in agricultural streams

Summary Small‐scale discontinuities, formed by accumulations of wood, are recognised as a key feature of functionally intact forested streams because they promote organic matter retention, increase habitat complexity and provide flow refugia. Re‐establishing such features in physically degraded streams is therefore a common priority for restoration schemes. Ecosystem engineering by beavers in the form of dam building might offer a natural mechanism for restoring degraded streams. Despite an increase in beaver reintroductions globally, the ecosystem engineering concept has rarely been applied to restoring biodiversity and ecosystem function, especially within degraded freshwater systems. By comparing multiple beaver‐modified and unmodified sites on headwater streams draining 13 ha of pastureland in eastern Scotland, U.K., we investigated if hydromorphological changes caused by reintroduced beavers (Castor fiber) translate into desirable biological responses when there is a long history of physical degradation and contraction of the regional species pool due to agricultural land use. Beaver modified in‐stream habitat by constructing 10 dams, thus creating a series of interconnected dam pools. Organic matter retention and aquatic plant biomass increased (7 and 20 fold higher respectively) in beaver ponds relative to unmodified channels, consistent with the lower fluctuation in stream stage observed below a series of dams. Growing season concentrations of extractable P and NO3 were on average 49% and 43% lower respectively below a series of dams than above, although colour and suspended solids concentrations increased. Macroinvertebrate samples from beaver‐modified habitats were less taxon rich (alpha diversity on average 27% lower) than those from unmodified stream habitat. However, due to significant compositional differences between beaver versus unmodified habitats, a composite sample from all habitats indicated increased richness at the landscape scale; gamma diversity was 28% higher on average than in the absence of beaver‐modified habitat. Feeding guild composition shifted from grazer/scraper and filter feeder dominance in unmodified habitats to shredder and collector‐gatherer dominance in beaver‐created habitats. Dam building by beaver in degraded environments can improve physical and biological diversity when viewed at a scale encompassing both modified and unmodified habitats. By restoring ecosystem processes locally, it may also offer wider scale benefits, including greater nutrient retention and flood attenuation. These benefits should be evaluated against evidence of any negative effects on land use or fisheries.

Succession-driven facilitation of macrofaunal communities in sublittoral blue mussel habitats

Whereas it is well known that ecosystem engineers can have positive effects on biodiversity, fundamental gaps still remain in our understanding of the underlying mechanisms in many marine systems. Individual- and population-level traits of engineering species are likely to determine their ability to modify the environment. Blue mussels function as important ecosystem engineer species in the Baltic Sea where they facilitate the existence of distinct associated communities. The population structure of these blue mussel beds fluctuates widely, but ecosystem effects of these fluctuations are poorly known. In this study, we experimentally and descriptively measured the effect of mussel succession stage with differing biomass, density and size structure on macrofaunal diversity and body size at 5 m depth. We found that mussel succession stage is an important determinant of faunal abundance, species richness and species assemblage. Our results demonstrate that mussel succession stage (size structure, density and biomass) highly affect the associated macrofaunal communities and the strength of facilitation in these systems. We also found that the body size of crustaceans and clams was positively correlated with mussel body size, increasing with a growing mussel body size. We suggest that it is of high importance to consider individual traits of ecosystem engineers and the types of environments in which they play critical roles in order to increase the value of the ecosystem engineering concept in ecology and conservation biology.

Functional Groups of Ecosystem Engineers: A Proposed Classification with Comments on Current Issues

Ecologists have long known that certain organisms fundamentally modify, create, or define habitats by altering the habitat's physical properties. In the past 15 years, these processes have been formally defined as "ecosystem engineering", reflecting a growing consensus that environmental structuring by organisms represents a fundamental class of ecological interactions occurring in most, if not all, ecosystems. Yet, the precise definition and scope of ecosystem engineering remains debated, as one should expect given the complexity, enormity, and variability of ecological systems. Here I briefly comment on a few specific current points of contention in the ecosystem engineering concept. I then suggest that ecosystem engineering can be profitably subdivided into four narrower functional categories reflecting four broad mechanisms by which ecosystem engineering occurs: structural engineers, bioturbators, chemical engineers, and light engineers. Finally, I suggest some conceptual model frameworks that could apply broadly within these functional groups.

Do Neotropical peccary species (Tayassuidae) function as ecosystem engineers for anurans?

Abstract:The concept of ecosystem engineering has catalysed novel approaches and models for non-trophic species interactions and ecosystem functions. Ecosystem engineers physically modify abiotic and biotic environments, thereby creating new habitats that can be colonized by a new suite of species. In the Peruvian Amazonas, we tested whether peccaries (Tayassuidae) function as ecosystem engineers by creating and maintaining wallows. Such wallows could be critical aquatic habitats and breeding sites for anuran species during dry seasons. We compared hydroperiods of 21 peccary wallows and 13 naturally formed ponds across three dry seasons and found that wallows had a consistently higher mean water surface area than ponds. We also examined the pH, dissolved oxygen and temperature, and found no significant differences in these parameters between water bodies. Wallows had a significantly higher density of tadpoles, metamorphs and adult anurans, as well as higher β-diversity and species richness than ponds. This study not only provides the first systematic evidence of the ecosystem engineering processes of peccaries, but also reveals the positive consequences of such for anuran species.

