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51.
Spatial studies of colonization and succession of soil algae and chemical analyses of the various soils on the cinde cone of Kilauea Iki in Hawaii Volcanoes National Park, Hawaii are outlined. There is a positive correlation between the diversity and quantity of soil algae with nutrient levels and organic matter accumulation in each locale. Three distinct edaphic-biotic zones existing in this area are differentially revealed by the soil chemical composition, quantity and diversity of soil algae, and as evident variations in higher plant growth and colonization. Varying colonization and successional phases of higher plant growth around standing and fallen tree snags killed by volcanic activity also reflect variations in the soil algal flora. These variations appear largely as a function of differential water interception, absorption, and retention as well as differential accumulation of organic matter, and the initiation of various biogeochemical cycles. 相似文献
52.
江苏省海滩植被演替的研究 总被引:1,自引:0,他引:1
宗世贤 《植物资源与环境学报》1992,1(1):13-17
江苏省海滩植被可分为滨海盐土植被、盐沼植被及海滩沙生植被三个基本类型。本文论述了这些植被类型的演替规律。滨海盐土植被与盐沼植被的演替,外因于土壤盐分含量递减与有机质含量的递增;海滩沙生植被的演替,外因于土壤沙颗粒大小及其相应的土壤含水量的变化,所以海滩植被演替为外因动态演替。 相似文献
53.
54.
Abstract. Woody biomass production in natural forests of arid and semi-arid regions is low. The fuelwood demand of settlements often exceeds the sustained yield and regeneration capacity of natural forests, which results in deforestation. Regeneration and woody biomass development was studied in cleared Acacia zanzibarica bushland in Bura, eastern Kenya. The area was cleared in 1982 and studied in 1988. The site had been colonized primarily by Acacia zanzibarica and A. reficiens. Mean density was 1333 trees/ha, mean total woody biomass (dry weight) 1954 kg/ha, equal to 2.53 m3/ha. Mean annual increment was 293 kg/ha, or 0.3 8m3/ha. Expressed as rain use efficiency, the natural dry matter productivity of the woody component equals 0.83 kg ha-1 yr-1 mm-1. The regeneration potential and some management implications are discussed. 相似文献
55.
Wang Yusheng 《Plant Ecology》1992,98(1):83-95
(1) | The influence of sheep grazing of moderate grazing (MG), heavy grazing (HG), inordinate grazing (IG), over grazing (OG), and extinct grazing (EG) on vegetation succession was studied in the Stipa baicalensis steppe during 1984–1986. |
(2) | The relationships between the relative sum of dominance ratio (RSDR) and the degree of succession (DS) at all stages of grazing succession in the Stipa baicalensis steppe were revealed in terms of the method of mathematical analysis under five grazing intensities mentioned above. |
(3) | The dynamic models of grazing succession that are based on accurate grazing intensities in relation to succession courses were constructed using RSDR5, and DS. The models may explain the rules of grazing succession in the Stipa baicalensis steppe. |
56.
W. F. Warwick 《Aquatic Ecology》1992,26(2-4):563-575
The effects of contaminants and organic pollution on the chironomid communities of two basins in Lac St. Louis, a river-lake on the St. Lawrence River above Montreal, Quebec, were assessed and compared using lake classification theory techniques and morphological deformity indices based on the ligulae and antennae ofProcladius, the dominant surviving component of the south-shore communities. Contaminants from the industrial complex around Beauharnois, Quebec, have seriously degraded communities along the south-shore gradient while the introduction of untreated domestic wastes from Laprairie, Quebec, has seriously affected the communities of the Laprairie basin. The interaction between trophic and contaminant effects constitutes a classic example of the setback or deflection in the trajectory of ecological succession in biological communities hypothesized by ODUM (1981, 1985). 相似文献
57.
Microstratification of phytoplankton in the large shallow Lake Balaton (Hungary) was studied during a 24 h period. Dissolved O2 showed biological stratification; flagellates exhibited a definite circadian rhythm. In the middle of the investigation a heavy storm broke out which was followed by the disappearance of differences between different layers of water. Storm-induced destratification is described by cluster-analysis. Abundances of dominant species changed differently in connection with the storm. Numbers of Nitzschia sp. increased due to stirring up from the sediment surface. Numbers of single-celled or colony-forming species (Cyclotella comta, Crucigenia quadrata, Coelosphaerium kuetzingianum) practically did not change. Numbers of all the three dominant filamentous species (Aphanizomenon fos-aquae f. klebahnii, Lyngbya limnetica, Planctonema lauterbornii) significantly decreased, which might be attributed to an unknown loss process and was followed by a competitive displacement by algae of small cell size. 相似文献
58.
59.
U. D. Bongale 《Plant and Soil》1981,60(2):289-293
Summary An attempt was made to study the number of species belonging to Cyanophyceae, Chlorophyceae and Bacillariophyceae in Lateritic,
Red and Black soils and also Dry lands (jowar, cotton and wheat) and Wet lands (paddy and sugar cane). Lateritic and black
soils had a poor algal flora and in general sandy soils were rich. Cyanophyceae appeared to be more resistant than Chlorophyceae
and Bacillariophyceae to desiccation.
Part of the Ph.D. Thesis approved by the Karnatak University (1976). 相似文献
60.
Synopsis A revitalized view of feeding by herbivorous marine fishes is sought through two questions. First, What characteristics of
major taxa of algae identify them as predictably high or low quality foods? Second, are marine algae valuable foods for fishes
which do not mechanically disrupt cell walls and do not harbor specialized enzymes or microbes capable of lysing cell walls?
Energy, ash and nutrient content of 16 species of marine algae were employed to assess food quality of fleshy red, green,
brown and calcareous red algae. On the basis of ash, calories, total protein and total lipid content, fleshy algae should
be superior to calcareous algae as foods for fishes; in addition, green algae should be superior to brown algae and brown
algae superior to red algae. When the probable digestibility of storage and extracellular carbohydrates is considered, green
and red algae are predicted superior to brown algae as food. Two species of damselfishes (Pomacentridae) from the Gulf of
California,Eupomacentrus rectifraenum andMicrospathodon dorsalis, eat red and green algae and ignore brown and calcareous algae. They feed, therefore, in a fashion consistent with predictions
based only on algal chemistry. These fishes absorb at least 20–24% of the biomass, 57–67% of the protein, 46–56% of the lipid
and 37–44% of the carbohydrate contained in algae eaten in the wild. Since these damselfishes do not masticate their food,
it appears that herbivorous fishes can digest major fractions of algal nutrients without mechanical destruction of algal cells. 相似文献