The time evolution of marginally trapped surfaces

In previous work we have shown the existence of a dynamical horizon or marginally trapped tube (MOTT) containing a given strictly stable marginally outer trapped surface (MOTS). In this paper we show some results on the global behavior of MOTTs assuming the null energy condition. In particular we show that MOTSs persist in the sense that every Cauchy surface in the future of a given Cauchy surface containing a MOTS also must contain a MOTS. We describe a situation where the evolving outermost MOTS must jump during the coalescence of two seperate MOTSs. We furthermore characterize the behavior of MOTSs in the case that the principal eigenvalue vanishes under a genericity assumption. This leads to a regularity result for the tube of outermost MOTSs under the genericity assumption. This tube is then smooth up to finitely many jump times. Finally we discuss the relation of MOTSs to singularities of a space-time.Comment: 21 pages. This revision corrects some typos and contains more detailed proofs than the original versio

The ecosystem approach in ecological impact assessment: Lessons learned from windfarm developments on peatlands in Scotland

The Ecosystem Approach introduced in 1994 through the Convention on Biological Diversity, together with related Ecosystem-based Management and Landscape Approaches are frequently called upon to improve ecological impact assessment. Current practice typically does not have such a systems focus and we explore the potential for explicitly adopting an Ecosystem Approach in the Environmental Impact Assessment process using wind energy development on peatland, in Scotland, as a case study. Based on a review of 21 windfarm projects (>50MW) approved by the Scottish Government we provide an overview of current practice and identify and discuss how the 12 principles of the Ecosystem Approach can help identify options for more appropriate impact assessment. These include defining functional units of analysis that reflect the spatial and temporal linkages of peatland elements through hydrological connections, rather than a focus on individual vegetation types and simple distance buffers. Our conclusions are not limited to peatland and are relevant wherever meaningful functional management units can be defined, including in marine environments. Our results also show that environmental statements for wind energy development in Scotland largely ignore ecosystem services and the people that benefit from them. As for threatened species and other biodiversity features, an Ecosystem Approach is a prerequisite to the meaningful inclusion of ecosystem services in impact assessment

Assessing the Impacts of Changing Connectivity of Hydropower Dams on the Distribution of Fish Species in the 3S Rivers, a Tributary of the Lower Mekong

Hydropower plants (HPPs) create barriers across rivers and fragment aquatic ecosystems, river reaches and habitats. The reservoirs they create slow the flowing water and convert the riverine into lacustrine ecosystems. The barriers created by HPPs interrupt the seasonal migrations of many fish species, while the reservoirs drive away fish species that are dependent on flowing water habitats. This paper assesses the distribution of fish species in the 3S rivers—Sekong, Sesan and Sre Pok, in Cambodia, Laos and Viet Nam—using IUCN Red List-assessed species distribution by HydroBasin Level 8 from the freshwater reports of the Integrated Biodiversity Assessment Tool (IBAT) and their connectivity with the Mekong. There are currently 61 commissioned dams in the 3S basins and a further 2 under construction, 23 of which are larger than the 30 MW installed capacity. A further 24 HPPs are proposed or planned in these basins. The changes in connectivity caused by the dams are measured by adapting the River Class Connectivity Index (RCICLASS); the original connectivity of the 3S basin taking into account the two major waterfalls in the Sesan and Sre Pok rivers was estimated at 80.9%. With existing dams, the connectivity has been reduced to 23.5%, and with all planned dams, it is reduced further to 10.9%. The resulting re-distribution of fish species occurring throughout the 3S basins is explored, by focusing on migratory guilds and threatened and endemic fish species. With all dams built, it is predicted that the total numbers of species in HydroBasins above the dams will be reduced by 40–50%. The Threatened Species Index is estimated to fall from over 30 near the confluence of the three rivers to less than 10 above the lowest dams on the 3S rivers. The analysis demonstrates how widely available global and regional datasets can be used to assess the impacts of dams on fish biodiversity in this region

