Tropical wetlands and REDD+: Three unique scientific challenges for policy

The carbon sequestration and storage value of terrestrial habitats is now increasingly appreciated, and is the basis for Payment for Ecosystem Service (PES) policies such as REDD+. Tropical wetlands may be suitable for inclusion in such schemes because of the disproportionately large volume of carbon they are able to store. However, tropical wetlands offer a number of unique challenges for carbon management and policy compared to terrestrial forest systems: 1) Tropical wetlands are dynamic and subject to a wide range of physical and ecological processes that affect their long-term carbon storage potential – thus, such systems can quickly become a carbon source instead of a sink; 2) Carbon dynamics in tropical wetlands often operate over longer time-scales than are currently covered by REDD+ payments; and 3) Much of the carbon in a tropical wetland is stored in the soil, so monitoring, reporting and verification (MRV) needs to adequately encapsulate the entire ecosystem and not just the vegetative component. This paper discusses these physical and biological concepts, and highlights key legal, management and policy questions that must be considered when constructing a policy framework to conserve these crucial ecosystems

Can the correlated stability conjecture be saved?

Correlated stability conjecture (CSC) proposed by Gubser and Mitra [1,2] linked the thermodynamic and classical (in)stabilities of black branes. In [3] it was shown that the thermodynamic instabilities, specifically the negative specific heat, indeed result in the instabilities in the hydrodynamic spectrum of holographically dual plasma excitations. Counter-examples of CSC were presented in the context of black branes with scalar hair undergoing a second-order phase transition [4,5]. The latter translationary invariant horizons have scalar hair, raising the question whether the asymptotic parameters of the scalar hair can be appropriately interpreted as additional charges leading to a generalization of the thermodynamic stability criterion. In this paper we show that the generalization of the thermodynamic stability criterion of this type can not save CSC. We further present a simple statistical model which makes it clear that thermodynamic and dynamical (in)stabilities generically are not correlated.Comment: 9 pages, 2 figures; v2: JHEP versio

Patterns of mangrove forest disturbance and biomass removal due to small-scale harvesting in southwestern Madagascar

Abstract: Informal small-scale mangrove wood harvesting has received limited attention, though it is a widespread threat to mangroves in many parts of the tropics. We investigated wood use and the impacts of harvesting on mangrove forests in the Bay of Assassins in southwest Madagascar. We measured forest structure, composition, and harvesting across 60 vegetation plots and investigated human uses of the mangroves through Rapid Rural Appraisal techniques. We found that unlike other mangroves in the region, those in the Bay of Assassins are dominated by Ceriops tagal. Tree harvesting rates are high, with a mean of 28.7% (SD 19.4) of trees harvested per plot. This is similar to heavily harvested mangroves in other parts of the tropics. A comparison of tree versus sapling importance of the different mangrove tree species indicates that the composition of the mangrove forest is changing, with C. tagal becoming more important. Livelihood activities drive the harvesting of certain species and size classes. Mangrove wood is used mainly for the construction of traditional housing and fencing. There are also emerging uses of mangrove wood, including seaweed (Kappaphycus alvarezii) aquaculture and the production of ‘sokay’, a lime render made by burning sea shells in mangrove wood kilns and used to improve the durability of houses. Small-scale selective harvesting of mangrove wood is important for local livelihoods but may have wide-ranging impacts on forest composition and structure. Demand for mangrove wood has grown in relation to new commodity chains for marine products, demonstrating the need for integrated landscape management that considers wetland, terrestrial and marine resources together

No-Drag String Configurations for Steadily Moving Quark-Antiquark Pairs in a Thermal Bath

We investigate the behavior of stationary string configurations on a five-dimensional AdS black hole background which correspond to quark-antiquark pairs steadily moving in an N=4 super Yang-Mills thermal bath. There are many branches of solutions, depending on the quark velocity and separation as well as on whether Euclidean or Lorentzian configurations are examined.Comment: references added; statements corrected; eliminated computation of jet quenching parameter from Wilson loop of [Liu, Rajagopal, Wiedemann, hep-th/0605178] using Euclidean string configurations since those authors advocate [hep-th/0607062, footnote 14] the use of spacelike Lorentzian string configurations instea

