Temporal variation of invertebrate communities in perennial wetlands

Temporal variability of wetland invertebrates was examined at two scales—inter-annual and seasonal—to determine whether it could confound results of spatially extensive wetland surveys. The inter-annual study collected samples from the Bullock Creek wetland (BCW) each summer for 4 years; the seasonal study collected samples quarterly for 14 months from two wetlands (Mahinapua and Shearer). Water pH, temperature and conductivity were also measured concurrently. Three site groupings were identified in BCW, reflecting differences in physical–chemical parameters, which varied temporally but never converged. Few annual differences were found in invertebrate relative abundances in BCW, and ordination produced three sample groups, each of which contained distinct invertebrate communities. Water pH differed consistently between Mahinapua and Shearer. Relative abundances of nine taxa varied seasonally; however, ordination showed that both wetlands always supported discrete invertebrate communities. These results suggest that temporal fluctuations of invertebrates do not affect our ability to discriminate between wetlands.     

Carbon storage in the grasslands of China based on field measurements of above- and below-ground biomass

Above- and below-ground biomass values for 17 types of grassland communities in China as classified by the Chinese Grasslands Resources Survey were obtained from systematic replicated sampling at 78 sites and from published records from 146 sites. Most of the systematic samples were along a 5,000-km-long transect from Hailar, Inner Mongolia (49°15′N, 119°15′E), to Pulan, Tibet (30°15′N, 81°10′E). Above-ground biomass was separated into stem, leaf, flower and fruit, standing dead matter, and litter. Below-ground biomass was measured in 10-cm soil layers to a depth of 30 cm for herbs and to 50 cm for woody plants. Grassland type mean total biomass carbon densities ranged from 2.400 kg m⁻² for swamp to 0.149 kg m⁻² for alpine desert grasslands. Ratios of below- to above-ground carbon density varied widely from 0.99 for tropical tussock grassland to 52.28 for alpine meadow. Most below-ground biomass was in the 0–10 cm soil depth layer and there were large differences between grassland types in the proportions of living and dead matter and stem and leaf. Differences between grassland types in the amount and allocation of biomass showed patterns related to environments, especially aridity gradients. Comparisons of our estimates with other studies indicated that above-ground biomass, particularly forage-yield biomass, is a poor predictor of total vegetation carbon density. Our estimate for total carbon storage in the biomass of the grasslands of China was 3.32 Pg C, with 56.4% contained in the grasslands of the Tibet-Qinghai plateau and 17.9% in the northern temperate grasslands. The need for further standardized and systematic measurements of vegetation biomass to validate global carbon cycles is emphasised.     

Macrobenthic communities of the Pechora Sea: the past and the present on the threshhold of the prirazlomnoye oil-field exploitation

On data of bottom sampling, carried out by means of grab, trawl and underwater photography in August–September of 1993 in the area of the Pechora Sea, quantitative regularities of macrobenthos distribution are described for the ecological monitoring purposes. Maps of -biodiversity and biomass indices, bottom communities and trophic zones, singled out by dominant method, are presented. Assessment of structure changes of the investigated area bottom communities during the last 60–70 years is fulfilled. It is shown that the described communities on the whole are of natural undisturbed character and that the revealed changes are within the natural fluctuations in the abundance of benthic populations or may be interpreted in terms of methodical differences in the data analysis and generalization by different authors.     

Problems of Artisanal Marine Fishermen in Ghana: The Way Ahead

Marine fishing is an important traditional economic activity of the coastal communities in Ghana and contributes over 80 per cent of the total fish catch. The traditional sector accounts for over 75 per cent of the marine catch. The small-scale artisanal marine fishing communities, which contribute less than 30 per cent of the traditional sector landings, are generally characterised by low levels of production and, hence, low incomes, poor living conditions and chronic indebtedness. Based on field data on artisanal fishing communities in the Ahanta West and Gomoa districts, this paper summarises the chronic problems of artisanal fishermen that perpetuate their precarious existence in the coastal environment. Overcoming the problems of these increasingly marginalised and migrant communities calls for the provision of supplementary employment opportunities, improved social services and the formation of solidarity groups to enhance access to micro credit. These would require technical and management training as well as support services from government and non-governmental organisations (NGOs).     

Australian geography seen from afar: through a glass darkly

Having been invited to contribute an external view of Australian geography, I concluded that such a task was impossible—that geographers elsewhere do not have a general view of Australian geography. I maintain that this is neither surprising nor significant, setting the argument within the context of a discipline fragmented along four major cleavage lines. Because of these cleavages, most geographers (like most other academics) work in small intellectual communities which are necessarily ‘parochial’: as a consequence, the discipline is characterised by a series of parts that do not make a coherent whole.     

长江口3个不同生态系的浮游植物群落

初步研究表明 ,长江口及邻近海域存在 3个不同的生态系 ,与以盐度划分的水团 (长江河口水、长江冲淡水、外海水 )基本一致 ,每个生态系包含 1个浮游植物群落。 1997～ 2 0 0 0年的 7个航次调查中共鉴定出浮游植物 393种 ,其中大部分为硅藻。长江口的浮游植物基本可归为 5个类群 :淡水类群、河口半咸水类群、近岸低盐性类群、外海高盐类群、海洋广布性类群。它们自西向东在 3个生态系中有明显的分布格局 ,并且随着长江径流量的变化而摆动和变化。根据栖息水域的盐度浮游植物可分为 3个群落 :河口群落、冲淡水低盐群落、外海高盐群落。     

Adaptive Strategies at the Ecosystem Level: Examples from Two Benthic Marine Systems

Abstract. Adaptive strategies on the ecosystem level are demonstrated using the properties of systems (community biomass, trophic level energy transfer). Development of stabilizing storages versus rapid turnover and energy transfer through the grazing food chain versus detritus food chain are shown to be adaptive processes leading towards an optimal performance of the system. A model of incorporation and processing of information in ecosystems is proposed which contains the essential features of evolution. The persistence of "interspecific altruism" is discussed.     

ISLANDS AS PLACES OF BEING AND BELONGING*

ABSTRACT. Islands, traditionally important units of research and analysis in ethnographic research, have come to be viewed as a problematic unit of analysis, as anthropologists have realized the close integration of island societies within the wider world. This article argues that islands are still useful and fruitful foci of research, if their particular character is explored from an islandic point of view. Through life‐story interviews conducted in three large, dispersed families of Caribbean origin, the article demonstrates that islands may be usefully conceptualized as sociocultural constructs that constitute important anchoring points as well as sources of identification for migrants and their descendants.