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71.
Abstract Efficient and accurate vegetation sampling techniques are essential for the assessment of wetland restoration success. Remotely acquired data, used extensively in many locations, have not been widely used to monitor restored wetlands. We compared three different vegetation sampling techniques to determine the accuracy associated with each method when used to determine species composition and cover in restored Pacific coast wetlands dominated by Salicornia virginica (perennial pickleweed). Two ground‐based techniques, using quadrat and line intercept sampling, and a remote sensing technique, using low altitude, high resolution, color and color infrared photographs, were applied to estimate cover in three small restoration sites. The remote technique provided an accurate and efficient means of sampling vegetation cover, but individual species could not be identified, precluding estimates of species density and distribution. Aerial photography was determined to be an effective tool for vegetation monitoring of simple (i.e., single‐species) habitat types or when species identities are not important (e.g., when vegetation is developing on a new restoration site). The efficiency associated with these vegetation sampling techniques was dependent on the scale of the assessment, with aerial photography more efficient than ground‐based sampling methods for assessing large areas. However, the inability of aerial photography to identify individual species, especially mixed‐species stands common in southern California salt marshes, limits its usefulness for monitoring restoration success. A combination of aerial photography and ground‐based methods may be the most effective means of monitoring the success of large wetland restoration projects.  相似文献   
72.
Changes in vegetation structure and biogeography due to climate change feedback to alter climate by changing fluxes of energy, moisture, and momentum between land and atmosphere. While the current class of land process models used with climate models parameterizes these fluxes in detail, these models prescribe surface vegetation and leaf area from data sets. In this paper, we describe an approach in which ecological concepts from a global vegetation dynamics model are added to the land component of a climate model to grow plants interactively. The vegetation dynamics model is the Lund–Potsdam–Jena (LPJ) dynamic global vegetation model. The land model is the National Center for Atmospheric Research (NCAR) Land Surface Model (LSM). Vegetation is defined in terms of plant functional types. Each plant functional type is represented by an individual plant with the average biomass, crown area, height, and stem diameter (trees only) of its population, by the number of individuals in the population, and by the fractional cover in the grid cell. Three time‐scales (minutes, days, and years) govern the processes. Energy fluxes, the hydrologic cycle, and carbon assimilation, core processes in LSM, occur at a 20 min time step. Instantaneous net assimilated carbon is accumulated annually to update vegetation once a year. This is carried out with the addition of establishment, resource competition, growth, mortality, and fire parameterizations from LPJ. The leaf area index is updated daily based on prevailing environmental conditions, but the maximum value depends on the annual vegetation dynamics. The coupling approach is successful. The model simulates global biogeography, net primary production, and dynamics of tundra, boreal forest, northern hardwood forest, tropical rainforest, and savanna ecosystems, which are consistent with observations. This suggests that the model can be used with a climate model to study biogeophysical feedbacks in the climate system related to vegetation dynamics.  相似文献   
73.
Archaeobotanical results based on a limited number of samples from three aceramic sites dating from 9800 to 7800 B.P., which are under excavation in the valley of the Middle Euphrates, are discussed. The finds are presented simply by presence, and are compared to the contemporary vegetation and finds from similar sites. Carbonised plant remains recovered by flotation from levels dated to between 9800 and 9200 B.P. (Dja'de and Jerf al Ahmar) indicate that wild cereals (einkorn wheat, rye and barley) and pulses (lentils, pea and bitter vetch) were exploited. Other plants such as wild grasses, Pistacia, wild almond and oak, suggest that the local vegetation provided a rich diversity of resources. A study of possible weed taxa is being carried out in order to see whether this assemblage could be used to identify the cultivation of morphologically wild cereals for this period. Ninth millennium B.P. levels at Halula see the appearance of domestic crops such as emmer, naked wheat and barley, but wild-type cereals persist. The cultivars appear to have been introduced from elsewhere and later ninth millennium B.P. species include olive and flax. Ash, vine, maple, plane, alder and elm from the gallery forest, wild rye, wild einkorn, deciduous oak, wild almond, Pistacia, and Pyrus, from the hinterland, indicate cooler conditions.  相似文献   
74.
