Use of Restored Small Wetlands by Breeding Waterfowl in Prince Edward Island, Canada

Abstract Since 1990 under the Eastern Habitat Joint Venture over 100 small wetlands have been restored in Prince Edward Island, Canada. Wetlands were restored by means of dredging accumulated sediment from erosion to emulate pre‐disturbance conditions (i.e., open water and extended hydroperiod). In 1998 and 1999 we compared waterfowl pair and brood use on 22 restored and 24 reference wetlands. More pairs and broods of Ring‐necked Ducks, Gadwall, Green‐winged Teal, and American Black Ducks used restored versus reference wetlands. In restored wetlands waterfowl pair density and species richness were positively correlated with wetland/cattail area, percent cattail cover, and close proximity to freshwater rivers. In addition, a waterfowl reproductive index was positively correlated with percent cattail cover. Green‐winged Teal pair occurrence in restored wetlands was positively correlated with greater amounts of open water and water depths. American Black Duck pairs occurred on most (86%) restored wetlands. Restored small wetlands likely served as stopover points for American Black Duck broods during overland or stream movements, whereas they likely served as a final brood‐rearing destination for Green‐winged Teal broods. We suggest that wetland restoration is a good management tool for increasing populations of Green‐winged Teal and American Black Ducks in Prince Edward Island.     

A Comparison of Remote Sensing and Ground-Based Methods for Monitoring Wetland Restoration Success

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.     

Measuring Success: Evaluating the Restoration of a Grassy Eucalypt Woodland on the Cumberland Plain, Sydney, Australia

Abstract We compared the floristic composition and structure of restoration areas of eucalypt woodland with untreated pasture (control) and remnant vegetation (reference) in western Sydney. The restored areas comprised over 1,000 ha of abandoned pasture, which had been treated to reduce weeds and planted with seedlings of 26 native plant species raised from seed obtained locally from remnant vegetation. Plantings were carried out 0–9 years ago. Floristic composition was measured in quadrats using frequency scores and cover abundance. As far as possible treatments and restoration ages were replicated across sites. Ordination and analyses of similarity failed to distinguish the composition of restored vegetation from that of untreated pasture, which were both significantly different from that of remnant vegetation. There was a weak compositional trend with age of restored vegetation, but this was not in the direction of increasing resemblance to remnant vegetation. There was some evidence for convergence in structural features of restored with remnant vegetation, but this was at least partly attributed to plant growth. Subject to constraints imposed by the sampling design, environmental factors, and spatial variation were discounted as explanations for the results. The results therefore suggest either failure of restoration treatments or a restoration trajectory that is too slow to detect within 10 years of establishment. Our conclusions agree with those of similar studies in other ecosystems and support: (1) the need to monitor restoration projects against ecological criteria with rigorous sampling designs and analytical methods, (2) further development of restoration methods, and (3) regulatory approaches that seek to prevent damage to ecosystems rather than those predicated on replacing losses with reconstructed ecosystems.     

Restoration of eutrophied shallow softwater lakes based upon carbon and phosphorus limitation

Plant communities from oligotrophic, poorly buffered waters are seriously threatened by both, acidification and eutrophication/alkalinization. Acidification is mainly caused by atmospheric deposition of acidifying substances while eutrophication is often the result of inlet of nutrient enriched, calcareous brook- or groundwater. The plant production in very soft waters is often limited by low levels of inorganic carbon, nitrogen and/or phosphorus. This paper deals with the possibilities for restoration of formerly oligotrophic but now eutrophied and alkalinized softwater systems. Restoration based upon nitrogen limitation is not likely to be successful as the atmospheric deposition of nitrogen in The Netherlands is very high. Phosphorus limitation can also be a problem. One can stop the input of phosphorus and remove the mud layer, but the problem remains that also the deeper mineral sandy sediments are saturated with phosphate. A possible remedy, however, is a combination of carbon- and phosphorus limitation. Many plants from eutrophic environments never occur in very soft waters, probably as a result of carbon limitation. In addition, mobilisation of phosphate is much lower in waters with very low bicarbonate levels. Restoration of a former oligotrophic softwater lake by reducing the inlet of calcareous surface water, in combination with removal of the organic sediment layer, appeared to be very successful. Many endangered plant species such asIsoetes echinospora, Luronium natans, Deschampsia setacea andEchinodorus repens developed spontaneously from the still viable seedbank.     

Molecular markers of nuclear restoration gene Rf1 in sunflower using bulked segregant analysis-RAPD

Restoration of cytoplasmic male sterility (CMS) in sunflower was demonstrated to be controlled by polygenes by analysing 982 effective crosses among 109 self-crossed lines and 16 CMS lines. Two self-crossed lines and one CMS line with distinct genotypes were applied to creation of segregating populations for DNA bulks of the target gene Rfl. Bulked DNA was prepared in order to investigate single gene Rfl and its gene marker among polygenic characters at the same genetic background. Using 80 10-mer operon primers, 620 RAPD reactions were carried out between fertile and sterile DNA bulks. In about 800 loci, primary results showed that 8 were related to the restoration genes. Furthermore. 2 were confirmed as RAPD markers for gene Rfl by examining 9 maintenance and 7 restoration lines. This method is the improvement for bulked segregant analysis[1] with which markers of single gene of target can be identified rapidly among polygenic characters.     

