Chin J Plant Ecol

Physiological Ecology Studies on Artemisia ordosica and Cynanchum komarovii in the Maowusu Sandland

Zheng Hai-lei, Huang Zi-chen, Dong Xue-jun

Chin J Plan Ecolo. 1992, 16 (3): 197-208.

Abstract ( 4155 )

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The growth of Artemisia ordosica, which is the main community-constructing species,appears in some locations in the Maowusu sandland. Cynanchum komarovii, a perennial species; however, grows luxurantly throughout the area. There is obviously succession between these two species in experimental area. The characteristics of the two species are explained by our investigation based on physiological ecology, reproductive biology and by the analysis of fundamental elements of the environment.A. ordosica and C. komarovii are characteristic of anisohydric and isohydric plants respectively. The photosynthesis, transpiration and stomatal behavior of the two species are distinctly different from one location to another. The water-use efficiency of C. komarovii is much higher than that of A. ordosica. Furthermore, C. komarovii is more drought resistant and therefore less sensitive to water stress; A. ordosica, however, is less tolerant therefore more sensitive to water stress. The result is that C. komarovii is more dominant than A. ordosica in survival competetion.In conclusion, one of the main external factors of succession is the water content of the soil; the major internal factors of succession are the distinctive water physiological-ecological and reproductive biological characteristics of the two species.

The Characteristics of Energy in the Formative Process of Net Primary Productivity of Larch Artificial Forest Ecosystem

Liu Shi-rong, Wang Wen-zhang, Wang Ming-qi

Chin J Plan Ecolo. 1992, 16 (3): 209-219.

Abstract ( 4156 )

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Based on the studies of ecosystem productivity and by means of calormetry measurement,the characteristics of energy in the formative process of net primary productivity of 21 years Dahurian Larch plantion ecosystem was studied systematically on Moer Shan Forest Farm in the eastern part of northeast China. The results showed that (1)Caloric content of plant samples varies with species, organs, ages, distributive layers and seasons. (2) Standing crop energy accumulated in the living plant is 269.719×1010 J/ha, while that accumulated in the dead plant is 36.817×1010 J/ha, in which 84.04% is in the litter and 15.96% in the standing dead plant. (3) Net energy production of Larch forest ecosystem is 264. 346 × 109 J/ha·a, 29.49 % of which goes into the litter in the form of litterfall and the rest retains in the plant for growth. The annual energy return of Larch forest ecosystem is 88.809 × 109 J/ha, with 32.39% from decomposition and rest accumulating in the litter. The energy transformation efficiency of Dahurian Larch plantation ecosystem is 2. 299%. Compared to the other plant communitie, Dahurian Larch plantation ecosystem is an energy metobolic system with a high energy conversion efficiency.

Study on the Absorption and Removal of Kandelia candel for Pollutant Cadmium

Zheng Feng-zhong, Lin Peng, Zheng Wen-jiao, Zhuang Zhi-xia

Chin J Plan Ecolo. 1992, 16 (3): 220-226.

Abstract ( 4098 )

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Seedlings of mangrove plant, Kandelia candek, were growed in sea water with 0.0025-25ppm Cd in sand culture. The main results showed as follows: The Cd contents in the different organs were: root>hypocotyl>stem>leaf. The Cd contents in the organs (y) increased with the increasing of Cd concentrations in the culture solution (x) and relationship between y and x was doubly logarithmic regression equation, eig., the equation of root Cd content and that of culture solution was: log(y) = 1. 8039 + 0.4311 log(x) showing a greatly significant relation. The Cd enrichment ratios in different organs of the seedling were 62.4 for leaf, 113.6 for stem, 187.2 for hypocotyl, 705.2 for root respectively in the solution treated with 2.5ppb. The amount of Cd accumulated was 239.47μg per seedling(mean d. w. 6.18g) treated with 25ppm for 4 weeks and 75.6% of which was in the roots. 2.4--36% of Cd added to culture solution were absorbed by the seedlings in all treated groups for 4 weeks. The Cd content in the root treated with 2.5ppm Cd for 10 weeks was 538.74μg/g but the seedlings had not been injured apparently, so that K candel could play an important role in absorption and removal of Cd from the soil of coastal swamp.

Biomass and Productivity by Natural Pinus henryi Forests

Xiao Yu

Chin J Plan Ecolo. 1992, 16 (3): 227-233.

