Interaction Of Plant Functional Characters And Rock Surface Habitat In Different Periods Of Bryophyte In Karst Area Of Central Guizhou

Plant functional traits can reveal plant adaptation strategies and resource allocation strategies.As the revealer of carbonate rock surface in karst area,bryophyte has formed a set of character strategies adapted to extreme environment,which plays an important role in promoting weathering of carbonate rocks,early biological succession,and forward succession of degraded ecosystems.Different rock types lead to different communities formed by lithophyte moss,which results in different rock weathering rates.At present,there are not enough researches on species substitution rules in different bryophyte stages and the relationship between bryophyte and environment.Therefore,in this experiment,Huaxi District in central Guizhou and Longli County in Qiannan Prefecture were selected as the research areas.Bryophytes of different periods were selected as the research objects,and typical areas with similar site conditions such as slope position and slope direction were selected as the sampling sites.Bryophyte rocks within the sampling sites were selected as sample sites,with a total of 48 sample sites.By combining field investigation and laboratory experiment,this paper quantitatively analyzes the functional traits,soil nutrients and soil microbial communities of bryophytes on the surface of carbonate rocks,and studies the relationship between bryophyte community structure characteristics and soil microorganisms and soil nutrients in different periods of bryophyte stages on the surface of carbonate rocks in karst areas of central Guizhou.The change law of functional traits of bryophytes on the surface of carbonate rocks,the law of bryophyte species substitution,and the interaction between bryophytes and rock surface habitat are revealed,which provides theoretical support for the biological restoration of large area karst rocky desertification in southwest China.The main conclusions of this study are as follows:(1)Bryophyte stage is divided into two stages: creeping bryophyte stage and erect bryophyte stage bryophyte community succession develops from creeping bryophyte stage to erect bryophyte stage.The composition of bryophytes in different periods was different at the level of family,genus and species.Bryophyte stage A total of 16 bryophyte species were collected from different periods.There were 5 families,7 genera and 7 species of bryophytes in creeping bryophyte stage and 9species of bryophytes in 8 genera and 5 families in upright bryophyte stage.The bryophyte life forms in creeping bryophyte stage are mainly horizontal and interleaved,while in upright bryophyte stage they are cluster.(2)There are significant differences in the height of bryophyte in different stages.The height of bryophyte in creeping phase(2.89cm)is significantly higher than that in vertical phase(1.91cm).The contents of chlorophyll a(0.53 mg/g)and chlorophyll b(0.55 mg/g)in creeping moss stage were higher than those in upright moss stage(0.29 mg/g)and chlorophyll b(0.28 mg/g),but the difference was not significant.In creeping bryophyte stage,total carbon,total nitrogen,total phosphorus,total potassium,C:N,C:P,N:P were 421.69 g/kg,3.14 g/kg,9.68 g/kg,3.72 g/kg,173.45,68.39,0.43,respectively.In the erect bryophyte stage,total carbon,total nitrogen,total phosphorus,total potassium,C:N,C:P,N:P were 285.34 g/kg,3.03 g/kg,11.91 g/kg,3.89 g/kg,156.82,33.24,0.31,respectively.With the succession of moss,the contents of total carbon and total nitrogen decreased gradually,while the contents of total phosphorus and total potassium increased gradually.The change trend of total carbon and total potassium was significant,while the change of total nitrogen and total phosphorus was not significant.The N:P ratio of bryophyte stage is less than 14,and the bryophyte growth on the surface of carbonate rocks in karst area is limited by N.In the creeping moss period,the thickness,coverage,biomass,saturated water absorption and saturated water absorption of bryophytes are 9.08 ㎝,79.37%,2988.09 kg/hm2,735.02% and 17449.57kg/hm2 respectively.In the upright moss period,The thickness,cover,biomass,saturated water absorption and saturated water absorption of bryophytes are 11.29 ㎝,71.11%,3700.43 kg/hm2,413.17%,11786.30 kg/hm2 respectively.Moss thickness and biomass increased gradually with moss succession,while moss coverage,saturated water absorption and saturated water absorption decreased gradually with moss succession.Moss thickness and saturated water absorption showed significant change trend with succession,while moss coverage,biomass and saturated water absorption showed no significant change trend.With the succession of mosses,the water retention ability of bryophytes decreased gradually.(3)In creeping bryophyte stage,bryophytes adopt high coverage,high plant height and high water absorption capacity,and have an open strategy to obtain resources quickly.With the improvement of the surface environment of the carbonate rocks,the bryophytes adopted the conservative strategy of low coverage,low plant height and low water absorption capacity.(4)In creeping moss stage,soil organic carbon,total nitrogen,total phosphorus,total potassium,C:N,C:P,N:P were 140.64 g/kg,19.38 g/kg,1.07 g/kg,1.84 g/kg,9.20,152.97,0.15,respectively.Soil organic carbon,total nitrogen,total phosphorus,total potassium,C:N,C:P,N:P were 83.51 g/kg,11.06 g/kg,0.93 g/kg,1.68 g/kg,10.37,109.00,0.14,respectively.On the whole,the nutrient content of rock surface soil decreased gradually with moss succession.The change trend of soil organic carbon and total nitrogen was significant,while the change trend of total phosphorus and total potassium was not significant.The ratio of C:N,C:P,N:P did not reach a significant level in different periods.The ratio of C:N gradually increased with succession,and the ratio of C:P and N:P gradually decreased with succession.The contents of soil organic carbon and total nitrogen in bryophyte stage were significantly higher than those in herbaceous community stage and forest stage in karst area of central Guizhou.The total phosphorus content was between herbaceous community and forest stage,and the difference was small.Although the soil layer of carbonate rocks surface bryophyte stage in karst area is shallow,the soil nutrient content is high.The C:N,N:P ratios in the bryophyte stage were lower than those in the herbaceous community stage and the forest stage in central Guizhou,and the C:P ratios in the bryophyte stage were higher than those in the herbaceous community stage and the forest stage.The soil nitrogen regression level in the bryophyte stage was high and the soil phosphorus regression was insufficient,which belonged to the P restricted type.(5)With the increase of the richness and evenness of the bacterial and fungal communities,the microbial community gradually became complicated.When the relative abundance >1%threshold,the bacterial communities in different periods were mainly composed of Actinobacteria(35.83%～41.07%),Proteobacteria(16.71%～17.17%),Acidobacteria,15.35%-15.78%),Chloroflexi(12.68%-15.63%),Cyanobacteria(3.24%-4.90%)and Myxomycota(2.3%-2.35%).The fungal community was mainly composed of Ascomycota(53.44%-75.59%),Basidiobolomycota(13.49%-32.66%)and Mortierellaomycota(7.05%-9.62%).Through functional annotation,52 bacterial ecological functional groups and 111 fungal ecological functional groups were obtained.The relative abundance of chemoheterotrophy in soil bacterial functional groups was always the highest in creeping and erect mosses,and showed a slightly decreasing trend with mosses succession.Among the functional groups of fungi,the relative abundance of saprophyte and animal and plant pathogens was the highest,and showed a trend of increasing gradually with bryophyte succession.(6)Soil organic carbon,total nitrogen and total potassium are the main environmental factors affecting the functional traits and microbial dominant species succession of bryophytes.In the process of bryophyte succession,bryophyte functional traits and microbial groups were significantly responsive to soil factors.There was a positive relationship between soil nutrient content and bryophyte functional traits.There was a negative relationship between soil nutrients and microorganisms.There was a negative relationship between functional traits of bryophytes and microorganisms.The synergistic effect between soil nutrients and functional traits promoted the process of moss succession.