The effects of recreated instream and ecotone structures on the fish fauna of an epipotamal river

Investigations of fifteen sections of seven Austrian epipotamal (barbel region) streams between 1981 and 1984 demonstrate the impact of instream river bed structures on fish communities. Reduced spatial heterogeneity due to river straightening resulted in decreasing species number, diversity, stock density and biomass. Reincreased variability of the river bed in the frame of a subsequent restructuring project improved all community-specific values significantly within a 3-year investigation period (1988–1990). Besides the regained habitat variability in form of riffle pool sequences and other instream structures, the newly created riparian zones obviously provided important niches, e.g. as refuge areas during flooding and as nursery grounds for fish fry. The positive effects of the recreated land/water ecotone are discussed with respect to river restoration projects.     

Rehabilitating degraded forests in Central Europe into self–sustaining forest ecosystems

There is a need for a consistent forest restoration strategy for the `Black Triangle', Central Europe. In the past 50 years, forests in this area have been heavily affected by industrial pollution. Recently, the amount of pollutants has decreased. This means that effective forest restoration programmes can be started. Forest decline must be seen as an ecological disturbance which cannot be solved by applying technical measures only. An ecosystem approach to forest restoration must be introduced into restoration policy and management. Basic principles and working methods of such an approach are briefly described and proposals are made for forest restoration policy, management and research in the area.     

Phosphorus eutrophication in the SW Frisian lake district 2. Phosphorus balances and simulation of reduction scenarios

The lakes and interconnecting canals in the S.W. Frisian lake district are highly eutrophic. In the mid-1980's a project on eutrophication and lake restoration research was started. This project was aimed at modelling water transport and phosphorus (P) dynamics and at simulating management scenarios. A simple dynamic P-balance model was used to calculate total phosphorus (TP) balances and to simulate three TP reduction scenarios in each of three lakes: Tjeukemeer, Groote Brekken and Slotermeer. The model covered three periods in 1985, 1986 and 1987. The external loads to Tjeukemeer were highest, moderate to Groote Brekken, and lowest to Slotermeer. The major P sources in the area were discharges from the surrounding polders, used mainly for agriculture, and from IJsselmeer.Despite a 75% TP-reduction in water from the surrounding polders the 0.07 mg l^–1 target level could be reached only occasionally in Tjeukemeer, while in the other two lakes this level was not even approached. The effect of a 75% reduction in water from IJsselmeer was greatest in Groote Brekken (but again approached the target only occasionally), moderate in Tjeukemeer and least in Slotermeer. The simulations showed that only a 75% reduction in both external loads (from polders and from IJsselmeer) will lead to achieving the target level in Tjeukemeer and Groote Brekken during the summer periods. In Slotermeer, a relatively isolated lake, other measures are necessary to reach the target level. The results are confirmed by an approximate theoretical analysis of the effects of load reduction.     

Water quality research in Loosdrecht lakes: the salient features

Ecosystem research by the working group Water Quality Research Loosdrecht lakes (WQL) was carried out from 1979 to 1990. A coordinated research programme, involving several research institutes and laboratories in The Netherlands, was initiated in 1983, i.e. a year before the reduction of external phosphorus loading by stripping, became effective. The paper summarizes the main results, with emphasis on insight they provide into the lake ecosystems.     

Soil restoration under pasture after lignite mining: Management effects on soil biochemical properties and their relationships with herbage yields

The recovery of soil biochemical properties under grazed, grass-clover pasture, after simulated lignite mining, was studied over a 5-year period in a mesic Typic Dystrochrept soil at Waimumu, Southland, New Zealand. The restoration procedures involved four replacement treatments, after A, B, and C horizon materials had been separately removed, from all except the control, and stockpiled for 2–3 weeks. In each replacement treatment, the effects of ripping to 1.8 m depth, mole drainage, and the use of fertilizer nitrogen were also investigated.Replacement treatment markedly influenced the recovery of herbage production and soil organic C and total N contents, N mineralization, microbial biomass (as indicated by mineral-N flush) and invertase and sulphatase activities. The effectiveness of replacement treatments decreased in the order: 1. control (no stripping or replacement). 2 A, B, and C horizon materials replaced in the same order. 3. A, B, and C horizon materials each mixed with an equal amount of siltstone overburden and replaced in order, 4. A and B horizon materials mixed before replacing over C horizon material.Ripping increased herbage production, net N mineralization, and to some extent microbial biomass. Drainage had little, if any, effect.Fertilizer N also stimulated herbage production, but depressed clover growth. Over 2.5 years, it had little detectable effect on the soil properties.Increases in soil invertase and, to a lesser extent, sulphatase activity during the trial were closely related to changes in herbage production. Microbial biomass increased more rapidly than did soil organic C in the early stages of the trial.Rates of net N mineralization strongly suggest that N availability would have limited pasture growth, especially in the treatments with mixed soil materials.