**3. Results and discussion**

#### **3.1 Global Forest assessment**

Forests are the most important ecosystems on the planet because they include a diverse range of plant species and are home to a diverse range of animal species, including microorganism. Forests cover over 31% of the total surface area on the planet or 4.06 billion hectares (40 million square kilometers). With around 1015 million hectares of forest cover, Europe is the second-smallest continent by area. With 842 million hectares of forest cover, South America comes in forest area in second category. With 593 ha of forest, Asia, the world's largest continent, has the second-smallest forest area. More than half of the world's forest cover is accounted for by five countries: Russia, Brazil, Canada, the United States, and China. When it comes to our world's forests, deforestation and degradation of forest significant issues: by 2030, nearly 47% of the world's forests will be deforested or degraded. More than half of the world's forest cover is accounted for by five countries: Russia, Brazil, Canada, the United States, and China. However, due to their huge size, forests cover just a small percentage of the land areas in most of these countries. Suriname, Guyana, the Federated States of Micronesia, and Gabon have the largest proportion of forest cover, with forest covering at least 90% of their land areas. More than two-thirds of the world's total forest acreage is shared by 10 countries [43].

*Impact on Forest and Vegetation Due to Human Interventions DOI: http://dx.doi.org/10.5772/intechopen.105707*

Russia, the world's largest country, has by far the most forest cover. With 815 million hectares, the country possesses more than one-fifth of the world's forest acreage (20.1 percent), making it the most wooded country on the planet. Russia's forest cover accounts for around 45% of its entire land area and 5.5% of the global land area. Only Canada, the United States, China, and Brazil have a larger overall land area than Russia. It also accounts for around 81% of Europe's total forest area and is the sole reason that the continent has the largest forest area among the seven continents. Russia has four categories of forest: recreational, reserve, field, and waterproof. The Russian forestry industry provides approximately \$200 billion each year. The 10 countries with the most forest cover are shown in **Figure 1**.

Forests are important resources for climate regulation. Every square kilometer of land in Amazonia emits 20 billion tons of water into the sky every day. That is 3 billion tons greater than the amount of water that pours out of the Amazon, the world's most plentiful river [44]. The most serious dangers to forests around the world are deforestation and forest degradation. Deforestation occurs when forests are converted to non-forest uses such as agriculture and road development. Forest ecosystems are said to be degraded when they lose their ability to provide vital goods and services to humans and the environment. More than half of the world's tropical forests have been destroyed since the 1960s, with more than 1 hectare destroyed or severely degraded every second. Cattle, insects, illnesses, forest fires, and other human-related activities affect an estimated 3.7 million hectares of Europe's woods [45].

#### *3.1.1 Deforestation*

Tropical deforestation is caused by a complex interplay of natural forces (social, ecological, economic, environmental, and biophysical). The particular mix of drivers differs by region of the world, country, and locality. Population growth, density, and

**Figure 1.** *Forest cover in the world (%).*

spatial dispersion are rarely the primary causes of deforestation. Taxation, subsidies, corruption, property rights, and other institutional elements are usually linked to economic forces. Cultural and sociopolitical variables, such as a lack of public support for forest protection and sustainable use, are also important [46]. Many areas continue to experience high rates of forest loss and degradation. Tools that can offer an integrated assessment of human impacts on forest biodiversity are needed. The modeling toolkit method proposed by Sturvetant et al. could be useful in these situations [47].

Deforestation and forest degradation are both harmful to forest health, but there is a distinction to be made. Brazil has around 497 million hectares of forest, accounting for about 12.2% of the world's total forest area. Around 92% of Brazil's forest is categorized as primary, which means it is carbon-dense and diversified. Deforestation in the Brazilian Amazon has hit the highest annual level in a decade. However, Brazil has set a goal of slowing the pace of deforestation to 3900 sq. km annually by 2020.

In the Amazon, forest degradation is a widespread occurrence that often affects a significantly larger area than clear-cut deforestation. Each year between 2007 and 2016, an average of 11,000 km2 of forest was degraded. In the same time period, this is twice the annual average for deforested lands. While deforestation progressed at a reasonably consistent rate during the study period, degradation fluctuated greatly over time, particularly from 2009 to 2016. The total degraded area per year fluctuated from a low of 2700 km2 in 2014 and a high of 23,700 km<sup>2</sup> in 2016 [48].

