Weather, climate, vegetation and soil

FOCUS QUESTIONS: How does the climate impact the ecosystem?

For the last lesson, we learnt that life forms in ecosystems compete with one another to become the most successful at reproducing and surviving in each niche, or environment.

Two main components exist in an ecosystem: abiotic and biotic.

ABIOTIC COMPONENTS

The non-living or physico-chemical factors like:

Air

Soil

Water

The basic compounds and elements of the environment.

ABIOTIC FACTORS

Classified broadly under three categories:

Climatic factors, including the climatic regime with physical factors in the environment, such as light, atmospheric temperature, wind, humidity

Edaphic factors, which relate to the composition and structure of the soil like its chemical and physical properties – like the soil type, soil profile, organic matter, minerals, soil water, and soil organisms.

Inorganic substances like water, carbon, sulphur, nitrogen, phosphorus, and so on. Organic substances like proteins, lipids, carbohydrates, humic substances etc.

BIOTIC COMPONENTS

Consists of the living parts of the environment.

The populations are those of: The animal community The plant community

The microbial community.

The biotic community is divided into autotrophs saprotrophs heterotrophs.

Autotrophs are called producers, transducers or convertors as well. Autortophs form the core of all biotic systems.

Now, climate is an important environmental influence on ecosystems. So let’s look closer.

Changing climate affects ecosystems in a variety of ways

Warming may force species to migrate to higher latitudes or higher elevations where temperatures are more conducive to their survival.

As sea level rises, saltwater intrusion into a freshwater system may force some key species to relocate or die, thus removing predators or prey that are critical in the existing food chain.

The two most important climatic factors for ecosystems are sunlight and water.

SUNLIGHT

Is necessary for plants to grow. To provide energy to warm the earth’s atmosphere.

Light intensity controls plant growth. Light duration affects plant flowering and animal/insect habits.

All living organisms require some amount of water.

Organisms in dry ecosystems are adapted to the conditions by storing water for use over long periods or becoming less active. At the other extreme, some plants and animals only survive by being submersed in water.

In the last 100 years:

Average global temperature has increased by 0.740C

Rainfall patterns have changed. The frequency of extreme events has increased.

Change has not been uniform on either a spatial or temporal scale, and the range of change, in terms of climate and weather, has also been variable.

Change in climate has consequences on the biophysical environment, such as Changes in the start and length of the seasons.

Glacial retreat. Decrease in Arctic sea ice extent. A rise in sea level.

These changes have already had an observable impact on:

1. Biodiversity at the species level, in term of Phenology

Distribution & populations

2. Ecosystem level, in terms of Distribution Composition & function.

Many changes have been reported in the distribution of species.

In general, many species have expanded their ranges:

Poleward in latitude

Upward in elevation.

Populations of many species have declined, and although in some cases climate change is believed to have contributed to the decline, attributing this is fraught with difficulty, as it is likely to be only one driver among many.

At the species level, changes observed that can be attributed to climate change involve those surrounding phenology (the timing of events).

Many birds and insects are showing changes:

Earlier onset of migration. Egg-laying.

Breeding.

In terms of ecosystems, there has been some evidence on changes in distribution. Desert ecosystems have expanded. Tree lines in mountain systems have changed.

Changes in the composition of ecosystems have also been observed increased lianas in tropical forest.

These changes may affect ecosystem function and the ecosystem services they provide.

Changes in biodiversity and ecosystem services due to climate change are not all negative, with some species either thriving or adapting.

Future projected changes in climate are much larger.

Approximately 10% of species assessed so far will be at an increasingly high risk of extinction for every 10C rise in global mean temperature.

Aquatic freshwater habitats and wetlands, mangroves, coral reefs, arctic and alpine ecosystems, and cloud forests are particularly vulnerable to the impacts of climate change.

Montane species and endemic species have been identified as being particularly vulnerable because of narrow geographic and climatic ranges, limited dispersal opportunities, and the degree of non-climatic pressures.

Potential impacts of climate change on genetic diversity are little understood, though it is thought that genetic diversity will increase the resilience of species to climate change.

Studying the potential impact of climate change on species indicates: Poleward shifts.

Changes in altitude.

Range expansions or contractions corroborating the current evidence in the most part.

The studies highlight the individualistic nature of species’ responses to climate change, which is likely to have a large impact on Future composition of ecosystems. Structure of ecosystems that may also change.

The ecosystem functions.

IN SUMMARY

Climate change is altering the pattern of life on the planet, causing widespread species extinction, migration and behaviour changes.

A changing climate forces plants and animals to migrate in order to survive.

Most plant species can migrate at only 1/10th of the speed required to keep up with human-induced climate change. Send questions and comments to kerryann.hepburn@gleanerjm.com