This paper describes the short-term responses of tundra vegetation and soils to aeolian sand and dust emanating from anthropogenically-bared surfaces in the low-arctic region of northwestern Siberia. Such surfaces, including roads and quarries, are increasing substantially each year as the region undergoes massive gas- and oil-producing development. Data are presented which emphasize the ‘cumulative’ impacts of corridor construction, namely those effects which are measurable laterally, at some distance from the actual surfaces of roads and quarries, four years after their creation. In particular, changes in plant communities are documented, in addition to the chemistry and macronutrient status of mineral soils and dominant vascular plants and mosses, respectively, as affected by road-dust. Dramatic changes in plant community composition and cover were evident up to 200 m downwind from a ‘typical’ sand quarry. Although a few species appeared to respond favourably to rapid sand deposition, the great majority that were beset with it have declined in status or disappeared altogether. The exceptions were those growth-forms having the ability to keep perennating buds at or above the surface of the deepening sand (e.g. Betula nana, Salix spp., and Polytrichum spp.). The most pronounced decreases recorded were among lichens, hepatics, Sphagnum spp., and pleurocarpous mosses. The decline in Sphagnum spp., which dominate the moss layer and contribute much of the hummock-hollow microtopography, is already having a profound impact on community structure by virtually eliminating surface heterogeneity. Rubus chamaemorus is one of the dominant plants found in the mires of the Yamal Region, and its fruit is coveted by the aboriginal Nenets population. Sixty-two per cent fewer berries than in similar areas elsewhere were recorded within 35 m of the eastern (leeward) edge of the road/railway ‘corridor’, as were reductions in the cover/ abundance and frequency of many plants, especially cryptogams. Over the long-term, we might expect additional changes to appear in the chemical relationships of R. chamaemorus in mires adjoining the ‘corridor’ — in particular more elevated levels than formerly of calcium in rhizomes and leaves. Previous studies of nutrient addition to Sphagnumdominated systems have demonstrated community-level changes in composition, cover, and productivity, over the long-term. What is most striking in the present study is that significant changes in the chemistry of the mineral-soil layer (10 cm depth), and in three of the more prominent plants rooted in this zone (species of Betula, Carex, and Rubus), were measureable only four years after the completion of the road. Perhaps less surprising, but no less alarming, is the fact that the living tissues of poikilohydric* Sphagnum mosses, which provide a thick carpet over the soil surface and so reduce changes in water consitions, are exhibiting altered concentrations of most macronutrients which may change their ecological relationships. As the general trend in both vascular and non-vascular plants was one of elevated nutrient absorption, the long-term prognosis is not good for a community which thrives in nutrient-poor conditions. Many of the existing problems which have degraded terrestrial arctic ecosystems and ecocomplexes are the result of cumulative impacts which were either unpredictable or ignored in the past. Given that we now know something about the long-term nature of both direct and indirect anthropogenic impacts, efforts should be made to reduce the effect of those practices which are deemed most damaging to the greatest number of prominent species or areas of terrain. Sand and dust are by-products that are characteristic of many types of infrastructural development in the Arctic as well as elsewhere, and have proven capable of altering vegetation and soils far from their source. The scale of impact:scale-of-reponse ratio, while often grossly disproportional and perhaps previously unforeseen by developers, is no longer a question that is open to debate. However, the long-term implications for food-web dynamics, including the collection of plant products by aboriginal peoples, are unclear. Other pertinent questions include whether the shortterm responses that have been measured are reversible, and whether additional damages can be reduced or prevented. Nowhere are such issues more critical at present than in the vast gas- and oil-fields of northwest Siberia, where both wildlife and the nomadic pastoralist economy of the Nenets depend on a viable tundra ecocomplex. A prudent approach by ‘western’ companies considering involvement in development of the region would advocate moderate investments in relatively inexpensive, low-technology solutions. Such a programme might include the fencing of roads and quarries to reduce wind, coupled with the immediate revegetation of erodable surfaces by genetically-manipulated 'southern‘ grasses, to be followed by genuine restoration attempts with native flora wherever possible. In the absence of such efforts, oil-company assurances that they can do their work ‘without further disturbance of grazing grounds’ (Specter, 1994ft) will ring hollow. © 1995, Foundation for Environmental Conservation. All rights reserved.
|DOI - pysyväislinkit|
|Tila||Julkaistu - 1995|
|OKM-julkaisutyyppi||A1 Vertaisarvioitu alkuperäisartikkeli|