The Asia-Pacific Region's total forest area in 1990 was 733.4 million ha, 726.3 million ha in 2000, 737.8 million ha in 2005, and 740.4 million ha in 2010, accounting for approximately 18.3% of the global forest area. Deforestation in the Asia-Pacific Region has decreased from an annual loss of more than 0.7 million hectares of forest from 1990 to 2000 to an annual increase of 0.5 million hectares from 2005 to 2010. There has been a considerable decrease in the net annual gain in forest area since 2005, from about 2.3 million hectares between 2000 and 2005 to approximately 0.5 million hectares between 2005 and 2010, **Figure 2**, [49].

According to FRA 2020, the rate of net forest loss decreased from 7.8 million ha per year in the 1990–2000 decade to 5.2 million ha per year in the 2000–2010 decade and 4.7 million ha per year in the 2010–2020 decade. In 2015, a statistical profile of the world's forest assessment revealed 3999 individuals and 234 nations and territories have a total forest area of 2 million hectares, with an annual change rate of 0.13%. Since 1990, the ration has dropped by 31.6%, from 4128 million hectares in 1990 to 3999 million hectares in 2015 [50]. According to the FAO, forests span approximately 3.9 billion hectares (or 9.6 billion acres), or approximately 30% of the world's land surface. Between 2000 and 2010, the FAO estimates that around 13 million hectares of forest were converted to other uses or lost due to natural causes.

#### *3.1.2 Biodiversity in human-modified landscapes*

The persistence of biodiversity in human-modified environments is critical for conservation and the maintenance of ecosystem services. Studies of biodiversity in settings where humans live, work, and extract resources could aid in the development of sound policies. However, research should cover relevant areas, and study topic biases should not result in gaps in the evidence base. Biodiversity is an important resource on the earth, but the world is in a declining stage of biodiversity. All flora, fauna, and microbes are slowly degrading and disappearing due to human activities. Global terrestrial forests account for 75% of terrestrial gross primary output and

*Impact on Forest and Vegetation Due to Human Interventions DOI: http://dx.doi.org/10.5772/intechopen.105707*

**Figure 2.** *Forest area change.*

80% of Earth's total plant biomass, encompassing 4.03 billion hectares or 30% of the planet's total land area [51].

#### *3.1.3 Assessment of carbon and human alteration*

The long-term or permanent transfer of forest to other land uses is referred to as deforestation. Deforestation and forest degradation constitute roughly one-fifth of total greenhouse gas emissions globally. Deforestation can have far-reaching consequences for society and the environment, from the local to the global. Forest users and managers are concerned about deforestation because it threatens their livelihoods [52]. Forest managers can help to reduce deforestation by improving knowledge of the importance of forests in landscapes. Deforestation can also harm the production, biodiversity, and health of neighboring forests. Forests are both a source of carbon emissions and a carbon sink due to forest fires, the carbon imbalance of old trees, and other non-cleaning forest processes. Forest investment and management of existing forests to address environmental issues are potential carbon-reduction strategies [53–55].

Forests play an important role in the Earth's carbon cycle, storing and releasing this vital element in a dynamic cycle of growth, decay, disturbance, and rejuvenation. Forests have helped to mitigate climate change by absorbing roughly one-quarter of the carbon released by human activities such as fossil fuel combustion. The carbon balance of the Earth is the ratio of CO2 emissions to CO2 uptake by oceans and terrestrial systems. Photosynthesis absorbs carbon from the atmosphere and deposits it in forests. Carbon sequestration refers to the process of carbon absorption and deposition. Since 1970, the net carbon balance has risen from 280 parts per million to more than 390 parts per million [56].

Terrestrial ecosystems are important players in the global carbon cycle. Annually, an estimated 125 Gt of carbon is exchanged between vegetation, soils, and the atmosphere. Forests account for over 80% of this exchange; research suggests that deforestation in the 1980s may have accounted for a quarter of all human carbon emissions.

Carbon is stored in both live and dead biomass, including standing timber, branches, foliage, and roots, as well as litter and woody debris. Any activity that changes the amount of biomass in vegetation and soil has the ability to either absorb carbon from the atmosphere or release carbon into it. CO2 emissions were totaled. Globally, there are approximately 3870 million acres of forest, with over 95% of it being natural. While forest areas in rich countries have stabilized, deforestation in underdeveloped countries has continued. The 2001 edition of The State of the World's Forests highlights two recent causes of forest destruction [57].