Drag force in a string model dual to large-N QCD

We compute the drag force exerted on a quark and a di-quark systems in a background dual to large-N QCD at finite temperature. We find that appears a drag force in the former setup with flow of energy proportional to the mass of the quark while in the latter there is no dragging as in other studies. We also review the screening length.Comment: 15 pages, typos removed, error corrected, refs adde

Ecotourism as a Tool for Mangrove Conservation

Intertidal mangrove forests cover much of the coastline of Southeast Asia, provide crucial ecosystem services to millions of people living in the coastal zone, and are some of the most biodiverse in the world. However, they are one of the most threatened ecosystems in the tropics due to land cover conversion to agriculture (rice, oil palm) and aquaculture. Several conservation tools have been suggested to reduce mangrove deforestation, with many recent tools based on financially valuing the mangrove ecosystem and using that money to incentivize habitat protection. An important set of ecosystem services that can potentially be paid for under some settings are cultural values, such as recreation, tourism, spiritual value and aesthetic value. Ecotourism potentially represents a set of sustainable tourism principles that utilize the cultural ecosystem services of habitats to provide income to tourism operators and local communities. While we don’t yet have a comprehensive and large-scale overview of the full extent of mangrove ecotourism activities in the region, numerous case studies suggest the importance of these activities in bringing mangroves and people together. However, ecotourism must be implemented correctly in order to minimize the adverse impacts of tourists on local habitats. These impacts can be physical, including increased shoreline erosion, noise and pollution, or social, including the exclusion of local tour operators and communities. We need to understand these impacts, and how to reduce them, if we want to better conserve mangrove forests using neoliberal approaches such as ecotourism

Ancient high-energy storm boulder deposits on Ko Samui, Thailand, and their significance for identifying coastal hazard risk

© 2016 Elsevier B.V. Coastal geomorphic processes associated with high-energy storm events are difficult to estimate over recent geological history, though their frequency and magnitude are important to assess in order to understand present-day coastal vulnerability. Studying ancient coastal boulder deposits can shed light on the previous physical conditions necessary for their deposition. In this study, we estimated the physical processes required to move reef-derived coral boulders on the east coast of Ko Samui, a rapidly developing tourist island off eastern peninsular Thailand. The position and dimensions of 97 coral boulders (weight: mean 2.9. t, max. 12.7. t; transport distance: max. 125. m) were measured at two sites and dated using uranium/thorium methods. Flow velocities of 2.3-8.6. m/s were required to transport the measured boulders, with individuals deposited up to 4.7. m above mean sea level. Age-dating suggests that events capable of the highest flow velocities occurred around AD 1600 and AD 1750. These were probably driven by tropical cyclones (typhoons). Boulder transport by events of similar magnitude has not been detected within the last 250. years. The non-occurrence of similar events in living memory has implications for hazard perceptions at this important tourist destination. However, there is also evidence of substantial Holocene sea-level changes in the Gulf of Thailand, as observed at nearby Ko Phaluai. This potentially offers a challenge for the interpretation of older boulders dating from the mid-Holocene, as sea level may have been more than 2. m higher than present. Thus, studies using coral boulders as a proxy for past storm-wave conditions must consider the broader sea-level history, and are probably best limited to the period post-2000. BP in the Gulf of Thailand

Drag Force in a Charged N=4 SYM Plasma

Following recent developments, we employ the AdS/CFT correspondence to determine the drag force exerted on an external quark that moves through an N=4 super-Yang-Mills plasma with a non-zero R-charge density (or, equivalently, a non-zero chemical potential). We find that the drag force is larger than in the case where the plasma is neutral, but the dependence on the charge is non-monotonic.Comment: 16 pages, 1 eps figure; v2: references added, typos fixed; v3: more general ansatz, new nontrivial solution obtained, nonmonotonicity of the drag force made explicit in new figure, version to appear in JHE

Dissipation from a heavy quark moving through N=4 super-Yang-Mills plasma

Using AdS/CFT, we compute the Fourier space profile of generated by a heavy quark moving through a thermal plasma of strongly coupled N=4 super-Yang-Mills theory. We find evidence of a wake whose description includes gauge fields with large momenta. We comment on the possible relevance of our results to relativistic heavy ion collisions.Comment: 17 pages, 2 figures. v2: reference added, other minor improvements. v3: improved the phrasing describing directional structure