Relationships Between Wild Ungulate Abundance And Vegetation,soil And Cattle Grazing In Northeast China

Cattle grazing in the forest is recognized as a limiting factor in the recovery of the Amur tiger and Amur leopard in Northeast China,including via bottom-up ecological interactions with wild ungulate prey and vegetation.There is a growing evidence base of the relationships between cattle,vegetation and wild ungulates,but there are important gaps which still remain concerning wild ungulate abundance in winter,fine-scale ungulate-vegetation relationships,and measures against well quantified cattle grazing intensity.We first present an extended analysis of the cattle-vegetation-ungulate relationships inside fenced grazing enclosures of a range of cattle densities in and around Hunchun National Nature Reserve(HNR)in 2018,including comparisons between inside and outside enclosures and the effects of cattle density on wild ungulate density and vegetation factors.We then established two 20 km x 20 km fixed monitoring plots in and around HNR and Xiaobeihu National Nature Reserve(XBH)in 2019,each divided into 100 grid cells of 2 km x 2 km.In November 2019 and 2020,a series of arbor tree,shrub and herbaceous plant measurements were recorded in a 30 m x 30 m quadrat in the center of each grid cell,as well as taking soil samples(in 2019)and setting one camera trap per quadrat to record cattle and wild ungulate Relative Abundance Indices(RAIs).We used a series of linear models,segmented piece regression models,generalized additive models,and zero-inflated negative binomial models as well as Mann-Whitney U tests to investigate relationships between wild ungulate abundance and vegetation and soil factors,and the effects of cattle grazing on them.We assessed soil samples for soil organic carbon(SOC)content in response to the recognized potential of forest cattle grazing to sequester carbon as a major climate change mitigation strategy.Our main results include:1)The strongest ungulate-vegetation relationships were found for arbor tree basal area and diameter at breast height(DBH).Both of these indicators influenced wild boar(Sus scrofa)and roe deer(Capreolus pygargus)abundance,and suggested that a landscape of fewer,larger trees supports higher densities than a landscape of many smaller trees.Data suggest that thresholds exist.2)Compared with outside grazing enclosures,inside enclosures had lower total arbor tree basal area,lower adult tree density,and higher average DBH of adult trees,suggesting that cattle grazing at certain densities can have long-term effects on changing vegetation structure,supporting higher wild ungulate densities.3)Annual shoot abundance of browse species(i.e.,staple forage plant abundance)was lower inside enclosures than outside,however their presence/absence and abundance were not directly related with cattle density,per se.Regardless,wild ungulate abundance was not related with annual shoot abundance at the standard statistical significance level(p<0.05),but relationships at p<0.1 were found,including indication of thresholds.4)Wild boar abundance was positively related with the average height of herbaceous plants;data suggest a threshold exists.Comparing average herbaceous plant height in 2019 with 2020 and relating these differences with cattle presence/absence during the grazing/growing season indicated that cattle grazing can maintain the same plant height between years,whereas cattle absence may result in plants being taller in the following year.Further investigation with long-term data would be beneficial.5)Inside enclosures,wild boar density increased with cattle density.There were no effects of cattle density on roe deer density or wild ungulate occurrence probabilities.6)A positive correlation was found between roe deer abundance and soil organic carbon(SOC)content,and SOC was higher where herbaceous plants were taller and where cattle were present compared with where cattle were absent.This result makes no inference about causation,but offers a starting point for integration into the long-term monitoring program and exploration of carbon accounting tools to support sustainable economic systems and provision of ecosystem services.7)Finally,this research has documented shared space use between cattle and wild ungulates,and found that the distribution of sika deer(Cervus nippon)in HNR clearly reveals a limiting effect of the G331 highway which must be considered in the wildlife restoration plan.