Habitat suitability of the Wadden Sea for restoration of Zostera marina beds

A conceptual model is proposed, describing potential Zostera marina habitats in the Wadden Sea, based on reported data from laboratory, mesocosm and field studies. Controlling factors in the model are dynamics, degree of desiccation, turbidity, nutrients and salinity. A distinction has been made between a higher and a lower zone of potential habitats, each suitable for different morphotypes of Z. marina. The model relates the decline of Z. marina in the Wadden Sea to increased sediment and water dynamics, turbidity, drainage of sediments (resulting in increased degree of desiccation) and total nutrient loads during the twentieth century. The upper and lower delineation of both the higher and the lower zone of potential Z. marina habitats appear to be determined by one or a combination of several of these factors. Environmental changes in one of these factors will therefore influence the borderlines of the zones. The lower zone of Z. marina will be mainly affected by increased turbidity, sediment dynamics, degree of desiccation during low tide and nutrient load. The higher zone will be affected by increases in water and sediment dynamics, desiccation rates and nutrient loads. Potential Z. marina habitats are located above approx. –0.80 m mean sea level (when turbidity remains at the same level as in the early 1990s) in sheltered, undisturbed locations, and preferably where some freshwater influence is present. At locations with a high, near-marine, salinity, the nutrient load has to be low to allow the growth of Z. marina. The sediment should retain enough water during low tide to keep the plants moist. Our results suggest that the return of Z. marina beds within a reasonable time-scale will require not only suitable habitat conditions, but also revegetation measures, as the changes in the environment resulting from the disappearance of Z. marina may impede its recovery, and the natural import of propagules will be unlikely. Furthermore, the lower zone of Z. marina may require a genotype that is no longer found in the Wadden Sea. Received: 26 April 1999 / Received in revised form: 15 October 1999 / Accepted: 16 October 1999     

Loss of aboveground forest biomass and landscape biomass variability in Missouri,US

Disturbance regimes and forests have changed over time in the eastern United States. We examined effects of historical disturbance (circa 1813 to 1850) compared to current disturbance (circa 2004 to 2008) on aboveground, live tree biomass (for trees with diameters ≥13 cm) and landscape variation of biomass in forests of the Ozarks and Plains landscapes in Missouri, USA. We simulated 10,000 one-hectare plots using random diameters generated from parameters of diameter distributions limited to diameters ≥13 cm and random densities generated from density estimates. Area-weighted mean biomass density (Mg/ha) for historical forests averaged 116 Mg/ha, ranging from 54 Mg/ha to 357 Mg/ha by small scale ecological subsections within Missouri landscapes. Area-weighted mean biomass density for current forests averaged 82 Mg/ha, ranging from 66 Mg/ha to 144 Mg/ha by ecological subsection for currently forested land. Biomass density of current forest was greater than historical biomass density for only 2 of 23 ecological subsections. Current carbon sequestration of 292 TgC on 7 million ha of forested land is less than half of the estimated historical total carbon sequestration of 693 TgC on 12 million ha. Cumulative tree cutting disturbances over time have produced forests that have less aboveground tree biomass and are uniform in biomass compared to estimates of historical biomass, which varied across Missouri landscapes. With continued relatively low rates of forest disturbance, current biomass per ha will likely increase to historical levels as the most competitive trees become larger in size and mean number of trees per ha decreases due to competition and self-thinning. Restoration of large diameter structure and forested extent of upland woodlands and floodplain forests could fulfill multiple conservation objectives, including carbon sequestration.     

The “ReDune” index (Restoration of coastal Dunes Index) to assess the need and viability of coastal dune restoration

Overpopulation and deficient management of the worlds coastlines have seriously degraded beaches and coastal dunes, which are environments that provide valuable ecosystem services to society. The need to restore these ecosystems is increasingly urgent; however, this is a complex task since variables that differ widely (i.e. ecological, geomorphological and socio-economic) must all be taken into consideration. The present study proposes an index in the form of a weighted checklist named the “ReDune” Index (Restoration of coastal Dunes). This index allows decision makers and non-specialized professionals with some level of understanding of coastal dynamics to decide whether coastal dunes (foredunes) require and can be restored. Furthermore, in cases where more than one coastal dune system is to be evaluated, the index can distinguish which are in the most urgent need of restoration. The index consists of four sections: the first evaluates the degree of perturbation. The second determines the presence of endogenous and exogenous stress factors that may compromise the long-term stability of the restoration. The third section is focused on highlighting the abiotic and biotic elements that may facilitate restoration. Finally, the fourth section contributes to the identification of interests related to the conservation of the site and the provision of ecosystem services. The index was tested on 31 locations along the Gulf of Mexico, with differing sedimentary, ecological and human pressure characteristics and clearly distinguished between locations where restoration is urgent from those where it is not. This index can be applied on any foredune.     