Control of sediment dynamics by vegetation as a key function driving biogeomorphic succession within fluvial corridors

AbstractRiparian vegetation responds to hydrogeomorphic disturbances and environmental changes and also controls these changes. Here, we propose that the control of sediment erosion and deposition by riparian vegetation is a key geomorphological and ecological (i.e. biogeomorphic) function within fluvial corridors. In a 3 year study, we investigated the correlations between riparian vegetation and hydrogeomorphic dynamics along a transverse gradient from the main channel to the floodplain of the River Tech, France. Sediment erosion and deposition rates varied significantly along the transverse gradient as a function of the vegetation biovolume intercepting water flow. These effects, combined with the extremely strong mechanical resistance of pioneer woody structures and strong resilience of pioneer labile herbaceous communities, Populus nigra and Salix spp., explain the propensity of biogeomorphic succession (i.e. the synergy between vegetation succession and landform construction) to progress between destructive floods. This geomorphological function newly identified as an ‘ecosystem function’ per se encompasses the coupling of habitat and landform creation, maintenance and change with fundamental ecosystem structural changes in space and in time. Three different biogeomorphic functions, all related to the concept of ecosystem engineering, were identified: (i) the function of pioneer herbaceous communities to retain fine sediment and diaspores in the exposed zones of the active tract near the water resource, facilitating recruitment of further herbaceous and Salicacea species; (ii) the function of woody vegetation to drive the construction of forested islands and floodplains; and (iii) the function of stabilised riparian forests to act as ‘diversity reservoirs’ which can support regeneration after destructive floods. Overall, this study based on empirical data points to the fundamental importance of sediment flow control by pioneer riparian vegetation in defining fluvial ecosystem and landform organisation in time and in space. Copyright © 2009 John Wiley & Sons, Ltd.

An Endangered Longhorn Beetle Associated with Old Oaks and Its Possible Role as an Ecosystem Engineer

For more than 10 years, ecologists have been discussing the concept of ecosystem engineering (i.e., nontrophic interactions of an organism that alters the physical state of its environment and affects other species). In conservation biology, the functional role of species is of interest because persistence of some species may be necessary for maintaining an entire assemblage with many threatened species. The great capricorn (Cerambyx cerdo), an endangered beetle listed in the European Union's Habitats Directive, has suffered a dramatic decline in the number of populations and in population sizes in Central Europe over the last century. The damage caused by C. cerdo larvae on sound oak trees has considerable effects on the physiological characteristics of these trees. We investigated the impacts of these effects on the species richness and heterogeneity of the saproxylic beetle assemblage on oaks. We compared the catches made with flight interception traps on 10 oaks colonized and 10 oaks uncolonized by C. cerdo in a study area in Lower Saxony (Germany). Our results revealed a significantly more species-rich assemblage on the trees colonized by C. cerdo. Colonized trees also harbored more red-listed beetle species. Our results suggest that an endangered beetle species can alter its own habitat to create favorable habitat conditions for other threatened beetle species. Efforts to preserve C. cerdo therefore have a positive effect on an entire assemblage of insects, including other highly endangered species. On the basis of the impact C. cerdo seems to have on the saproxylic beetle assemblage, reintroductions might be considered in regions where the species has become extinct.

Mangrove crabs as ecosystem engineers; with emphasis on sediment processes

The benthic fauna in mangrove forests is usually dominated by burrowing sesarmid (Grapsidae) and fiddler crabs (Ocypodidae). They are herbivores that retain, bury, macerate and ingest litter and microalgal mats. Most species within these two groups actively dig and maintain burrows in the sediment as a refuge from predation and environmental extremes. Based on the current knowledge on the biology and ecology of these crabs, it seems obvious that their activities have considerable impact on ecosystem functioning. However, no convincing conceptual framework has yet been defined into which the role of these crabs can be identified and characterized. The attributes by which these abundant animals affect the microbial and biogeochemical functional diversity fit well into the concept of ecosystem engineering. The conceptualization of mangrove benthic communities within this framework is distinguished and documented by examples provided from the most recent literature on mangrove ecosystem functioning. It appears that the features and processes driving the engineering effects on distribution and activity of associated organisms operate differently for sesarmid and fiddler crabs. The most obvious and well-documented difference between engineering effects of the two types of crab seems to be associated with foraging. More attention must be devoted in the future to elucidate engineering aspects related to crab burrows in mangrove environments. Particularly comparative work on the burrow-dwelling life styles of the two types of crab is needed.

