Habitat Restoration Techniques Research Articles

Microbial community composition of translocated ancient woodland soil: a case study

Soil translocation is an ecological habitat restoration technique, which consists of moving the entire topsoil from a donor site to a chosen receptor site. We investigated soil chemistry and microbiology changes three growing seasons after the salvage of semi‐ancient woodland soil (0.94 ha) to a nearby receptor pasture due to road widening works (Kent, United Kingdom). We sampled (1) Intact woodland soils adjacent to the area of soils that was translocated to represent the lost donor site; (2) The soil from three growing seasons after it had been translocated; and (3) Grassland soils adjacent to the translocated soil to represent the original receptor site. The intention was to ascertain if shifts in soil chemistry and microbial community composition (phospholipid fatty acid analysis, PLFA) occurred due to soil translocation. PLFA signature biomarkers demonstrated the overall microbial community profile of the translocated and woodland soils were similar; however, salvaged soils had a 40% increase in the arbuscular mycorrhizal fungi bioindicator fatty acid 16:1ω5, a 10% decrease in the Gram‐positive bacterial fatty acids, and increased pH (5.01–5.77) compared to the original donor woodland soil. Microbial community composition (PLFA) correlated well with soil pH across all sites. Considering that pH increases with soil depth in this location, it is likely that mixing of soil horizons during translocation increased the topsoil pH causing changes in the soil microbial communities. We concluded that after three growing seasons, the chemical and microbial properties of the salvaged soil were characteristic of a woodland soil but showed signs of disturbance.

Stability in reproductive timing and habitat usage of Chinook salmon across six years of varying environmental conditions and abundance

AbstractThe spatial and temporal distribution of spawning activity by autumn‐run Chinook salmon Oncorhynchus tshawytscha (Walbaum) was examined across multiple years. The study period included two years of extreme drought conditions when water temperatures in the spawning reach of the Stanislaus River were considered sub‐optimal for spawning and egg incubation. Despite varying levels of superimposition, redd counts and densities remained stable and positively associated with river location, indicating that superimposition may be driven by habitat preference rather than the absence of suitable spawning locations. Spawning occurred slightly later during drought years (6–10 days later compared with wetter years). This delay was attributable to deferred migration instead of deferred spawning, and the majority of redds were constructed at water temperatures exceeding the optimal temperature range. As a consequence, estimates of juvenile production during 2014 and 2015 were among the lowest on record. These findings may be related in part to the high hatchery contribution to the population, above‐average temperatures during spawning and incubation, and superimposition rates. Management recommendations include adequate cold‐water storage in the upstream reservoir, refined spawning habitat restoration techniques in the light of superimposition rates and, on a broader system scale, actions that reduce the amount of stray hatchery Chinook salmon.

Evaluation of the removal of impassable barriers on anadromous salmon and steelhead in the Columbia River Basin

AbstractDespite the popularity of barrier removal as a habitat restoration technique, there are few studies that evaluate the biological effects of restored stream crossings. An extensive post‐treatment study design was used to quantify fish populations (e.g. species, life stage, abundance) and habitat attributes (e.g. gradient, geomorphic channel units) at 32 culvert removal or replacement projects to determine their effectiveness in restoring habitat access for juvenile salmon, Oncorhynchus spp., and steelhead, O. mykiss (Walbaum), in the Columbia River Basin, USA. Anadromous fish (steelhead, Chinook salmon O. tshawytscha [Walbaum]) abundance, juvenile steelhead abundance and habitat conditions were not significantly different between paired reaches (i.e. upstream and downstream of former barrier sites), suggesting these sites are no longer full barriers to movement. This suggests that barrier removal projects on small Columbia Basin streams provide adequate fish passage, increased habitat availability and increased juvenile anadromous fish abundance immediately upstream of former barriers.

