Global analysis of seagrass restoration: the importance of large‐scale planting Tập 53 Số 2 - Trang 567-578 - 2016
Marieke M. van Katwijk, Anitra Thorhaug, Núria Marbà, Robert J. Orth, Carlos M. Duarte, Gary A. Kendrick, Inge Althuizen, Elena Balestri, Guillaume Bernard, Marion L. Cambridge, Alexandra H. Cunha, Cynthia Durance, Wim Giesen, Qiuying Han, Shinya Hosokawa, Wawan Kiswara, Teruhisa Komatsu, Claudio Lardicci, Kun‐Seop Lee, Alexandre Meinesz, Masahiro Nakaoka, Katherine R. O’Brien, E.I. Paling, Chris Pickerell, Aryan M. A. Ransijn, Jennifer Verduin
Summary
In coastal and estuarine systems, foundation species like seagrasses, mangroves, saltmarshes or corals provide important ecosystem services. Seagrasses are globally declining and their reintroduction has been shown to restore ecosystem functions. However, seagrass restoration is often challenging, given the dynamic and stressful environment that seagrasses often grow in.
From our world‐wide meta‐analysis of seagrass restoration trials (1786 trials), we describe general features and best practice for seagrass restoration. We confirm that removal of threats is important prior to replanting. Reduced water quality (mainly eutrophication), and construction activities led to poorer restoration success than, for instance, dredging, local direct impact and natural causes. Proximity to and recovery of donor beds were positively correlated with trial performance. Planting techniques can influence restoration success.
The meta‐analysis shows that both trial survival and seagrass population growth rate in trials that survived are positively affected by the number of plants or seeds initially transplanted. This relationship between restoration scale and restoration success was not related to trial characteristics of the initial restoration. The majority of the seagrass restoration trials have been very small, which may explain the low overall trial survival rate (i.e. estimated 37%).
Successful regrowth of the foundation seagrass species appears to require crossing a minimum threshold of reintroduced individuals. Our study provides the first global field evidence for the requirement of a critical mass for recovery, which may also hold for other foundation species showing strong positive feedback to a dynamic environment.
Synthesis and applications. For effective restoration of seagrass foundation species in its typically dynamic, stressful environment, introduction of large numbers is seen to be beneficial and probably serves two purposes. First, a large‐scale planting increases trial survival – large numbers ensure the spread of risks, which is needed to overcome high natural variability. Secondly, a large‐scale trial increases population growth rate by enhancing self‐sustaining feedback, which is generally found in foundation species in stressful environments such as seagrass beds. Thus, by careful site selection and applying appropriate techniques, spreading of risks and enhancing self‐sustaining feedback in concert increase success of seagrass restoration.
Linking reductionist science and holistic policy using systematic reviews: unpacking environmental policy questions to construct an evidence‐based framework Tập 46 Số 5 - Trang 970-975 - 2009
Andrew S. Pullin, Teri Knight, Andrew R. Watkinson
Summary 1. There is a mismatch between broad holistic questions typically posed in policy formation and narrow reductionist questions that are susceptible to scientific method. This inhibits the two‐way flow of information at the science‐policy interface and weakens the impact of applied ecology on environmental policy. 2. We investigate the approaches to building policy in the health services as a model to help establish a framework in applied ecology and environmental management by which reductionist science can underpin decision making at the policy level. 3. A comparison of policy documents in the health and environmental sectors reveals many similarities in identifying approaches and specific interventions that might achieve policy objectives. The difference is that in the health services, information on the effectiveness of potential interventions is far more readily available through the collaborative process of systematic review. 4.
Synthesis and applications. Decision makers are increasingly looking to produce policies that are shaped by evidence through evidence‐based policy making. The approach that we outline here provides a framework for structuring systematic reviews to deliver the evidence on key policy issues in a way that will see a faster return and provide better use of the systematic review methodology in environmental management.
Restoration of drained peatlands in southern Finland: initial effects on vegetation change and CO<sub>2</sub> balance Tập 36 Số 5 - Trang 634-648 - 1999
Veli‐Matti Komulainen, Eeva‐Stiina Tuittila, Harri Vasander, Jukka Laine
Summary 1. Components of the CO2 balance for a drained minerotrophic fen and a drained ombrotrophic bog were measured for permanent plots using static chamber techniques for 1 year before and 2 years after a rewetting treatment in part of both sites. During the same period, changes in ground and bottom layer vegetation composition were monitored. 2. After the treatment, the water table rose, the average increase being 25 cm for the fen site and 20 cm for the bog site. In the untreated areas the average water table remained at the pretreatment level. 3. There was a clear change in vegetation composition in the rewetted area of the fen site where the cover of cottongrass Eriophorum vaginatum L. increased drastically. The change in vegetation composition seemed to be dependent on the nutrient status of the sites, being faster at the more nutrient‐rich fen site. 4. The rates of CO2 efflux from the soil surface decreased on those rewetted plots where all vegetation had been removed. In 1996, the CO2 efflux rates from the soil surface of the untreated plots were about twice as high as from the rewetted plots with a high water table. 5. The change in water table levels and vegetation composition affected the seasonal (mid‐May to end of September) CO2‐C balances. For the rewetted area of the fen site, the CO2‐C balance varied from 162 to 283 g m–2, being greatest in a plot with dense E. vaginatum cover and a high water table. For the rewetted area of the bog site, the CO2‐C balance varied from 54 to 101 g m–2, being greatest in a hollow‐level plot with a high water table and mire vegetation. For the untreated areas, the CO2‐C balance was close to zero (3 g m–2 at the bog site) or negative (–183 g m–2 at the fen site), when carbon fixation by the tree stand was omitted. 6. The results are encouraging from the practical point of view as restoration of both fen and bog sites initiated vegetation succession and CO2‐C balance development towards those of pristine mires.
