The city walls of Xiazhou City are all made of loess, and no stone is used from beginning to end, but it is very solid when it was first built, even if it is a city wall made of stone, it may not be able to compare, and the cost of the loess city wall is naturally much cheaper than the stone city wall, so this is a very cost-effective method of building the city, which is very suitable for the construction of the city wall in areas lacking stone.

Of course, now Datang has a more cost-effective cement concrete material, which is better than using loess and stone, the cost is actually not high, because if you use concrete to pour the city wall, you only need to pour it on the outermost and innermost sides, and the middle is directly filled with loess, or it is not bad to empty it as a house, in short, concrete building is definitely the best method, and, with the development of the railway, each city can obtain this advanced building material at a lower cost, This results in a relatively strong city wall at the lowest cost.

Standing on the wall of Xiazhou City, Li An looked at the scenery outside the city, and next to him was Li Hanlu, who accompanied him.

A breeze blew, making Li An's hair flutter, and Li Hanlu's hair was also blown and dancing, because it was the wind of early spring, so it looked a little cold, but it was not so cold that it was uncomfortable, it was not a very comfortable wind.

There are a lot of vegetation outside the city, but not a lot, it seems very sparse, which is different from the original historical record of the Huxia Empire, according to the historical records, when the Huxia Empire built the Tongwan City, it was surrounded by abundant water and grass, and the excellent environment with a pleasant climate, otherwise Helian Bobo would not have chosen the capital in this place, and he could choose the capital in this place, which is enough to show the importance of this place, indicating that the scenery of this place is very beautiful.

"The poplar trees, and some weeping willows, are bare and desolate in this season."

Li An looked at the small amount of vegetation outside the city and spoke.

Due to the increase in human activities, the environment here has been greatly damaged, and this damage has become more and more serious day by day for hundreds of years, and by this time, there has been a trend of desertification, and if it is not treated, in a few hundred years, it will really become a desert.

At the beginning, the reason why this place was rich in water and grass was because there were almost no traces of human activities here, and all kinds of animals and plants could grow normally and would not be destroyed, and as the Huxia Empire positioned this place as the capital, the people gathered around began to increase step by step, and the environment began to be destroyed, and the continuous war made the surroundings even more devastated, after the Huxia Empire was destroyed, the population here did not become so much, but there were still some people living here, and, The damage of the war is indeed quite large, resulting in great changes in the environment here, and later the people living here must cultivate the land in order to support themselves, and after the population is larger, it is necessary to pioneer to increase the area of cultivated land, so that it is simply constantly destroying the ecological environment, and then making the ecological environment worse and worse, and desertification will naturally follow.

"Yes! This is the case with trees in the north, which lose their leaves once the weather arrives, and it is said that there are many trees in the south that are green all year round. ”

Li Hanlu opened his mouth and said.

Li An nodded and said: "What's more, there are no four seasons in some areas in the south, only the rainy season and the dry season, that is, it often rains during the rainy season, and the rivers can't accommodate it, and when it comes to the dry season, it doesn't rain for several months in a row, and many plants will be dried up."

"Rainy season and dry season, it must be a wild land far to the south"

Li Hanlu opened his mouth and said.

Li An nodded in approval and said: "There are indeed more evergreen plants in the south, but there are very few in the north, but many evergreen trees in the south can be planted in the north, so that the winter in the north will not be monotonous." ”

When wandering around Xiazhou City, Li Ang found that there are almost no green plants on the roads inside Xiazhou City, which has a great impact on the environment, you must know that after having green plants, the city will look more vibrant, and if all the roads in the entire city are lined with bare trees, it will give people a very desolate feeling, which also has a great impact on people's mood, will make people feel extremely bad, and even make people have symptoms of depression.

In the interior of the capital, there are a lot of deciduous shrubs on both sides of the road, such as weeping willows or something, such plants are bare in winter, really lifeless, but some roads are planted with evergreen trees in all seasons, so that the city is very vibrant, and it is full of lively atmosphere all year round, such as around Pingkangfang, there are many evergreen trees planted, many of which are planted by the merchants of the shops themselves, so that they are also to better attract guests to come, and the picture is for benefits.

And in Li An's heart, all the roads of the city should be planted with this evergreen plant in all seasons, instead of planting shrubs that fall in autumn, which has almost become the standard in later generations, but it has not yet been popularized in the era of Datang, and the plan to promote the evergreen trees on urban roads has begun to brew in Li An's heart and can be implemented at any time.

However, this is destined to be a long-term project, not a short time to complete, after all, there are so many cities in Datang, there are too many trees in it, some trees have a history of hundreds of years, if you say that you cut down, it is too cruel, it will destroy the history of a city, so this needs to be well planned, small trees can be cut down, replaced with evergreen trees in all seasons, preferably high-quality good trees, low-quality evergreen trees do not be, and for deciduous trees that are more than 100 years old, It is really not easy for these trees to grow for so many years, and the city with old trees has a sense of history, and the city without old trees seems to have no cultural heritage.

Historical heritage is very important for a city, a city with historical heritage will create a sense of belonging, so that people's spirit can have a good home, and a new city does not have this feeling.

