The environmental adaptability of natural vegetation in arid desert areas is urgent!

Camel thorn is a legume family, and camel thorn is a deciduous shrub. The branches are prickly, the leaves are oblong, the flowers are pink, they bloom in June, they are the most blooming in August, each flower can be open for more than 20 days, bearing pods, racemes, and the root system is generally up to 20 meters. Drawing groundwater and nutrients from the desert and deep Gobi, it is a naturally growing, drought-tolerant plant that can be found throughout Xinjiang.

Camel spines have two kinds of nectar glands inside and outside the flower, and the nectar glands outside the flower secrete and coagulate into sugar grains, called spiny sugar, and the group yield can reach 30-40 kg. Camel thorn is the grass of camels, so it is also called camel grass, which is a dwarf surface plant. At the foot of the majestic Qilian Mountains, on the vast Gobi Desert, there is a unique plant in the northwest inland - camel thorn, no matter how harsh the ecosystem and survival environment, this deciduous shrub can tenaciously survive and expand its sphere of influence.

You don't see it in the endless Gobi Desert, in an environment where aspen can't survive, only clusters of camel thorns show the vitality of life in the sun.

Populus euphratica has a special ability to survive. Its roots can penetrate into the formation below 10 meters to absorb groundwater, and it can also store a large amount of water in its body, which can prevent drought. The cells of Populus euphratica have special functions and are not harmed by alkaline water; The concentration of cell fluid is very high, and it can continuously draw water and nutrients from groundwater containing saline.

When the branches of the poplar are broken, the sap that flows out of the fracture evaporates, leaving alkaloids. In addition to eating, pocypine can also be used to make soap or to make tanning. People use Populus euphratica to produce alkali, and a large poplar tree can produce dozens of catties of alkali a year.

The short-lived chrysanthemum is one of the shortest-lived plants in the world, and it has a lifespan of less than a month. This habit is the result of its adaptation to a special living environment. Short-lived chrysanthemum is also called"Tooth grass", is a plant of the Asteraceae family that lives in the Sahara Desert of Africa.

There is a prolonged drought and very little rainfall. Many desert plants have degraded leaves, the ability to conserve water, and adapt to arid environments. However, short-lived chrysanthemum is different in that it has developed a special habit of rapid growth and maturity.

As soon as there is a little rain in the desert and the ground is a little wet, it will sprout and bloom immediately. The entire life cycle of a lifetime, with only a short period of three or four weeks Its tongue-like flowers are arranged around the head inflorescence, like serrations. Interestingly, the flowers of the short-lived chrysanthemum are extremely sensitive to humidity and close quickly when the air is dry; When slightly wet, it opens quickly and produces results quickly.

When the fruit is ripe, it shrinks into a spherical shape, and it rolls in the wind, spreading to other countries and multiplying to future generations. Because it has a short life and comes and goes in a hurry, it is called"Short-lived chrysanthemum"。

In order to reduce water evaporation, leaf degradation, keratinization of stem flesh, and storage of water in arid environments, the roots of vegetation are relatively slender and easy to absorb deep groundwater. As for the shape of the leaves, they are mostly needle-pricked, with a small leaf surface and a slightly light color. Examples are cacti, camel thorns, etc.

The environmental adaptability of vegetation in arid desert areas can be expressed in the shape of low-rise vegetation, somewhat like mangrove forests (except for Populus euphratica, etc.), with slender and emerald green leaves. Such as camel thorns, jiji grass, etc.

Tropical desert climate.

The typical vegetation is tropical desert vegetation, which belongs to the sparse vegetation dominated by super-xerophytic semi-trees, semi-zygotic shrubs and shrubs, or xerophytic succulents.

The typical soil is desert soil, and the formation conditions of desert soil are: scarce rainwater, strong wind, strong evaporation, large temperature difference, sparse vegetation, and very small coverage. The organic matter content of the desert map is very small, and the surface is mostly gravel desert, which is strongly calcareous and alkaline, and there is a gypsum layer in the lower part.

Surface water resources are scarce. For example, in the Arabian Peninsula.

There are seven countries that are flowless, and there is not a single river with water all year round.

In tropical rainforest systems, the root cause of soil barrenness is the vigorous decomposition of organic matter and nutrient recycling, and the lack of nutrient accumulation and replenishment in the soil. Tropical rainforests have a hot and rainy climate, with strong surface runoff and leaching, so the soil is very poor.

