| Ephemeral plant is a special plant species which is able to make full use of springmelting snow water and rainwater, to start and soon finish a life cycle before droughtsummer season is coming. They distribute only in the north of Xinjiang province,China, and they plays an important role in reducing sand storm, wind-breaking andsand-stabilizing, protection and improving ecological environment. Moreover, therehave a majority of species which are valuable in feeding, medicinal and ornamentalpurpose, therefor ephemeral plants consist of the biological resource pool with uniqueand very high potential value for utilization. Recently, the ephemeral plants whichhave characteristics of high photosynthesis efficiency, short life cycle, fast growthbecome a hot research field. Dew is one of the important water sources which supportthe existence of plants, it played an important role on maintaining the water balanceof arid region. To clarify the mechanism of ephemeral plant response to the additionof dew, Lappula semiglabra populations were subjected to different dew treatmentsfrom May to June in2013in the southern Gurbantunggut Desert. The results showthat plant growth was sensitive to changes in dew. A randomized block designed fieldtrial, which contained three watering treatments (No-cover, Lo-cover, and CoverTreatments). The main results indicated:(1) During May to June in2013measurements were taken to investigate the dewaccumulation in the southern Gurbantunggut Desert, in three different treatments(cover, half-cover, and no-cover). Dew quantities were measured using the cloth-platemethod. The results indicated that dew amounts is0.3076mm/d in no-cover treatment,0.1953mm/d in low-cover treatment, and0.0636mm/d in cover treatment. There was apositive linear correlation between dew amounts and relative humidity, while meantemperature and wind speed was negatively linearly related to dew amounts andsignificant relationship was found between dew amounts and wind speed, relative air humidity and air temperature.(2) Plant traits are associated with fundamental behavior and function of plantindividual, community, and ecosystem. It can reflect plant survival strategy responseto different environmental factors. Based on the analysis of the plant traits, averageplant height in no-cover treatments was25.4%and26.6%higher than low-cover andcover treatments. plant crown in no-cover treatments was29.8%and74.5%higherthan low-cover and cover treatments. Root character analyses indicate that root lengthand root diameter reduced are not significantly with dew decreased. Compared to thelow-cover and cover treatments, the average root length in no-cover treatments wasincreased by4.2%and4.0%, and the average root diameter in no-cover treatmentswas increased by6.1%and17.1%. Leaf character analyses indicate that leaf area, leafthickness, leaf area index and chlorophylls increased significantly with dew addition.Compared to the low-cover and cover treatments, the average leaf area in no-covertreatments was increased by10%and30%, the average leaf thickness in no-covertreatments was increased by8%and32%, the average leaf area index in no-covertreatments was increased by33.7%and79.5%, and the average chlorophylls inno-cover treatments was increased by16%and71%. At the same time, the number offlowers and fruit of the Lappula semiglabra populations were also significantlyincreased by enhanced dew input. Compared to the low-cover and cover treatments,the number of flowers in no-cover treatments was increased by55.5%and187.0%,the fruit in no-cover treatments was increased by50.6%and80.0%. In a word, On thepremise of dew loss, the survival strategy of ephemeral plant is that reducing plantheight, crown, leaf area and leaf area index, maintaining relatively stable leafthickness and chlorophylls, root traits are not significantly change with dew lessen,moreover the number of flower and fruit are reduce significantly，but The weight andvolume of the fruit are not significantly change with dew lessen.(3) Plant growth was sensitive to changes in dew amount. Average leaf water potential in No-cover treatments was29.2%higher than Cover treatments andphotosynthetic capacity was23.8%higher.(4) The number of fruit was71.6±15.3per individual in No-cover treatments,42.4±13.7in Low-cover treatments and34.4±18.7in Cover treatments. The number of fruitper plant decreased strongly when plants were transplanted to lower dew treatments(68.9and108.1%reductions when transplanted to Low-cover and Cover treatments,respectively). However, the weight of fruit was no significantly changed fromNo-cover to Low-cover and Cover. Fruit weight was0.001354±0.000065g perindividual in No-cover treatments,0.001321±0.000072g in Low-cover treatments and0.001370±0.000047g in Cover treatments. Root dry mass increased when plantswere transplanted to lower dew treatments (72.1and98.3%reductions whentransplanted to Low-cover and Cover treatments, respectively), and there weresignificantly different between No-cover and Cover treatments. The opposite trendwas seen in root dry mass, leaf dry mass decreased strongly when plants weretransplanted to lower dew treatments (3.5and9.6%reductions when transplanted toLow-cover and cover treatments, respectively). Plant in Cover treatments producedmore fruit dry mass than plant in No-cover, the percentage of fruit dry mass wasminimum value. The opposite trend was seen in fruit dry mass, plant in Low-covertreatments produced more fruit dry mass than plant in No-cover and Cover treatments.In a word, our results showed that Lappula semiglabra in a desert ecosystem to lowerdew caused strong shifts in reproductive allocation. Plants from a nature dew habitatto lower dew habitat tend to fitness through higher reproductive allocation.(5) Based on the analysis of the time-specific life table, dew enhances survival time(29.2%), survival rate (12.2%), age (107.3%), and life expectancy (86.7%) of Lappulasemiglabra. It also reduces mortality rate (-61.8%) and vanish rate percentage(-67.5%). Additionally, based on the survival analysis, dew enhances the survivalfunction value (56.7%), reduces the cumulative mortality rate (-52.8%), mortality density function value (-36.8%), and hazard function value (-61.8%). Biomassanalyses indicate that aboveground dry mass increased significantly with dew addition,but root dry mass did not. Aboveground dry mass in natural dew treatments was141.7%higher than non-dew treatments. The results of this study have ecologicalsignificance and provide guidance for plant protection and ecological environmentconstruction in arid areas. |
PDF Full Text Request