We explored the difference between the concentrations of different N forms and other chemical properties between stream water and riparian zone wetland soil water in the Loch Vale Watershed which is located on the eastern slope of the Continental Divide in Rocky Mountain National Park, Colorado, USA. The nitrate N concentration in stream water were significantly higher than in soil water of the three wetlands, while no significant difference appeared in ammonium N. The pH values were higher and conductivity values were lower in stream water than in wetland soil water. However, significant difference also appeared between nitrate N concentrations, pH and conductivity values in the water sampled from different positions of streams. The stream tributary water had higher nitrate N concentrations, higher pH and higher conducitity values. We also conducted experiments to compare the difference between the productivity, total N concentrations in biomass and soil of upper layers. At the end, we concluded that the wetlands distributed along the streams in Loch Vale Watershed had little effect on the nitrogen load of the stream water there,

The paper deals mainly with the caloric content and its dynamics of various layer mature leaves of dominating plants in a subtropical rain forest on Hexi, Fujian. In the forest, the caloric content of dominating plant leaves in a year was as follows. In arborous layer it was 19.94～21.18 kJ·g-1 for Castanopsis hystrix, 20.34～21.33kJ·g-1 for C. uraiana, 19.98～21.04kJ·g-1 for Syzygium hancei, 21.99～23.21 kJ·g-1 for Cryptocarya chinensis and 19.17～21.08kJ·g-1 for Rhandia densiflora, respectively. In shrub layer, it was 18.45～20.20kJ·g-1 for Ardisia quinquegona, 19.18～20.04kJ·g-1 for Psychotria rubra. 17.36～ 18.47kJ·g-1 for Blastus cochinchinensis, 17.14～18.44kJ·g-1 for Lasianthus wallichii, 17.11～18.44 kJ·g-1 for Ardisia gigantifolia and 19.50～20.14 kJ·g-1 for Sarcandra glabra, respectively. In herbaceous layer, it was 18.22～19.98 kJ·g-1 for Angiopteris fokensis and 15.11～16.75 kJ·g-1 for Pronephirium simplex, respectively. In Woody liana, it was 19.73～22.57kJ·g-1 for Ecdysanthera utilis, 19.43～21.11 kJ·g-1 for Spatholobus suberectus and 18.87～20.37 kJ·g-1 for Tetrastigma planicaule, respectively. The layer mean caloric value followed the following order: arborous layer>shrub layer> herbaceous layer. The caloric value of liana was no less than that of arbor. The special organic compounds (e. g. , milk sap, oil spot and aromatic compounds, etc. )affected the caloric values of the plants, the caloric content increased when plants contained those compounds. The caloric value of fallen leaves was greater than that of the fresh mature leaves of various layer.

This paper deals with the characters of the flora, type, physiognomy, structure, species diversity and succession of the mangrove communities in Yingluo Bay of Gauangxi. In this district ,the mangrove communities consist of 6 species belonging to 6 genera in 4 families. Using clustering analysis, twenty two plots of the mangrove communities were classified into eleven formations. The classification results are: (l) Form Bruguinera gymnorrhiza, (2)form Bruguieira gymnorrhiza+ Rhizophora stylosa, ( 3 ) Form Rhizophora stylosa , (4) form Rhizophora stylosa+ Kandelia candel, ( 5 )form Kandelia candel, ( 6 )Form Kandelia candel+ Aegicerad corniculatum, ( 7 ) Form Kandelia candel + Avicennia marina, (8)Form Aegiceras corniculatum , ( 9 )Form Avicennia marina, ( 10 ) Form Avecennia marina + Aegiceras corniculatum and ( 11 ) Form Excoecaria agallocha. The physiognomy of the mangrove communities was dominated by both the life form (Rannkiaer’s system,1967)with phanerophyte and the leave characters with mesophylls,coriaceous texture,single form and entire margin. The structure of the mangrove communities was rather simple, one layer or two layers. The constructive species and dominant species of the mangrove communities were evident. Compared with those of terrestrial plant communities, the species diversity indices of the mangrove communities were much low. Under the influence of soil texture, nutrition, environment salinity as well as the mangrove’s adaptability to the salt environment, various types of the mangrove communities form evident ecological series. Along with the relative reduction of sea level and physical and chemical amendment of the soils, the mangrove community succession was gradual and progressive, from simple pioneer stage to the ultimate or terrestrial stage. The succession change was brought about by the mangrove themselves an the habitat. At each succession stage, the mangrove species modified the environment to be less suitable for themselves but more suitable for others. Thus the species replacement was orderly and predictable, and permited directionality for succession. With the modification of the soils from sandy, silt to clay, the changes of the mangrove communities were sequential. On the basis of their development and zonation, the typical successive series of the mangrove communities in Yingluo Bay are as Fig. 2.

Using field investigations and laboratory experiments, the saline-alkali resistant characters in P. chinampoensis and A. littoralis var. sinensis of alkalization meadow in Songnen Plain were ecophysiologically studied. The results show that both plant species were able to grow in saline, moist and barren soil. The soil in which P. chinampoensis grew was rich in basic salt(Na2CO3) while the soil in which A. littoralis var. sinensis grew was rich in neutral salt (NaC1), indicating their difference in salinealkali resistant characters. The different stress of NaC1 and Na2CO3, content had obvious effects on cell membrane permeability or proline content. The relationship between the stress and cell membrane permeability or proline content could be expressed by logistic curve y = k/( 1 +ea-bx )or straight line y=a+bx. It illustrates that P. chinampoensis was sensitive to the stress due to NaC1. On the contrary, A. littoralis var. sinensis was sensitive to the stress due to Na2CO3. It was true for both species that the ecological adaptation to natural conditions was similar to the physiological adaptation to experimental conditions.

