The Preliminary Research On Effects Of Altered Precipitation On Grasshopper Behaviour In Songnen Grassland

The influence of altered precipitation patterns on dynamics of animals is a key problem in global change ecology. Grasshoppers are common generalists in grassland, and previous research focused on their population and community in response to climate change. However, individual characteristic, especially for behaviour may be important for the response of ecosystem to climate change. In this study, a field experiment with changing the amount of rainfall was conducted to examine the effects of altered precipitation on a generalist grasshopper (Euchorthippus unicolor) behaviour including time allocation, foraging, and habitat selection in meadow steppe over two years. The knowledge may take potential importance in predicting dynamics of grasshopper population and sustaining management of grassland ecosystems. The main results are as follows:(1) Vegetation characteristics were affected by changed amount of rainfall. Plant species richness, plant coverage, and plant height tended to reduce where precipitation altered including increasing rainfall and decreasing rainfall (P>0.05).(2) Time allocation of grasshoppers was significantly affected by altered precipitation (P<0.001). Quiescence time significantly decreased in both increasing and decreasing precipitation treatments, compared to the control, but feeding time increased. And furthermore, the magnitudes of net effects of decreasing precipitation were higher than that of increasing precipitation.(3) Changing precipitation significantly affected diet selection of grasshoppers. In 2009 and 2010, grasshoppers spent more time on feeding Phragmites australis where precipitation decreased than where the controls were. While time spent feeding Leymus chinensis was not significantly affected.(4) Height of grasshopper habitat was affected by changed precipitation. Habitat height of grasshopper had a shift with preferring to select middle and low position of vegetation in both increasing and decreasing precipitation treatments, compared to the control where grasshopper preferred to high habitat of vegetation.(5) Altered precipitation had similar impacts on switching frequencies of grasshoppers. Time in walking and jumping of grasshoppers increased in changed precipitation treatments. And the magnitudes of net effects of decreasing precipitation were larger than that of increasing precipitation.Overall, changes in precipitation significantly altered behaviour of grasshopper, including foraging and habitat selection, thereby influencing dynamics of grasshopper population. Thus, studying the responses of ecosystems to climate change will benefit from not only changes in population and community of insect but also alteration in behaviour at individual level in grasslands.