Effect of climate change on plant biodiversity

Environmental conditions play a key role in defining the function and distribution

Range (biology)

In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...

of plants, in combination with other factors. Changes in long term environmental conditions that can be collectively coined climate change

Climate change

Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

are known to have had enormous impacts on plant diversity patterns in the past and are seen as having significant current impacts. It is predicted that climate change will remain one of the major drivers of biodiversity

Biodiversity

Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

patterns in the future.

Palaeo context

The Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

has experienced a constantly changing climate

Climate

Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...

in the time since plants first evolved. In comparison to the present day, this history has seen Earth as cooler, warmer, drier and wetter, and CO₂ (carbon dioxide

Carbon dioxide

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

) concentrations have been both higher and lower. These changes have been reflected by constantly shifting vegetation

Vegetation

Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...

, for example forest

Forest

A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

communities dominating most areas in interglacial

Interglacial

An Interglacial period is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age...

periods, and herbaceous

Herbaceous plant

A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...

communities dominating during glacial periods. It is has been shown that past climatic change has been a major driver of the processes of speciation

Speciation

Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...

and extinction

Extinction

In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

. The best known example of this is the Carboniferous Rainforest Collapse

Carboniferous Rainforest Collapse

The Carboniferous Rainforest Collapse was an extinction event that occurred around 305 million years ago in the Carboniferous period). Vast coal forests covered the equatorial region of Euramerica...

which occurred 350 million years ago. This event decimated amphibian populations and spurred on the evolution of reptiles.

Modern Context

There is significant current interest and research focus on the phenomenon of recent anthropogenic climate changes, or global warming

Global warming

Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

. Focus is on identifying the current impacts of climate change on biodiversity, and predicting these effects into the future.

Changing climatic variables relevant to the function and distribution of plants include increasing CO₂ concentrations, increasing global temperatures, altered precipitation

Precipitation (meteorology)

In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...

patterns, and changes in the pattern of ‘extreme’ weather events such as cyclones, fires or storms.

Because individual plants and therefore species can only function physiologically

Plant physiology

Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology , plant ecology , phytochemistry , cell biology, and molecular biology.Fundamental processes such as photosynthesis, respiration, plant nutrition,...

, and successfully complete their life cycles under specific environmental conditions (ideally within a subset of these), changes to climate are likely to have significant impacts on plants from the level of the individual right through to the level of the ecosystem or biome

Biome

Biomes are climatically and geographically defined as similar climatic conditions on the Earth, such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems. Some parts of the earth have more or less the same kind of abiotic and biotic factors spread over a...

Effects of CO₂

Increases in atmospheric CO₂ concentration for affect how plants photosynthesis

Photosynthesis

Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...

e, resulting in increases in plant water use efficiency, enhanced photosynthetic capacity and increased growth. Increased CO₂ has been implicated in ‘vegetation thickening’ which affects plant community

Community (ecology)

In ecology, a community is an assemblage of two or more populations of different species occupying the same geographical area. The term community has a variety of uses...

structure and function. Depending on environment, there are differential responses to elevated atmospheric CO₂ between major ‘functional types’ of plant, such as and

C4 carbon fixation

C4 carbon fixation is one of three biochemical mechanisms, along with and CAM photosynthesis, used in carbon fixation. It is named for the 4-carbon molecule present in the first product of carbon fixation in these plants, in contrast to the 3-carbon molecule products in plants. fixation is an...

plants, or more or less woody species; which has the potential among other things to alter competition between these groups. Increased CO₂ can also lead to increased Carbon : Nitrogen ratios

Carbon to nitrogen ratio

The C/N ratio or carbon-to-nitrogen ratio is a ratio of the mass of carbon to the mass of nitrogen in a substance. It can, amongst other things, be used in analysing sediments and compost...

in the leaves of plants or in other aspects of leaf chemistry, possibly changing herbivore

Herbivore

Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...

nutrition.

Effects of temperature

Increases in temperature raise the rate of many physiological processes such as photosynthesis in plants, to an upper limit. Extreme temperatures can be harmful when beyond the physiological limits of a plant.

Effects of water

As water supply is critical for plant growth, it plays a key role in determining the distribution of plants. Changes in precipitation

Precipitation (meteorology)

are predicted to be less consistent than for temperature and more variable between regions, with predictions for some areas to become much wetter, and some much drier.

General effects

Environmental variables will not act in isolation, but also in combination with one other, and with other pressures such as habitat

Habitat

* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

degradation and loss or the introduction of exotic species. It is suggested that that these other drivers of biodiversity change will act in synergy with climate change to increase the pressure on species to survive.

Changes in distributions

If climatic factors such as temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

and precipitation

Precipitation (meteorology)

change in a region beyond the tolerance of a species phenotypic plasticity

Phenotypic plasticity

Phenotypic plasticity is the ability of an organism to change its phenotype in response to changes in the environment. Such plasticity in some cases expresses as several highly morphologically distinct results; in other cases, a continuous norm of reaction describes the functional interrelationship...

, then distribution changes of the species may be inevitable. There is already strong evidence that plant species are shifting their ranges in altitude and latitude as a response to changing regional climates.

When compared to the reported past migration rates of plant species, the rapid pace of current change has the potential to not only alter species distributions, but also render many species as unable to follow the climate to which they are adapted. The environmental conditions required by some species, such as those in alpine regions may disappear altogether. The result of these changes is likely to be a rapid increase in extinction risk. Adaptation

Adaptation

An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....

to new conditions may also be of great importance in the response of plants.