The sense of belonging is a very important thing, after having a sense of belonging, people can better unite and work better in one direction, so as to make a city more vibrant.

"That's what my husband said! Just like our house, except for the orchard, most of the trees are evergreen all year round, and it is really comfortable to stay inside, and sometimes I forget what season it is. ”

Li Hanlu said with relief.

At home on the outskirts of Chang'an City, Li An planted a large number of precious tree species, and most of the trees planted in his residential area are evergreen high-quality tree species in all seasons, and the rest of the yard has some deciduous flowers and trees.

And Ang Lee also found a very good way to make these flowers and trees not visible in the winter, but in the spring, they can be admired.

This is naturally the flower pot technology, the precious flowers and trees are planted in large pots, and the flowers are enjoyed in the spring, which is called a pleasing to the eye, and the mood will be better, and when the leaves fall in autumn, let the next person move all the flower pots in the yard and store them in the yard where they do not often go, so that they can continue to enjoy it in the coming year, so that they can do both.

Of course, after all, this is in Li An's own home, and he can be so capricious, but if it is on both sides of the road in the city, the cost of using this method is too great, and the prosperous area of the capital can naturally be carried out, and the rest of the places can be forgotten! It is more reliable to honestly plant evergreen trees in all seasons.

"I think that on both sides of the streets of all the cities of Datang, some evergreen trees should be planted, so that in winter, you can see green when shopping in the city, which will make people feel good, and some can also be planted on both sides of the road outside the city, and the trees are not very expensive, not worth a few dollars, by the way, all the sides of the railroad tracks should also be planted with trees, especially in the desert area, so that the scenery along the way will not be so monotonous, and even, you can plant some poplar trees in Xiazhou."

Li An said.

Datang resources are limited, and the construction of the railway has consumed too many resources, so after the construction is completed, there are no saber trees on both sides of the road, which is obviously inappropriate, especially in the desert area, tall trees should be planted on both sides of the railway, such as tall and drought-tolerant poplar trees are a very good tree, and it is the most suitable to be placed on both sides of the Xiazhou City Railway.

In addition, since the people of Xiazhou have lived in Xiazhou City, there should be a variety of trees, especially drought-tolerant trees such as poplars, only in this way can the ecology here be restored as soon as possible, so that the environment of Xiazhou City can return to the original appearance when Helian Bobo built Tongwan City.

It is said that there is a very big desert, which was originally full of yellow sand, and human beings have no way to survive, but under the organization of the imperial court, a large group of people entered this desert and used the method of artificial forests to wipe out a large-scale desert and turn the desert into a forest, which is simply an incredible miracle, but it is indeed done, as long as the method of afforestation is adopted, It is possible to turn desertified land back into forests, and in some cases, when humans come together, they can overcome some natural phenomena.

Li Hanlu nodded, and asked lightly, "What are you doing with so many poplar trees?" ”

Li An pointed to the sand and dust raised from time to time in the distance, and said: "Madam, please look, the climate here is already relatively bad, as soon as the wind blows, the sand and dust will float up, such an environment will definitely not make people comfortable, it was not like this before, hundreds of years ago, it was still a paradise with abundant water and plants, but now there is a phenomenon of desertification, if this situation is allowed to develop, in a few hundred years this will be a real desert, it is not inhabitable, and the people here can only leave their hometowns, The only way to avoid this is to plant more trees to curb the deterioration of the environment, and even make it the same beautiful environment as it was hundreds of years ago. ”

Since ancient times, there have been many cities in the desert, and even, there are such environmental scenes in film and television dramas, a grand city stands in the desert, which makes people wonder, there are many places to build cities, why build cities in the desert? The environment in the desert is not very good, there is flying sand everywhere, and there is nothing worse than here.

In fact, no one will choose to build a city in the harsh desert, which is a very stupid approach, and the city in the desert is often built before, and when the city is built, this is not a desert, at least it should be an oasis with a water source, the city is built on the oasis, but due to the continuous deterioration of the environment, as well as the destruction of the war, the environment outside the city has become more and more desertified, from a distance, it looks like a city completely standing in the desert.

However, in the interior of this desert city, there are generally oases and water sources, so although there is sand everywhere outside the city, it is enough to have an oasis and water source in the city, which is also very beneficial for defending against foreign enemies, and the enemy can not get any useful items except sand outside the city, and once the fresh water carried is cut off, it is a dead end.

"Planting trees can make Xiazhou back to the previous Xiazhou with abundant water and grass? It's as simple as that? ”

Li Hanlu obviously couldn't believe it, after all, she hadn't heard of such a thing, so naturally she couldn't believe it, and even everyone in this era would find it hard to believe.

"Simple? It's not easy! Planting trees on desertified land is not an easy task, it requires a lot of manpower and financial resources, each tree has to be watered from a long distance, to ensure the survival of trees, how can it be a simple matter? If you don't have perseverance, you can't do it. ”

Li An said.

"Xiazhou City has a population of tens of thousands, a person planting a tree, that is tens of thousands of trees, as long as the trees are planted every year, it is completely possible to plant the desert here into forests, and poplar is the local tree species here, first carry out some seedlings, and then distribute them to the people, so that every family can plant trees, so, it is not much difficult!"

Li Hanlu said lightly.