Extinction & Plants

Human destruction of the living world is causing a “frightening” number of plant extinctions, according to scientists who have completed the first global analysis of the issue.

They found 571 species had definitely been wiped out since 1750 but with knowledge of many plant species still very limited the true number is likely to be much higher. The researchers said the plant extinction rate was 500 times greater now than before the industrial revolution, and this was also likely to be an underestimate.

Researchers have discovered 2,000 new types of plants in just the last year. But it's not all good news for the natural world as a fifth of all plants are in danger of extinction.

 

The world’s seed-bearing plants have been disappearing at a rate of nearly 3 species a year since 1900 ― which is up to 500 times higher than would be expected as a result of natural forces alone, according to the largest survey yet of plant extinctions.

The number of plants that have disappeared from the wild is more than twice the number of extinct birds, mammals and amphibians combined. The new figure is also four times the number of extinct plants recorded in the International Union for Conservation of Nature’s red list.

The team found that roughly half of all reported plant extinctions occurred on isolated islands, where species are more vulnerable to environmental changes brought on by human activity. The islands of Hawaii proved the single most dangerous place for plant species, with 79 extinctions reported there since 1900. Other places with particularly high extinction rates included the Cape Provinces of South Africa, the island of Mauritius, Australia, Brazil and India.

For the past 45 years, Steve Perlman has dedicated himself to saving Hawaii’s dying species of plant life. As a field botanist for the Plant Extinction Prevention Program, Perlman focuses on cultivating rare plants in the wild, often navigating unchartered territory to locate the last survivors. He and his team rappel off of cliffs, helicopter into remote valleys and hike miles into the Hawaiian wilderness in search of these rare species. Without his daring work, these plants may be lost forever to history.

 

The main cause of the extinctions is the destruction of natural habitats by human activities, such as cutting down forests and converting land into fields for farming.

Due to human activities, populations of many species have become small and isolated. In this situation they become subject to genetic drift and inbreeding, resulting in loss of genetic variation, an increase in homozygosity, and possibly a decrease in viability (inbreeding depression). This process, here referred to as genetic erosion, may significantly increase the extinction probability of populations or even species, and is therefore currently an important issue in conservation biology.

Plants are considered a critical resource because of the many ways they support life on Earth. They release oxygen into the atmosphere, absorb carbon dioxide, provide habitat and food for wildlife and humans, and regulate the water cycle. Because of the many ways plants help the environment, their importance should not be forgotten.
 

Oxygen Provision
Without plants, humans and animals would have less fresh air to breathe. Through the process of photosynthesis, plants release oxygen back into the atmosphere. What you may not have known is that plants from the ocean are what provide most of the air that we breathe. These single celled plants that thrive in the ocean are also known as phytoplankton. Green terrestrial plants make up the rest of atmospheric oxygen that’s essential for the survival of living organisms.

Carbon Sinks
During this time of climate uncertainty, it’s important to realize the role plants can play to help mitigate the effects of climate change. One of the biggest environmental issues the world faces today is the burning of fossil fuels which has resulted in high levels of carbon dioxide in the atmosphere. Although climate change is a reality the world must face, society is still highly reliant on fossil fuels to supply energy needs. This is where plants come in to play. Terrestrial and oceanic plants are considered carbon sinks because of their ability to store carbon dioxide from the atmosphere . Important carbon sink ecosystems include: grasslands, tropical rainforests, peat bogs, wetlands, coral reefs and coastal ecosystems.

Habitat
Plants are also important because they provide habitats for wildlife and humans. For example, many species of birds rely on trees and shrubs for habitat, whether they live in the crevices of trees or build nests on branches. Healthy habitats also provide wildlife with roosting cover and shelter from predators. Unfortunately, habitat loss is considered one of the causes for species endangerment and extinction. Forest ecosystems continually face deforestation in the form of fires, clear cutting for agriculture and ranching, and unsustainable logging. Plants play a pinnacle role in many of the Earth’s ecosystems so their presence is important to ensure wildlife and ecosystem health.

Food
Since plants are considered primary producers, they play an important role in feeding the Earth’s wildlife and humans. Herbivores, such as deer, rely on plants directly to meet their dietary needs, while carnivores, such as lions, feed on animals that also feed on plants for their survival. And omnivores, such as humans, rely on both. Whether directly or indirectly all wildlife and humans rely on plants for sustenance.

