the importance of biodiversity
From the remote reaches of Siberia to the bustling streets of New York City, and everywhere in between, every aspect of human existence on this planet is supported by resources produced in nature.
Ecosystem services are the life support which keep us on this planet. From food and natural resource production to creating oxygen and sequestering carbon, managing watersheds and preventing floods and land slides, weather modification, soil conservation and the list goes on.
While the relationship between the natural world and a person living in an urban setting might not be direct, the linkage still exists. Without these ecosystem services we would not be able to survive on this planet.
Biodiversity is the backbone of every ecosystem with each subset of the animal kingdom filling its own unique roll. From caterpillars to wolves, each level of the food web enables the cycle to continue. If any level falters or fails then the rest come crashing down with it.
The tale of yellowstone
The common tale of biodiversity is the reintroduction of wolves back into Yellowstone Natl. park in 1995. Yellowstone was dealing with issues stemming from a booming population of herbivores which were destroying plant life and waterways. When wolves were reintroduced to the park they were able to mitigate herd movements and keep they away from the low valleys and waterways. With less pressure on the struggling foliage it was able to recover and start providing these ecosystem services mentioned earlier.
When wolves were reintroduced a process called a trophic cascade began. This is a top down effect where the most apex members of a food web effect every lower tier. When the flora recovered it provided habitat for terrestrial creature and solidified river bed with their root structures. Animals populations outside of wolves which had been receding for decades suddenly began to tick back up. This was attributed to the increase of plant biodiversity due to the herbivore populations declining.
After 30 years now, the wolves have once again brought balance back to Yellowstone and has set a stood as an example of what restoring an ecosystem looks like. Balance is needed for an ecosystem to function, and to achieve balance every level of system. Like a triangle every tier is supported by the one below and for the system to function properly each level must be strong [21].
“If we lose plants and insects and the food webs collapse then we will lose our major decomposers and our world will begin to rot.”
Figure 4.1
4 functions of a healthy ecosystem
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Ecosystems capture and transfer energy, typically through photosynthesis, where plants convert solar energy into chemical energy. This energy flows through the food chain, supporting producers, consumers, and decomposers.
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Ecosystems recycle essential nutrients like carbon, nitrogen, and phosphorus. Decomposers break down organic material, returning nutrients to the soil, which are then absorbed by plants to support new growth.
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Healthy ecosystems help regulate climate and water cycles. Forests, wetlands, and oceans, for instance, absorb and release water, influencing local and global weather patterns. They also help mitigate the impacts of extreme weather events and maintain water quality.
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A functioning ecosystem supports a wide variety of species, which contributes to genetic diversity and ecosystem resilience. Biodiversity helps ecosystems adapt to changes, recover from disturbances, and maintain overall stability.
Figure 4.2
native vs non-native
Amongst naturalists, horticulturalists, restoration ecologists and entomologists there is controversy of how to most effectively return a developed piece of land back to nature. Globalization has spread all kinds of plants to every corner of the world where they continue to thrive. A vast majority of the non-native species found in the wilderness can be traced back to a person who planted them in their garden and by one means or another they escaped. These plants are able to outcompete and dominate native species primarily because herbivores will not eat non-native species. With progressively more land being taken by non-native species which face no predators, the areas which native species can live and thrive in is shrinking.
What is the importance of native species? Native species tend to support a much wider and more diverse set of species which is catered to the environment they exists in. While burning bush does not support a lot of life in New England, in Asia it supports a wide variety of animal life. While non-native species do support life through carbon sequestration, resource production, habitat and food production. They are not able to do these things nearly as well as a native species which have co-evolved together.
Specialist pollinators are a type of pollinator which relay on one species of plant as their only food source and play a key role in the reproduction of native species in any given area. Without specialist pollinators these plant species would not be able to pollinate and thrive. As non-native species have outcompeted with these native plants, there has been a significant decline in specialist pollinators.
Native plants and trees support far more life than non-native alternatives. With non-natives taking over, it has drastically reduced the biodiversity in natural areas due to the limited generalist species which are able to exist in these environment, Generalist species are not able to play the same role as their specialized counterparts which has reduced the amount of energy being sent up the food chain. While non-native plants on their own are not a major ordeal, the impacts they have up the food web make the issue a lot larger than it initially presents itself [22].
Figure 4.3
Insects
Insects are the backbone of the food web. They are the primary plant consumers and because of that they are the primary link between flora and fauna. Insects take the energy produced by photosynthesis and help move that energy up the food chain all the way to the apex predators. These apex predators eventually die and are decomposed by various invertebrates and scavengers providing more energy to the lowest links of the food chain before than energy is eventually transferred all the way back to the top.
Grasshoppers and caterpillars are perhaps the two most important insects on this planet, they transfer more energy than any other insects up the food chain [23]. However, insects are not able to store much energy which is why abundance is becoming a major concern.
It takes 6,000-9,000 caterpillars to get one clutch of chickadees to fully develop. Insects like these are heavily reliant on native species to provide food and habitat for survival and as native plant populations have dwindled so has insect populations [24].
chemical transfer through the food web
The term bioaccumulation refers to the buildup of substances, especially pollutants like pesticides or heavy metals, within an organism over time, as they are taken up and stored faster than they are broken down or excreted [25]. This is especially common with insects as they are virtually the only creatures which can use the modern lawn as a habitat. Herbicides are absorbed by insects and transfer up the food web through consumption.
Because these chemicals take much longer to break down, they slowly amass into toxic quantities which are unsuitable for life. The classic example of bioaccumulation is DDT. DDT was a pesticide used to control insects, contaminated the environment, including waterways and the food chain. When bald eagles consumed contaminated fish, DDT accumulated in their bodies, interfering with their ability to produce strong eggshells [26].
After legislation was passed in 1972 banning the spraying of DDT did the eagle population slowly start to rebound. This stands as a testament to the impacts of prolonged exposure to harmful synthetic chemicals which were initially vetted by risk assessment organizations like the EPA and IARC. While issues as drastic as the DDT crisis are not currently apparent, with time the larger implications of our current care practices will become clear.