Sustainable Forest Management in a Changing Climate
Find out why Earthwatch is supporting forest research and how it will help to tackle climate change.
The Importance of Forests
Billions of people around the world rely on trees and forests for food, shelter, fuel, medicines, stable soils, clean air and fresh water. Forests harbour more species than any other terrestrial habitat, safeguarding the world's biological heritage. Forests are integral components of many landscapes, and play a central role in the cultural fabric of diverse societies. In recent years, the role of forests in capturing and storing carbon dioxide emissions from human activities has come to the fore. Carbon emissions from the destruction of forests and the burning of fossil fuels are contributing to global warming and associated changes in the world's climate.
Forests and Climate Change
Climate change will affect forests, and the multitude of services they provide, in many ways.
Both climate and forests are highly complex systems whose behaviour and interactions are difficult to predict. However, several lines of evidence, including reconstructions of past climates using tree pollen in lake sediments, experiments on tree seedlings in the laboratory, and monitoring of forest ecosystems, allow us to make tentative predictions of the changes we can expect to see, even within our own lifetimes.
Forests hold more carbon in trees and soils than any other terrestrial habitat. Climate change and elevated carbon dioxide in the atmosphere will increase the growth of trees that live in colder climates, thereby capturing more carbon. However, climate change will also increase the activity of the bacteria and fungi that break down carbon compounds stored in forest soils, releasing carbon dioxide back into the atmosphere. If decomposition outpaces tree growth, then these forests will paradoxically increase the carbon dioxide concentration of the atmosphere.
The warm tropical forests of the world also remove carbon dioxide from the atmosphere, but logging can increase forest susceptibility to the droughts that are expected to become more frequent in many regions under climate change. Droughts make forests flammable, and large areas of tropical forests have burned during droughts in recent years. More subtle perturbations of the ecological interactions among trees, herbivores, predators, parasites and diseases are also likely to alter the structure and functioning of the world's forests.
People and Forests
Increased susceptibility to fire of logged tropical forests illustrates the importance of humans in determining the fate of ecosystems under climate change.
Most, if not all, forests are in some way affected by the actions of humans. This is obvious in plantations that provide wood for paper and timber, or in agricultural landscapes where trees provide additional food and shelter for livestock.
The vast, isolated forests of northern Canada and Siberia, or the deep jungles of South America, would seem to be a pristine wilderness untouched by humans. However, fur trappers and hunters have long gathered their quarry in the cold north, while soil pits in the Amazon Basin reveal charcoal and potsherds that hint at the large indigenous populations supported there, prior to the arrival of the Europeans. Reconstructions show that forest composition and location changed dramatically with climatic fluctuations during the Ice Ages, as seeds germinated in areas that became suitable, and trees died where local climates were no longer able to support them. We can therefore expect similar migrations in the future.
In southern England, beech trees are expected to decline due to drought, while mediterranean species could thrive. An important difference between the present and the past is the impact of human populations. People now use large areas of land for agriculture and could prevent the climate change-driven migration of trees, and the many other species that trees support.
It is therefore clear that any study of the impacts of climate change on the services provided by trees and forests must consider the people who use and manage these resources. The main goal of the Regional Climate Centres is to help find methods of managing forests that will maximize the benefits we derive from them into the future, the type of management under consideration is dependent upon the history of the forest in question.