Glocal woodlands – The rescaling of forest governance in Scotland

As a response to global crises of climate change and biodiversity loss, the UN has called for restoring a billion hectares of land. In recognition, both governments and the private sector have pledged to restore landscapes through planting millions of hectares of forests. Private sector investment is to play a critical role in meeting these goals, through instruments such as biodiversity offsetting, philanthropy, voluntary carbon markets, sustainability funds, and climate bonds. Such instruments allow for the value of place-based ecosystems, such as standing forests, to be circulated globally. No longer are forests horizontal (in terms of their extent on a map); they are also vertical, in terms of their entanglements with institutions, and actors, operating at various scales. An overarching emphasis on the private sector however obscures the role of state institutions in engaging these multi-scalar institutions and actors. Bringing the dimension of scale to tree planting, we examine the ways in which woodland creation, a ‘national’ policy priority for the Scottish government, brings together actors, both ‘local’ and ‘global’, in an unequal context. Our analysis uncovers that in retreating from directly creating and managing woodlands to playing a supportive regulatory role, Scottish Government's forest policies increasingly rescale forest and landscape governance to private and non-profit sectors, and to individual landowners and communities. These actors, who are differently endowed in terms of resources, participate in forestry developments on an uneven playing field. Moreover, questions around power and distribution of benefits arise as woodland expansion increasingly becomes part of green investment portfolios, environmental, social, and corporate governance (ESG) commitments, offsetting, and individual philanthropy. A relational view of scale that examines prevailing relations of power and resources in given socio-political contexts can both animate and inform current discourses and policies on tree planting for climate change mitigation.ISSN:0264-8377ISSN:1873-575

Glocal woodlands – The rescaling of forest governance in Scotland

As a response to global crises of climate change and biodiversity loss, the UN has called for restoring a billion hectares of land. In recognition, both governments and the private sector have pledged to restore landscapes through planting millions of hectares of forests. Private sector investment is to play a critical role in meeting these goals, through instruments such as biodiversity offsetting, philanthropy, voluntary carbon markets, sustainability funds, and climate bonds. Such instruments allow for the value of place-based ecosystems, such as standing forests, to be circulated globally. No longer are forests horizontal (in terms of their extent on a map); they are also vertical, in terms of their entanglements with institutions, and actors, operating at various scales. An overarching emphasis on the private sector however obscures the role of state institutions in engaging these multi-scalar institutions and actors. Bringing the dimension of scale to tree planting, we examine the ways in which woodland creation, a ‘national’ policy priority for the Scottish government, brings together actors, both ‘local’ and ‘global’, in an unequal context. Our analysis uncovers that in retreating from directly creating and managing woodlands to playing a supportive regulatory role, Scottish Government’s forest policies increasingly rescale forest and landscape governance to private and non-profit sectors, and to individual landowners and communities. These actors, who are differently endowed in terms of resources, participate in forestry developments on an uneven playing field. Moreover, questions around power and distribution of benefits arise as woodland expansion increasingly becomes part of green investment portfolios, environmental, social, and corporate governance (ESG) commitments, offsetting, and individual philanthropy. A relational view of scale that examines prevailing relations of power and resources in given socio-political contexts can both animate and inform current discourses and policies on tree planting for climate change mitigation

Multifunctionality of a peri-urban landscape: exploring the diversity of residents’ perceptions and preferences

Developing successful policies for sustainable land use requires understanding the perspectives of different actors. This study explored how residents–an often under-represented and un-organized group–vary in their valuation of ecosystem services (ES) and perception of multifunctionality in a peri-urban setting. We conducted 127 interviews in the Kromme Rijn region of the Netherlands guided by an interactive, visual canvas tool (STREAMLINE). We addressed four research questions: (1) Is there variation among residents regarding preferences for ES? (2) Which competing interests do residents see in this landscape? (3) Where are hotspots of perceived multifunctionality? and (4) Can the level of perceived multifunctionality be explained by its location on the rural–urban gradient? Our findings demonstrate that while the majority of ES are important to residents of a peri-urban landscape, there is variation in relative preference towards a subset of ES (mainly provisioning services). A typology of preferences distinguishes three groups: (A)‘I want it all’–all ES (very) important; (B)‘I want most of it’–majority of ES important; and (C)‘I want some’–several ES not important at all. The majority of competing interests identified by respondents were between biodiversity and either a provisioning or cultural service. Universal hotspots of perceived multi-functionality overlapped with the area around residential areas, whereas natural (grassland) areas and water were considered multifunctional by only a small share of respondents. These perceptions and preferences do not necessarily align with current policy and management efforts, it is advised that residents’ perceptions and values are better accounted for in landscape governance