The Resource Selection,movement Characteristics And Vegetation Effects Of Goats In The Hilly Loess Plateau

The hilly Loess Plateau is one of the most degraded ecosystems in the world,where grazing activities are the main type of land use.Better understanding of the pattern,behavior and driver of spatiotemporal distribution of the goats can lead to better understanding of foraging strategies,as well as providing management practices and policy for sustainability of these semi-arid landscapes and associated ecosystem services.This study was conducted at Bashigou watershed in the western Loess Plateau.181 days(one goat per day)of GPS tracking from 2013 to 2017,field vegetation data,and Normalized Difference Vegetation Index(NDVI)were obtained.“3S” techniques,Preference Index,integrated Step Selection Analysis and Hidden Markov Model were combined to assess how biotic and abiotic factors affect the resource selection,and movement characteristics of free-ranging goats,and grazing intensity effects on the vegetation community structure.The main results and conclusions are:1.The spatial distribution pattern of goats was mainly influenced by biotic factors,though the goats tended to use gentler slopes throughout the year which likely reduced energy expenditure.They preferentially used areas with higher forage quantity in the spring,areas of higher forage quality in terms of abundance of palatable species in the summer and autumn,and areas of higher forage quantity or accessibility in the winter.We developed a conceptual foraging model based on the pattern of preferences for forage quantity and quality of the goats,and inferred that the herbivores select areas with higher forage quality only when the forage quantity is plentiful,otherwise they select areas with higher forage quantity.The model incorporates spatiotemporal distribution of foraging resources and responsive behavior of herbivores in the landscape and provides insight into the potential mechanism underlying behavioral patterns,and ultimately may aid in prediction of behavior of herbivores in heterogeneous environment.2.Goats have flexible behavior regulation ability in heterogeneous environment,helpful to increase feeding efficiency,energy acquisition,and reduce energy consumption,which is consistent with the optimal feeding theory.The movement characteristics of goats are related to topography and forage resources at different spatial-temporal scales.On a multi-year scale,in the area with higher NDVI,the angulation with horizontal plane,path tortuosity,and probability of exploration behavior of goats were higher while the probability of foraging behavior was lower.On area with higher slope,the movement speed and probability of exploration behavior of goats were lower while the path tortuosity and probability of foraging behavior were higher.On the seasonal scale,the daily movement distance,time and speed of goats were highest in summer,lowest in winter,and middle in spring and autumn.The percent of foraging behavior of goats was highest in winter with scarce food resources.In the summer and autumn with abundant food resources,the percent of foraging behavior of goats was the lowest,and middle in spring.On the hourly scale,the angulation with horizontal plane,path tortuosity and percent of foraging behavior increased with the increase of daily moving time,while the percent of exploration behavior decreased.3.The spatial distribution of grazing intensity in the mountain was uneven,with a mean value of 0.50 goats/ha,and 95% of the study area had less than 1.30 goats/ha.The monthly utilization of biomass and rate changed over different months,and generally peaked at the periods of high biomass.Utilization rates(July)lower than 45% and 20%made up approximately 95% and 60% of the study area,respectively.This finding indicated that most study areas belong to light or moderate grazing intensity.The spatial relationship between grazing intensity and monthly aboveground biomass showed a significantly negative linear relation.However,the grazing effect on the plant growth rate was complex,and various relationships were developed at different plant growth stages.On the basis of field sampling vegetation data,the grazing intensity had minimal relationship with vegetation community structure characteristics,such as aboveground biomass,density and height,diversity,evenness,dominance,and Importance Value of grasses,though Importance Value of forbs increased with the increase in grazing intensity.In order to achieve ecologically healthy and economically sustainable grazing intensity,utilization rate should be adjusted in the high biomass period and forage grass should be supplemented or the number of goats should be reduced at the end of the growing season.In conclusion,the temporal and spatial distribution of forage resources have an important influence on the resource selection and movement characteristics of livestock.In this region,grazing has no obvious influence on plant community.An in-depth understanding of livestock movement patterns and characteristics in the landscape is conducive to a better understanding of resource selection,behavior,foraging strategies and potential mechanisms of herbivores,as well as providing a theoretical basis for the formulation of grazing management policies and the realization of ecology healthy and economic sustainability.