Northern Australia, Amazon River in South America.

river basins, the Congo River basin in Africa, Central America, and numerous Pacific islands.

Tropical rainforest is the ecosystem with the highest resistance stability on the earth, with a hot climate all year round, abundant rainfall, little obvious seasonal differences, and biological communities.

The succession rate is extremely fast, and it is the habitat of more than half of the world's animal and plant species.

Tropical rainforests are undoubtedly one of the most precious resources that the Earth has given to all living things on Earth. Since more than 25% of modern medicines are now extracted from tropical rainforest plants, tropical rainforests are known as the "world's largest pharmacy". At the same time, due to the photosynthesis of numerous rainforest plants.

The ability to purify the earth's air is particularly powerful, and the Amazon rainforest alone produces 1 3 percent of the world's total oxygen, so it is known as the "lungs of the earth".

In arid areas, the ecological environment is very fragile. The common characteristics of the arid region of Northwest China and other arid regions in the world are scarce precipitation, dry climate, strong sunshine and evaporation, scarce surface runoff, poor water resources, and extremely fragile ecological environment.

The lower reaches of inland rivers and the marginal areas of oases in China are the main ecological and environmental fragile areas, and under the action of human factors and various natural factors, a variety of ecological and environmental problems have arisen, threatening the living environment of oases and the sustainable development of society. Among them, the most harmful and impactful is land desertification. "Desertification" refers to the decline and destruction of the productive potential of land, which eventually leads to the degradation of ecosystems similar to desert landscapes.

The problems of desertification in arid areas are mainly manifested in wind-blown sand, drought and salinity. According to the United Nations, about 1 3 of the world's land area and 1 5 of the world's population are threatened by desertification, which is growing at a rate of about 6,104 per year

km2 The area of desert Gobi and desertified land in China is about that.

km2 occupies the land area. In particular, in the past 20 years, the area of desertified land has averaged 2460 km2 per year

The speed is expanding. Every year, China's losses due to desertification can reach 54 billion yuan.

Table Extent of desertification in Hexi region of Gansu Province (1994-1996) (unit: 104

HM2: Gansu Province is one of the regions with rapid development of desertification in China. Hexi is a key area in Gansu Province that is affected by desertification, and desertified land accounts for more than 95% of the province's area. The results of the census of desertified land in Gansu Province are presented in tables and tables.

In addition to the conditions listed in the table, the frequent occurrence of extremely large sandstorms is also an important feature of desertification hazards in Hexi. Due to its topography, desert distribution and wind characteristics, the Hexi Corridor has become one of the sandstorm-prone areas in Northwest China. It is characterized by the high frequency of sandstorms and the intensity of sandstorms.

Table Desertification hazards in Hexi region.

Due to the uneven spatial and temporal distribution of water resources and the irrationality of development and utilization, the ecological environment has changed in arid areas. For example, in Xinjiang, the flow of springs along the Kuitun River was in 1972.

M3A, which was left only in 1985.

m3a, cut. The flow rate of Hutubi Spring is decreasing at a rate of 7%, the water table near Manas is decreasing at a rate, etc. In Egypt, 96% of the country's land is desert or semi-desert, and 95% of the population is concentrated on the banks of the Nile, a situation that severely inhibits the country's economic development, which is also a manifestation of the fragile ecological environment in the arid zone.

Answer C analysis: The knowledge point tested in this question is the adaptation of organisms to the environment When answering, you can start from the performance of organisms adapting to the environment

Answer: Organisms must adapt to the environment in order to survive, for example, plants in the desert must be drought-tolerant to survive Leaves are specialized into thorns, which can reduce transpiration, reduce water loss, and adapt to the drought and water-scarce environment; It has a well-developed root system that can absorb water deep in the soil and adapt to arid and water-scarce environments; The fleshy stems are very thick, which can retain a lot of water and adapt to an arid and water-scarce environment; The leaf surface is thin and wide, the water stored in the leaf is less, and the area of transpiration is large, so the transpiration is vigorous, and a lot of water is lost, which is not suitable for the drought and lack of water

Therefore, the key to answering such questions is to understand that different organisms adapt to their environment in different ways