| Conservation and reintroduction of rare and endangered plants with Extremely Small Populations has been much attention during recent years.Ostrya rehderiana is one of the Plant Species with Extremely Small Populations,which now only distributed in the Western Tianmu Mountain,Zhejiang Province.Based on the field survey and lab experiment,we studied the ecological stoichiometric characteristics of O.rehderiana saplings?<10yrs?,its planted individuals?40yrs?and natural individuals?100yrs?during the growth season in this paper.Our research were focused on the following four aspects:?1?the seasonal dynamic of ecological stoichiometry for its saplings,the planted individuals and the natural individuals;?2?comparison of the ecological stoichiometry between the upper and the lower level with in the canopies of the planted individuals and natural individuals;?3?analysis of.the soil ecological stoichiometry of its saplings,the planted individuals and the natural individuals in Western Tianmu Mountain;?4?comparison of the ecological stoichiometry between O.rehderiana and O.carpinifolia On this basis,it is compared with the stoichiometric characteristics of plants and soil in the major ecosystems of the country.The main research results are as follows:?1?The results suggested there was different change in C,N and P contents in the saplings,the planted individuals and the natural individuals.Generally,its foliar C contents ranged from 437.201±1.23?526.95±24.72 mg·g-1,with the average of 477.5mg·g-1,which was higher that of global plants.At the same time,its foliar N contents ranged from 9.78±2.92?49.49±6.54 mg·g-1,and its mean N content(21.98 mg·g-1)was also higher that of global plants.On the contrary,its foliar P contents ranged from1.01±0.60?1.62±0.43 mg·g-1,meanwhile its mean P content(1.99 mg·g-1)was lower that of global plants.Compared with O.rehderiana,the foliar C,N and P contents of O.carpinifoliasuggest the utlization resources of O.carpinifolia is stronger that of O.rehderiana.?2?The results showed there was different C,N and P contents among the the saplings,the planted individuals and the natural individuals.The sequence for the foliar C content was the saplings>O.carpinifolia>the planted individuals>the natural individuals,and for the foliar N and P content were O.carpinifolia>the saplings>the planted individuals>the natural individuals and the planted individuals>O.carpinifolia>the natural individuals>the saplings,respectively.?3?The results also suggested there was obvious different allocation among C,N and P contents within the canopis.In generally,C content of the upper level within the canopy for natural individuals was higher that of the lower level,while both N and P contents of the upper level were lower those of the lower level within canopy.For the planted individuals,the C content of the upper level within the canopy was nearly identical to that of the lower level,but both C and N content of the upper level showed ralatively lower comparing with the lower level.For both the natural and planted individuals,C conten of the second order branch within the canopy were higher that of the first order branch,but both N content and P content of the second order branch within the canopy were lower those of the first order branch.The C,N and P contents of male inflorescence in the upper level were higher those of the lower level within natural individual canopy,and fruit inflorescence also showed the similar trendency.Additionally,both C and P contents in fruit inflorescence decreased with the growth season,otherwise the N in the fruit inflorescence increased with season.The C,N and P contents of the reproductive modulars of O.carpinifolia were higher than those of O.rehderiana.?4?The C,N and P contents varied remarkedly among the different modulars,in which the bud C content was higher than the others.The sequence for C content was the bud>the second order branch>leaf>male inflorescence>the first order branch>fruit inflorescence.And then,the sequence for N content was the male inflorescence>fruit inflorescence>bud>leaf>the first order branch>the second order branch,Pcontent was bud>male inflorescence>fruit inflorescence>leaf>the first order branch>the second order branch.The sequence for C:N ratio was the first order branch>bud>leaf>the second order branch>fruit inflorescence>male inflorescence,meanwhile,the seguence for C:P and N:P were the second order branch>the first order branch>leaf>fruit inflorescence>bud>male inflorescence>fruit inflorescence>male inflorescence>leaf>the first order branch>bud>the second order branch.?5?In general,the soil C content of was lower that of most forest soil,meanwhile both soil N and soil P content were obivous lower than those of means in China and subtropical forest soils.The soil C content in the plantes individuals was highe than that in natural individuals,partly due to artificial clean-up.Based on the ecostoichiometric characteristics,the paper suggest the growth of both the natural and the planted individuals were restricted by P element,and saplings growth was restricted by N element.Suggestions:Take appropriate management measures to gradually reduce the area of Phyllostachys edulis forest,restore and improve the natural plant habitat,especially soil nutrient status.For Ostrya rehderiana in different growth stages,reasonable formula fertilization is used for curing.In the future,we will continue to carry out research on the stoichiometric direction of different species of Ostrya Scop,and provide a scientific basis for the reasonable protection and management of Ostrya Scop species. |
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