| There are a few Artocarpus nanchuanensis community in the field, and rare Artocarpus nanchuanensis seedlings in forests, which has limited community regeneration.Therefore, this study firstly investigated the existing natural Artocarpus nanchuanensis community, and then using Artocarpus nanchuanensis seedlings that artificial cultivation as the research object to study the morphological characteristic> biomass allocation from one to five years old of Artocarpus nanchuanensis seedlings and leaf photosynthesis of different leaf ages in Artocarpus nanchuanensis seedlings, in order to explore the varying pattern of their morphological characteristic, the differences in biomass allocation, the diurnal variation of photosynthesis of leaves with different ages and the correlation between the Pn and environmental factors. This study could provide theoretical basis and technical support for the cultivation of Artocarpus nanchuanensis seedlings, and basic data for the restoration and the management of subtropical evergreen broad-leaved forest ecosystem.Based on the data from the field, there were130species of vascular plants belonging to70families and108genera in4communities. There were different plant community types in different soil types. Gramineae、Liliaceae、Euphorbiaceae、 Leguminosae、Lauraceae、Compositae、Moraceae、Fagaceae、Myrsinaceae、 Rosaceaethe as main families in Artocarpus nanchuanensis communities. Artocarpus nanchuanensis communities stratified significantly. The species composition of each structural level existed on some differences, the same distribution zone differences were relatively small. Artocarpus nanchuanensis was the dominant species or constructive species in the upper layer of the communities, but there was very few Artocarpus nanchuanensis saplings in communities. Artocarpus nanchuanensis communities species richness and diversity index values presented consistent trend in different soil types, a) Neosinocalamus affinis-Artocarpus nanchuanensis:herb layer>shrub layer>tree layer; b) Artocarpus nanchuanensis-Toxicodendron vernicifluum and Artocarpus nanchuanenis-Camptotheca acuminate:shrub layer> herb layer> tree layer. Species richness index of herb layer of Artocarpus nanchuanensis communities changed to a lesser extent in different soil types, the largest tree layer. The evenness indices were low, and varied between communities. Tree layer enenness index had significant difference, no significant differences in herb and shrub layers. Community1, community3and community4evenness index presentd:tree layer<shrub layer<herb layer, communities2showed:tree layer> shrub layer> herb layer.With the increase of Artocarpus nanchuanensis seedling ages, the trend of midrib angle change was decreased firstly, then increased, specific leaf area showed opposite trend, leaf dry matter content increased, leaf length/leaf width, petiole angle and specific petiole length of different age classes seedlings had no obvious change rule. Leaf length/leaf width, midrib angle and specific petiole length of from1to3age seedlings had the sequence of current year leave>one year leaf, petiole angle had the opposite sequence. The leaf dry matter content of current year leaves were higher than those of one year, but specific leaf area of current year leaves were higher than those of one year except for2age seedlings.The number of branches and branch average length of each age class seedlings increased varies with seedling age increasing, primary branches and secondary branches presented the greatest increases from3to4age seedlings. Branchlets length-width ratio increased gradually from1to4age seedlings, then decreased gradually; Specific stem length of different age class seedlings showed the trend of gradually reduce in generally.The root volume of Artocarpus nanchuanensis increased obvious in3-4age seedlings, the disparity even to11.2times between3and4age seedlings. The taproot root length of performance decreased with increasing age classes. The root length of taproot root was less than that of lateral root.With the increase of seedling ages, the biomass and its components of the undergrowth single Artocarpus nanchuanensis increased. In which the difference of branch biomass is biggest, the disparity achieves478.9times. The aboveground biomass generally allocated in the order stem biomass> leaf biomass> branch biomass. The stump and coarse roots in different ages seeding dominated the underground biomass. the average biomass distribution rate of various sizes of roots had the sequence of stump root biomass>coarse root biomass>minor root biomass. As a main part of biomass, the proportion of aboveground biomass in total biomass decreased with the increase of seeding age and finally tended to stabilize. The single biomass and the biomass in different organs are more relevant to basal diameter (D) alone than the height (H) and HD2, a power function model was the better one. The allometric equation of minor root biomass was the worst one, the rest were better, the correlation coefficient ranged from0.873to0.989. It indicated that the biomass allometric equations has been established is feasible.It was found that both current year leaf and one year leaf growth Artocarpus nanchuanensis seedlings had one single pattern, which had no "midday depression". For the current year leaf, daily averages of Pn, Ls, WUE were higher than the one year leaf. However, the daily averages of Tr, Gs, Ci that one year leaf were higher than the current year leaf. By drawing the light response curves and by taking the relative physiological indexes into account, LSP of one year leaves was277.52umol-m-2·s-1、363.145μ.mol·m-2·s-1for current year leaves, LCP of both were very low. It indicated that Artocarpus nanchuanensis seedling is a shade tolerant plant. Correlation analysis showed that the major environmental factors of Pn were PAR and Ta. PAR was significantly positively correlated with Ta, Vpdl. Each environment facter had an effect on each other. |
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