The CO2 levels in the atmosphere have risen from 400 parts per million (ppm) for the first time in 55 years of measurements to over 410.79 ppm in the latest CO2 reading [58]. Human activities have emitted almost 400 petagrams of carbon (C) into the atmosphere. Human activities, such as the combustion of fossil fuels and land usage, contribute to the atmospheric CO2 content. Plants and soils retain about 2000 PgC, with forests and forest soils containing 60% of this amount. Changes in human activities could aid in the preservation of forest carbon stores and promote more CO2 uptake and storage [59].

#### **3.2 Forest biodiversity**

The range of living organisms that occupy forests, as well as the ecological responsibilities they play in an ecosystem, is referred to as forest biological diversity. It includes not just trees, but also the numerous plants, animals, microorganisms, and species that live within them. Forest biological diversity can be considered at several levels, including ecosystem, landscape, species, population, and genetic. According to the state of the world's forests 2020, the majority of the Earth's terrestrial biodiversity is found in forests. Forests provide habitat for 80% of amphibian species, 75% of bird species, and 68% of mammalian species. A number of fish and shellfish species use mangroves as breeding grounds and nurseries. They help to collect sediments that would otherwise harm seagrass meadows and coral reefs.

It listed 2.12 million species in the world in 2020. **Figure 3** shows that the number of described species in the world is 105 million insects, over 11,000 birds, over 11,000 reptiles, and over 6000 mammals [60].

The overall variability of life on Earth is characterized as global biodiversity. The current number of species on Earth is estimated to be between 2 million and 1 trillion [61]. Biodiversity has increased and decreased over time for (supposedly) abiotic reasons such as climate change. Biodiversity loss involves both the global extinction of many species and the local decline or loss of species in a specific environment. The latter phenomena can be either temporary or permanent, depending on whether the environmental deterioration that causes the loss is reversible via ecological restoration or ecological resilience or is effectively permanent [62, 63].

#### **3.3 Impacts and changes due to human intervention**

Ecological succession is the relatively predictable shift in forest types over time, typically decades. Environmental factors such as soil type, water regimes, vegetation history, climate, and invasive species all have an impact on succession. All of these characteristics are influenced by humans, yet the relationship between them and humans might be ambiguous.

Forest lands are increasingly under development pressure, which may result in parcelization and fragmentation. When the forest canopy is dissected for houses,

*Impact on Forest and Vegetation Due to Human Interventions DOI: http://dx.doi.org/10.5772/intechopen.105707*

#### **Figure 3.**

*Numbers of described species in the world.*

lawns, roadways, and other infrastructure, this is referred to as fragmentation. The annual net loss of forest area decreased from 7.8 million hectares in the 1990s to 4.7 million hectares from 2010 to 2020 [64]. The presence of more humans in the landscape raises the chance of exotic invasive species spreading. Invasive characteristics in native species can sometimes be promoted. Human impacts on forests have altered key biological traits, allowing species such as deer, Pennsylvania sedge, and ironwood to become invasive at times.

These native species have, in turn, weakened ecological dynamics even further. Although the effects of climate change have been clearly documented, the effects on forests have been more difficult to determine. Predictions of future forest effects are much less trustworthy. Changes in carbon dioxide levels, land use, natural cycles, and other factors all have an impact on climate change. Temperature, precipitation, and extreme events are all showing the consequences.

The best way for forest owners to prepare their woods for change and work with change is to actively manage to lessen environmental stress. Forest management, including timber harvesting, has been shown to increase commodities and services. Management leads to a more resilient and healthier forest.

The increase and contraction of forest cover are erratic. Deserts, farms, and urban areas flow all over the world, and although some countries are rapidly removing trees from their ecosystems, others are increasing their forest cover. Since 1990, the world's forested land area has shrunk by 2 million square miles (3.1 million square kilometers), with the majority of the losses occurring in South America and Sub-Saharan Africa. Human activities have put a significant burden on the Amazon Rainforest, one of the world's most important carbon sinks, in recent decades. Brazil's expanding road network has been critical to economic success, but the landscape has frequently suffered as the country's GDP per capita rises [65].