Habitat restoration benefits wild bees: A meta‐analysis

Abstract Pollinator conservation is of increasing interest in the light of managed honeybee (Apis mellifera) declines, and declines in some species of wild bees. Much work has gone into understanding the effects of habitat enhancements in agricultural systems on wild bee abundance, richness and pollination services. However, the effects of ecological restoration targeting “natural” ecological endpoints (e.g. restoring former agricultural fields to historic vegetation types or improving degraded natural lands) on wild bees have received relatively little attention, despite their potential importance for countering habitat loss. We conducted a meta‐analysis to evaluate the effects of ecological restoration on wild bee abundance and richness, focusing on unmanaged bee communities in lands restored and managed to increase habitat availability and quality. Specifically, we assessed bee abundance and/or richness across studies comparing restored vs. unrestored treatments and studies investigating effects of specific habitat restoration techniques, such as burning, grazing, invasive plant removal and seeding. We analysed 28 studies that met our selection criteria: these represented 11 habitat types and 7 restoration techniques. Nearly all restorations associated with these studies were performed without explicit consideration of habitat needs for bees or other pollinators. The majority of restorations targeted plant community goals, which could potentially have ancillary benefits for bees. Restoration had overall positive effects on wild bee abundance and richness across multiple habitat types. Specific restoration actions, tested independently, also tended to have positive effects on wild bee richness and abundance. Synthesis and applications. We found strong evidence that ecological restoration advances wild bee conservation. This is important given that habitat loss is recognized as a leading factor in pollinator decline. Pollinator responses to land management are rarely evaluated in non‐agricultural settings and so support for wild bees may be an underappreciated benefit of botanically focused management. Future restoration projects that explicitly consider the needs of wild bees could be more effective at providing nesting, foraging and other habitat resources. We encourage land managers to design and evaluate restoration projects with the habitat needs of wild bee species in mind.

Examining the role of terrestrial lichen transplants in restoring woodland caribou winter habitat

The development of habitat restoration techniques for restoring critical woodland caribou (Rangifer tarandus caribou) winter habitat will play an important role in meeting the management thresholds in woodland caribou recovery plans. The goal is to restore disturbed environments within critical winter habitat for the declining woodland caribou. Woodland caribou are diet specialists, utilizing lichen-rich habitat for forage during winter months. Cladonia sub-genus Cladina is the most frequently eaten species during this time. Herein, we provide: 1) A review of previously used methods for transplanting Cladonia sub-genus Cladina and their feasibility in restoring woodland caribou winter habitat; 2) A stepby- step protocol on how to carry out a terrestrial lichen transplant program (using Cladonia sub-genus Cladina and C. uncialis); and, 3) An evaluation of our protocol through the establishment of a case study in northern British Columbia. Our results indicate that transplanting C. sub-genus Cladina fragments is the most efficient technique for transplanting terrestrial lichen communities, but transplanting lichen ‘patches’ or ‘mats’ may also be effective.

A \u2018Landscape physiology\u2019 approach for assessing bee health highlights the benefits of floral landscape enrichment and semi-natural habitats

Understanding how anthropogenic landscape alteration affects populations of ecologically- and economically-important insect pollinators has never been more pressing. In this context, the assessment of landscape quality typically relies on spatial distribution studies, but, whether habitat-restoration techniques actually improve the health of targeted pollinator populations remains obscure. This gap could be filled by a comprehensive understanding of how gradients of landscape quality influence pollinator physiology. We therefore used this approach for honey bees (Apis mellifera) to test whether landscape patterns can shape bee health. We focused on the pre-wintering period since abnormally high winter colony losses have often been observed. By exposing colonies to different landscapes, enriched in melliferous catch crops and surrounded by semi-natural habitats, we found that bee physiology (i.e. fat body mass and level of vitellogenin) was significantly improved by the presence of flowering catch crops. Catch crop presence was associated with a significant increase in pollen diet diversity. The influence of semi-natural habitats on bee health was even stronger. Vitellogenin level was in turn significantly linked to higher overwintering survival. Therefore, our experimental study, combining landscape ecology and bee physiology, offers an exciting proof-of-concept for directly identifying stressful or suitable landscapes and promoting efficient pollinator conservation.

Can fish habitat restoration for rheophilic species in highly modified rivers be sustainable in the long run?

As a result of the ongoing loss of freshwater biodiversity, restoration of riverine habitats is high on the agenda. However, it remains controversial if commonly used instream fish habitat restoration techniques have sustainable effects in highly modified waterbodies.This study compared the effects of introducing four different instream structures (bank rip-rap, benched bank rip-rap, successively grown riparian wood and introduced dead wood, nine replicates each) on the fish community distribution in the river Günz in Germany. To assess the sustainability of the restoration measures, different time points (seven and two years after the restoration) and seasons were considered.Out of all measures, the introduction of dead wood had strongest effects on fish aggregation (biomass and density) as well as on species richness and diversity. Even seven years after restoration, no alterations in the density and demography of target species in conservation was detectable.These results suggest that instream habitat restoration measures are unlikely to fully mitigate deficiencies in highly modified rivers. Consequently, the investment of resources for aquatic restoration may have greater effects in systems that are closer to an optimal state, unless greater effort into restoration beyond the main channel is made.

