You still think raising chickens under the forest is ecological agriculture.

As an important form of mountain economy, chicken breeding under forest has become the starting point of economic development in some places. Green food (eggs, meat) produced by chickens under the forest is also respected by some people who advocate ecological products and organic food.

However, most people do not know that while raising chickens under the forest brings economic benefits to farmers, it also has a very serious impact on the soil under the forest, especially on the vegetation and soil of natural forest land. In mountain natural forest land, especially in some water conservation areas, chicken breeding should be very cautious, and the size of environmental carrying capacity and ecological threshold should be fully considered.

We investigated the effect of different density of chicken under forest on soil in Sidaohe village, Baoshan town, northern mountain area of Huairou District, Beijing City.

1050 chickens per hectare

Effects on soil stability

When 1050 chickens were raised per hectare, soil stability decreased by 30% in one month, 47% in two months and 51.5% in three months. However, the decrease in the late stage was smaller than that in the early stage.

Effect of soil infiltration rate on soil permeability

1050 chickens per hectare, soil infiltration rate was 62.1% at the beginning of breeding, about 1 month, soil infiltration rate decreased to 34.1%, decreased by 28%, decreased rate was 45%; 2 months after breeding, soil infiltration rate decreased to 24.8%, decreased by 37.3% in 2 months, decreased rate was 60%; continued breeding to 83 days, soil infiltration rate decreased to 21.6%, decreased by 40.5%, decreased rate was 65%. The infiltration rate decreased rapidly in the early stage of cultivation and slowly in the late stage, indicating that the infiltration rate tended to be stable and the deterioration trend was restrained. This means that vegetation cover is increasing, and that the consumption of plants by chickens and the self-recovery of plants tend to balance.

Effect of soil nutrient cycling on soil nutrient cycling

Cultivation density 0.50 per hectare, cultivation for 30 days, nutrient circulation rate decreased by 71%, vegetation basically lost, most of the land surface bare; 60 days after cultivation, nutrient circulation decreased by 74%, month-on-month decreased by 11%; 83 days after cultivation, nutrient circulation rate decreased by 84%. At the later stage of cultivation, the plants in the cultivation experimental area were almost lost. The proportion of decrease is larger than that of soil infiltration and soil stability. Soil nutrient cycling is closely related to vegetation, so vegetation is the most direct and sensitive factor, followed by soil infiltration capacity and stability.

750 chickens per hectare

Effects on soil stability

When 750 chickens were raised per hectare, soil stability decreased by 6% in 1 month, 12% in 2 months and 15% in 3 months. The reason for the decrease of soil stability at the bottom in the later period of chicken breeding may be that the temperature is high, the rain is abundant, the plant grows luxuriantly and the biomass accumulates greatly in August and September, so the vegetation recovers in the later period of breeding, which makes the decrease of soil stability slow down.

Effect of soil infiltration rate on soil permeability

750 chickens per hectare, soil infiltration rate 60.6% at the beginning of breeding, 36 days of breeding, soil infiltration rate decreased 4.4%, the reduction rate was 7.3%, 61 days of breeding, soil infiltration rate decreased 8.3%, the reduction rate was 13.7%, 83 days of breeding soil infiltration rate decreased 12.4%, the reduction rate was 20.5%.

Effect of soil nutrient cycling on soil nutrient cycling

The nutrient cycling rate decreased by 11.9% after 30 days, by 18% after 60 days and by 23.1% after 82 days when the breeding density increased to 750 birds per hectare.

450 chickens per hectare

Effects on soil stability

When 450 chickens per hectare were planted, soil stability showed a steady downward trend during the last 3 months of chicken rearing, and soil stability values decreased by 3%, 7% and 4% respectively compared with the previous month. After 3 months, it reached the lowest level of 69.6%, which decreased by 11.5% compared with 81.1% without stocking, and the reduction rate was 14%.

Effect of soil infiltration rate

When the cultivation density was 450/ha, the soil infiltration rate showed different characteristics from that of 1050,750/ha. During 3 months of cultivation, soil infiltration rate was 62.4% at the beginning of cultivation, decreased by 5.9% at 36 days, and decreased by 9.5% at 61 days; decreased by 6.2% at 83 days, and decreased by 51.9% at 83 days.

Effects on soil nutrient cycling rate

When the breeding density increased to 450 birds per hectare, the nutrient recycling rate decreased by 15% after 30 days; after 60 days, the nutrient recycling rate decreased by 16%, less than 1% compared with the previous month, which could be regarded as no obvious change, because the plants grew vigorously in August and September; after 83 days, the nutrient recycling rate decreased by 27%, and the previous month decreased by 13.5%.

150 chickens per hectare

Effects on soil stability

When the density was 150 chickens per hectare, the soil stability did not change obviously after raising chickens. In the later stage, the density of breeding was less than 150 per hectare due to natural enemies, and the soil was more stable.

Effect of soil infiltration rate on soil permeability

150 chickens were raised per hectare. The soil infiltration rate did not change obviously after 3 monitoring.

Effect of soil nutrient cycling on soil nutrient cycling

The density of breeding was 150 birds per hectare, and the vegetation in the breeding area did not change obviously. After being eaten by chickens, the plants recovered in the season when the plants grew vigorously. Mechanical damage to the soil surface is also not evident. Therefore, the soil nutrient cycling rates calculated by SSA did not change.

Excessive density will permanently affect the ecology of forest land

In short, the higher the breeding density, the greater the intake of chickens on plants and the greater the loss of vegetation. The higher the breeding density, the greater the mechanical damage of chickens to the ground. In addition, chickens have the habit of making nests on the beach, which changes the surface structure, and the soil crust and vegetation coverage in the evaluation model decrease greatly. After chickens were raised under the forest, the infiltration rate of soil changed after the vegetation and ground surface were affected. The decrease of soil infiltration rate means that the vegetation that intercepts and retards rainfall decreases, and also means that the characteristics of soil surface have changed, and the ability of soil to conserve and accumulate surface water decreases. If you want to not change the characteristics of the soil under the forest, you must limit the density of chickens to a certain number. However, in practice, can this "highest density" make farmers profitable?

In addition to the serious influence on soil stability, soil infiltration rate and soil nutrient cycle, chicken under forest also has different degrees of influence on plants and animals in forest environment, which makes profound changes in forest environment.

The digging behavior of chickens disturbed the litter layer thoroughly, reduced the population of soil animals, and changed the population structure. Because chickens have selectivity in feeding, vegetation composition and structure change, and succession of plant community is inevitable. Changes in vegetation and soil will inevitably lead to changes in microorganisms.

Raising chickens under high density forest will destroy vegetation seriously, and then seriously affect the circulation function of soil nutrients. This effect is severe and long-lasting, and even if farming is stopped, the regenerated vegetation differs greatly from the native vegetation. The primary vegetation was mainly composed of perennial herbs and shrubs, and the secondary vegetation was mainly composed of short-lived and annual herbs after raising chickens under high density forest. It remains to be seen how the change or succession of this vegetation will change.