Habitat management can do wonders for us.
When done well, it enables us to walk with the tigers of the Indian grasslands, or take fresh breaths of Atlantic Rainforests. We are lucky enough to have the latter in the UK, on the western coast!
When done badly... habitat management can make us forget about all that ever coming true.
Habitat management can be used for non-conservation purposes, such as harvesting and selling purplewood. Biodiversity needs to be taken into account even in areas selected for commercial activities. One of the biggest reasons is due to habitat biodiversity (number of species present) generally increasing habitat resilience - an especially important aspect in managing climate change.
Habitat Management (Definition)
A habitat represents the totality of abiotic factors with which the biota (living organisms) interacts to survive.
Habitat management refers to the management of natural, semi-natural or man-made environments, which intend to enhance or preserve certain resources.
Habitat manipulation (management) can be done to:
- Enhance abiotic features and quality
- Increase a habitat's capacity to provide for one threatened species
- Preserve natural supplies such as wood, fuel, new foods and medicines
- Change biodiversity interactions (e.g. the number of mesopredators).
Mesopredators are animals that both prey on others and are preyed upon, e.g. coyotes or red foxes.
Ways to achieve manage or change a habitat include physical environmental changes, e.g. soil creation, social, e.g. resource allocation among individuals or chemical, e.g. pH alteration.
Habitat Management for Conservation
The carrying capacity of an environment can be managed to select for desirable species in a habitat.
The carrying capacity is the maximum population size of a particular species that the environment can sustainably support without significant negative impacts on their quality of life.1
One such desirable element can be an old tree. Even one single individual of a tree species has the potential to become a (micro)habitat.
Trees allow other species such as lichens to grow on them and provide microhabitats for semiaquatic and aquatic species, where water accumulates in tree cavities. The underside of a tree's canopy is also sheltered from abiotic elements such as sun rays and high wind velocity, creating less exposed conditions for other species. Threatened species such as European ferns prefer the shady, humid conditions underneath trees. The roots of a tree further communicate via fungal connections (mycorrhizae) with other roots.
Such a tree would be part of a habitat management plan that creates permanent vegetation for wildlife. Additionally, controlling invasive species, building boxes and nests, improving forest edges and creating wildlife corridors all promote biodiversity conservation. Habitat management for conservation considers the individual needs and characteristics of each species that occurs or may occur inside it.
Warblers (small insectivorous songbirds) require dense shrubbery, such as bramble, hawthorn and young trees. If these are removed, the warblers need to move somewhere else.
Habitat management is even more important for habitat specialists, which are those species that are highly adapted to survive in relation to one or very few other species.
Marine iguanas can only thrive on the seaweed that grows around the Galápagos Islands, with some additional nutrients obtained from insects or lichens.
Habitat Management Plan (Sampling and Indexes)
Management plans are important for biodiversity conservation, especially for captive breeding and release programmes, in-situ conservation projects and carbon sink projects. They all need to be backed by field data.
The best habitat management plan is sometimes the one in which we don't interfere with the habitat at all!
Habitat management techniques
To get this data and assess the health of a habitat, ecological sampling techniques are needed, such as belt transects (squares of biodiversity sampled along a line).
Then, we count biodiversity using specific indexes. Two popular ones are Simpson's Diversity Index and Shannon Diversity Index.
OK, this will look more complicated than it actually is, but bear with me!
Simpson's Diversity Index (D) can be used here to assess a habitat's biodiversity and management practices.
D = 1 - Ʃ 𝑛(𝑛-1)/𝑁(𝑁-1)
𝑛 = the number of individuals identifiable as from one species
𝑁 = the total number of all individuals
Ʃ = sigma (sum up the number obtained after applying the shown n or N formula)
This index focuses on species dominance by quadrats. The final index number (D) can only be between 0 and 1, but never bigger than 1 (e.g. D = 0.768).
For species diversity, one Crocus flower and one water lily receive the same coefficient (which is 2) as 10 crocus flowers and 20 water lilies because both only represent two species.
In our imaginary quadrat, Crocus n (no. of individuals) = 10 and Water lily n (no. of individuals) = 20.
N = 10 +20 = 30.
Crocus n-1 = 9 & n(n-1) = 10x9 = 90.
Water lily n-1 = 19 & n(n-1) = 20x19 = 380.
The Ʃ of n(n-1) is calculated for all species (here crocus and water lily at 380 + 90 = 470).
Results: D = 1 - Ʃ 𝑛(𝑛-1)/𝑁(𝑁-1) = 1 - [470/(30x29)] = 1 - 0.540229 = 0.459
D = 0 means no species diversity.
0 < D < 1 means relative diversity (most frequent).
D = 1 means complete diversity.
Species abundance is the presence of multiple species in a quadrat (as opposed to only two, for instance).
The Shannon Diversity Index (H) is based on the 20th-century physicist's Claude Shannon, and is a measure of the variability and richness of a given ecosystem. The Shannon biodiversity index can be used to compare different ecosystems, or to track changes in the diversity of a single ecosystem over time.