Sediment macroinvertebrate community functioning in impacted and newly-created tidal freshwater habitats

Although experiencing strong anthropogenic pressures in many estuaries, the ecology of tidal freshwater areas remains largely undocumented. As part of a restoration project in the freshwater zone of the Schelde estuary (Belgium), a new tidal habitat restoration technique (Controlled Reduced Tide system, CRT) was hypothesised to successfully compensate for the impairment of contemporary habitats. The suitability of this newly-created habitat (CRT) and the estuary was investigated over a period of three years for its macroinvertebrate community development. In both the estuary and the CRT, habitats along a flooding gradient were monitored. Differences between the CRT and reference sites in community functioning were explored according to environmental characteristics and organism biological attributes using the RLQ ordination analysis together with the fourth-corner method. Frequently flooded reference sites exhibited environmental characteristics resulting from a hydrological shear stress. In the CRT, after a rapid removal of the terrestrial fauna at low and mid elevations, the low-energy hydrology led to taxonomic and functional enrichment. The RLQ analysis produced significant environmental filtering of biological attributes mainly related to the terrestrial–aquatic transition and to the environmental stressors. This provides an example of life history modification via estuarine ecosystem management.

Comparison of salt marsh creeks and ditches as habitat for nekton

Salt marshes are dynamic systems supporting a diverse assemblage of resident and transient nekton (free-swimming fish and decapod crustaceans). Within a marsh, many sub-habitats are used by nekton, including ditches and natural creeks. While the use of natural creeks is well doc- umented, the role of ditches as habitat for nekton remains less well known. The present study describes the nekton-support function of this prolific marsh sub-habitat, and compares it to tidal creeks. Sampling was conducted in the summer of 2008 in a microtidal, polyhaline salt marsh on Fire Island, NY, USA. Ditches and creeks were found to have different nekton communities. Creeks had significantly higher species richness and represented nearly all ditch species. Prolonged anoxia (up to 18 h) in ditches is suggested as a significant factor contributing to differences in the creek and ditch nekton community. Upper portions of ditches and creeks differed for resident nekton species, with higher species richness and density of the mummichog Fundulus heteroclitus in the upper portion of creeks than in the upper portion of ditches. Additional differences were seen in the nekton commu- nity composition of open and naturally plugged ditches, where the densities of individual species (such as F. heteroclitus, which was more abundant in open ditches) also differed. Ditches are a major habitat type in salt marshes of the northeastern USA, such as at the Fire Island marsh site studied here, and as efforts are considered to remove ditches from marshes as a habitat restoration technique, their nekton support function should be considered.

Gravel Addition as a Habitat Restoration Technique for Tailwaters

AbstractWe assessed the efficacy of passive gravel addition at forming catostomid spawning habitat under various flow regimes in the Cheoah River, a high‐gradient tailwater river in North Carolina. The purpose was to provide a case study that included recommendations for future applications. A total of 76.3 m3 (162 tons) of washed gravel (10–50 mm) was passively dumped down the streambank and into the channel in four locations. Gravel sites differed in terms of average reach slope, bank slope, and the initial volume of gravel added, which could have influenced gravel entrainment. Maps of gravel movement under various flows suggested that large‐magnitude discharges (≥113 m3/s) caused extensive migration; however, less obvious, smaller discharges (∼28 m3/s) still caused substantial shifting, which may influence the stability of catostomid spawning substrates. Following gravel addition, the proportion of gravel in the streambed was significantly higher at all gravel sites. However, comparisons of sites to reference stream reaches suggested that sand, gravel, and cobble were still extremely deficient. Additionally, the volume of gravel was inadequate to create gravel depths that provided suitable habitat for catostomid spawning. Although periodic, passive gravel additions may take years to provide suitable spawning habitat for some fish species, we found that river chub Nocomis micropogon utilized the newly added gravel for spawning.

