| The agro-pastoral ecotone of North China is a typical ecological fragile and undeveloped area with a cold-arid climate, scarcest resources, economic poverty and degrade ecology. In the paper, based on the objective evaluation of agriculture and animal husbandry production situation, the agriculture and animal husbandry productivity development approach was discussed with paying attention to both ecological benefits and economic profits, and the succession and enhancement principle and mechanism of ecosystem productivity was elucidated under the background that a part of farmland was returned to grassland or forestland.According to the results from the recent 20 years statistical material, in the ecotone the annual yield of grain and oil crops fluctuated greatly, the acute fluctuation of grain production resulted in severe grain shortage for people's life demand. According the grain and oil crops yield, the population overloading ratio was 39.3% under primary life level and 69.4% under well-off life level. The estimated potential grain productivity could satisfy the residents' grain demand under surplus consumption life level, but frequent natural disaster made it difficult to achieve the potential grain productivity, and the endeavor to strengthen the grain self-sufficiency would decrease farmers' economic income from the farmland.The result from the productive investigation of agriculture and animal husbandry showed that the current statistical method for animal husbandry output value existed defects, and it caused that the apparent proportion of animal husbandry output value was increased greatly in the gross output value of farming, forestry, animal husbandry and fishery. But in fact, the available output value of animal husbandry occupied only 19% of the gross output value of agriculture. The actual animal husbandry in the agro-pastoral ecotone depended on farming and was put in an inferior position compared with farming. Animal husbandry production was severely short of forage and feed. The farmers obtained the relative good economy profit of animal husbandry by hunger feeding pattern and externalizing environmental cost. According to the apparent proportion of animal husbandry output value, the strategy that animal husbandry was regarded as the dominant industry to develop was unpractical in the agro-pastoral ecotone of North China. To resolve the negative externalities of animal husbandry, establishing policy mechanism of ecological compensation, developing eco-economic industry to substitute animal husbandry, all these should be further studied.Concentrate feeding could promote the sheep to increase body weight effectively, but the ratio of economic output value to input was below 1, and concentrate feeding caused the farmers lose money. For the farmers, grazing pasture without expense was the preferred selection to gain the more economic income by externalized environmental cost. The natural cold climate was suitable for dairy cows breeding, but the severe forage shortage was the enormous obstacle to develop milk production due dairy cows population stress. The net economic income could be increased by expanding raising scale. But the higher cost input of forage and feed caused the dairy cows production profit too low. The dairy cows production with half shed-feeding and half pasturing made the farmer gain a better economic benefit per cow unit by grazing the pasture without expense and utilizing the agricultural byproducts than those who took up dairy cows production with shed-feeding, but the dairy cows developing mode with half shed-feeding and half pasturing was unsustainable.The topography characterized as slope land and shoaly land with staggered distribution and spatial soil natural variation provided the premise condition to reasonably distribute vegetation and realize the agricultural resources to be moderately exploited. Economic agriculture production should be regarded the main aspects in the better shoaly farmland. The soil erosion mass in the manmade grassland was remarkably decreased after returning the farmland to grassland in the slope farmland. But for the farmers with a unique intention to gain more income, the rapid decrease of the biomass and output value of grassland made the project of returning farmland to grassland difficult to become the farmers' automatic behavior, and caused the ideal beneficial recycling 'de-farming→planting grass→raising animals→earn money' difficult to be realized.In order to realize moderate exploitation with eco-economic balance of the agricultural resource in slope farmland and the barren among young elm forest belt, the cropping pattern with "plastic-film mulching over furrow, ridge without plough" of pumpkin production and farmland ecological effects of young elm forest - pumpkin strip intercropping were studied. These cropping patterns realized the microhabitat differentiation and pumpkin production coupling, where the microhabitat differentiation could enrich water and fertilization in the same field. The economic productivity enhancement was achieved with the net output value of pumpkin 5.08 times that of oat, and plastic-film mulching over furrow and un-plough could decrease soil erosion mass effectively. At the same time, since the branch tendril covered the gap between pumpkin planting-ditch and elm forest land, the soil water storage was remarkably increased, it promoted the grass and elm to rapidly grow. So the ecological and economic productivity of the ecosystem was co-enhanced in the slope land.To solve the actual problems of shortage and bad quality of forages in current agro-pastoral ecotone of North China and realize forage with high yield and good quality, the ecological and productive effects of plastic-film mulching and nitrogen application on forage maize was studied. Plastic-film mulching increased forage maize biomass by 25.5% and improved its nutritive quality. Water