Ambrosia trifida is a widespread weed of compositae in the Northeast of China and its allelopathic effects were studied in order to elucidate its spreading mechanism. Firstly, the allelopathic effects of different parts of A. trifida were investigated, and some interesting results were found out. 1)The water extract of shoot had significant inhibitive effects on crop seed (soybean, maize. wheat and rice)germmation and primary growth, and changed the crop root morpha. The most allergic species were soybean and maize. 2)The water ex tract of root had no effect on seed germination, but had a different effect on crop primary growth The extract could inhibit root elongation of wheat by 34% while it stimulated bud growth by 31%. 3)Volatile and soil had no effects on the crop seed germination and growth Sceondly, the GC and GC/MS analysis of water extract in A.trifida showed that α-pinene, β-pinene, cineole. camphene, spanthueol might be the potential all elochemicals in its water extract. Results obtained in this study indicate that the allelopathic effecls might play an important role in the spreading of the weed.

On the basis of the theory of modularity and with the analysis of relatedness degree adopted in the grey system theory, the correlation of the ecological factors and the modular structure of young tree population of Gordonia acumenata in the slash, which was created by a windstorm on Mt. Jinyun in 1989, was investigated. The results show that the modular structure of four years old Gordonia acumenata population consisted mainly of five components, i.e. first grade branch system, second grade branch system, present year branch system, spatial structure system and leaf system. They could be expressed by the dynamic features such as the number or total diameter or total length of the first grade branches, the number or total diameter or total length of the second grade branches, the number of present year branches, the first grade branches of three years old, and the total number of leaves, respectively. The correlation among the former four components were very outstanding. The last one, including the area of the leaves situated on stem, the height of the first grade branch and the height of the first leaf on stem, were relatively stable and were slightly affected by other factors. Generally, the total N, total P, total K, organic matter content and pH-value of soil were more important, as compared with elevation, size of gap and slope gradient of the sample plot. Analysis of grey relatedness degree is simple and direct technique to research the correlation among the modular structure of plant population and ecological factors. To some extent, multiple linear regression can express the quantitative relation and mechanism of the action of them.

The natural regeneration of the forest in Shandong peninsula was measured using a routine method from 1990 to 1994 and the original data was analyzed with method of Path Analysis using computer. The results show that the effects of crown density and the percentage vegetation cover on the sapling quantity were the largest. Both were the most important among the six factors affecting the regeneration. The forest regeneration was indirectly affected by slope and soil thickness, which represent topography and soil fertility of the forest, to a smaller extent as compared to the two factors mentioned above. The forest tree density was not significantly related to the sapling quantity and influenced the regeneration to a small extent. Bare rock percentage had little importance in multiplication of saplings because there were not many bare rocks in the forests, in general. Path Analysis could uncover the causality in interaction among variables, thus more could reveal the further relationship among variables.

Based on the consecutive measurement (1981～1990), we studied the surface run off in three types of vegetation. The results show that the hydrological profit of the mixed forest was far higher, by every means, than those of the Eucalypt forest and the Naked land. Furthermore, the profit was more and more evident with time. The minimum rainfall of initiating surface runoff was 30.2mm in the mixed forest, 5.1mm in the Eucalypt forest and 6.0mm in the naked land. The depth of saturated soil was 12.6cm, 3. 4cm and 6.3cm, respectively. Theoretically, the authors demonstrated the ways in which surface runoff generates in the three types of vegetation and proposed that the land of the Eucalypt forest is more susceptible to forming the surface crusting because of the bigger rain drop going through the Eucalypt canopy. All above provide a very meaningful result for water and soil conservation, and thus bridge the gap of research on the multiple profit of forest in water and soil protection for coastal land.

The responses of eight species of tree legumes to rhizobial reinoculation were reported in this paper. The reinoculation seedlings (RISs) had many nodules while the unreinoculated seedlings (controls) had none or few. The height, dry weight and total nitrogen of RISs were 0.7～3.2, 1.3～15.8 and 1.3～14.8 times higher than those of the controls, respectively. More than half of the nitrogen required for seedlings growing came from nitrogen fixation by nodules, most of the fixed nitrogen were transported and stored in aboveground than in underground plant parts. A significant correlation existed between the fixed nitrogen and the biomass of seedlings. Nitrogen fixation promoted the uptake and accumulation of phosphorus and potassium by RISs. Of the eight species, both Albizia falcata and Erythrophloeum fordii performed well with their own rhizobial symbiont and exhibited high N2-fixing potentials.

The effects of cutting frequency on the growth and reproduction of common wold rice (Oryza rufipogon), an endangered species, were studied with an experimental population cultivated in Wuhan (114˚18′E, 30˚32′N). Cutting above-ground part inhibited obviously shoot density, height, above-ground biomass, biomass per shoot and percentage of sexual reproduction while it promoted to some extent the accumulated shoot height and the percentage of photosynthesis system. The more frequently the cutting was made, the stronger the effects were. The Promotion, however, was promised at the expense of material and energy from the below-ground stems and roots. An excessive cutting would reduce not only the sexual reproduction but also the growth to such a large extent that the population could be no longer existence. This indicates that over-frequent destroying the above-ground part of common wold rice might be one of the most important reasons for local extinction of some populations of the species.

Under specified condition of pollution, the content of endogenous proline was negatively correlative to the K+ efflux in leaves. The relation between the proline content and the K+ efflux may change among species and maturity of leaves. In general, the content of proline in the mature leaves was higher than that in the old leaves and the K+ efflux of the old leaves was higher than that of mature leaves, Spraying proline had a protective effect against sulfurous acid insult.