Spatial ecology
Encyclopedia
Spatial ecology is a specialization of ecology
and geography
that is concerned with the identification of spatial patterns and their relationships to ecological events. In spatial ecology, ecological events can be explained through the detection of patterns at a given spatial scale
; local, regional, or global. Through the application of spatial statistical analysis, factors leading to ecological events can be determined and verified. The field of landscape ecology
is based on the principles of spatial ecology.
Although spatial ecology deals with spatial patterns, it is usually based on observational data
rather than on an existing model
. This is because nature rarely follows set expected order. To properly research a spatial pattern or population, the spatial extent to which it occurs must be detected. Ideally, this would be accomplished beforehand via a 'benchmark' spatial survey, which would determine whether the pattern or process is on a local, regional, or global scale. This is rare in actual field research, however, due to the lack of time and funding, as well as the ever-changing nature of such widely-studied organism
s such as insect
s and wildlife
. With detailed information about a species' life-stages, dynamics, demography, movement, behavior, etc., models of spatial pattern may be developed to estimate and predict events in unsampled locations.
imagery and geographic information systems in a particular area has led to increased analysis and identification of spatial patterns over time. These technologies have also increased the ability to determine how human activities have impacted animal habitat and climate change
.
and principal coordinate analysis of neighbor matrices (PCNM), one can identify spatial relationships between organisms and environmental variables at multiple scales.
In ecology, there are two important sources of spatial autocorrelation, which both arise from spatial-temporal processes, such as dispersal
or migration
:
Most ecological data exhibit some degree of spatial autocorrelation, depending on the ecological scale (spatial resolution) of interest. As the spatial arrangement of most ecological data is not random, traditional random population samples
tend to over-estimate the true value of a variable, or infer significant correlation
where there is none. This bias
can be corrected through the use of geostatistics and other more statistically advanced models. Regardless of method, the sample size must be appropriate to the scale and the spatial statistical method used in order to be valid.
Theoretically, any of these structures may occur at any given scale. Due to the presence of spatial autocorrelation, in nature gradients are generally found at the global level, whereas patches represent intermediate (regional) scales, and noise at local scales.
The analysis of spatial ecological patterns comprises two families of methods;
Spatial patterns have different ecosystem functioning in ecology for examples enhancen productive.
and community ecology. The spatial heterogeneity of populations and communities plays a central role in such ecological theories such as succession
, adaptation
, community stability, competition
, predator-prey interactions, parasitism
, and epidemic
s. The rapidly expanding field of landscape ecology utilizes the basic aspects of spatial ecology in its research.
The practical use of spatial ecology concepts is essential to understanding the consequences of fragmentation
and habitat loss for wildlife. Understanding the response of a species' to a spatial structure provides useful information in regards to biodiversity conservation
and habitat restoration.
Spatial ecology modeling uses components of remote sensing and geographical information systems (GIS).
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
and geography
Geography
Geography is the science that studies the lands, features, inhabitants, and phenomena of Earth. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...
that is concerned with the identification of spatial patterns and their relationships to ecological events. In spatial ecology, ecological events can be explained through the detection of patterns at a given spatial scale
Scale (spatial)
Spatial scale provides a "shorthand" form for discussing relative lengths, areas, distances and sizes. A microclimate, for instance, is one which might occur in a mountain valley or near a lakeshore, whereas a megatrend is one which involves the whole planet....
; local, regional, or global. Through the application of spatial statistical analysis, factors leading to ecological events can be determined and verified. The field of landscape ecology
Landscape ecology
Landscape ecology is the science of studying and improving relationships between urban development and ecological processes in the environment and particular ecosystems...
is based on the principles of spatial ecology.
Overview
In nature, organisms are neither distributed uniformly or at random, forming instead some sort of spatial pattern. This is due to various energy inputs, disturbances, and species interactions that result in spatially patchy structures or gradients. This spatial variance in the environment creates diversity in communities of organisms, as well as in the variety of the observed biological and ecological events. The type of spatial arrangement present may suggest certain interactions within and between species, such as competition, predation, and reproduction. On the other hand, certain spatial patterns may also rule out specific ecological theories previously thought to be trueAlthough spatial ecology deals with spatial patterns, it is usually based on observational data
Empirical
The word empirical denotes information gained by means of observation or experimentation. Empirical data are data produced by an experiment or observation....
rather than on an existing model
Scientific modelling
Scientific modelling is the process of generating abstract, conceptual, graphical and/or mathematical models. Science offers a growing collection of methods, techniques and theory about all kinds of specialized scientific modelling...
