Fire effect on habitats

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Introduction

There is no doubt that fire is the most important factor among the natural and human factors that affect the wildlife resource safety. Fire is not only sudden and extensive but also harmful to wildlife habitat. The fire has a destructive impact on the wildlife environment such as the forest. The effect of fire on animals is mainly manifested in two aspects: direct and indirect effects. The direct effects are mainly in burns and deaths, while the more profound effects are indirect effects. The indirect effects are mainly through the effects of vegetation, physical and chemical properties of soil, and so on, to change the habitat of animals and act indirectly on living things. Thus, affecting the species and number of animals. The following essay will examine fire effect on habitats in forms of the soil microorganism, perennial trees, water environment, water environment and so on to take a further look at the profound extent.

Fire intensity on soil microorganism

The number of microorganisms in the woodland after fire was obviously higher than that in the unburned forest land, and the proportion of bacteria increased obviously, while the proportion of fungi and actinomycetes decreased obviously. The analysis of soil microbial communities in the severe fire, moderate burning and unfired samples of Larix gmelinii in 2003 and other similar examples demonstrated that there were significant differences between soil nutrients and soil moisture in the burning slash, soil microbial biomass, microbial metabolism and utilization of carbon resources in the burned slash (Reinhart et al., 2016). There was no significant difference in soil microbial community structure between fire samples and control groups, but there was no significant difference in soil microbial carbon and nitrogen ratio and diversity index. That is to say, high intensity fire reduced species richness, species dominance, and community evenness index. Generally speaking, the maximum limit temperature of fungus growth is 105 ℃, while the high temperature of burning is 800 ℃ (Chen et al., 2008). Therefore, the number of bacteria, fungi and actinomycetes decreased in the year of high intensity burning. Fungi than bacteria, actinomycetes acid resistance. After high intensity burning, the above-ground fungi proliferate in large numbers. After moderate intensity burning, the number of bacterial fungi and actinomycetes in the field showed an increasing trend, but the number of these three groups decreased after a period of time after the fire, because, the pH of most fungi adapted to life was 5 ~ 9, but the soil pH was less than 4 during this period, so the soil pH decreased. After low intensity burning, the above ground porosity increased, while fungi and actinomycetes belonged to aerobic bacteria, and bacteria belonged to anaerobic bacteria. Therefore, the number of fungi and actinomycetes increased and the number of bacteria decreased (Wang et al., 2014). The influence of forest fire on microbes was unforeseeable, but it was sure that high intensity fire had fatal effects on soil microbes, and the low medium intensity changed the soil environment, and the change of microorganism was not obvious.

Fire effect on perennial trees

Forest, as one of the most important habitats for animals, becomes increasingly irreplaceable for its important function. At the same time, perennial trees play an important role in maintaining the function of the forest. Once fire happens in the forest, trees will be directly affected. The growth cycle of trees is long, and it usually takes decades to grow into big trees, some even hundreds of years. Once burned by fire, it is difficult to recover in a short time. When trees are burned down, the ability of forests to produce oxygen will be greatly weakened. If there is a large-scale forest fire, the air oxygen content and negative ion content in this area will be greatly reduced. Vegetation changes in the forest land after the fire, due to the death of the tree layer, the ecological environment changes sharply and will destroy the ecological balance (Luis, Martín De et al., 2004). The composition, coverage, and height of the ground cover change accordingly. Furthermore, the general trend produces against the context is the increase and development of light and drought tolerant species.

The vegetation types, height, and density will be affected to a certain extent. For birds, their nesting periods may also be influenced in forms of the length of the period. The nesting period may be longer or later than expected. Because of the change of planting environment, some animals are unable to defend themselves against predators and their living conditions are threatened.

In mild and partial moderate burning forest land, the change of living floor layer is less obvious than that of heavy burning forest land because the change of Arbor layer is not obvious. After the forest fire, perennial trees were burned and the ecological balance that had been formed for many years was destroyed. For instance, due to the reason that trees absorb most of the sun and nutrients, the growth of low shrubs and vines is inhibited, and a well-structured and the well-functioning ecological harmonious forest is formed (O'Dea et al., 2003). Yet the tall trees have been destroyed, the shrubs and vines that have lost their control have grown wildly, and the sun, water, and nutrients have been seized, making it difficult for other plants to survive. In 1987 the Great Xing' a Mountains fire destroyed all the coniferous trees on a hillside. Nearly thirty years have passed since the fire, and the trees that sprouted after the fire were surrounded by shrubs and by the twining of vines. The original ecological environment has been destroyed and many of the animals that used to live here have long disappeared. It has become a paradise for forestry pests such as rats. Without artificial cultivation, it is estimated that it will take at least a hundred years to restore the function of the forest, and it may take hundreds of years to restore the forest completely.