Ecosystem engineering in space and time

The ecosystem engineering concept focuses on how organisms physically change the abiotic environment and how this feeds back to the biota. While the concept was formally introduced a little more than 10 years ago, the underpinning of the concept can be traced back to more than a century to the early work of Darwin. The formal application of the idea is yielding new insights into the role of species in ecosystems and many other areas of basic and applied ecology. Here we focus on how temporal, spatial and organizational scales usefully inform the roles played by ecosystem engineers and their incorporation into broader ecological contexts. Two particular, distinguishing features of ecosystem engineers are that they affect the physical space in which other species live and their direct effects can last longer than the lifetime of the organism--engineering can in essence outlive the engineer. Together, these factors identify critical considerations that need to be included in models, experimental and observational work. The ecosystem engineering concept holds particular promise in the area of ecological applications, where influence over abiotic variables and their consequent effects on biotic communities may facilitate ecological restoration and counterbalance anthropogenic influences.

Ecosystem engineering: the impact of bioturbation on biogeochemical processes in marine and freshwater benthic habitats

In aquatic ecosystems, invertebrate bioturbation significantly influences microbial activities and biogeochemical processes in sediments by modifying water and sediment fluxes at the water-sediment interface. We apply the concept of ecosystem engineering to develop a qualitative general understanding of the role of bioturbation on microbial processes in different benthic environments. We hypothesized that the effects of the bioturbation mode (sediment reworking, biogenic structure building, bioirrigation) on microbial processes vary between diffusion- and advection-dominated benthic environments because bioturbation does not have the same influences on hydrological exchanges (and the flux of resources for micro-organisms living in sediments) at the water-sediment interface of the two systems. To test this hypothesis, we experimentally compared the influence of three bioturbation modes (fine-sediment reworking, U-shaped structure burrowing, and gallery-network burrowing) in a diffusion-dominated system (fine sediments/low interstitial flow rates) and an advectiondominated system (coarse sediments/advection of water in sediments). Our analysis demonstrated that bioturbation modes in the two systems had different impacts on microbial activities. For instance, U-shaped tube burrowing by animals increased O2 consumption in the diffusion- dominated system but produced the opposite effect in the advection-dominated system. The influence of bioturbation was also negatively related to interstitial flow rate, the bioturbation having a higher influence on O2 consumption in the diffusion-dominated system than in the advection-dominated system. According to our hypothesis, bioturbation modified microbial processes in sediments depend on the hydrological characteristics of the system. In the diffusion-dominated system, invertebrate bioturbation can produce water fluxes at the watersediment interface that may strongly influence microbial processes in sediments. In contrast, in the advectiondominated system, invertebrate bioturbation can only modify the water circulation patterns in sediments, moderately affecting microbial processes. Consequently, it is necessary to use a conceptual framework which takes into account the features of sediment habitats in order to allow a better prediction of bioturbation effects on sediment biogeochemistry. With this aim, the conceptual scheme of ecosystem engineers can be an organizing principle to integrate the complex relationships among physical habitat, bioturbation mode and microbial activity.

Using ecosystem engineers to restore ecological systems

Ecosystem engineers affect other organisms by creating, modifying, maintaining or destroying habitats. Despite widespread recognition of these often important effects, the ecosystem engineering concept has yet to be widely used in ecological applications. Here, we present a conceptual framework that shows how consideration of ecosystem engineers can be used to assess the likelihood of restoration of a system to a desired state, the type of changes necessary for successful restoration and how restoration efforts can be most effectively partitioned between direct human intervention and natural ecosystem engineers.

Characterizing ecosystem‐level consequences of biological invasions: the role of ecosystem engineers

Invasions by exotic species represent both threats to ecosystems as well as opportunities to learn more about them. Among the invaders that will have the largest impacts are those that directly modify ecosystems and thus have cascading effects for resident biota. Exotics can affect ecosystems by altering system‐level flows, availability, or quality of nutrients, food, and physical resources (e.g. living space, water, heat or light). The invader‐mediated control of physical resources, typically achieved through the modification of habitats, has received limited attention in invasion biology. This reflects a general trend in ecology, and only recently has the concept of ecosystem engineering been developed to account for the role of species that shape habitats. Plants and animals in terrestrial and aquatic systems can both create and destroy structure. When introduced into ecosystems, these exotic engineers cause physical state changes with effects that ramify throughout the system. Although the consequences of these modifications are varied and complex, insight gained from general ecological principles offers an opportunity to predict what invaders will do upon their integration into systems. Examples from the literature suggest that introduced ecosystem engineers that increase habitat complexity or heterogeneity tend to cause abundances and/or species richness to rise, while those that decrease complexity tend to have the reverse effect. In assessing such patterns, however, it is critical to also consider spatial scales and the life habits of resident organisms. In addition to providing predictive power, recognition of engineering as a major means by which invasive species affect ecosystems provides a unifying theme for invasion biology and offers a chance to consider more fully the general role of species in ecosystems.