| Alpine musk deer(Artiodactyla,Ruminantia Moschus sifanicus)is a type of highland ungulates in the northwestern and southwestern China.In November 2002,it was promoted into the first-grade list of the key protected wildlife in China.The Helan Mountain is vital distribution area for this species,due to unique geographical location:surrounding by desert,the Yellow River and urban area.These geographic features protect population fluctuation from migration of alpine musk deer.However,because of rarity and high commercial value,alpine musk deer suffered illegal poaching and faces extinct.Lacking basic data severely blocks conservation and restoration of this species.To solve this problem,this study investigated diet composition,nutrient strategy,habitat selection and habitat suitability assessment of alpine musk deer,and further comprehensively analyzed their survival status in the Helan Mountains.The results will be of great significance for population protection and restoration,and also provides theoretical basis and scientific guidance for ecosystem management and bio-diversity conservation in Helan Mountains.Based on individuals location data collected from infrared camera surveys in 2013,we sampled vegetation within their habitats in the following surveys during 2014-2016.We sampled fecal and plants and used fecal sub-microanalysis to determine seasonal food composition.By measuring nutrients compositions in fecal samples,we estimated food nutrient composition and selection strategy of alpine musk deer.We adopted Traces test,quadrat and foot-print chain tracing method to analyze seasonal habitats selection and their seasonal differentiation.With MAXENT model combined with 3S technique,we also evaluated habitat suitability of alpine musk deer in Helan Mountains.Because of yearly fecal samples diffidence,we combined two years of samples to ensure 70 fecal samples per season and total 280 independent samples in a full year.For each of the hay and the grass period,we collected thirty one of plant species(19 families).Totally 750 quadrats and 307 control ones were used for habitats selection analysis.The results as followed:(1)In Helan Mountains,alpine musk deer foraged 31 species(genera)of plants every year.Among them(19 families),Rosaceae was 22.9%,Leguminosae 11.6%,Caprifoliaceae 9.6%,Salicaceae 8.4%and Asteraceae 7.1%,they composed main foods.Alpine Musk deer favorites shrubs and herbs,while Salix character,Leptodermis ordosica,and Astragalus chingianus appeared in all seasons foods.Though yearly food compositions had no significant differences,some specific species only appeared in certain seasons foods.During spring and summer,the foraging species was the most diverse(31 species or genera).The value of Shannon-Wiener H'in autumn was highest than those of the other seasons,meanwhile index J' showed the same pattern and was highest(1.28),followed by those in winter.Both of the niche breadth of food(B)were higher in autumn and winter than in spring and summer,and value in autumn was higher than in winter.(2)According to analysis of nutrient strategy and related factors and data from optimized CCD response surface model on protein,energy,tannin and food components,we found that,in the hay period,alpine musk deer often choose vegetation with high crude protein content,high energy,high crude fiber,high fat content and low tannin content;in the grass period,they favorite plants with high ash content,high crude fat content,low protein,low energy and low tannin content.The nutrition choice was a complicated process,resulted from multi-factor interaction rather than single factor,and the crude protein,the energy and the tannin content acted as main factors affecting diet composition of musk deer.Availability and palatability of plants also influenced food selection of alpine musk deer in different seasons.When abundant,musk deer more likely chose leaves,herbs and bryophytes of fresh and juicy plants.Under the climate,environment and other limited factors,they selected readily available species with relatively poor palatability,such as trees bark,horny epidermis and filamentous high-altitude herbs.With food shortages in winter,these had high priority for alpine musk deer.(3)Habitat selection analysis showed that food,hidden,and human disturbance acted as important factors affecting habitat selection of alpine musk deer.There had some seasonal differences in habitat selection:In spring,13 kinds of factors functioned on habitats selection of alpine musk deer.It tended to live in mixed coniferous forest with Juniperus rigida,Pinus tabulaeformis,Populus davidiana and Ulmus glaucescens.Their territories were the areas of high altitudes,high-density scrub,high shrubs,high hiding,shady slope and far away from bare rock and water.In summer,12 kinds of factors functioned on habitats selection of alpine musk deer.It tended to live in the mid-slope of the shady or semi-shady slopes in Picea crassifolia forests.Their territories were the areas of high-density trees,low density shrubs,high altitude,near water,high hiding and far away from human disturbance.In autumn,12 kinds of factors functioned on habitats selection of alpine musk deer.It tended to be living in the mixed coniferous forest of Picea crassifolia forests.They liked activities in the hidden level,sunny slope,far from bare rock and human disturbance,low shrubs density's habitat.Their territories were the areas of high hiding,sunny slope,low shurbs density,high density of tall tree and far away from the bare rock and human disturbance.In winter,13 kinds of factors functioned on habitats selection of alpine musk deer.It tended to live in the mountain coniferous forest and subalpine meadow shrub.Their territories were the areas with high density of trees,high altitude,high slope,low density of vegetation,far away from the bare rocks and tree distance.Our study disclosed that,altitude of the musk deer habitats was low in the grass period than in the hay period,this was related to plant distribution,light and topography.Habitat selection and utilization were dynamic and influenced by many factors such as food,human disturbance,concealment,mating and lactation.(4)Assessment on habitat suitability of alpine musk deer showed that:Thirteen environmental factors affected the habitat suitability of alpine musk deer.Factors including coniferous forest,distance from water source,distance from forest ridge,altitude,distance from mine and distance from road were of the most effect to habitat suitability.Slope,grassland,broad-leaved forest,and shrub less,and alpine meadows and deserts contributed least.Along with increase of slope,distance from the mine,road and ranger stations and decrease of distance from the water source,habitat suitability of alpine musk deer gradually increased.For altitude between 1 400-2 800m,habitat suitability increased with altitude.Beyond 2 800m,habitat suitability decreased with altitude this disclosed that alpine musk deer prefer areas far from human disturbance and steep mountain region.The suitable habitats for alpine musk deer are mainly located in the southern Helan Mountains within Ningxia Hui Autonomous Region and the middle and northern Helan Mountains within Inner Mongolia Autonomous Region.There still have some fragmented habitats in the northern Helan Mountains within Ningxia Hui Autonomous Region and the southern Helan Mountains within Inner Mongolia Autonomous Region.The total suitable habitat area cover 120.24 km,accounting for 3.27%of the total area of Helan Mountains.Human disturbance,altitude,slopes and forests type play as major factors affecting alpine musk deer habitat selection in Helan Mountains.Efficient measures should be taken as soon as possible to improve the quality of habitat and promote the population of musk deer by establishing ecological corridors. |
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