| Climate warming threatens the structure and function of forest ecosystems worldwide and has a serious impact on biodiversity.Bashania faberi is the staple food of giant pandas.Climate warming will lead to limited growth and sharp decline in the existing areas.At present,the research on the distribution and impact of climate warming on Bashania faberi is mostly based on data modeling,while the research on the impact of field simulation on Bashania faberi ecosystem is still less.In addition,the Rusa unicolor is another important organism in the bamboo ecosystem,which can excrete a large amount of dung.However,the impact of the input of Rusa unicolor dung on the bamboo ecosystem in the context of climate warming is still unclear.Based on this,this study used the Open Top Chamber to carry out a field simulated warming experiment under the bamboo forest in Wolong Ecological Reserve to explore the effects of different warming intensities(CK: warming 0 ℃,W1: warming 1.5 ℃,W2: warming 3 ℃,W3: warming4.5 ℃)on the growth and physiology of the bamboo and the properties of soil and soil bacterial communities at different depths(0-10 cm,10-20 cm)of the soil.Meanwhile,the effects of the addition of Rusa unicolor dung(CK: 0,M1: 0.142%,M2: 1.426%,M3:2.852%)under two temperature conditions(15 and 20 ℃)on the soil nutrients,enzyme activities,their metrological characteristics and microbial metabolism limitation of the bamboo ecosystem were explored using an indoor incubation experiment.to the results can provide scientific insights for the management and maintenance of the bamboo ecosystem under the global climate change condition in the future.The main findings are as follows:(1)After the end of the warming test,the basal diameter of CK,W1 and W3 of Bashania faberi did not change significantly,while the basal diameter of W2 increased significantly by 18.8%.The plant heights in CK,W1,W2 and W3 treatments were significantly increased,compared with CK,W1,W2 and W3 increased by 13.1%,52.7%and 34.5% respectively.Compared with CK,the content of chlorophyll a in W3 treatment increased significantly,and the content of chlorophyll b in W2 and W3 treatments increased significantly.It indicated that warming may increase the rate of photosynthesis,thus accelerating plant growth.The contents of superoxide dismutase(SOD)and peroxidase(POD)in Bashania faberi had no significant changes under different warming treatments.Compared with CK,W2 and W3 treatments significantly increased the content of malondialdehyde(MDA)in Bashania faberi,indicating that the senescence process of Bashania faberi leaves was accelerated.(2)Warming significantly increased the contents of soil organic matter,total phosphorus,total potassium,available potassium and nitrate nitrogen.Compared with CK,in 0-10 cm soil layer,warming treatments significantly increased soil organic carbon,with an increase of 19.3%-27.1%;the total potassium content of soil increased by 19.1%and 42.8% respectively under W2 and W3 treatments.Compared with CK,in 10-20 cm soil layer,soil organic carbon increased by 93.9% and 97.7%,total nitrogen increased by44.1% and 49.4%,and available phosphorus increased by 26.4% and 28.6% respectively under W2 and W3 treatments.Compared with CK,the total phosphorus under W2 treatment increased significantly(39.0%).It showed that warming increased soil nutrients.(3)Warming significantly reduced the bacteria Chao1 and Faith in 10-20 cm soil layer Fith＿pd and Shannon index,indicating that warming significantly reduced bacteriaα diversity.Compared with CK,in 10-20 cm soil layer,the relative abundance of Nitrospirae in W2 and W3 treatments decreased significantly,while the relative abundance of Bacteroides in W2 treatment increased significantly.Warming increased the complexity,average degree and network density of bacterial network,and increased the interaction between bacterial groups.In 10-20 cm soil layer,the functional abundance of bacteria associated with nitrification and aerobic nitrite＿oxidation under W1 and W2 treatments was significantly lower than CK.(4)In order to investigate the ecological restoration effect of deer dung on the soil of the cold arrow bamboo system under the background of climate warming,indoor cultivation experiments were conducted.At 15 ℃,the addition of Rusa unicolor dung only changed the carbon and nitrogen ratio of soil.Compared with M1,the carbon and nitrogen ratio in M3 treatment increased significantly.At 20 ℃,compared with M1,soil organic carbon under M2 and M3 treatments decreased significantly by 6.59% and 7.01%,respectively.The addition of dung increased the contents of total nitrogen and total phosphorus in soil.Compared with CK,M3 treatment significantly increased the content of total nitrogen in soil(7.4%);M1,M2 and M3 treatments significantly increased the total phosphorus content(15.3-23.0%).At 20 ℃,the ratio of carbon to nitrogen and the ratio of carbon to phosphorus decreased significantly with the increase in dung dosage.(5)With the amount of dung added,the changes trend of soil enzyme activity and enzyme stoichiometric ratio were the same under the two temperatures.Compared with CK,the activities of BG enzyme and NAG+LAP enzyme were increased under M2 and M3 treatments at two temperatures,and the enzyme C/N ratio was significantly decreased under M3 treatment,while the enzyme C/P ratio was significantly increased under M2 and M3 treatment.Through vector analysis,it was found that the vector angle in M2 and M3 treatments was significantly lower than that of CK,indicating that the application of dung reduced the microbial phosphorus limit.PLS-PM analysis and correlation analysis showed that total nitrogen,soil C/P ratio and microbial biomass drove phosphorus limitation.This indicates that dung input stimulates the growth of soil microorganisms,thereby secreting more ecological enzymes to alleviate phosphorus limitation. |
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