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Rewilding: What is it?

Rewilding is the idea of re-establishing native habitat and species in areas that have been disturbed by anthropogenic (human) land uses. Rewilding in your own garden can include anything from a small patch where you don't mow and don't use chemicals, to acres of native plantings. Rewilding still makes a difference even if it's just adding native plants from your region to your cultivated garden. 

Why Rewild?

Stem the critical loss of pollinator insects that we depend on for food production.

 

We are currently undergoing the largest extinction event since the last ice age, and the primary cause is habitat loss. Most people work and live in completely disrupted environments where the native plants have been replaced with exotic ornamentals, mowed grass, monoculture crops, gazing livestock, or asphalt and concrete. If you think about all the places you spend time, or pass when you travel, how many of them actually resemble native habitats? Overgrown does not equate to a native habitat! Often areas that appear "natural" can be dominated by non-native invasive exotics (i.e. aggressive plants that are not native). For example many parks and waterways in middle Tennessee where I live are full of privet and Japanese honeysuckle which choke out the native plants. 

These altered human landscapes may be considered more attractive or useful, however they are largely biological wastelands. The species of birds, mammals and insects in a given area are dependent on the plants that are also from that area because they evolved in association with each other. Without the native plants, the amount of native species of animals that an area can support becomes vastly diminished.

The community of plants, fungi, insects, birds, animals and other organisms that collectively comprise the ecosystem depend on one another for survival. When the system is out of balance, or non-existent, beneficial species decline and disappear, while pest species increase. Insects are not generally our favorite types of "wildlife", but they definitely contribute more to our survival than most. Bees and other pollinators play an enormous role in crop productivity - to the estimated tune of $3 Billion annually in the US. Without pollinators, production of fruits and vegetables declines substantially. This puts humanity, including the developed world, at risk of famine. As an example of a critical loss of beneficial species - more than half of all native bee species in the United States (with sufficient data to assess them) is in decline. One in 4 species in the US is considered at risk of extinction (read the full study here​).

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When habitats lack native plant diversity - such as in monoculture environments like mown lawns, or crop fields - the balance of predator-prey insects shifts and predatory insects decline. This leads to an explosion of pest species, and the need to use chemical pesticides to control them. The idea behind providing small (or large!) areas of native habitat is to provide the environment that these predatory insects (such as ladybugs, lacewings, hoverflies and parasitic wasps) need to thrive to keep pest species (such as aphids, mealybugs and caterpillars) under control. 

Trees and plants have the effect of cooling through shading, evapotranspiration, and the reflection of heat. Vegetated areas are shown to be significantly cooler than urban "heat islands". Trees and plants around the house can provide insulating value against temperature changes by shading and reflecting solar energy in the summer and providing wind protection in the winter. Also, the less mowing we do, the less we are actively burning fossil fuels - a primary source of carbon release. 

 

Trees and plants also capture carbon and store it - with trees being the ultimate carbon capture and storage machines. Great carbon sinks, woods and forests absorb atmospheric carbon and lock it up for centuries (Woodland Trust). And tree leaves - which capture the carbon through photosynthesis - are efficiently arranged to gain the most light exposure in the least amount of area. If you took all the leaves off of a tree with a 30-foot diameter crown and laid them flat, they would cover (very approximately and depending on crown shape) around 2,800 square feet. A tree with a 50 foot crown diameter might have a leaf area of around 7,900 square feet. (calculated by ground area of the crown x 4). It's makes devoting even a small part of the yard to planting trees worth considering. 

Vegetation (especially trees) capture intense rainfall and hold rainwater temporarily within their canopy, thus reducing initial flow of rainwater. In addition, vegetation limits flood risk by encouraging better infiltration of water into the soil, which reduces surface water flows (see the article where I got this excerpt). The root systems of trees also create a network of dense erosion control - which is why most streams must have a certain minimum buffer of trees in modern logging and development. Perennial plants and grasses are also excellent for erosion control because of their extensive root systems. There is a direct relationship between the height of grass and it's root depth. So even leaving normal turf varieties unmown will have the effect of increasing root depth and mass. Take a look at the following graphics showing the difference between root depths of various native species.

Increase garden yields without the use of chemical pesticides

Increased energy efficiency, absorption of heat and atmospheric carbon

Prevent flooding and control erosion

Other Resources

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