Functional ecology

Functional ecology is a branch of ecology that focuses on the roles, or functions, that species play in the community or ecosystem in which they occur. In this approach, physiological, anatomical, and life history characteristics of the species are emphasized. The term 'function' is used to emphasize certain physiological processes rather than discrete properties, describe an organism's role in a trophic system, or illustrate the effects of natural selective processes on an organism. This sub-discipline of ecology represents the crossroads between ecological patterns and the processes and mechanisms that underlie them. It focuses on traits represented in large number of species and can be measured in two ways. The first being screening, which involves measuring a trait across a number of species, and the second being empiricism, which provides quantitative relationships for the traits measured in screening. Functional ecology often emphasizes an integrative approach, using organism traits and activities to understand community dynamics and ecosystem processes, particularly in response to the rapid global changes occurring in earth's environment. Functional ecology is a branch of ecology that focuses on the roles, or functions, that species play in the community or ecosystem in which they occur. In this approach, physiological, anatomical, and life history characteristics of the species are emphasized. The term 'function' is used to emphasize certain physiological processes rather than discrete properties, describe an organism's role in a trophic system, or illustrate the effects of natural selective processes on an organism. This sub-discipline of ecology represents the crossroads between ecological patterns and the processes and mechanisms that underlie them. It focuses on traits represented in large number of species and can be measured in two ways. The first being screening, which involves measuring a trait across a number of species, and the second being empiricism, which provides quantitative relationships for the traits measured in screening. Functional ecology often emphasizes an integrative approach, using organism traits and activities to understand community dynamics and ecosystem processes, particularly in response to the rapid global changes occurring in earth's environment. Functional ecology sits at the nexus of several disparate disciplines and serves as the unifying principle between evolutionary ecology, evolutionary biology, genetics and genomics, and traditional ecological studies, and attempts to understand species' 'competitive abilities, patterns of species co-occurrence, community assembly, and the role of different traits on ecosystem functioning'. The notion that ecosystems' functions can be affected by their constituent parts has its origins in the 19th century. Charles Darwin's On The Origin of Species is one of the first texts to directly comment on the effect of biodiversity on ecosystem health by noting a positive correlation between plant density and ecosystem productivity. In his influential 1927 work, Animal Ecology, Charles Elton proposed classifying an ecosystem based on the how its members utilize resources. By the 1950s, Elton's model of ecosystems was widely accepted, where organisms that shared similarities in resource use occupied the same 'guild' within an ecosystem. Beginning in the 1970s, an increased interest in functional classification revolutionized functional ecology. 'Guilds' would be re-termed 'functional groups', and classification schemes began to focus more on interactions between species and trophic levels. Functional ecology became widely understood to be the study of ecological processes that concern the adaptations of organism within the ecosystem. In the 1990s, biodiversity became better understood as the diversity of species' ecological functions within an ecosystem, rather than simply a great number of different species present. Finally, in the 2000s researchers began using functional classification schemes to examine ecosystems' and organisms' responses to drastic change and disturbance, and the impact of function loss on the health of an ecosystem. Functional diversity is widely considered to be “the value and the range of those species and organismal traits that influence ecosystem functioning” In this sense, the use of the term “function” may apply to individuals, populations, communities, trophic levels, or evolutionary process (i.e. considering the function of adaptations). Functional diversity was conceived as an alternative classification to schemes using genetic diversity or physiological diversity to measure the ecological importance of species in an environment, as well as a way to understand how biodiversity affects specific ecosystem functions, where in this context, 'biodiversity' refers to the diversity of ecosystem functions present in a given system. Understanding ecosystems via functional diversity is as powerful as it is broadly applicable and gives insight into observable patterns in ecosystems, such as species occurrence, species competitive abilities, and the influence of biological communities on ecosystem functioning. A key interest of modern research in Functional Ecology is the impact of functional diversity on ecosystem health. Unsurprisingly, biodiversity has a positive impact on the productivity of an ecosystem. Increased functional diversity increases both the capacity of the ecosystem to regulate the flux of energy and matter through the environment (Ecosystem Functions) as well as the ecosystem's ability to produce resources beneficial to humans such as air, water, and wood (Ecosystem Services). Ecosystem Functions are drastically reduced with decreases in the diversity of genes, species and functional groups present within an ecosystem. In fact, reductions in functional diversity broadly impact the survivability of organisms in an environment regardless of functional group, trophic level, or species, implying that the organization and interaction of communities in an ecosystem has a profound impact on its ability to function and self-sustain. Furthermore, diversity improves environmental stability. The greater an ecosystem's diversity, the more resilient it is to changes in species composition (e.g. extinction events or invasive species) and extraneous changes to environmental conditions (e.g. logging, farming, and pollution). Moreover, the benefits that diversity provides to an environment scale non-linearly with the amount of diversity. Unfortunately, this relationship also acts in the opposite direction. The loss of diversity non-linearly disrupts ecosystems (even stable ones); this negative impact is especially detrimental when the loss is across trophic levels. For, example, the loss of a single tertiary predator can have cascading effects on the food chain, resulting in reduction of plant biomass and genetic diversity. This in turn can alter the 'vegetation structure, fire frequency, and even disease epidemics in a range of ecosystems'. The effects of diversity on ecosystems are so powerful, that they can rival the impact of climate change and other global ecosystem stressors. Alternatively, in rare situations, diversity has been shown to retard ecological productivity. In experimentally concocted microscopic environments, a diverse culture of bacteria was unable to out-produce a homogeneous culture of an 'efficient' control strain. However, the statistical validity and setup of these experiments have been questioned, and require further investigation to carry substantial merit. In general, the current consensus that diversity is beneficial to ecosystem health has much more theoretical and empirical support and is more widely applicable. Most models of complex functional diversity are only effective in a small range of spatial scales. However, by defining the functional trait probability density as a 'function representing the distribution of probabilities of observing each possible trait value in a given ecological unit,' the results of many models can be generalized to larger scales. At larger spatial scales, more environmental heterogeneity may increase opportunities for species to exploit more functional groups. Consistent with this conclusion, tests of theoretical models predict that the net effects of biodiversity on ecosystem functions grow stronger over time, over larger spatial scales, and with more heterogeneous natural resources. However, these results are expected to underestimate the actual relationshipm impling that large space and time scales coupled with diverse resources are more than necessary to sustain an ecosystem.