| By monitoring on seasonal dynamic changes and daily dynamic changes photosynthesis and respiration of different types of microbiotic crusts moving dune,semi-fixed sand dune and fixed dune of horqin Sandy in In(?) Mongolia semi-arid region.,synchronous monitored on biological fact(?) which effect on respiratory characteristics and light close characteristics (including soil physical and chemical properties, soil nutrient and moisture, air temperature, humidity, rainfall and ray of light intensity) an abiotic factors (including soil microbial biomass carbon and nitrogen, alga plant numbers, algae biomass and mosses),correlation between parameters of Photosynthesis and respiration with various indicators of environmental factors,the results are as followed(1)Diurnal changes of photosynthesis of biological crusts show that as enhancement of natural light intensity and temperature rised, the value of Fv:Fm declines first and then rises, at 12:00-14:00 the value fell to the minimum. With the weakening of light intensity on the afternoon, the value Fv:Fm rises gradually and at 16:00-18:00 recovery to the morning value. The value of Fv:Fm showed significant differences among Different types biological crust.changing trend is:moss crusts on fixed dune> algal crusts on fixed dunes>algal crusts on semi-fixed dunes.The value of Yield changing trend in different types of biological crusts is:moss crusts on fixed dune>alg crusts on fixed dunes>algal crusts on semi-fixed dunes,keeping consistent with the trend of Fv:Fm.biological crusts respiration on Daily dynamic changes indicates that algal crusts on semi-fixed dunes and mobile sand dunes are unimodal curve.The whole crust respiration rate begins to constantly increase at 6:00 and reaches the peak value at 8:00. Then begins to fall down, at about 22:00 to lower level..duial dynamic changes on respiration rate shows double-peak curve of algal crusts on Fixed dunes and moss crusts on fixed dunes,respectively having the highest peak, and the minimum peak.The peak value occurs at around 22:00,minimum peak around at 14:00.Respiration rate in different types of biological crusts is:moss crusts on fixed dune>algal crusts on fixed dune>semi-fixed dunes>mobile dunes. soil respiration rate of Mobile dune shows significantly smaller than the dune crusts'(2)The seasonal dynamic changes of microbiotic crusts photosynthesis show that different types of microbiotic crusts during the same season the daily average value of Fv:Fm are expressed as:moss crusts on fixed dune> algal crusts on fixed dune>algal crusts on semi-fixed dunes.mean value of Fv:Fm expressed as summer>spring>autumn. In moss crusts on fixed dunes in different seasons seasonal variation.Overall, seasonal changes trends of daily average of Yield is almost identical to Fv: Fm.the value of Yield reduced obviously than Fv:Fm,but daily changes of Yield value are more greater. This show that Yield value is more sensitive than Fv:Fm in responsing to the external environment condition. The seasonal dynamic changes trend of microbiotic crusts on respiration show that different types microbiotic crusts in the same season respiratory rate is:moss crusts on fixed dunes>algae crusts on fixed dunes>algae crusts on semi-fixed dunes. The seasonal changes of microbiotic crusts'respiratory rate is summer>spring autumn.The same types microbiotic crusts respiratory rate in summer and spring have significantly difference with autumn (P<0.05). While same types of microbiotic crusts respiratory rate in the same season also exists obviously differences.(3)The relationship between parameters on photosynthesis and respiration of microbiotic soil crusts and environment show that the biological factors have different influences on photosynthesis and respiration. The correlation between respiration of algae crust on semi-fixed dunes and abioge azotobacter,fungi is significant (P<0.01). The correlation between respiratory rate of algae crusts on fixed dunes and fungi, microbial biomass carbor nitrogen, algae plants and mosses of biomass reached a significant level (?) 0.01).respiratory rate of moss crusts on fixed dunes with organic, actinomycetes, and fungal correlation reached obviously significant level (?) 0.05).And have no significant correlation with microbial biomass carbon and nitrogen,total nitrogen, biomass. But there is no correlation betwe photosynthetic Yield value and biological factors. Abiotic factors have th(?) different influence on photosynthesis and respiration of microbiotic crusts When light intensity reaching saturation can promote both reflect; When ligh intensity below the saturation point it can inhibit both reaction. the correlation between Yield value of moisture content and fixed dunes algae crust and fixed dunes moss crust is significantly(P<0.05),by instead semi-fixed dunes crust. And the correlation does not reach to a significant level between moisture content and different microbiotic crusts' respiratory rate. Daily changes of soil respiration are closed which relates with temperature and humidity. Soil respiration rate changes are positively with temperature and are negative correlation with humidity. Among microbiotic crusts soil nutrient negative correlation with humidity. Among microbiotic crusts soil nutrient and photosynthetic Yield value and respiratory rate, only mosses crusts on respiratory rate of fixed dunes correlation and organic achieved significant (P <0.01), with total nitrogen correlation reached the level of significant (P 0.05). The correlation of microbiotic crusts respiratory rate on rainfall was significant (P<0.01). The correlation between photosynthesis Yield value and fixed dunes algae crust and fixed dunes mosses crust of rainfall reached the level of significant (P<0.05), algae crusts on semi-fixed dunes and pH value was a significant negative (P<0.05). |
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