What is Habitat Fragmentation?

Habitat fragmentation is the process of separating an intact, continuous habitat into small, isolated patches. Although fragmentation does not directly destroy habitats, it destabilizes the environment and causes animals to be separated from resources that are key for survival. This leads to severe wildlife population decline, in which wildlife has decreased by 73 percent within the past 50 years. The effects of habitat fragmentation include increased risk of extinction, disruption of vital natural processes, and interruption of ecosystem system services that are needed for human survival. Habitat fragmentation can be caused by natural events, such as forest fires or volcanic eruptions, but it is often caused by human interference. 

Habitats Fragmented by Human Development

Humans corrupt natural habitats through several different practices such as industrialization and urbanization. When people construct roads, highways, bridges, or buildings to expand transportation and urban development, they often build them through natural habitats and disrupt their integrity. For example, major roads are frequently built directly through large, healthy forests. The road becomes a barrier that animals need to cross to access food, shelter, and other animals. Without easy access to these key resources, the chances for animal reproduction and survival are severely diminished. Additionally, the construction process and clearing of natural land to expand transportation and urban development leads to landscape destruction, soil degradation, and staggering pollution. The interference and fragmentation of natural habitats leads to increased risk for extinction.

Increased Risk for Extinction

Through habitat fragmentation, species become more susceptible to extinction not only due to the inability to access essential resources, but also due to decreased genetic diversity. Genetic diversity is essential for the long term sustainability of a species, as having a wide range of different traits increases a species’ ability to adapt and survive against environmental changes, pressures, and threats. When animals are barricaded into small, isolated patches, their natural movement significantly decreases. This limited mobility can lead to inbreeding and lack of gene flow, reducing the long-term health of the population and increasing the risk of disease and vulnerability to predators.

Why Genetic Diversity is Important

Genetic diversity not only impacts the survival of a specific species, but it also impacts the survival of an ecosystem as a whole. Genetic diversity increases the resilience of ecosystems by creating a population with a unique combination of genes. This unique combination of genes allows individuals to perform different roles within an ecosystem, such as pollination and seed dispersal. Habitat fragmentation greatly disrupts these key ecosystem processes. 

Disruption of Natural Processes

When habitats are fragmented into separated and isolated patches, key natural processes that maintain the health of the ecosystem are interrupted.

Seed Dispersal and Habitat Fragmentation

For example, key natural processes like seed dispersal and pollination can’t properly take place when habitat fragmentation occurs. During seed dispersal, animals carry seeds across long distances to spread the growth of plants. Habitat fragmentation alters and increases the distance between trees and plants, making it difficult for animals to travel between patches. This means that seeds don’t spread as widely, leading to limited plant regeneration and further species decline.

Habitat Fragmentation Effects on Pollination

In the same vein, pollinators need to travel across long distances to pollinate and maintain the health of plants. Due to the escalated distance between plants from habitat fragmentation, pollinators are less likely to reach other plants to pollinate, thus leading to plant reduction. Not only are animals and their surroundings negatively impacted from the decline in the ecosystem caused by habitat fragmentation, but humans suffer as well. 

Interruption of Ecosystem Services for Humans

Although it may seem that habitat fragmentation primarily impacts animals and their surroundings, humans are greatly impacted as well. Ecosystems are responsible for “the air we breathe, the food we eat, and the natural places that we visit to nurture our bodies and minds.” For example, wetlands play a role in purifying water and providing flood protection. Additionally, forests play a crucial role in sequestering carbon from the atmosphere and maintaining purified air. Other important services that the ecosystem performs are maintaining soil fertility and agricultural productivity. When wetlands or forests are fragmented, their ability to perform these essential ecosystem services diminishes. The loss of ecosystem services can even make detrimental impacts beyond the environment, such as on the economy of communities. In order to maintain these essential ecosystem services, communities need to work together to find solutions for and mitigate the negative effects of habitat fragmentation. 

How To Reduce Habitat Fragmentation

Habitat fragmentation is a critical issue that is affecting the health of humans and the environment, making it essential to address on local, national, and worldwide scales. Currently, rules and policies such as the Endangered Species Act (ESA) in the U.S. and international agreements, like the Convention on Biological Diversity (CBD), protect critical habitats from being fragmented by human development and set goals to create habitat preservation across borders. Additionally, land managers employ techniques such as wildlife corridors, wildlife crossings, conservation easements, and buffer zones to alleviate the detrimental impacts of habitat fragmentation. Informing the public about the consequences of habitat fragmentation and the vitality of biodiversity conservation is key for combating the negative impacts of habitat fragmentation. 

The media, campaigns that advocate for the preservation of the environment, and school programs and curricula, such as Population Education’s lesson Pondering Pandas, can raise awareness of the negative effects of fragmentation and provide steps both individuals and communities can take to reduce it. Additionally, opting for sustainable lifestyles, decreasing unnecessary resource consumption, and supporting conservation efforts can all help mitigate fragmentation. Habitat fragmentation can be combated when there is effort and cooperation on both community and individual levels. 

The elementary lesson on habitat fragmentation, Pondering Pandas, is available as part of the lesson plan library Counting on People: K-5 Activities for Global Citizenship.

Image credits: Forest fragmentation (Harikrishnan S, CC BY-SA 4.0, via Wikimedia Commons); Road through red squirrel habitat (Jim Barton / Red squirrel road sign / CC BY-SA 2.0); Bee (bee by Pimthida is licensed under CC BY-NC-ND 2.0)