Behavioral Activity Of Plateau Pika And Its Response To Two Disturbances In Alpine Meadow

Plateau pika(Ochotona curzoniae)is a small mammal herbivore on the QinghaiTibet Plateau.Its herbivory and excavation behavior will directly affect the changes of vegetation and biodiversity in alpine grassland.Affected by the joint effects of overgrazing and rodent disturbances,the plant community and soil characteristics of alpine meadows will change,and plateau pika will adjust their behavior patterns due to changes in habitat environmental factors and food composition.At present,the response of pika’s behavioral activity under the joint effects of overgrazing and rodent disturbances is not clear.27 experiment plots with an area of 25 m × 30 m were designed in Keqi River Beach,Henan Mongolian Autonomous County,Qinghai Province.A two-factor(plateau pika density and mowing intensity)and three-level(high,medium,and no interference)controlled experiments were used to continuously record the behavior of plateau pikas by camera,and to analyze the changes of vegetation community and soil characteristics in alpine meadow.We explored the effects of vegetation and soil characteristics on the plateau pikas behavior patterns under the disturbances of grazing intensity and pika density.The main results are as follows:(1)In this paper,a plateau pika monitoring system,which realizes non-contact,continuous and digital monitoring of plateau pika,was constructed by integrating image automatic acquisition,optimizing digital image processing algorithm and intelligent recognition technology.The experimental results show that the detection accuracy,recall rate and weighted average value of the plateau pika are 87.20 %,83.37 %and 85.24 %,respectively.Therefore,the monitoring system can accurately realize the behavior supervision of the plateau pika.(2)In the monitoring of the activity rhythm of plateau pika,the peak period of ground activity of plateau pika appeared at 10 : 00 and 16 : 00,and there was no ground activity at night.There were significant differences in the relative richness index and frequency of foraging,vigilance,movement and other behaviors of pikas at different hours(P < 0.05).There were significant differences in the behavior of pikas at different hours in the relative richness index and the frequency of digging foraging,vigilance,movement and other behaviors(P < 0.05).For the dynamics of monthly behavior,the density of plateau pika significantly affected the hour relative abundance index(P <0.05),but had no significant effect on the behavior frequency.There were significant differences of the relative richness index of plateau pikas and the frequency of digging foraging,vigilance,movement and other behaviors among different months(P < 0.05).The frequency of digging foraging behavior was the highest in April.In order to reduce the large area of patchy degraded alpine meadow,rodent control measures should be carried out before March every year.Among the behavior patterns of plateau pika,the proportion of digging foraging is the highest,indicating that plateau pika may face the problem of lack of food resources.(3)In this study,vegetation height,coverage,biomass,functional group dominance and plant diversity were selected to reflect the changes of habitat vegetation characteristics under two disturbances of mowing intensity and pika density.The two disturbances and their interactions significantly affected the vegetation height and coverage of plateau pika habitat(P < 0.05).With the increase of time,the coverage of vegetation community decreased significantly.Mowing significantly reduced the aboveground biomass of vegetation and the importance value of Gramineae functional groups,but increased the importance value of Cyperaceae functional groups(P < 0.05).The density of plateau pikas significantly reduced the importance value of grass functional groups(P < 0.05).Severe mowing significantly reduced Simpson index,Shannon-Wiener index and species richness index of alpine meadow vegetation community(P < 0.05).There were significant differences in vegetation coverage,aboveground biomass,important values of functional groups of Gramineae,Cyperaceae,Leguminosae and Forbs,Simpson index,Shannon-Wiener index,species evenness index and species richness index of vegetation communities among different years(P < 0.05).The interaction between year and mowing intensity had a significant effect on the important values of sedge and compositae functional groups(P < 0.05).The interaction between year and pika density had a significant effect on the important value of sedge functional group(P < 0.05).(4)The physical and chemical properties of grassland soil under two disturbances showed dynamic changes.Experiment period,mowing intensity and their interaction had significant effects on soil temperature(P < 0.05),and experiment period had extremely significant effects on soil water content and electrical conductivity(P < 0.01).The average soil temperature in 2021 was significantly lower than that in the other three years,which was 5.13 °C,5.66 °C and 5.97 °C lower than that in 2018,2019 and 2020,respectively.Heavy mowing treatment significantly increased soil temperature(P <0.05),which was higher than that of non-mowing treatment and moderate mowing treatment.Mowing intensity and their interaction had a very significant effect on total nitrogen and total phosphorus(P < 0.01),the experiment period and pika density had a significant effect on pH in soil(P < 0.05).With the increase of the experiment period and mowing intensity,total nitrogen and total phosphorus showed a trend of increasing first and then decreasing.The increase in the number of pikas led to a significant decrease the pH in soil.The pH of the high-density pika treatment was 0.23 lower than that of the non-pika treatment.The pika density had no significant effect on soil total nitrogen and total phosphorus content.(5)The results showed that there was a significant difference between the daily temperature change and that of the diurnal variation of the relative abundance index,the frequency of digging foraging behavior and guarding of plateau pika(P < 0.05).There was a strong correlation between the monthly temperature change and that of monthly changes of the relative richness index of the time,the frequency of digging foraging behavior,the frequency of vigilance and other behaviors(P < 0.05).The frequency of digging foraging behavior,the frequency of vigilance,the frequency of other behaviors were strong correlation with the monthly air humidity,respectively(P< 0.05).The frequency of digging foraging behavior and the monthly change of vigilance frequency were significantly correlated with monthly precipitation(P < 0.05).Seasonal changes in alerting behavior frequency and moving behavior frequency were significantly correlated with seasonal air humidity(P < 0.05).In summary,the plateau pika monitoring system as designed in this study provides new research ideas and effective technical measures for pika behavior research.Both mowing intensity and pika density can cause changes in vegetation height,coverage,and important values of functional groups in pika habitats,and the main reason for the decrease in biomass and diversity is mowing intensity.Mowing intensity and plateau pika density had significant effects on the vegetation community characteristics of pika habitat,but there was no significant correlation between habitat changes and daily behavior rhythm of plateau pika.Air temperature and relative humidity is the main reason for the change of plateau pika behavior patterns.