Application of genetic markers to the discrimination of European Black Poplar (Populus nigra) from American Black Poplar (P. deltoides) and Hybrid Poplars (P. x canadensis) in Switzerland

European Black Poplar (Populus nigra) is considered a rare and endangered tree species because of severe reduction of its natural riverine habitat and potential hybridisation with the related non-indigenous taxa P. deltoides and P. x canadensis. As it is difficult to distinguish these taxa solely based on their morphology, we applied a PCR-based assay with an easy-to-use and robust molecular marker set (cpDNA trnL-trnF/RsaI RFLP, nDNA win3 and nDNA POPX/MspI RFLP) in order to identify pure P. nigra. Different plant tissues could be used for fast and standardised DNA extraction. The application of the three marker types was tested on a number of different Populus taxa, and they were also used for the verification of pure P. nigra in a sample of 304 putative P. nigra individuals from Switzerland. Cross-checking of the DNA data with those using a traditional allozyme approach resulted in complete agreement. The availability of molecular identification methods is an important prerequisite for the conservation of European Black Poplar, because pure, non-introgressed plant material can then be used in restoration projects of European floodplains.     

Dredge and fill regulatory constraints in meeting the ecological goals of restoration projects

Regulators face the problem of ensuring that wetland functions that are lost due to permitting actions are restored via mitigation of those impacts. While there has been considerable study of wetland function, little of it has been directed toward the practical assessment of mitigation success. Development of quantitatively based rapid assessment methods would provide valuable assistance to the regulatory community. Regional and local goal setting, including a determination of whether strict in-kind restoration or restoration of habitat balance is preferable, is needed to ensure that the ecological health of the area is restored to the greatest extent possible.     

Monitoring attributes for ecological restoration in Latin America and the Caribbean region

Ecological restoration is becoming mainstreamed worldwide but target ecosystems' responses to restorative interventions are not sufficiently monitored, in terms of the wide range of ecological, social, and economic attributes available. In order to highlight and better understand this problem, we conducted a literature review of the ecological, social, and economic attributes cited in the scientific literature used for monitoring the success of ecological restoration projects in Latin America and the Caribbean region, where no regional study of this kind has previously been conducted. In 84 of the 91 articles retained for the study, ecological indicators were evaluated, while only seven articles included measurements of socioeconomic indicators. Regarding the Society for Ecological Restoration Primer attributes of restored ecosystems, we only found indicators measuring attributes 1–6, with attribute 1 (species assemblages) predominating (73%), followed by physical conditions (54%) and ecological functions (51%). Brazil was the country in the region where most monitoring was being carried out (51% of the articles), and tropical rainforest (33%) and tropical dry forest (25%) were the ecosystem types where ecological restoration was most frequently monitored. Highly vulnerable ecosystems such as mangroves and paramos were underrepresented. Attributes related to ecosystem stability or to governance and education of communities were not monitored at all. More real long‐term monitoring, instead of chronosequences, is needed, especially where understanding socioeconomic implications of, and barriers to, effective ecological restoration is a top priority.     

Conservation-oriented restoration—a two for one method to restore both threatened species and their habitats

There is an urgent need for a new conservation approach as mere designation of protected areas, the primary approach to conserving biodiversity, revealed its low conservation efficiency and inability to cope with numerous challenges faced by nature in the Anthropocene. The paper discusses the new concept, which proposes that ecological restoration becomes an integral part of conservation planning and implementation, and is done using threatened plant species that are introduced not only into locations where they currently grow or grew in the recent past, but also into suitable locations within their potential distribution range. This new concept is called conservation-oriented restoration to distinguish it from the traditional restoration. Although the number of restoration projects focusing on recreation of once existing natural habitats is instantly growing, the majority of ecological restoration projects, in contrast to conservation-oriented restoration, have predominantly utilitarian goals, e.g.improvement or air quality, erosion control or soil replenishment. Conservation-oriented restoration should not be seen as an alternative either to the latter, or to the conservation dealing with particular threatened species(species-targeted conservation). These three conservation approaches, traditional ecological restoration, species-targeted conservation, and conservation-oriented restoration differ not only in broadly defined goals and attributes of their targets, but also in the types of ecosystems they are applicable to, and complement each other in combating global deterioration of the environment and biodiversity loss.