. This is because nature rarely follows set expected order. To properly research a spatial pattern or population, the spatial extent to which it occurs must be detected. Ideally, this would be accomplished beforehand via a 'benchmark' spatial survey, which would determine whether the pattern or process is on a local, regional, or global scale. This is rare in actual field research, however, due to the lack of time and funding, as well as the ever-changing nature of such widely-studied organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
s such as insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s and wildlife
Wildlife
Wildlife includes all non-domesticated plants, animals and other organisms. Domesticating wild plant and animal species for human benefit has occurred many times all over the planet, and has a major impact on the environment, both positive and negative....
. With detailed information about a species' life-stages, dynamics, demography, movement, behavior, etc., models of spatial pattern may be developed to estimate and predict events in unsampled locations.
History
Most mathematical studies in ecology in the nineteenth century assumed a uniform distribution of living organisms in their habitat. In the past quarter century, ecologists have begun to recognize the degree to which organisms respond to spatial patterns in their environment. Due to the rapid advances in computer technology in the same time period, more advanced methods of statistical data analysis have come into use. Also, the repeated use of remotely sensedRemote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...
imagery and geographic information systems in a particular area has led to increased analysis and identification of spatial patterns over time. These technologies have also increased the ability to determine how human activities have impacted animal habitat and climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
.
Scale
In spatial ecology, scale refers to the spatial extent of ecological processes and the spatial interpretation of the data. The response of an organism or a species to the environment is particular to a specific scale, and may respond differently at a larger or smaller scale. Choosing a scale that is appropriate to the ecological process in question is very important in accurately hypothesizing and determining the underlying cause. Most often, ecological patterns are a result of multiple ecological processes, which often operate at more than one spatial scale. Through the use of such spatial statistical methods such as geostatisticsGeostatistics
Geostatistics is a branch of statistics focusing on spatial or spatiotemporal datasets. Developed originally to predict probability distributions of ore grades for mining operations, it is currently applied in diverse disciplines including petroleum geology, hydrogeology, hydrology, meteorology,...
and principal coordinate analysis of neighbor matrices (PCNM), one can identify spatial relationships between organisms and environmental variables at multiple scales.
Spatial Autocorrelation
Spatial autocorrelation refers to the value of samples taken close to each other are more likely to have similar magnitude than by chance alone. When a pair of values located at a certain distance apart are more similar than expected by chance, the spatial autocorrelation is said to be positive. When a pair of values are less similar, the spatial autocorrelation is said to be negative. It is common for values to be positively autocorrelated at shorter distances and negative autocorrelated at longer distances. This is commonly known as Tobler's first law of geography, summarized as “everything is related to everything else, but nearby objects are more related than distant objects”.In ecology, there are two important sources of spatial autocorrelation, which both arise from spatial-temporal processes, such as dispersal
Biological dispersal
Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...
or migration
Human migration
Human migration is physical movement by humans from one area to another, sometimes over long distances or in large groups. Historically this movement was nomadic, often causing significant conflict with the indigenous population and their displacement or cultural assimilation. Only a few nomadic...
:
- True/inherent spatial autocorrelation arises from interactions among individuals located in close proximity. This process is endogenous (internal) and results in the individuals being spatially adjacent in a patchy fashion. An example of this would be sexual reproductionSexual reproductionSexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
, the success of which requires the closeness of a male and female of the species. - Induced spatial autocorrelation (or ‘induced spatial dependence’) arises from the species response to the spatial structure of exogenous (external) factors, which are themselves spatially autocorrelated. An example of this would be the winter habitat range of deer, which use conifers for heat retention and forageForageForage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...
.
Most ecological data exhibit some degree of spatial autocorrelation, depending on the ecological scale (spatial resolution) of interest. As the spatial arrangement of most ecological data is not random, traditional random population samples
Random sample
In statistics, a sample is a subject chosen from a population for investigation; a random sample is one chosen by a method involving an unpredictable component...
tend to over-estimate the true value of a variable, or infer significant correlation
Correlation
In statistics, dependence refers to any statistical relationship between two random variables or two sets of data. Correlation refers to any of a broad class of statistical relationships involving dependence....
where there is none. This bias
Systemic bias
Systemic bias is the inherent tendency of a process to favor particular outcomes. The term is a neologism that generally refers to human systems; the analogous problem in non-human systems is often called systematic bias, and leads to systematic error in measurements or estimates.-Bias in...
can be corrected through the use of geostatistics and other more statistically advanced models. Regardless of method, the sample size must be appropriate to the scale and the spatial statistical method used in order to be valid.
