Three common Appalachian plant species (Juncus effusus L., Scirpus validus L., and Typha latifolia L.) were planted into small-scale constructed wetlands receivingprimary treated wastewater. The experimental design includedtwo wetland gravel depths (45 and 60 cm) and five plantingtreatments (each species in monoculture, an equal mixture of the three species, and controls without vegetation), with two replicates per depth × planting combination. Inflow rates (19 L day-1) and frequency (3 times day-1) were designed to simulate full-scale constructed wetlands as currently used for domestic wastewater treatmentin West Virginia. Influent wastewater and the effluent from each wetland were sampled monthly for ten physical, chemical and biological parameters, and plant demographic measurements were made. After passing through these trough wetlands, the average of all treatments showed a 70% reduction in total suspended solids (TSS) and biochemical oxygen demand (BOD), 50 to 60% reduction in nitrogen (TKN), ammonia and phosphate, anda reduction of fecal coliforms by three orders of magnitude. Depth of gravel (45 or 60 cm) had little effect on wetland treatment ability, but did influence Typha and Scirpus growth patterns. Gravel alone provided significant wastewater treatment, but vegetation further improved many treatment efficiencies. Typha significantly out-performedJuncus and Scirpus both in growth and in effluent quality improvement. There was also some evidence that the species mixture out-performed species monocultures.Typhawas the superior competitor in mixtures, but a decline in Typha growth with distance from the influent pipe suggested that nutrients became limiting or toxicities may have developed. 相似文献
Much hill land pasture in the Appalachians is brush infested. Reclamation procedures which are low cost and require low input are needed to provide hill land pasture owners with ways to maintain production on these lands. A field experiment was carried out to evaluate the effectiveness of grazing either sheep ( Ovis sp.) or goats ( Capra sp.) separately or in combination for brush clearing on hill land pasture. Cutting or herbicide followed by grazing with sheep or goats were also compared. The experiment was conducted on a 1.8 ha powerline right of way for five years (1986 to 1990). Goats reduced brush cover from 45% to just over 15% in one year. Sheep took 3 years to bring about the same result. Cutting and herbicide application increased animal effectiveness, primarily that of sheep, but increased costs. Three year variable costs for brush clearing with goats were estimated at $33 ha-1, sheep cost was $262 ha-1, while cutting costs were $133 and herbicide $593 ha-1. Brush was cleared more cost effectively and rapidly by goats, but at the end of 5 years all treatments reduced brush cover to 2%. 相似文献
Competitive effects of dense herbaceous vegetation (ground cover) can inhibit forest restoration on mine sites. Here we review the evidence of ground cover interactions with planted tree seedlings on coal surface mines of the eastern US, discuss recent research into these interactions, and draw conclusions concerning ground cover management when restoring forests on reclaimed coal mines. Reclaimed mine sites have a high potential to support productive forests, however forest establishment is inhibited by reclamation practices that included soil compaction, and the seeding of competitive ground covers. In the first few years after tree planting, a dense ground cover of grass and legume species commonly seeded on mine sites often affect growth and survival negatively. Herbaceous vegetation providing less extensive and competitive ground coverage may either facilitate or inhibit tree establishment, depending on site conditions. The use of quality planting stock promotes the competitive ability of seedlings by improving nutrient status and the ability to capture available resources. Herbaceous species have contrasting functional characteristics, and thus compete differently with trees for available resources. Negative interactions with trees are more frequently reported for non-native cool-season grasses than for native warm-season grasses, while the effects of legumes change over time. Further research is needed to fully understand the mechanisms of tree/ground cover interactions. The development of seeding mixes that can control erosion, facilitate survival and growth of planted trees, and allow establishment by unplanted native species would aid forest restoration on eastern US, coal mines.