utilization efficiency was increased by 15.7% by plastic-film mulching.Nitrogen application increased the forage maize biomass yield by 36.1% and 106% in meadow chestnut and sand meadow chestnut soils, respectively. In the two soil types, the content and yield of crude protein and crude fat of the forage maize were enhanced significantly with the increase of nitrogen application. The yields of crude protein and crude fat increased by 1.60 and 2.10 times in meadow chestnut soil, and by 2.74 and 1.36 times in sand chestnut soil, respectively. The nitrogen application increased the water use efficiency (WUE) of the forage maize by 27%-45% in meadow chestnut soil, and by 50%-97% in sand chestnut soil. Nitrogen applications of less than 200 kg/hm~2 in meadow chestnut soil and more than 135 kg/hm~2 in sand chestnut soil were appropriate to ensure high yield and good quality as well as high nitrogen fertilizer and water use efficiencies of forage maize. Thus it was concluded that nitrogen application and plastic-film mulching on forage maize was an effective technique to improve biomass, nutrition quality, and fertilizer and water utilization efficiencies in the area.With support from the state policy and new technologies of Zhangbei Experimental Station, the agricultural eco-system's structure and function was adjusted in the agro-pastoral ecotone of North China. In slope inferior land with abandoned cultivation planting grass was for ecological restoration, and in shoaly superior land planting cold-season vegetable was for good economic profit. So the structure differentiation and re-coupling enhanced eco-system productivity. A case study was conducted on a village named Yejiacun in Zhangbei County, Hebei Province, which was a successful example with ecosystem structure and function adjustment. The results showed: by adjusting agricultural ecosystem structure and effective substituting economic crops, the ecosystem functions were differentiated and realized different productive and ecological intention. In shoaly farmland, cold-season vegetables substituted for the traditional grain crops with taking advantage of the natural cold climate, and by the market exchange of vegetable and grain, the economic productivity was enhanced greatly. Because of the obvious advantage in the marketable monopolization, the planting area of vegetable was rapidly increased, but the total biomass decreased by 27.5%. Shoaly farmland sharing 56.1% of the total farmland area produced the net output values that were 2.68 times that of the original whole agricultural eco-system, and labor profit ratio and cost profit ratio were increased greatly, and resulted in that material and energy input was transferred to shoaly farmland. A great deal of artificial supplementary energy was input into shoaly and realized the energy surplus of the agricultural eco-system from energy deficit, and made the agricultural ecosysem much opener. Labor intensive vegetable production absorbed a large quantity of labor forces and caused the labor force resource to be relatively short from surplus. The intensive economic production in shoaly farmland supported the ecological construction and realized the extensive ecological function enhancement in the slope land sharing 43.9% of the total area of the research area. The production structure adjustment of farming and animal husbandry was triggered by vegetable production, the animal husbandry was in inferior situation for its economic inefficiency and lack of forage. In the research area, the animal husbandry shrank more, and the total animal amount decreased, and realized the balance of forage supply and demand, so externalized environmental cost decreased to minimum.To counter the problem that selling vegetable was just selling water, the paper clarified the fact that selling vegetable was just buying water by introducing the concept "virtual water resource". The result showed: the water consumption of vegetable production in the agro-pastoral ecotone of North China was less than that of grain crops production in farming area. And vegetable production also took on water saving advantage compared with the traditional crops in the area. The net output value per unit area of vegetable was 3.47～3.98 times that of bought grain crops. The agro-pastoral ecotone of North China gain much cheaper water resource by the trade between vegetable and grain from farming area. The fact that the total sold water resource with high price was more than bought water resource from farming area made the ecotone get the faster development opportunity and more economic profit. It became the effective way to shake off poverty rapidly and realize self-development for the undeveloped and ecological fragile region.The enhancement mechanism of eco-system productivity with eco-economic balance was as follows: On the basis of agro-ecosystem structural differentiation, artificially effective combination realized subsystems coupling, and the new coupled system generated new attributes to enhance system productivity. To enhance the system productivity, the following two conditions must be satisfied: one was the sufficient condition, i.e., adjusting and rebuilding the agricultural production structure, and the other was the necessary condition, i.e., system opening operation. For the ecotone that did not have enough food to satisfy the farmers' life, the agro-pasture production must take the step of leaping development by using market mechanism and take the advantage of typic crop production to gain excess profits by market exchange so as to rebuild and evolve the agro-pasture production structure with eco-economic balance. As a conclusion, the mechanism of "with science and technology power to start, government to impel, market to promote, and farmers self-drive" is the persistent driving force in the ecotone between agriculture and animal husbandry of North China. |
PDF Full Text Request