Pattern
Spatial patterns, such as the distribution of a species, are the result of either true or induced spatial autocorrelation. In nature, organisms are distributed neither uniformly nor at random. The environment is spatially structured by various ecological processes, which in combination with the behavioral response of species’ generally results in:- Gradients (trends) steady directional change in numbers over a specific distance
- Patches (clumps) a relatively uniform and homogenous area separated by gaps
- Noise (random fluctuations) variation not able to be explained by a model
Theoretically, any of these structures may occur at any given scale. Due to the presence of spatial autocorrelation, in nature gradients are generally found at the global level, whereas patches represent intermediate (regional) scales, and noise at local scales.
The analysis of spatial ecological patterns comprises two families of methods;
- Point pattern analysis deals with the distribution of individuals through space, and is used to determine whether the distribution is random. It also describes the type of pattern and draws conclusions on what kind of process created the observed pattern. Quadrat-density and the nearest neighborNearest neighbor searchNearest neighbor search , also known as proximity search, similarity search or closest point search, is an optimization problem for finding closest points in metric spaces. The problem is: given a set S of points in a metric space M and a query point q ∈ M, find the closest point in S to q...
methods are the most commonly used statistical methods. - Surface pattern analysis deals with spatially continuous phenomena. After the spatial distribution of the variables is determined through discrete sampling, statistical methods are used to quantify the magnitude, intensity, and extent of spatial autocorrelation present in the data (such as correlogramCorrelogramIn the analysis of data, a correlogram is an image of correlation statistics. For example, in time series analysis, a correlogram, also known as an autocorrelation plot, is a plot of the sample autocorrelations r_h\, versus h\, ....
s, variograms, and peridograms), as well as to map the amount of spatial variation.
Research
Analysis of spatial trends has been used to research wildlife management, fire ecology, population ecology, disease ecology, invasive species, marine ecology, and carbon sequestration modeling using the spatial relationships and patterns to determine ecological processes and their effects on the environment.Spatial patterns have different ecosystem functioning in ecology for examples enhancen productive.
Interdisciplinary
The concepts of spatial ecology are fundamental to understanding the spatial dynamics of populationPopulation ecology
Population ecology is a sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment. It is the study of how the population sizes of species living together in groups change over time and space....
and community ecology. The spatial heterogeneity of populations and communities plays a central role in such ecological theories such as succession
Ecological succession
Ecological succession, is the phenomenon or process by which a community progressively transforms itself until a stable community is formed. It is a fundamental concept in ecology, and refers to more or less predictable and orderly changes in the composition or structure of an ecological community...
, adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
, community stability, competition
Competition (biology)
Competition is an interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource used by both is required. Competition both within and between species is an important topic in ecology, especially community ecology...
, predator-prey interactions, parasitism
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
, and epidemic
Epidemic
In epidemiology, an epidemic , occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience...
s. The rapidly expanding field of landscape ecology utilizes the basic aspects of spatial ecology in its research.
The practical use of spatial ecology concepts is essential to understanding the consequences of fragmentation
Habitat fragmentation
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...
and habitat loss for wildlife. Understanding the response of a species' to a spatial structure provides useful information in regards to biodiversity conservation
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
and habitat restoration.
Spatial ecology modeling uses components of remote sensing and geographical information systems (GIS).
See also
- Spatial AnalysisSpatial analysisSpatial analysis or spatial statistics includes any of the formal techniques which study entities using their topological, geometric, or geographic properties...
- Edge effectEdge effectThe edge effect in ecology is the effect of the juxtaposition or placing side by side of contrasting environments on an ecosystem.This term is commonly used in conjunction with the boundary between natural habitats, especially forests, and disturbed or developed land. Edge effects are especially...
- Spatial dependenceSpatial dependenceIn applications of statistics, spatial dependence is the existence of statistical dependence in a collection of random variables or a collection time series of random variables, each of which is associated with a different geographical location...
- GeostatisticsGeostatisticsGeostatistics is a branch of statistics focusing on spatial or spatiotemporal datasets. Developed originally to predict probability distributions of ore grades for mining operations, it is currently applied in diverse disciplines including petroleum geology, hydrogeology, hydrology, meteorology,...
- Landscape EcologyLandscape ecologyLandscape ecology is the science of studying and improving relationships between urban development and ecological processes in the environment and particular ecosystems...
- Geographic information scienceGeographic Information ScienceGeographic information science is the academic theory behind the development, use, and application of geographic information systems...
External links
- Spatial Ecology, hosts software for use in spatial ecological analysis.
- Spatial Ecology Research Programme at the University of Helsinki
- Spatial Ecology Lab at the University of Queensland
- Ecography publishes peer-reviewed articles on spatial ecology.
- National Center for Ecological Analysis and Synthesis at the University of California, Santa Barbara
- Spatial Ecology Lab at the University of Alaska, Fairbanks