In the past few years, there were few floods in Guangxi, and the weather was relatively dry...... Some people analyzed: because Guangxi has planted a large number of eucalyptus, eucalyptus trees are pumping machines, absorbing and consuming a lot of water, and even draining the groundwater, eucalyptus has reduced the rainwater in Guangxi.
This year, Guangxi has received a lot of rain in a row, and floods have also risen in many places...... As a result, some people analyzed: because Guangxi has carried out a large number of eucalyptus cleaning operations and cleaned up a lot of eucalyptus trees, there is a lot of rain and floods in Guangxi this year......
Drought is the fault of eucalyptus; Waterlogging is also the fault of the eucalyptus.
This makes the eucalyptus trees on the mountain depressed, why is it all my fault?
We know that forests are the largest terrestrial ecosystem on the planet, and they are the resources and environment on which human beings depend for survival and development. It regulates the circulation of air and water in nature, affects climate change, protects the soil from wind and rain, and reduces the harm caused by environmental pollution.
Whether it is a century-old tree or a fast-growing eucalyptus tree, it is an important part of the forest, and we should not exclude eucalyptus trees from the forest because they are exotic or because they grow fast.
Otherwise, it is either a double standard or a cover-up.
It is already a well-established fact that eucalyptus trees grow fast.
In order to achieve such rapid growth and growth, it is necessary to consume a lot of water and nutrients, and you will not really think that eucalyptus trees are "raised" by fog and "blown" by air.
Eucalyptus is just one of thousands of trees, and it will not have any "special functions", in terms of absolute water consumption and nutrient consumption, eucalyptus will surpass other tree species, but it will be higher than other tree species in terms of water and nutrient use efficiency.
Studies have shown that for every 1 kilogram of dry matter produced, eucalyptus consumes 510 litres of water, compared to 600 litres for sunflower, 800 litres for cotton, 800 litres for acacia and sandalwood, and up to 1,000 litres for conifers such as pine!
Obviously, with the same amount of water and nutrients, eucalyptus synthesizes more biomass than other tree species, which is why eucalyptus grows more rapidly than other tree species.
Eucalyptus is a shallow-rooted tree species, its root system is mainly distributed between 0.5 m and 1 m underground, up to 2 m, and in the case of annual rainfall greater than 800 mm, the root system of eucalyptus does not absorb groundwater.
Even in the event of a large dry weather, the eucalyptus root system will only absorb soil moisture within 4 meters below the ground, and will not have a serious impact on the groundwater at a depth of tens of meters, let alone drain the groundwater.
The canopy of eucalyptus is like a big umbrella, which can reduce solar radiation, reduce the heat reaching the ground, make the temperature in the forest significantly lower than that outside the forest, and at the same time, it can also reduce precipitation to directly wash the woodland, part of the rainwater is intercepted by the canopy, and most of it falls to the dead branches and leaves under the tree, and then penetrates into the soil, is stored, forming a huge "reservoir".
Of course, some are absorbed by plant roots such as eucalyptus, while others return directly to the atmosphere through evaporation.
Only about 1% of the water absorbed by eucalyptus trees from their roots remains in the plant for growth, while the remaining 99% is lost to the atmosphere through the trunk, branches, leaves, and of course, mainly leaves.
Academically, this phenomenon is called transpiration.
Transpiration, which is not only affected by external environmental conditions, but also regulated and controlled by the plant itself, is therefore a complex physiological process. The main processes are: water in the soil→ root hairs→ inner ducts in roots→ ducts in stems→ ducts in leaves→ stomata → atmosphere.
Due to the large planting density of eucalyptus, the main trunk of eucalyptus is obvious, but the side branches are also very numerous, layered, densely distributed, so the transpiration of eucalyptus is very large, it is estimated that 1 hectare of eucalyptus forest evaporates more than 8,000 tons of water a year.
It is this transpiration that keeps the air in the forest area moist, lowers the temperature, and allows the local rain to be abundant, forming a virtuous cycle, thus effectively regulating the climate.
Speaking of which, some people will ask, walking into the eucalyptus forest, there is no beautiful feeling of lush trees, birds singing and flowers, and in the summer it will obviously feel more sultry than other forests, which makes people restless.
What's going on here?
For eucalyptus plantations based on timber, the ecosystem is certainly much simpler than the natural ecosystem, not to mention that in order to pursue economic benefits, abandon biodiversity, excessive pursuit of pure forestation, and the management methods are both simple and crude, such as removing all the shrubs and weeds in the forest, this "one-size-fits-all" approach directly leads to the much-criticized "no grass grows under the forest".
There is no shrub layer such as miscellaneous trees, no vegetation layer on the ground, and there are only some dead branches and fallen leaves under the forest, not to mention any beauty, and even some of the functions of water conservation and soil and water conservation have been lost.
Although there are such and such problems in Guangxi eucalyptus, it may also affect the local small environment, but it is not enough to change the overall environment, we can not blame all the extreme weather such as heavy rain, floods, droughts, etc.
Statistics show that the forest coverage rate of Guangxi is 62.55%, the forest area is 222.96 million mu, including 84.9 million mu of natural forest area, 138.06 million mu of plantation area, although eucalyptus has replaced pine, fir and become the first major tree species of Guangxi plantation, but its planting area is only 45.5 million mu, accounting for 32.9% of the plantation forest, accounting for only 20.4% of the total forest.
In addition to eucalyptus, Guangxi also has a large number of pine, fir, firepower nan, camphor, acacia, rice and other tree species, even in the timber forest, the area of other broad-leaved trees is 65.47 million acres.
In the years of rapid development of eucalyptus in Guangxi, it happened to coincide with the intensification of the greenhouse effect, global warming, accelerated melting of glaciers, rising sea levels, and redistribution of precipitation, resulting in frequent and intensified extreme weather......
For example, sudden rainstorms, prolonged droughts, etc., "the wind does not adjust and the rain does not go well", it is no wonder that people naturally think of eucalyptus trees in the mountains.
The reasons behind the so-called "wind and rain are not smooth" are complex and multifaceted.
For example, the water conservancy facilities are backward, and the water cannot be retained during the flood season, and the quality of the forest is not high, and there are too many eucalyptus trees in some areas......
However, we should be soberly aware that the main reason is global warming.
If the "pot" is thrown at the eucalyptus tree, is it unfair to the eucalyptus?