Deforestation disrupts ecosystems that are essential to both animals and humans. Every year, we take down more than 15 billion trees. Humans have transformed 420 million hectares of wooded land into different uses since 1990. Over

one billion acres of forest have been removed to make space for strip mining, cattle grazing, and industrial sprawl. Animal feces from factory farms pollute the air, water, and land, hastening climate change. More greenhouse gas emissions from industrial agriculture remain in the atmosphere when forests are cut down. Forests operate as a "carbon sink," collecting CO2 and converting it into the oxygen we breathe [66].

During Australia's "Black Summer" season, which began on January 1, 2019, more than 24 million hectares (59 million acres) were burned. Fires raged through forests in Victoria, Queensland, and New South Wales for 8 months. More than 510,000 hectares were burned in one incident (1.26 million acres). The total area burned during the Black Summer is believed to be 24 million hectares (59 million acres), nearly the size of the whole United Kingdom [67].

The main causes of deforestation are forest fire, livestock grazing, commercial agriculture, growing animal feed, excessive use of palm oil, illegal logging, mining extraction, paper production, urbanization, and desertification of land. People who live near woods bear the brunt of deforestation's consequences. Forests are home to millions of wild animal and plant species. When humans destroy trees for short-term economic gain, we endanger our species' long-term survival. Thus, each nation must first protect the natural forests and biodiversity, cope with development in an environmentally friendly manner, mitigate long-term impacts onsite, promote plantation, protect natural habitats, and control environmental pollution.

## **4. Conclusion**

Forest lands are increasingly being pressured for development, which may result in parcelization and fragmentation. Fragmentation occurs when the forest canopy is cut up for houses, lawns, roadways, and other infrastructure. The increased presence of people increases the likelihood of exotic invasive species spreading. Since 1990, the world's forested acreage has shrunk by 2 million square miles (3.1 million square kilometers). Forests act as "carbon sinks," absorbing CO2 and turning it into the oxygen we breathe. More than one billion acres of forest have been cleared to make way for strip mining, cattle grazing, and industrial sprawl.

One of the major contributors to increased greenhouse gas emissions is deforestation. Deforestation is responsible for 60% of forest loss in Latin America and Southeast Asia. Poverty and rapid population expansion are the primary causes of deforestation. Agricultural output is said to be responsible for over 80% of current world deforestation. Forest fragmentation can have a long-term impact on the health and vitality of the forest ecosystem. Human-caused fragmentation was greatest in Europe, whereas it was least in South America. Forest removal, as well as accompanying grazing and mining activities, has exacerbated erosion and landslides in the Dolomites, the Maritime Alps, and the south-central Italian Alps.

Drylands cover around 38% of the Earth's land surface. Much of northern and southern Africa, western North America, Australia, the Middle East, and Central Asia are among them. Land degradation has been noted as a specific threat in India, Pakistan, Zimbabwe, and Mexico. Inadequate forest management is one of the elements contributing to the negative human impact on urban and suburban forests. Pollutants in the atmosphere, as well as emissions from industry and cities (sulfur dioxide, ozone, nitrogen oxides, and particulate matter PM10 and PM2.5), all contribute to environmental degradation.

#### *Impact on Forest and Vegetation Due to Human Interventions DOI: http://dx.doi.org/10.5772/intechopen.105707*

Biodiversity is a valuable resource on the planet, but the globe is experiencing a decline in biodiversity. Biodiversity research in areas where humans live, work, and extract resources may contribute to the formulation of sensible policy. However, research should cover important topics, and study topic biases should not result in evidence gaps. Extinction and speciation have an impact on global biodiversity. Mammal species, for example, have a mean life span of 1 million years. Biodiversity has increased and decreased over time for (supposedly) abiotic reasons.

The primary causes of global deforestation are logging, shifting agriculture, agricultural expansion, and urbanization. To reverse deforestation and biodiversity loss, we must alter our food systems. Agribusinesses must follow through on their commitments to deforestation-free commodity chains. People who live near woodlands bear the brunt of the repercussions of deforestation. Millions of wild animals and plant species live in forests. When humans damage trees for short-term economic benefit, we threaten the long-term existence of our species. Each country must first safeguard its natural forests and wildlife.
