Ttansportation Corridors

In the context of global change, one of the major concerns is researchers' ability to predict the movements of populations and communities. It is accepted that the area of Arctic ecosystems will decrease under a warming climate, but it is not clear how plants and animals will migrate north, either individually or collectively. This concern has prompted a debate over the role of transportation corridors in plant movement and migration. Roads, railways, and rivers are widespread throughout the Arctic, connecting people and resources to the south more often than to the east or west. Such transportation corridors are dynamic areas in terms of concentrating settlements and human activities in otherwise remote lands, and many different types of surface disturbance regimes are associated with them. Among the proven disadvantages, perhaps the strongest empirical data are those supporting the role of corridors as avenues of successful nonnative flora introduction. Weedy or "ruderal" plants (species that are adapted to sites with recent disturbance), often of Mediterranean provenance, are rapidly dispersed by seeds, spores, and other propagules as new roads are built so that additional founder populations are readily established far from the source population. These data are abundant for ecosystems ranging north from boreal to Subarctic and even the Low Arctic. This was not the case in much of North America and Eurasia before World War II.

Another major effect of northern roads and railways is the direct alteration of hydrology. A railway or road exerts its maximum influence on the movement of surface water when it is aligned at right angles to the direction of water movement. In areas with an intersecting network of roads, flooded areas are common and often extremely difficult to drain. For example, a 7.0 km road constructed through a portion of flat, coastal lowland at Prudhoe Bay, Alaska, resulted in the flooding of 134 ha (18 ha km-1 of road). Subsequent effects of impeded drainage include changes in surface albedo (reflectivity), active layer and permafrost, soil temperature and decomposition, and an increase in aeolian sands and dust. These processes, moreover, are strongly interrelated and feedbacks among them are to be expected. In North America, the number of major northern roads increases each year, with several new highways in the planning stages for the western Canadian Arctic and northern Qu├ębec. New roads and a railway are currently under construction in conjunction with petroleum development across the reindeer pastures of Yamal Peninsula in northwest Siberia, and a road is proposed for facilitating mining on Svalbard.

0 0

Post a comment