Water Cycle Regulation
About 10% of the moisture in the atmosphere is released by plants through the process of transpiration. Plants uptake water through their roots and release water vapour through small pores on the underside of their leaves. Through this process of transpiration plants also help circulate water from the soil back into the atmosphere. Not only that, but plants help stabilize bodies of water such as rivers, lakes and streams. Plant roots improve soil stability, prevent landslides, and keep these ecosystems intact.

Reasons of Extinction


Agriculture
Industrial agriculture is all about controlling nature, curating the land for human use, and choosing which plants are valuable. While much of biodiversity loss is a secondary result of farming techniques (think: habitat loss or unintended chemical runoff), plants are often eradicated on purpose (think: weeds). You may not consider plants when thinking about extinctions, but it is a very real and urgent concern, with one in eight plants facing extinction. An example you’ve likely heard of is the threatened species milkweed, which the vulnerable monarch butterfly relies on for reproduction. Milkweed is often killed with herbicides or mowed away from hedgerows and roadsides.

 Beyond wild plants, agricultural diversity is also being lost. One estimate suggests that 75 percent of agricultural crops have been lost since 1900, with important rice, wheat, and yam species at risk today. This lack of diversity in food crops is risky for human food security, especially in the face of a changing climate.


Habitat Loss
Deforestation and urbanization combine to create two reasons why plants and animals become extinct. Deforestation is leveling forests to harvest the wood or create space for building or agriculture, while urbanization is the turning of once-rural areas into cities. As the human population grows, more and more land has to be cleared and urbanized for living space. This shrinks habitat for animals and plants. Each year, 36 million acres of natural forest is leveled, according to the World Wildlife Fund. The forest provides habitat for 80 percent of the world's species, the group reports.


Global Warming
Global warming is the ongoing increase in the Earth's atmospheric and ocean temperatures created by the greenhouse effect; a temperature increase of even 1 degree can affect plant and animal life. The report cited by National Geographic News looked at 25 biodiverse areas around the world, such as the Caribbean Basin and the Cape Floristic Region in South Africa, and concluded that current carbon dioxide amounts eventually will double in the areas studied. This could lead to the extinction of 56,000 plant species and 3,700 animal species in those areas alone, the study found.


Exotic Species Introduction
When animals and plants that are not native to a region are introduced to the ecosystem, they can cause serious damage to the local plants and animals, and potentially contribute to their extinction. Native species must compete with the exotic species for basic needs such as food and water. If the exotic species is more aggressive than the native species, the native species then runs the risk of extinction. The introduction of the Nile perch into the Lake Victoria ecosystem in Africa represents a prime example of this, according to "Causes and Consequences of Species Extinctions," a paper published by Princeton University Press. The Nile perch was introduced to the area in the 1950s and by the 1980s, a population boom of these fish contributed to the extinction of between 200 and 400 native fish species.


Overexploitation
Overexploitation, also called overharvesting, is the excessive harvesting of an animal or plant species, making it harder for the species to renew its numbers. The Princeton University Press paper points to the Steller's sea cow, which was discovered in 1741, overexploited, and then became extinct in 1768. Save the Frogs, a frog conservation group, notes that several frog species feel the effects of overharvesting for food, pet and scientific purposes. Fish also fall prey to overexploitation. According to Greenpeace, more than 70 percent of fisheries worldwide are either "fully exploited, over exploited, or significantly depleted."


Solutions

NTBG partners with the Plant Extinction Prevention Program (PEPP) to help conserve the rarest plants, those with fewer than 50 individuals remaining in the wild. Nearly 240 Hawaiian plant species have fewer than 50 wild individuals remaining.

Collecting propagules for long term storage, research, propagation and outplanting, protecting wild plants, surveying for new plants, and monitoring populations are the primary activities mandated by PEPP. NTBG biologists assist PEPP in these activities.

Many of the collections made by PEPP on Kauaʻi are propagated at NTBG’s Conservation and Horticulture Center and established ex situ in NTBG gardens. Many seeds of these rare species are stored in our Seed Bank and Laboratory.

A short documentary about preventing native hawaiian plants from going extinct featuring the work of botanist Hank Oppenheimer

 
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