REVIEW: Reducing the ecological consequences of night‐time light pollution: options and developments Tập 49 Số 6 - Trang 1256-1266 - 2012
Kevin J. Gaston, Thomas W. Davies, Jonathan Bennie, John Hopkins
Summary
Much concern has been expressed about the ecological consequences of night‐time light pollution. This concern is most often focused on the encroachment of artificial light into previously unlit areas of the night‐time environment, but changes in the spectral composition, duration and spatial pattern of light are also recognized as having ecological effects.
Here, we examine the potential consequences for organisms of five management options to reduce night‐time light pollution. These are to (i) prevent areas from being artificially lit; (ii) limit the duration of lighting; (iii) reduce the ‘trespass’ of lighting into areas that are not intended to be lit (including the night sky); (iv) change the intensity of lighting; and (v) change the spectral composition of lighting.
Maintaining and increasing natural unlit areas is likely to be the most effective option for reducing the ecological effects of lighting. However, this will often conflict with other social and economic objectives. Decreasing the duration of lighting will reduce energy costs and carbon emissions, but is unlikely to alleviate many impacts on nocturnal and crepuscular animals, as peak times of demand for lighting frequently coincide with those in the activities of these species. Reducing the trespass of lighting will maintain heterogeneity even in otherwise well‐lit areas, providing dark refuges that mobile animals can exploit. Decreasing the intensity of lighting will reduce energy consumption and limit both skyglow and the area impacted by high‐intensity direct light. Shifts towards ‘whiter’ light are likely to increase the potential range of environmental impacts as light is emitted across a broader range of wavelengths.
Synthesis and applications. The artificial lightscape will change considerably over coming decades with the drive for more cost‐effective low‐carbon street lighting solutions and growth in the artificially lit area. Developing lighting strategies that minimize adverse ecological impacts while balancing the often conflicting requirements of light for human utility, comfort and safety, aesthetic concerns, energy consumption and carbon emission reduction constitute significant future challenges. However, as both lighting technology and understanding of its ecological effects develop, there is potential to identify adaptive solutions that resolve these conflicts.
Impacts of salvage logging on biodiversity: A meta‐analysis Tập 55 Số 1 - Trang 279-289 - 2018
Simon Thorn, Claus Bässler, Roland Brandl, Philip J. Burton, Rebecca E. Cahall, John L. Campbell, Jorge Castro, Chang‐Yong Choi, Tyler Cobb, Daniel C. Donato, Ewa Durska, Joseph B. Fontaine, Sylvie Gauthier, Christian Hébert, Torsten Hothorn, Richard L. Hutto, Eun‐Jae Lee, Alexandro B. Leverkus, David B. Lindenmayer, Martin К. Obrist, Josep Rost, Sebastian Seibold, Rupert Seidl, Dominik Thom, Kaysandra Waldron, Beat Wermelinger, Maria‐Barbara Winter, Michał Żmihorski, Jörg Müller
Abstract
Logging to “salvage” economic returns from forests affected by natural disturbances has become increasingly prevalent globally. Despite potential negative effects on biodiversity, salvage logging is often conducted, even in areas otherwise excluded from logging and reserved for nature conservation, inter alia because strategic priorities for post‐disturbance management are widely lacking.
A review of the existing literature revealed that most studies investigating the effects of salvage logging on biodiversity have been conducted less than 5 years following natural disturbances, and focused on non‐saproxylic organisms.
A meta‐analysis across 24 species groups revealed that salvage logging significantly decreases numbers of species of eight taxonomic groups. Richness of dead wood dependent taxa (i.e. saproxylic organisms) decreased more strongly than richness of non‐saproxylic taxa. In contrast, taxonomic groups typically associated with open habitats increased in the number of species after salvage logging.
By analysing 134 original species abundance matrices, we demonstrate that salvage logging significantly alters community composition in 7 of 17 species groups, particularly affecting saproxylic assemblages.
Synthesis and applications. Our results suggest that salvage logging is not consistent with the management objectives of protected areas. Substantial changes, such as the retention of dead wood in naturally disturbed forests, are needed to support biodiversity. Future research should investigate the amount and spatio‐temporal distribution of retained dead wood needed to maintain all components of biodiversity.