Abstract ( 2117 )

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The biomass and net primary production of 28—37 year-old natural Pinus henryi forests were investigated and analyzed. The results showed that, the biomass of arbor layer, undergrowth (including herb) layer together with the dead materials were 81.28 t/ha, 1.45 t/ ha and 11.16t/ha respectively. The net primary production of arbor layer was 6.94t/ha·a, of which leaf accounted for about 45%, extinction coefficient of the forest had a average of 0.33. The biomass and net primary production of the stands were closely proportional to LAI. Regarding the aboveground production structure, the branch weight was mainly distributed in the mid-lower part of the crown, and leaf weight percentage increased in the lower part of the crown with needle age. The length of root system for P. henryi forests was about 99.4km/ha, of which fine roots accounted for 58% of the total.

Patterns of Clonal Growth in Leymus chinensis Population

Wang Yu-sheng, Li Jing-xin

Chin J Plan Ecolo. 1992, 16 (3): 234-242.

Abstract ( 3549 )

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Statistical analyses over time suggest that Leymus chinensis rhizone lengths and branching angles are independent of each other, and also of the previous branching angles and rhizome lengths. This paper shows that the process of clonal growth in Leymus chinensis is consistent with stochastic simulation models and random-walk models. This study represents the application of random-walk models to pattern of the vegetative spread of clonal plant Leymus chinensis. There was no statistical difference between observed ramet displacements and displacements predicted in a correlated random-walk and diffusion models. These models can be used to make quantitative predictions about the spread of Leymus chinensis population.

Xeromorphic Characters in the Vegetative Organs of Peqanum harmala

Zhang Hong, Chen Li-chun, Hu Zheng-hai

Chin J Plan Ecolo. 1992, 16 (3): 243-248.

Abstract ( 2430 )

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Peganum harmala, a xerophyte, growing in extremely dry habitats or in salt marshes possessed distinct xeromorphic characters. The thickened tap root appeared, to consist of 2 or 3 rings of anomalous vascular bundles surrounding the central cylinder which might be an important, adaption to dry condition. The succulent stem was characterized by a well-developed water-storing tissue in the cortex, phloem, especially in the pith. Leaves were also succulent without trichomes. The outer walls of the epidermal cells were covered by thich cuticle whose surface was ridged. The guard cells of the stomata were at almost the same plane level with other epidermal cells. The stomatal size was larger and its frequency was lower than those of other xerophytes. Two types of tissues could be distinguished in mesophyll: palisade tissue and water storage tissue. The veins in the leaves were not so developed. Ratio of the external leaf surface to its volume was smaller than mesophytes. According to the structural features mentioned above it can be concluded that Peganum harmala is a typical succulent xerophyte.

A Preliminary Study on the Soil Seed Banks of Different Successional Stages of Subtropical Evergreen Broad-Leaved Forest

Xiong Li-min, Zhong Zhang-cheng, Li Xu-guang, Wang Li

Chin J Plan Ecolo. 1992, 16 (3): 249-257.

Abstract ( 4655 )

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The successional series of subtropical evergreen broadleaved forest in Jinyun Mountain of Sichuan province has been divided into six stages in this paper. They are: (1) old-field; (2) shrub grassland; (3) masson pine forest; (4) evergreen needle and broadleaved mixed forest dominated by masson pine; (5) needle and broadleaved mixed forest dominated by evergreen broadleaved species; (6) evergreen broadleaved forest. Five 0.5m2 soil sample measured 10cm high from each of six stages were taken to laboratory to let seeds in the soil germinating. From the appearance of seedlings, we concluded followings: A. At the early stages of succession (from old-fieds to masson pine forest), the number of seeds and species diversity decreased with the development of succession. In these stages, the deeper the soil stratification is, the less the number of seeds is. At the later stages of succession(from masson pine forest to evergreen broadleaved forest), the number of seeds is increased with succession evolution. In different stratification of same stage, the number of seeds is nearly the same. B. Most of seeds in different stages are herb species. C. If humidity and light is fixed, the number of germinated seeds is interrelated with temperature. More than 80% seeds of most species are germinated in six weeks. D. The species composition between above ground vegetation and soil seed banks are nearly the same at the early stages of succession, but it is very different in the later stages. The sampling volume of soil seed banks and the signification of soil seed banks in vegetation succession have also been discussed in this paper,

The Statistical Analysis Between Winter Steppe Grass Yield in Tiansan North Slope and Meteorologic Conditions

Huang Jing-feng, Li Jian-long

Chin J Plan Ecolo. 1992, 16 (3): 258-265.

Abstract ( 3514 )

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On the besis of steppe grass yield during 1966--1987 in Ziniguan stud sheep farm and meteorologic data of shawan station, the grass yield variation and the effect of meteorologic conditions on grass yield were studied by statistical methods of correlation analysis, integral regression and stepwise regression analysis. The results showed that the grass yield does not increase or decrease with time, the percipitation is a key factor. April—June and September—October were key periods. Finally, a grass yield predicting model was established.