浙江海岛盐生植被研究Ⅱ──天然植被类型及开发利用   总被引:4,自引:0,他引:4  
天然盐生植被是海岛盐生植被的主体,类型丰富,分布广泛,在海岛植被的研究及开发利用中占据重要地位。目前,天然盐生植被的分类尚无统一标准与系统。本文根据作者1990~1993年在浙江海岛用样方法(H.VonPost,1851;陈彦卓,1965)测定的样地数据,参照《中国植被》的分类方法,根据群落的外貌与结构、生态地理、动态和种类组成等特征进行分类,其中对群系级单位侧重于种类组成,并采用建群植物的重要值(J.T.CurtisandR.P.McIntosh,1951)作为分类的定量指标。据此,浙江海岛天然盐生植被可划分为3个植被型、8个群系组、18…  相似文献   
75.
对淤泥湖水生植被的天然恢复过程、群落组成、结构、功能与动态等进行了定位研究(1992~1995).该湖水生植物共有20科29属41种.4种生活型的植物种类在该湖均有分布,以沉水草本(15种)和挺水草本(13种)为多.8个分布区类型中世界广布成分16种和东亚成分10种.群落结构包括层次结构和层片结构.该彻共有8个群落类型;群落现存量3208.8g·m-2,全湖植被资源贮量为16365.2t.  相似文献   
76.
77.
Communities of plant-parasitic nematodes collected from five different vegetation types (canopy woodland, savannah, gallery forest, cultivated perennial, and annual plants) and soils (yellowish red latosols, dark red latosols, arenosols, acrisols, and gleysols) were studied. Ninety percent of the soil samples collected from savannah contained at least four genera of plant-parasitic nematodes. The highest population densities were recovered from perennial plants and from acrisols. Nematodes from perennial and annual plants formed one cluster, which had a similar flexible-beta distance to that from the gallery forest. The distance in the native savannah and in canopy woodland was very different. Distance values for the soil aspect were similar for arenosols, yellowish, and dark red latosols. The value for acrisols was much larger than for the other soils.  相似文献   
78.
A combined palynological and phytosociological methodological approach was used in the reconstruction of precultural forest vegetation in a small model area of Bílý Kí-Janík in the Moravskoslezské Beskydy mountains (northwest Slovakia). Two pollen diagrams show the predominance of Fagus sylvatica, Abies alba and Picea abies in past natural mixed forests. The present-day occurrence and distribution of forest herbs allow the differentiation of five past vegetation types with above mentioned forest climax trees covering the area before the beginning of human interference. A map of reconstructed natural vegetation is presented which can be used for revitalization of present secondary spruce plantations, heavily affected by air pollution.  相似文献   
79.
The floristic and structural differentiation of vegetation along the altitudinal gradient in four subalpine forests of different developmental stages on Mt. Fuji has been studied. Near the forest limit a micropattern of vegetation corresponding to the altitudinal zonation has been observed which elucidated the mechanisms of development of the vegetation zonation. As to early stages of vegetation development only two types can be distinguished: the volcanic desert above 1500 m and the pioneer forests below. As to later stages a differentiation of subzones includes from higher to lower altitudes: the Alnus maximowiczii, Betula ermanii, Abies veitchii and Tsuga diversifolia forests. Larix leptolepis and Sorbus americana ssp. japonica, appear as co-dominants in ecotonal communities between the principal subzones and are also important pioneers in early stages. Similarity analyses reveal that the upper subalpine Alnus-Betula forests can be regarded as early successional phases of the climax Abies-Tsuga forests of the lower subalpine zone. The regular arrangement of A. maximowiczii-B. ermanii-A. veitchii is studied along the gradient from the margin to the interior of the forest growing near the forest limit where locally favourable conditions prevail. Growth form, height growth, photosynthetic activity, seed supply, and seedling distribution of the three principal species have been compared, as well as biomass and production relations in contiguous forests of these species. The marginal Alnus type community is productive and disturbance-tolerant, and has a wide ecological and sociological amplitude along the gradient, while the central Abies community is accumulative and disturbance-intolerant, and has a narrower tolerance range, but is superior in competition under stable habitat conditions. A vegetation organization, ‘temporal multi-storeyed structure’, is suggested which means that a zonal pattern of vegetation within a climax region develops by successive replacement of successional species along an environmental gradient.  相似文献   
80.
Three associations of the Nanocyperion teneriffae Lebrun 1947 (Sporoboletalia festivi Lebrun 1947) are described. They are physiognomically and ecologically similar to associations of the Mediterranean Isoeto-Nanojuncetea Br.-Bl. et Tx. 1943 and Helianthemetalia guttati Br.-Bl. 1940. They are rich in very specialized therophytes and resurrection plants.
Meinem Lehrer H. Walter, Stuttgart gewidmet.  相似文献   
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