Why is the output value of a single variety of plant plane planting method relatively low?

As far as crop planting methods are concerned, whether it is grain, vegetables, fruit trees, trees, Chinese herbal medicines, tobacco and other crops or cash crops, most people are used to operating a single variety of plane planting methods. This cultivation method not only can not make full use of land, but also is a great waste of natural resources such as solar energy, atmospheric rainfall and air carbon dioxide. Because light and carbon dioxide are the basic raw materials of crop photosynthesis, 90% ~ 95% of dry matter in crops and other plants is organic matter that plants can synthesize CO and water in the air through sunlight.

According to experiments, the short-term utilization rate of solar energy by plants can be as high as 5%, but at present the utilization rate of light energy by plants in the world is only 0.1%; The solar energy utilization rate of crops in China is only 0.3% ~ 0.4% on average, especially in the single-layer crop planting area, between the previous crop and the next crop, and between plants and rows, which wastes a lot of sunlight, but in the seedling stage of this single-layer plane planting, the solar energy interception rate and utilization rate are even lower. Surprisingly, in the commercial tropical forest, because there are trees, shrubs, climbers, herbs, ground mosses and lichens with different levels and heights in the unit area, these dense branches and leaves (or crowns) make the whole woodland space form a complex vertical multi-layer three-dimensional structure. The average utilization rate of light energy is 3.5% (which is 8 ~ 12 times that of plane planting crops), and the average biological yield of forest per 667 square meters is 30 tons, which is 45.5 times that of farmland biological yield of 0.66 tons. Why is the light energy utilization rate and biological yield of this forest so high? The main reason is that the forest has a complex and reasonable multi-layer vertical structure, which is suitable for the growth of its various organisms. The three-dimensional "complex group" formed by this multi-dimensional space can make full use of light, water, fertilizer, gas and heat to the maximum extent, so that the limited natural resources can be utilized layer by layer.