H = - Σ(n/N) x Ln(n/N)
Ʃ = sigma, the sum of numbers
n/N (sometimes noted as pi) = the number of individuals of one species n divided by the total number of all individuals of all species N.
Ln = natural logarithm
Crocus n (no. of individuals) = 10 and Water lily n (no. of individuals) = 20.
N = 30 => Crocus n/N = 10/30 = 0.333 & Water lily n/N = 20/30 = 0.666 => Σ(n/N) = 0.333 + 0.666 = 0.999
Ln(n/N) = -0.4065
Results: H = - Σ(n/N) x Ln(n/N) = -0.999 x -0.4065 = 0.592
There are other community and biodiversity index calculation methods too, but these two are among the most used.
Habitat Management Area
A habitat area refers to the total space that wildlife needs in order to survive and thrive. Some species, such as Eurasian wolves, need large areas of up to, or more than 1,000 square kilometres sometimes due to prey scarcity and pack size. Great-crested newts may prefer small ponds only a few meters wide and sometimes even less than one meter deep. This is to avoid predatory fish that could eat their eggs.
Changes to a habitat management area can occur due to natural elements such as natural succession or climate change.
A good understanding of habitat management leads to accurate predictions of how a habitat evolves.
Habitats are visually identifiable. Hundreds of them exist, from the mangroves of Panama to the Atlantic benthos (sea floor), but for the most part, large habitat areas can be split into woodland, fields and wetlands.
Habitat management examples
Forest habitats in the UK may include Caledonian pine forests, broadleaved forests, plantations or temperate Atlantic rainforests. Unique animals such as lynxes, European bison and pine martens can only live there.
Frequent habitat management techniques for woodlands include tree ring barking, forest meadow creation, planting, wildlife conservation, the introduction of carnivores to control the number of grazers that could prevent forest expansion by eating young saplings, etc.
Field habitats have been intensively used by people for millennia, and represent open lands that support grasses, herbs, and other non-woody plants. Trees are scarcer than in woodlands and the soils more exposed, with a higher degree of sunlight that allows for example for the plantation of crop plants such as wheat and corn.
Grasslands, savannas and prairies, with plant species such as cowslip and meadow foxtail, or animal species such as pronghorns, meadowlarks and shrews. Habitat management for fields includes the creation of drainage channels, wildflower sowing, or rotation grazing and plantation.
Wetlands are characterized by wet conditions, either permanently or seasonally, and either freshwater, brackish or saltwater. Organisms living in these types of environments typically need specialized adaptations, such as webbing, impermeable fur oils or feathers or root systems that help plants anchor in place. They are especially sensitive to pollution and changes in water pH, oxygen levels and salinity (e.g.
Marshes, fens, deltas and oceans are all examples of wetland ecosystems, with species including egrets, snakes, salamanders, sharks, dolphins, etc. Habitat management needs to consider the crucial ebb and flow processes and floodplains on which wildlife depends. They are heavily impacted by dredging, damming and river diversion, as well as off-chance events such as oil spills, or periodic events, like sewer overflows.
Principles of Habitat Management
For the most part, the principles of habitat management for all types of habitats are based on modifying biotic and abiotic factors. This is to ensure four primary aspects that allow for survival: water, food, shelter and space (along with the competition that comes with it).
The management of abiotic factors has significant impacts on the health of its inhabitants. Temperature, pH, habitat shape, light, level of fragmentation, vegetation age structure, mineral levels and moisture levels are all examples of abiotic factors that must be controlled within a habitat. If any of these factors become too extreme, it can cause stress or even death to the organisms living there.
The sex ratio (the percentage of females and males) inside turtle or crocodilian eggs is determined by the ambient temperature in a process that is called temperature sex-determination.
Mineral and nutrient levels are especially important when building and managing habitats.
The management of biotic factors includes food availability, for example, red meat for raptors and nectar for pollinators, control of predation (e.g. bears, cats), control of prey (e.g. deer, rabbits), control of pathogens (e.g. rabies), and especially, species reintroductions (e.g. beavers in England, European bison in Scotland) and habitat rehabilitation.
I hope that this article helps bring a better understanding of the primary types of habitat management and of general habitat management techniques. An important element of dynamism is attributed to all environments, as they are likely to evolve and change as the climate changes too.
Habitat Management - Key takeaways
- Despite their diversity, habitats and their microhabitats can be classified into categories such as woodland, wetland and fields, and studied according to these criteria.
- The management of biotic and abiotic factors brings about changes in the four main aspects that influence wildlife survivability rates: water, food, shelter and space.
- Large areas aren't necessarily needed by all species, but in order to co-exist peacefully, habitat management may need to occur over large areas that accommodate a diverse range of organisms, enough to tolerate territorial disputes, give climate change & ecological succession flexibility, and cushion human-animal conflicts.
- Management decisions must be taken in conjuncture with ecological data. Data can be obtained through various sampling and calculation methods, such as Simpson's or the Shannon Diversity Index.
- Habitat management is, in general, a branch of ecology, but can be employed for economic reasons, as well as for geological preservation and other reasons.
References
- Carrying capacity in biology, britannica, 2022, https://www.britannica.com/science/carrying-capacity. Accessed 10.09.22
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