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In order to understand the growth characteristics and differences of different Ormosia henryi provenances in Guiyang, we collected seeds from ten different provenances of O. henryi and conducted seedling experiments. We compared differences in seedling height, root collar diameter, biomass, leaf photosynthetic parameters, photosynthetic pigment, activity of nitrate reductase, content of nitrate nitrogen and the root activity of the biannual seedlings, and then analyzed the differences in ten provenances of O. henryi. The results were as follows:(1)There were significant differences in the net photosynthetic rate(Pn), stomatal conductance(Gs), intercellular carbon dioxide concentration(Ci), transpiration rate(Tr)and water use efficiency(WUE)among ten O. henryi provenances(P<0.05), indicating that different O. henryi provenances showed significant differences in photosynthetic characteristics and light use efficiency. Plants from Hangzhou and Yongkang of Zhejiang had the higher photosynthetic growth potential.(2)There were significant differences in chlorophyll content, nitrate reductase, nitrate nitrogen and root activity among provenances. The contents of chlorophyll a and chlorophyll b and total content of chlorophyll were the highest in Jian'ou of Fujian provenance. These plants could efficiently transfer the accumulated light energy during the initial reaction of photosynthesis and promote carbon assimilation. Huaxi of Guizhou provenance had the highest nitrate reductase activity, the highest nitrate nitrogen content, and strong utilization ability of nitrogen elements, which could promote the synthesis of plant protein, amino acid and chlorophyll. The root system from plants in the Wangmo of Guizhou provenance had the greatest activity and the ability to absorb nutrients.(3)There were significant differences in the distribution of seedling height, ground diameter and biomass among all provenances. The plants from Hangzhou of Zhejiang provenance had luxuriant branches and leaves, developed roots and good growth performance, while the plants from Huangshan of Anhui provenance were short and had poor growth performance. Hangzhou of Zhejiang provenance distributed more biomass in roots and leaves to increase the ability of roots to absorb nutrients and leaves to acquire light energy. Huangshan of Anhui provenance accumulated the least biomass and had the worst growth.(4)The adaptability of ten provenances of O. henryi was comprehensively evaluated by principal component analysis. The results showed that Hangzhou of Zhejiang provenance > Liping of Guizhou provenance > Yongkang of Zhejiang provenance > Wangmo of Guizhou provenance > Jian'ou of Fujian provenance > Kaili of Guizhou provenance > Shiqian of Guizhou provenance > Hauxi of Guizhou provenance > Pingtang of Guizhou provenance > Huangshan of Anhui provenance. In conclusion, Plants from Hangzhou of Zhejiang, Liping of Guizhou and Yongkang of Zhejiang O. henryi provenances had high potential for adaptation and growth potential in Guiyang. [ABSTRACT FROM AUTHOR]

Casuarina equisetifolia coastal protection forest(C. CPF)is an important barrier of coastal ecology in Hainan Island, and natural regeneration is of great significance for it to play a role of protection function continuously. It is found that undergrowth natural regeneration is difficult in the most area of C. equisetifolia forests in Hainan Island, however, there is a phenomenon of good regeneration in the local area. In order to explore the cause of the great disparity in the natural regeneration, and to provide certain theoretical basis for promoting the transformation of C. CPF from plantation to near-natural forest, the main factors affecting the natural regeneration of C. CPF were studied through the analysis of the differences of regeneration quality for different forest lands. Seventy-three temporary plots were established in the C. CPF in Hainan Island, and statistical methods, such as variance analysis and correlation analysis, were used to study the effects of climate zones, stand conditions, soil factors and litter accumulation on natural regeneration quality and density. The results were as follows:(1)The regeneration of C. CPF in wet zone was significantly better than that in dry zone;(2)There was significantly negative correlation between C. equisetifolia stand density and regeneration density or herb coverage, but other factors of stand conditions had little effect on regeneration;(3)There was no significant diffe-rences in soil pH value and nutrients in the sample plots with different regeneration qualities, but ammonium nitrogen promoted the regeneration of seedlings and organic matter did the regeneration of saplings to some extent;(4)The accumulation of litter was not conductive to natural regeneration as a whole. The results indicate that the climate factor, density of C. equisetifolia stands and accumulation quantity of C. equisetifolia litters were the main impact factors for the natural regeneration of undergrowth in C. CPF. [ABSTRACT FROM AUTHOR]

Successful natural regeneration can play its ecological protection function with three conditions:(1)Abundant and good seed resources;(2)Micro-habitat suitable for seed germination;(3)Ecological conditions for the sur-vival of seedlings and young trees. However, Casuarina equisetifolia coastal protection forest(C. CPF)in Hainan Island exists unable to naturally regenerate by itself. To explore obstacle factors of unable natural regeneration of C. equisetifolia itself, the ecological conditions affecting seed germination of C. equisetifolia, such as C. equisetifolia allelopathy, soil pH, salinity, temperature, matrix type and moisture were studied. The reason is that ecological conditions affecting seed germination are one of the three conditions that restrict the success of natural regeneration, and the other two conditions are the quantity and quality of provenances, and ecological conditions for survival of seedlings and saplings respectively. C. equisetifolia cones, litters and in-situ habitat soil were collected from the C. CPF near Houwei Village, Haikou City, Hainan Island. The seed germination test was conducted by paper dish method, with 100 seeds per dish and three repeated treatments. The C. equisetifolia litter, humus and sandy soil extracts were diluted into five concentration gradients respectively and a total of 15 extracts were obtained. The pH was set to 5.0, 5.5, 6.0 and 6.5 concentration gradients for the germination solution. Salinity was set to 0.02%, 0.05% and 0.10%. The temperature was set to 25, 30 and 35 ℃. The PEG method was used for water stress test, with five concentration gradients of 0, 50, 100, 150 and 200 g·L-1. The orthogonal test was designed as three factors and four levels. The results were as follows:(1)There was no significant difference of seed germination rate between CK group and the one treated with different water extract concentrations of different extracts.(2)pH, salinity and temperature within the set range had no significant effects on seed germination rate of C. equisetifolia.(3)The germination rate of C. equisetifolia seeds treated with PEG solution with different concentration gradients was significantly different, and the seed germination rate of C. equisetifolia decreased sharply with the increase of PEG solution concentration.(4)Different matrices and watering frequencies also had significant effects on seed germination rate. Combining PEG drought stress, matrix and watering frequency, it can be found that C. equisetifolia seeds have weak drought resistance and are sensitive to water, therefore, moisture is the main limiting factor for the germination of C. equisetifolia seeds. Meanwhile, the poor water retention of litters and coastal sandy soil also restricts the germination of seeds to varying degrees. [ABSTRACT FROM AUTHOR]