Student of sciences botany department. From gujranwala, Pakistan
Climate is constantly changing from the time since plants evolved and it will continue to change. The emission of greenhouse gases, and anthropogenic activities are the main reason for adversely changing climate. CO2 concentration and temperature are increasing day by day, and these factors affect the plants, animals, and even the whole ecosystem in different ways. The changing temperature has an impact on community-level dynamics by making mismatches in community interaction, altering the species survival rate, and shifting species distribution. The plant requires less water for photosynthesis when CO2 concentration increases and longer and warmer growing seasons, overtake the closing of stomata. So, this means increased plant growth will consume more water from the soil, a net result of drier land. The Mediterranean-type ecosystem is at great risk because they are more sensitive to changes that are brought about by global warming.
Climate change and its effects on community structure
For more than two centuries, the concentration of CO2 has been increasing gradually. This increasing atmospheric CO2 concentration affects the photosynthesis process of the plant, which improves the rate of photosynthesis, and water use efficiency, and increases plant growth. Leaf stomatal conductance to water vapor decreases by an increase in CO2 concentration which reduces the transpiration rate, this increases the soil moisture content. Different plants show different responses to the increased concentration of CO2 depending on the environment. According to the studies, C3 plants show an increased photosynthetic rate when CO2 is doubled but not in C4 plants. C4 plants can survive better than C3 plants in a drought. Due to increased atmospheric CO2, the production of grasses increases because the habitats migrate to other areas to compensate for temperature shifts. It also acidifies the ocean and is a threat to marine life.
With the increase in temperature, the physiological processes of the plant also increase depending on the plant type, such as photosynthesis. An increase in the chemical reactions results in this increase in the photosynthetic rate and many other physiological processes. Enzymatic activities also doubled at every 10°C rise in temperature. Beyond a limit this rise in temperature is harmful to the plant, sometimes, is the main cause of higher desiccation rate.
The main reason for raising the temperature is the emission of greenhouse gases and the burning of fossil fuels. This emission is increasing day by day which results in increasing the temperature of the Earth. Earth’s temperature is 1.1°C higher than it was in the past (the 1800s). Raising temperature causes earlier bloom in plants resulting in mismatched timing between plants and pollinators. With warmer conditions pests and pathogens become more active. Due to climate change, the prolonged season of pests increases their population in this way there is an increased threat to their targeted species. Increased temperature beyond optimal limits decreases the grain yield, reproductive processes, pollination, and plant growth. In yield growth of crops e.g., soybean, corn, and cotton increases when the temperature is up from 29 to 32°C and yield decreases when the temperature increases to this limit. Raised temperature increases the sea level by about 0.12 per year. This sea raise is the main cause of floods, tsunamis, and cyclones which cause massive destruction. Drought, flooding, the decline in biodiversity, severe fire, and melting polar ice are the results of climate change. Heatwaves and longer droughts will stress the plant and made them less productive.
The distribution of plants in an area is determined by the water supply in that area. Precipitation change is considered to be less constant than temperature. Precipitation change is more variable between regions, with the calculation of some areas to be much drier and some much wetter. If soil moisture decreases it will have negative effects on the growth of plants, and change the community structure and dynamics of the ecosystem as well. Drought conditions leave tree communities and many plants defenseless to fire, in these conditions rate of survival lessens and declines the biodiversity.
There will be changes in the distribution of the species if the climatic factors exceed the limit of species phenotypic plasticity. When environmental conditions required by some plants such as alpine regions may vanish, these results will in rising in extinction risk. The extinction of species can be very dangerous for humans because plants will stop providing their services. Wintering and breeding ground of birds can also be affected by climate changes, birds use this area to recharge and feed themselves after long migrating hours. If these areas are affected by climate, this will affect the birds too. During the last glacial period, lowland communities and forests become smaller and these smaller areas become islands (made up of drought resisting plants and many shade-loving plants). Climate change also results in changes in community composition.
Change in the environmental factors changes the life cycle events, such as flowering is related to temperature. Confusing causes due to climate changes will result in the extinction of both pollinators and plant populations. British flowers have changed their flowering time, insect-pollinated plants flower before wind-pollinated plants, and annual plants earlier than the perennial plants.
Climatic changes cause an increase in phenotypic plasticity and species to change rapidly as it was expected. Due to an increase in the genetic bottleneck, genetic diversity decreases drastically. A decrease in species richness and genetic mutation boosts the option of extinction.
Change in plant distribution occurs due to changes in symbiotic fungi associated with plant root which is affected by climatic changes.
Grasses spread in the areas, by shifting the fire in this way changes species composition.
Raised temperature enables the herbivores to move in alpine regions, thus affecting the composition of that area.
Through the above discussion, one can conclude that climate change is a factual threat to our time. It is caused by human activities and has drastic effects on the whole community structure. Food insecurity, natural disasters and extreme weather, high temperature, increased concentration of CO2, excessively affect the most vulnerable species those who are least responsible for it. National and international actions and policies are required to address global warming and tackle climate change. But communities, households, and individuals have a vital role to play too.
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