Predicting the extinction risk of plant species is not easy however. Estimations from particular periods of rapid climatic change in the past have shown relatively little species extinction in some regions, for example. Knowledge of how species may adapt or persist in the face of rapid change is still relatively limited.

Changes in the suitability of a habitat for a species drive distributional changes by not only changing the area that a species can physiologically tolerate, but how effectively it can compete with other plants within this area. Changes in community composition are therefore also an expected product of climate change.

Changes in life-cycles (phenology)

The timing of phenological

Phenology

Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate...

events such as flowering are often related to environmental variables such as temperature. Changing environments are therefore expected to lead to changes in life cycle events, and these have been recorded for many species of plants. These changes have the potential to lead to the asynchrony between species, or to change competition between plants. Flowering times in British plants for example have changed, leading to annual plants flowering earlier than perennials, and insect pollinated plants flowering earlier than wind pollinated plants; with potential ecological consequences. A recently published study has used data recorded by the writer and naturalist Henry David Thoreau

Henry David Thoreau

Henry David Thoreau was an American author, poet, philosopher, abolitionist, naturalist, tax resister, development critic, surveyor, historian, and leading transcendentalist...

to confirm effects of climate change on the phenology of some species in the area of Concord, Massachusetts

Massachusetts

The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...

Indirect impacts of climate change

All species are likely to be not only directly impacted by the changes in environmental conditions discussed above, but also indirectly through their interactions with other species. While direct impacts may be easier to predict and conceptualise, it is likely that indirect impacts are be equally important in determining the response of plants to climate change.

A species whose distribution changes as a direct result of climate change may ‘invade’ the range of another species for example, introducing a new competitive relationship.

The range of a symbiotic fungi associated with plant roots may directly change as a result of altered climate, resulting in a change in the plants distribution.

A new grass may spread into a region, altering the fire regime and greatly changing the species composition.

A pathogen or parasite may change its interactions with a plant, such as a pathogenic fungus becoming more common in an area where rainfall increases.

Increased temperatures may allow herbivores to expand further into alpine regions, significant impacting the composition of alpine herbfield

Herbfield

Herbfields are plant communities dominated by herbaceous plants, especially forbs and grasses. They are found where climatic conditions do not allow large woody plants to grow, such as in subantarctic and alpine tundra environments...

s.

There are innumerable examples of how climate change could indirectly affect plant species, most of which will be extremely difficult to predict.

Higher level changes

Species respond in very different ways to climate change. Variation in the distribution, phenology and abundance of species will lead to inevitable changes in the relative abundance of species and their interactions. These changes will flow on to affect the structure and function of ecosystems.

Challenges of modelling future impacts

Accurate predictions of the future impacts of climate change on plant diversity are critical to the development of conservation strategies. These predictions have come largely from bioinformatic strategies, involving modelling individual species, groups of species such as ‘functional types’, communities, ecosystems or biomes. They can also involve modelling species observed environmental niches

Ecological niche

In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...

, or observed physiological processes.

Although useful, modelling has many limitations. Firstly, there is uncertainty about the future levels of greenhouse gas emissions driving climate change and considerable uncertainty in modelling

Global climate model

A General Circulation Model is a mathematical model of the general circulation of a planetary atmosphere or ocean and based on the Navier–Stokes equations on a rotating sphere with thermodynamic terms for various energy sources . These equations are the basis for complex computer programs commonly...

how this will affect other aspects of climate such as local rainfall or temperatures. For most species the importance of specific climatic variables in defining distribution (e.g. minimum rainfall or maximum temperature) is unknown. It is also difficult to know which aspects of a particular climatic variable are most biologically relevant, such as average vs. maximum or minimum temperatures. Ecological processes such as interactions between species and dispersal rates and distances are also inherently complex, further complicating predictions.

Improvement of models is an active area of research, with new models attempting to take factors such as life-history traits of species or processes such as migration into account when predicting distribution changes; though possible trade-offs between regional accuracy and generality are recognised.

Climate change is also predicted to interact with other drivers of biodiversity change such as habitat destruction and fragmentation, or the introduction of foreign species. These threats may possibly act in synergy

Synergy

Synergy may be defined as two or more things functioning together to produce a result not independently obtainable.The term synergy comes from the Greek word from , , meaning "working together".-Definitions and usages:...

to increase extinction risk from that seen in periods of rapid climate change in the past.

External links

(2008) Government report on the effects of climate change on agriculture, land resources, water resources, and biodiversity in the United States.
(2003) Summary report from an international conference on Global Climate Change and Biodiversity.
(2008) Discussion on the future of modeling climate change impacts on plant species distributions.
(2005) The Millennium Ecosystem Assessment, including discussion of the effects of climate change on biodiversity
Global Change Biology - a scientific journal with articles relating to the interaction between global changes such as climate, and biological systems
(2011) After the birds vanish, the plants are next to go - New Scientist
New Scientist
New Scientist is a weekly non-peer-reviewed English-language international science magazine, which since 1996 has also run a website, covering recent developments in science and technology for a general audience. Founded in 1956, it is published by Reed Business Information Ltd, a subsidiary of...

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Palaeo context

Modern Context

Effects of CO2

Effects of temperature

Effects of water

General effects

Changes in distributions

Changes in life-cycles (phenology)

Indirect impacts of climate change

Higher level changes

Challenges of modelling future impacts

See also

External links

Effects of CO₂