Enhancing fauna habitat in grazed native grasslands and woodlands: use of artificially placed log refuges by fauna

To assess whether faunal habitat can be enhanced by using artificial refuges, and whether different species preferentially use refuges with differing structural characteristics, we monitored faunal usage of artificially placed log refuges in grazed semi-arid grasslands and woodlands in Terrick Terrick National Park in Victoria. In total, 1131 log refuges were placed at 91 sites across major vegetation types in the reserve. The effect of refuge age was assessed by comparing faunal usage between new refuges and 271 old refuges that had lain in situ for more than 15 years. Refuges were surveyed for fauna monthly between June 2000 and January 2001. Different species preferred refuges with different characteristics. Overall terrestrial fauna, and three native species (Diplodactylus tessellatus, Morethia boulengeri and Suta suta) in particular, were significantly more abundant beneath old refuges, whereas the introduced Mus musculus was significantly more abundant beneath new refuges. Five species (Crinia signifera, Morethia boulengeri, Menetia greyii, Sminthopsis crassicaudata and Suta suta) were significantly more abundant beneath Eucalyptus logs that were large, wide, partially decayed, contained many holes and/or covered many subterranean invertebrate holes. This study demonstrates the effectiveness of installing log refuges in grassy landscapes as a survey method for vertebrate fauna and as a potential habitat-restoration technique to help conserve grassland fauna.

Management of habitat for rehabilitation and enhancement of salmonid stocks

Most of the river systems in the British Isles have been subjected to anthropogenic influence to varying degrees over recent times, in many instances leading to deleterious impacts on salmonid habitat to the detriment of populations. This paper considers the range of management options that can be utilised to overcome habitat degradation. When examining salmonid habitat management three areas need to be taken into account: water quality, water quantity and the physical structure of the riverine environment. Although discussed separately, it should be remembered that these components of habitat are inter-related, and should be viewed as a continuum. Water quality problems include pollution from point and non-point source pollutants, although major improvements in the former have been achieved in recent years via the legislative framework and further benefits may be anticipated from the introduction of the Water Framework Directive. However, diffuse forms of pollutant, notably silt, still remain a significant threat to salmonid habitat and are yet to be tackled in any meaningful way. Changes to modern agricultural and land management practices are urgently required. Water quantity is impacted upon in a number of ways ranging from abstraction, which may reduce flows, through to land-use and flood defence that may alter the shape of the hydrograph changing velocities and influencing stream power. Society’s conflicting demands are bound to increase these pressures, although imaginative and integrated planning of schemes can avoid many deleterious impacts and actually provide benefits to salmonid populations, provided the ecological requirements of the species are taken into account. Arguably a more flexible and targeted approach to river regulation and abstraction would be beneficial to salmonid populations. Degradation of physical stream habitat has been widespread caused primarily by insensitive land-use practices, agriculture and flood defence. A significant commitment to consider long-term investment of resources will be required to negate the widespread deterioration in habitat caused by such damaging management techniques. Although a wide range of physical habitat restoration techniques have been demonstrated both in-stream and within the riparian zone with significant success, it is suggested that some form of land-use regulation is required to prevent further damage. Treating the root cause of the problems of deterioration with respect to water quality, quantity and physical habitat, and not just the symptoms, should be a fundamental priority for salmonid management in the 21st century.

An evaluation of instream habitat restoration techniques on salmonid populations in a Newfoundland stream

The effect of three types of habitat improvement structures were evaluated in Joe Farrell's Brook, a small second order salmonid stream in Newfoundland, Canada which had been adversly affected by forest harvesting activities. Fish populations and key habitat attributes were monitored prior to and, in two subsequent years after, boulder clusters, V-dams and half-log covers were placed at selected sites in channellised reaches. Boulder clusters proved to be the most effective structure, increasing densities of 0+, 1+, and 3+ juvenile Atlantic salmon (Salmo salar L.) after placement of instream devices. V-dams proved to be effective in increasing both the density of brook trout (Salvelinus fontinalis Mitchel) and Atlantic salmon through the creation of more diverse pool habitat. Half-log covers increased the number of juvenile salmon age 0+ through an increase in instream cover. These increases in salmonid abundance, however, were considered not to be solely attributed to an improvement in physical habitat. Other factors may influence or modify productivity of the stream reaches treated. For example, relative abundance, size distribution, biomass, and production are controlled by physical and chemical habitat variables and are modified through inter- and intra-specific competition. The general conclusion was that the restoration techniques increased habitat heterogenity and the degree of habitat complexity in channellised sections; therefore, reducing competition and increasing production. © 1997 John Wiley & Sons, Ltd.

An evaluation of instream habitat restoration techniques on salmonid populations in a Newfoundland stream

An evaluation of instream habitat restoration techniques on salmonid populations in a Newfoundland stream