Fire effect on the water environment

It is beyond denying that after a severe fire, some forest burning ash will flow into the river and accordingly bring serious pollution to the water environment, threaten the survival and safety of aquatic organisms, and destroy the ecological balance of aquatic organisms. Moreover, the destruction of water environment turns in the shape of soil erosion. After the forest fire, for the reason that the vegetation is destroyed in a large area, the function of sand fixation and water conservation is decreased, when there is heavy rain (Amirbahman et al., 2004). Under the circumstance, it is easy to form soil and water loss, and even debris flow and other serious natural disasters may occur. Soil erosion is one of the important symbols of the regional ecological environment. Fire results in vegetation destruction and soil erosion, surface runoff is easy to occur after precipitation, erosion of the surface is aggravated, soil fertility decreases, soil layer becomes thinner, soil moisture evaporates strongly, surface wind increases, and local microclimate changes. Caused by drought and flood.

Fire effect on the change of physical and chemical properties of soil

The changes of meteorology and vegetation caused by fire have a certain effect on the physical and chemical properties of soil water, fertilizer, gas, and heat. Fire reduces forest leaf area, thus reducing canopy transpiration and water loss. Where all vegetation is burned, the soil gets wet and even marsh. From the external characteristics, the residual carbon debris and ash, except part of surface runoff loss, have begun to decompose and infiltrate into the soil layer. Fire increases the temperature of the soil and decreases the frozen layer. After the fire, the black soil surface can increase the absorption of solar energy and the decrease of soil surface organic matter, which can promote the heat conduction into the mineral soil layer. Land the increase of temperature is beneficial to the decomposition of litter, can improve soil fertility, promote the germination of reproductive bodies and increase the food and nutritional value of herbivores (Chen et al., 2010). Because of the change of the surface environment and the change of the water and heat conditions, the organic matter of the burning forest land is lower than that of the unburned forest land, which is favorable to the decomposition of organic matter. At the same time, because of the vigorous activity of aerobic microbes, the mineralizing of soil organic matter was accelerated, and the upper soil nutrients, such as total nitrogen and available nutrients, were increased, which made some nutrient elements become easily absorbed by plants.

Fire effects on regional climate

In the short term, the temperature of local or small environment can be increased greatly, the wind force increases, the temperature difference between day and night intensifies, and the frost-free period is also prolonged. From the point of view of annual precipitation, precipitation in fire area decreases evaporation increases and relative humidity decreases (Costanza et al., 2011).

The fire effect on animals

There are two situations in which fire affects animals, the direct effects of combustion and the indirect effects of changing the habitat of animals. The direct effect of fire on animals is to make the cave anoxic or diffuse into harmful gases and kill the animals (Vogl, 1973). The indirect effect of fire on animals is that fire changes the environment and changes the species, abundance, and reproduction of animals. The inlay distribution of the aged and young vegetation will be formed when the fire intensity is different from the forest area, thus increasing the diversity of fauna. On the contrary, the vegetation is completely burned out or a large area of dense forest area, the animal diversity is not high. Fire heats the soil, decreases the permafrost, and broad-leaved trees replace conifers, thus improving plant and animal nutrition. Changes in the food sources of wild animals will affect their species after fire.

The fire effect of the area and scope of the habitat

The area and scope of the habitat will be under great impact from the fire. There is no doubt that the most intuitive impact of fire on the habitat is the reduction of the area whose reduction mainly depends on the severity degree and extent of the fire. In the wildlife environment, the size of the habitat is basically the size of all the individuals in the group (Siahmansour, 2013). Due to the sudden reduction of habitat, some animals are forced to find other habitats. In the case of red-crowned cranes, in the Zhalong protection area in China, the red-crowned cranes are forced to look for other nest sites for which their best choice is the remainder of the reed with a height of more than 1.5m. The fire has great influence on the nesting environment, nest site selection, nest material and other factors of the red-crowned crane. The height of the remaining Reed area around the nest is the main factor in the selection of the nest site of the red-crowned crane, and the second factor is the vegetation type. The fire affected the initial nesting period of the red-crowned crane, and the nesting period of the red-crowned crane was delayed by 4 ~ 5 days compared with the normal year. In addition, the nest distance of the red crowned crane is affected by the fire. The distance from human disturbance and burning ground is reduced by nearly 20%.

Conclusion:

In conclusion, the fire will destroy the ecological balance, causes soil erosion, changes the surface vegetation, and results in the degradation of the forest ecosystem, especially biological community. Due to the destruction of wildlife habitat and the ecological environment caused by fire, the impact on human life and property and the sustainable development of the social economy is extremely serious. It is very urgent to figure out ways to protect wildlife habitat against fire and other natural disasters. Fire prevention should arouse the general concern of the whole society.

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