Trees are recognized by everyone, and I cannot imagine our landscape without them. Trees are an important part of the Earth’s biomass, providing many benefits. Trees have been described as Earth’s lungs or vacuum cleaner, as they exchange oxygen and carbon dioxide in the atmosphere through photosynthesis.
There are close to 60,000 tree species worldwide. According to the New York State Department of Environmental Conservation website, there are over 100 different tree species in the state’s forests, which are owned both privately and publicly. New York City, in 2020, reported to have 168 different tree species, which includes some in botanical gardens.
In general, people are able to recognize a few common tree species, especially this time of year as the leaves start to change. Yet most say all trees look alike. Trees are often taken for granted and assumed they will always be there. As a global society, we need to begin to understand the important role trees play in the environment.
Worldwide, the diversity of trees in forests provides habitats for half of the global population of plants and animals. In New York, squirrels and birds need trees. In the tropics, meanwhile, plants (such as orchids), fungi, birds, invertebrates (insects and spiders), amphibians (frogs and salamanders), reptiles and even mammals live in and are dependent on trees for their survival.
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As we come to grips with the changing climate, trees are being credited with carbon storage and adding biodiversity to forests, as well woodlands and grasslands in a natural environment. In our cities and other populated areas trees are also critical, as they provide shade to keep city hardscapes cool and can help stabilize areas that are prone to erosion, especially along streambanks.
During the past five years, a Global Tree Assessment has been conducted to determine the extinction risk of the world’s 58,497 tree species. This study found that 30% of the tree species are threatened with extinction, and at least 142 species are now considered extinct in the wild.
Habitat destruction, timber harvesting and the spread of invasive pests and diseases were found to be the primary factors for the declining number of tree species worldwide. Additionally, the report noted that the changing climate was also having an impact.
Not surprisingly, the diversity of tree species is not evenly distributed worldwide. Temperate zones, such as those found in North America, Europe and Asia, had low tree species diversity. These temperate areas also have fewer tree species threatened with extinction. Central and South America and other tropical areas have a higher number of tree species, leading to greater diversity, but these areas also face a greater threat of tree species extinction.
More information can be found on the GlobalTree Portal, which provides information on the world’s trees with species-specific information about their distribution, conservation status and conservation actions.
Some of the proposed conservation actions in the Global Tree Assessment include greater focus on planning and implementing biodiversity conservation to include ecosystem restoration, plus placing greater emphasis on the importance of trees globally.
Tree species have evolved with a changing climate for millions of years. It seems that human interference is creating even more pressure on their habitat and diversity. Climate scientists are indicating that trees can be an answer to our changing climate; however, globally, we need to understand and appreciate their role for the benefit of all on Earth.
The next time you see a tree, perhaps consider what its benefits might be other than as a source of wood. When purchasing wood, strive to use wood that has been sustainably grown.
Judy Wright is the senior agriculture specialist with Cornell Cooperative Extension of Seneca County. For more information, visit senecacountycce.org or call (315) 539-9251 ext. 109.