Habitat fragmentation- degradation of large habitats

Habitat fragmentation in conservation biology, is considered a primary concern. It focuses on the destruction of once large, stable forest blocks to a less permanent environment, primarily through human perturbations, such as land clearance and vegetation change between forms. The world’s major cause of extinction of biodiversity is habitat loss and fragmentation. A complete loss of biodiversity, as well as biodiversity modification and degradation of large habitats into smaller areas, are the greatest environmental danger to ecological diversity.

Both natural forces and human actions induce fragmentation, both operating over varying time and spatial scales. The landscape’s physical features linked to very slow geomorphic processes (e.g. erosion) can also cause patches to remain isolated over time frames. Fragmentation has often a different impact depending on the source of fragmentation (e.g. agricultural fragmentation vs. logging). Consequently, successful steps are required to conserve biodiversity in fragmented landscapes (1).

The fragmentation of the habitat also involves that the contiguous areas of habitat to smaller, more spatially distinct fragments, and the habitat loss is generally associated with the fragmentation of habitat (2). While some ecosystems are naturally abiotic and biotic in their natural environments (3) human activities are highly fractured and alter the nature and connectivity of ecosystems (4) in the term. To protect biodiversity and ecosystem functioning, it is therefore important to consider the causes and effects of habitat fragmentation. The word fragmentation was historically employed for the definition of ecological changes from two distinct landscape contexts. The primary organisms are relaxing those that are intact during fragmentation and now relax to a few species and the decreased role of the environment (5).

Habitat fragmentation

Although some habitats are naturally patchy in terms of abiotic and biotic conditions (Wu and Loucks 1995), human actions have profoundly fragmented landscapes across the word (Haddad et al. 2015), altering the quality and connectivity of habitats.

Therefore, understanding the causes and cons- sequences of habitat fragmentation are critical to preserving biodiversity and ecosystem functioning historically the term fragmentation has been used to describe the ecological changes arising from two different landscape contexts. The first of these are relaxing systems—those intact at the time of fragmentation and which are now relaxing to few species and diminished ecosystem function (e.g., Laurance et al. 2011).

Landscape fragmentation decreases the area of the original ecosystems and increases the total linear edge feet, preferring species that live on borders to the detriment of the inner species that require large continuous patches. Ecological experts including Wilcox and Murphy find that the most significant threat to biodiversity is habitat destruction and the key cause of the current ecological crisis. Habitat fragmentation reduces landscape capacity to sustain in four main ways: Loss of original habitat, increased isolation of patches, reduced habitat patch size, increased edge, and modification of natural disturbance regimes.

Loss of original habitat- Habitat fragmentation

The loss of original habitat is probably the most severe adverse effect of fragmentation. Work indicates that habitat loss has much more effect on wildlife populations than changes in spatial habitat arrangements. More than 90% of the grassland east of the Mississippi River has been destroyed, around 90% of wetlands removed and 80% of Indiana dialects have been destroyed. Habitat losses such that many species will be constantly displaced and other populations dramatically reduced. It pushes the remaining species to the few remaining available areas, through competition, crowding, stress, and disease outbreak potential (6).

Reduction in habitat patch size

The key effect of fragmentation is the reduction in habitat patch size. Biologists suggest that the extinction rate of species is inversely linked to its size in an isolated habitat area. The smaller the remains of indigenous ecosystems, the less likely that they provide food, cover and other services to sustain the indigenous wildlife population. Small areas are often more vulnerable to destructive incidents, including fire and extreme weather, which can decimate local communities. The area of interior habitat is also declined by fragmentation. Internal habitat is the region far enough from the edge to retain the original, larger habitat populations.

Increased edge and isolation

Even if the edge of some species may increase because of fragmentation, some researchers believe that increasing the edge can harm native biodiversity protection. The edges act as barriers to some of the predators. For edging prey species or species moving through narrow corridors, high predator densities along borders that lead to higher morbidity. Fragmentation results in increased patch isolation. The migration of species from the surrounding patches will benefit the populations of wildlife in isolated areas. As fragmentation continues, however, the distances between the patches become longer and the rate of dispersal is decreasing. Species that move between patches also decrease in diversity; small species with limited mobility are particularly sensitive to distance. As immigration rates decrease, the number of species in a patch can decrease to zero over time due to factors such as inbreeding and catastrophic disruption (7).

Habitat fragmentation

Ecological implications of habitat fragmentation

Three generally established mechanisms mediate the ecological implications of fragmentation, while habitat fragmentation essentially stems from the loss of habitats. First of all, which are directly due to habitat loss. Second, the changes in the landscape’s spatial configuration are explicitly due to them, like isolation. Finally, the interaction of these fragments and their matrix (for example spillover) may be due to the indirect or interaction impact of habitat loss and spatial change (8).

With the loss of habitat resulting in changes in both habitat quantity and structure (e.g. decreased patch dimensions, increased separation from the patches and increasing edge area), fragmentation-mediated processes cause widespread responses in population, environment, and ecosystem levels. These include reduced residence and movement between fragments, a lower species wealth between taxonomic groups, and reduced nutrient retention (9).

References

  1. Clements FE (1936) Nature and structure of the climax. J Ecol 24:252–284
  2. Collinge SK (2009) Ecology of fragmented landscapes. Johns Hopkins University Press, Baltimore.
  3. Dagnachew, M., 2016. A Review on the Effect of Habitat Fragmentation on Ecosystem, Journal of natural sciences research., 6(15).
  4. Didham RK, Kapos V, Ewers RM (2012) Rethinking the conceptual foundations of habitat fragmentation research. Oikos 121:161–170
  5. Laurance WF, Camargo JLC, Luizao RCC, Laurance SG, Pimm SL, Bruna EM, Stouffer PC, Williamson GB, Benitez-Malvido J, Vasconcelos HL, Van Houtan KS, Zartman CE, Boyle SA, Didham RK, Andrade A, Lovejoy TE (2011) The fate of Amazonian forest fragments: a 32-year investigation. Biol Conserv 144:56–67.
  6. Nick et al., 2015. Habitat fragmentation and its lasting impact on Earth’s ecosystems. Science Advances, 1(2).
  7. Nick et al., 2015. Habitat fragmentation and its lasting impact on Earth’s ecosystems. Science Advances, 1(2).
  8. Robinson GR, Holt RD, Gaines MS, Hamburg SP, Johnson ML, Fitch HS, Martinko EA (1992) Diverse and contrasting effects of habitat fragmentation. Science 257:524–526
  9. Wu JG, and Loucks OL (1995) From balance of nature to hierarchical patch dynamics: a paradigm shifts in ecology. Q Rev Biol 70:439–466.