Effect of Precipitation on Chemical Element Migration in Soil of Tropical Monsoon Forest and Rubber Plantation

He Yuan-qiu, Wang Ming-zhu, Zhao Qi-guo

Chin J Plan Ecolo. 1992, 16 (3): 266-275.

Abstract ( 3821 )

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The parper studies the effect of precipitation on litter decomposition and migration of several chemicals.

1. Diao luo montain in Hannan island is characterized by larger precipitation. Therefore, precipitation is direcly proportional to leak water and soil moisture content but in inverse proportion to element concentration in tropical monsoon forest and rubber plantation. The overall concentration of all 9 elements concentration in water is in the order of ditch water>Well Water>soil seepage water>run off>river water>leak water percipitation. The concentration of each element in all water is in the order of SiO2, K2O, Na2O, CaO, MgO and P2O5, MnO, Fe2O3, Al2O3.

2. Precipitation accelerates the litter decomposition and the element release and promotes material cycle and exchange. Decomposition of leaf litter in rain season is 16. 6–28. 8% faster than that in dry season in the early ninety days. Total element return capacity in dry season is more that in rain season. Return of SiO2 is much more that CaO,N, MgO and K2O. But return of CaO, N is more in rain season, return of SiO2 is more in dry season.

3. Elements migration restricted by precipitation may be attributed to three aspects, i. e. ground migration, soil migration and mixed migration. Ground migration takes up to 51.7–59.3 percent of the total migration capacity; decreasing and enrichment of Fe and A1 is the main feature of element magration; enrichment and lack of nutrient is the results of element migration. Monsoon forest accumulates 172.5kg/ha·yr, rubber plantation lacks 13.6kg/ha·yr. In addition, the bulk of element migration is occurred from August go October when the precipitation and it′s intensity are both high.

4. Element concentration of precipitation and all kinds of water may be expressed and predicted by equation.

5. In planting of tropical economic crops and tree, protected measures must be taken such as building terrace, suitable close planting and reasonable intercropping and so on. Otherwise, nutrient element leach and soil fertility reduction would not be avoided.

Study for the Ecological Environment and Vulnerable Reasons of the Ammopiptanthus nanus

Pan Bo-rong, Yu Qi-li, Yan Cheng

Chin J Plan Ecolo. 1992, 16 (3): 276-282.

Abstract ( 4097 )

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The rare endangered plant Ammopiptanthus nanus is a kind of evergreen broadleaved shrub endemic to the desert in the central part of Asia. It is only distributed in Kezilesu Kirgiz Autonomous Prefecture of Xinjiang and the Soviet Union. Now the plant is under the second-grade protection of the state and the first-grade in Xinjiang.Through the field investigation on Ammopiptanthus nanus and in the light of the climate conditions in the range, this paper analysed temperature, illumination,moisture and soil in the ecological environments. The vulnerable reasons of the plant was studied.As a result of analysis and study, the bioecological characteristics of Ammopiptanthus nanus have been found preliminarily as follows: Cold resistant,heat resistant and tolerant to wide range of temperature variation, light demanding with some features of shade preference, drought resistante, and fairly salinization resistant.The vulnerabling of the plant can be attributed to: 1. Special shape of the seed which makes the seeds difficult to spread and to get the suitable conditions for growth. 2. Prone to pests. 3. Upplaned cutting of the plant for firewood.In view of the above results, we suggested the conservation should be started at once, besides, nature reserver supported with necessary protective measures must be established as soon as possible.

Studies on the Ecological Geographic Distribution and Synecological Characteristics of Elaeagnus Mollis Sorub in Shanxi Province

Shangguan Tie-liang, Zhang Feng, Bi Run-cheng

Chin J Plan Ecolo. 1992, 16 (3): 283-291.

Abstract ( 3856 )

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Elaeagnus mollis is in the second grade protection in China. It is endemic to China. E. mollis scrub in lower mountain and loess-hill areas of southwest Shanxi province develop perfectly under a special ecological environment. The geographical elements, dominated by temperatical ones, are complex. The community possesses the physiognomy and structure of the warm-temperate deciduous broad-leaved shrubland.Analysis shows that E. mollis scrub in the preserve are a well-preserved and precious communities with various typical structural types. According to the integration of importance value and other characteristics of shrub layer and herb layer, this paper has described 8 associations.At the end of this paper, the authors also proposed same proposals ways exploit, utilize and protect the E. mollis scrub.