Ecosystem services
An ecosystem consists of a community of living organisms interacting with one another and with their physical environment. These interactions involve biological components, such as plants, animals, and microorganisms, as well as physical characteristics, including temperature, water availability, sunlight, and soil conditions.
Climate change is affecting ecosystems across the planet. This affects everything from the availability of water to the distribution of plant and animal species. As temperatures rise and precipitation patterns change, how ecosystems respond to environmental conditions may differ (possibly substantially) from those under which they developed. Therefore, understanding how ecosystems function, how they respond to disturbances, and how they can adapt to a changing climate is essential for managing natural resources in the decades ahead.
Ecosystems provide numerous benefits that support human life and economic activity. These benefits, commonly called ecosystem services, generally fall into four categories: provisioning, regulating, supporting, and cultural.
Provisioning services include the production of food, freshwater, timber, and other natural resources.
Regulating services involve natural processes that influence climate, water quality, flooding, and disease.
Supporting services include nutrient cycling, pollination, and other ecological processes that sustain life.
Cultural services encompass recreation, tourism, spiritual connections, and the cultural significance of natural environments.
An example of a coastal marine ecosystem is shown below in Figure 1. Wetlands and coastal vegetation can filter water, store carbon, and reduce the impacts of waves and coastal flooding. At the same time, these environments support fisheries, tourism, recreational activities, and biodiversity.
Figure 1. Example of coastal ecosystem services
Net primary productivity
Many cosystems are critical for keeping the Earth's carbon balance in check because of something called net primary productivity (NPP).
Figure 2. Net primary productivity
We can think of this like a paycheck. There are your earnings- the gross primary productivity (GPP) from photosynthesis- and there are the taxes (respiration). During optimal growing conditions the GPP is high and R is is much lower. When plants become more stressed the respiration can exceed the GPP for days to weeks. When this occurs NPP will become much lower. Semi-arid/arid ecosystems tend to have much lower NPP than areas with more precipitation.
Figure 3. Spatial map of NPP
Rainforests tend to have the highest rates of NPP, though our croplands and grasslands can also have reasonably high NPP. Forest clearing in Africa and especially the Amazon was significant in much of the last part of the 20th century and has continued in spurts in the 21st century. The Amazon Rainforest has often been called "the lungs" of our planet because of the carbon sequestration and oxygen the plants release. Slashing and burning of the forest means that stored carbon is released into the atmosphere, furthering the greenhouse effect. Much of this shift has been due to agricultural conversion (crops/pasture) as the land is very fertile for a little while after its cleared.
Figure 4. Drivers of forest loss in the modern era
Closer to home, warmer temperatures and increased precipitation has led to more favorable conditions for Eastern Red Cedar to spread through the prairies. These trees are an issue because they reduce forage (bad for cattle or bison) and they reduce surface water and can also reduce groundwater levels. The map in Figure 5 shows how far north and west the Eastern Red Cedar invasion got during the first twenty years of the 21st century. These trees also increase the risk of larger and more destructive wildfires on the Great Plains.
Figure 5. Map of Eastern Redar Cedar density in 2018 compared to 2000.
