| Grassland agriculture climate is an important basis for cropping and livestock,which has a great influence on agricultural development.Under global climate change,the climate factors that affect the growth and distribution of plants and animals of grassland agriculture have changed.The scientific analysis of spatial-temporal variations based on the above factors is important,not only in theory but also in practice,in order to promote the economic development of grassland agriculture,adapting and buffering the impact of global climate change on grassland agriculture.Grassland agriculture includes plants and animals.Plants provide food for animals and animals transmit seeds to plants.They are interdependent and interact with each other.This paper takes China as the research area divides it into arid climate zone,temperate climate zone,cold climate zone,and polar climate zone according to the Koppen climate classification.Using the grid data(daily minimum temperature and daily maximum temperature)and stations data(daily mean temperature,daily mean relative humidity,and daily mean wind speed)from 1961 to 2016 provided by the National Meteorological Information Center of China,this paper studies the temporal-spatial patterns of plant hardiness zone,plant heat zone,animal(cattle)cold stress zone,and animal(cattle)heat stress zone in the different climate zones in China.The plant hardiness(heat)zone helps to determine the distribution of plants according to their cold tolerance(heat tolerance).The animal cold(heat)stress reduces animal production efficiency,reproduction,and welfare,and the identification of cold(heat)stress zone is conducive to the risk assessments of cattle production.The study provides a scientific reference for the coordinated development of plants and animals.The main conclusions are as follows:(1)The average annual extreme minimum temperature of arid climate zone,temperate climate zone,cold climate zone,and polar climate zone were-26.12°C,-5.21°C,-28.83°C,and-26.48°C,respectively.They showed a significant increasing trend,and the order of increment was as follows: polar climate zone(0.57°C/10a)> cold climate zone(0.47°C/10a)> arid climate zone(0.41°C/10a)> temperate climate zone(0.36°C/10a).The plant hardiness zone of China mainly included zones 4(-34.4?-28.9°C),5(-28.9?-23.3°C),6(-23.3?-17.8°C),and 9(-6.7?-1.1°C).Zones 4,5,and 6 were distributed in turn of latitude and altitude decreasing,widely in the north of China,while zone 9 was distributed in the central part of the south of China.The changes of plant hardiness zone in China mainly showed that warm zones replaced cold zones,and the northern boundary of the zone moved to high latitudes and high altitudes.The changes indicated that some plant species might have moved north and upward,and the boundaries of biodiversity might have changed.Some plants that can adapt to local cold weather conditions can be introduced in these sensitive areas of climatic change.(2)On average,the number of days with annual daily maximum temperature > 30°C in the arid climate zone,temperate climate zone,cold climate zone,and polar climate zone were 32 d,57d,14 d,and 11 d,respectively,all showing a significant increasing trend than before,and the order of increment was: temperate climate zone(1.48d/10a)> arid climate zone(1.32d/10a)> cold climate zone(0.86d/10a)> polar climate zone(0.34d/10a).The plant heat zone of China mainly included zones 1(<1d),2(1?7d),4(14?30d),and 7(60?90d).Zones 1 and 2 were mainly distributed in high latitude and high altitude areas,such as Qinghai-Tibet Plateau,Daxingan Mountains,and Xiaoxingan Mountain,zone 4 was distributed in Northeast China and Inner Mongolia,and zone 7 was distributed in the North China,East China,Central China,and Northwest China.The main characteristic of the changes of the plant heat zone in China was the northward and upward shift of the zone,except for the Qinghai-Tibet Plateau.Changes in plant heat zone have caused that local species will no longer suitable for growing because of the overheated environment,which may cause the plant to migrate or extinct.This is of great significance for the biodiversity,plant biomass and yield,and the nutritional value of animals in some areas where the summer is very hot.(3)The wind chill temperature(WCT)was lower in cold months(January,February,and December),and was lowest in January.The order of cold stress on cattle from strong to weak was as follows: cold climate zone(-11.00)> polar climate zone(-8.62)> arid climate zone(-8.49)> temperate climate zone(2.05).Except for the temperate climate zone,all climate zones reached moderate cold stress.The WCT values were lower in the high latitude and high altitude areas,and the cold stress on cattle was more serious.The change rates of WCT in cold months in arid climate zone,temperate climate zone,cold climate zone,and polar climate zone were 0.44/10 a,0.10/10 a,0.32/10 a,and 0.86/10 a,respectively,which indicated that the cold stress on cattle in each climatic zone was alleviating.In cold months,mild cold stress was distributed in western and central regions;moderate cold stress was distributed in most areas of Northwest China,North China,and Northeast China;severe cold stress was distributed in the eastern part of Inner Mongolia Plateau,the northern region of Northeast Plain and central area of Qinghai-Tibet Plateau.From the 1960 s to the 1990 s,cold stress in most parts of North China was alleviated in January,indicating that climate warming affected the distribution of cold stress,and made it alleviate.From the 1990 s to the 21 st century,the cold stress in Northwest China became serious,indicating that it was greatly affected by climate change.During this period,the warming trend in winter slowed weakly and even turned into a cooling trend in some regions.Furthermore,the study of different levels of cold stress zone is of great significance to the impact of the external stress environment based on open or semi-open cattle breeding models.(4)The temperature-humidity index(THI)was higher in the warm months(June,July,and August),and was highest in July.The order of heat stress on cattle from strong to weak was as follows: temperate climate zone(75.19)> arid climate zone(65.15)> cold climate zone(64.69)> polar climate zone(59.05).Temperate climate zone reached the threshold of mild heat stress.The THI values were higher in the southern regions of low latitude,the northwest inland of high latitude,and the southern part of Qinghai-Tibet Plateau.The change rates of THI in the arid climate zone,temperate climate zone,cold climate zone,and polar climate zone were 0.29/10 a,0.02/10 a,0.32/10 a,and 0.17/10 a,respectively,indicating that the heat stress on cattle in each climate zone was increasingly severe,which had a negative impact on the distribution and pattern of cattle husbandry.In warm months,mild heat stress was distributed in the Tarim Basin in the northwest of China,most area of the southeast of China and southern part in the northeast of China;moderate heat stress was distributed in the southern coastal areas and Middle-Lower Yangtze Plains;severe heat stress was distributed in the middle latitude in the eastern region of China.From the 1980 s to 1990 s,the heat stress in the Northwest China Inland,Northeast Plain,and North China Plain was serious in July.The study of heat stress zone has practical significance for the site selection of new livestock farms,the risk assessment of existing farms,and the adoption of mitigation measures,and can provide a theoretical basis and decision-making reference for the government and related industries. |
PDF Full Text Request