Assessment of Wildfire Hazards with a Semiparametric Spatial Approach

Rural households in agricultural economies are vulnerable to several environmental risks such as fires, floods, and droughts that may affect their productivity in whole or in part. These hazards are especially relevant in developing countries where farmers have few or no access to traditional risk-transfer techniques, such as insurance and finance, and where low governmental investments in rural infrastructure, risk assessment techniques, or early warning systems makes the aftermath of such hazards more expensive and results in slower recovery for those who are affected. In this paper, we use historical satellite data (Terra) of burned areas in South America to fit a semiparametric spatial model, based on kernel smoothing and on a nonlinear relationship between average time between events and damage, to assess the environmental hazard affecting the land’s productivity. The results were twofold: first, we were able to develop a spatial assessment of fire hazard, and second, we were able to evaluate how much a farmer may lose in terms of productivity per hectare due to the environmental hazard. The methodology may be easily adapted to other world regions; to different environmental hazards such as floods, windbreak, windthrow, or related land-use changes; or to integrate various environmental hazards simultaneously, as long as they can be monitored via remote sensing (e.g., satellite imagery, aerial photographs, etc).     

Forest protected area governance in Bangladesh:a focus on the legal and policy framework

In the context of renewed interest in collaboration in natural resource management,the collaborative governance approach has lately been introduced to the forest Protected Areas(PAs)in Bangladesh.The adoption of this co-management approach is seen as an attempt to influence the governance process towards a transformation from the conventional custodian system to a more participatory management regime.Recognition of rights and responsibilities,effective participation,and equitable distribution of benefits amongst the key stakeholders working under a facilitative policy and legal framework are believed to address the broader goals of sustainable development Notwithstanding the resurgence of interest in governance of forest PAs through the co-management approach,academic research on the subject remains limited.This article attempts to review selected key information and milestones on the forest PAs governance with special reference to the major policies and legal documents.With a brief introductory section,this article focuses on the genesis and selected major features of the Forest PAs in the country.The discussion then dwells on the policy and legal framework and provides a critique on its relevance for promoting community participation.The existing institutional arrangements for community engagement in protected area governance are also analyzed in light of the national and international commitment and policy obligations on the part of the country.The salient observations and key findings of the study include the following:(1)despite its limitations,comanagement as concept and practice has gradually taken roots in Bangladesh;(2)the degree and level of active community participation remain low and limited,and there is also clear weakness in conscientizing and orientating the local community on the key legal and policy issues related to PA governance in the country;and(3)policy makers,practitioners,and other local stakeholders related to PA governance need to be oriented on international commitment and national de     

WATERSHED IMPERVIOUSNESS IMPACTS ON STREAM CHANNEL CONDITION IN SOUTHEASTERN PENNSYLVANIA1

ABSTRACT: Forty‐six independent stream reaches in southeastern Pennsylvania were surveyed to assess the relationships between geomorphic and habitat variables and watershed total impervious area (TIA) and to test the ability of the impervious cover model (ICM) to predict the impervious category based on stream reach variables. Ten variables were analyzed using simple and multivariate statistical techniques including scatter‐plots, Spearman's Rank correlations, principal components analysis (PCA), and discriminant analysis (DA). Graphical analysis suggested differences in the response to TIA between the stream reaches with less than 13 percent TIA and those with greater than 24 percent TIA. Spearman's Rank correlations showed significant relationships for large woody debris and sinuosity when analyzing the entire dataset and for depth diversity and the standard deviation of maximum pool depths when analyzing stream reaches with greater than 24 percent TIA. Classification into the ICM using DA was 49 percent accurate; however, the stream reaches did support the ICM in other ways. These results indicate that stream reach response to urbanization may not be consistent across geographical regions and that local conditions (specifically riparian buffer vegetation) may significantly affect channel response; and the ICM, used in the appropriate context, can aid in the management of stream reaches and watersheds.     

Conflicting processes in the wetland plant rhizosphere: Metal retention or mobilization?

Increasingly wetlands are used for treatment of metal-contaminated water or as a cover over metal-enriched mine tailings. Natural wetlands may also be contaminated with metals from anthropogenic sources. While wetland conditions tend to be favorable for immobilization of metals, wetland plants could influence metal mobility through redox and pH processes in the rhizosphere. Our current knowledge of these processes is reviewed, focusing on the question of whether the advantages of growing wetland plants in metal-contaminated sediments outweigh the disadvantages. Wetland plants alter the redox conditions, pH and organic matter content of sediments and so affect the chemical speciation and mobility of metals. Metals may be mobilized or immobilized, depending on the actual combination of factors, and it is extremely difficult to predict which effects plants will actually have on metal mobility under a given set of conditions. However, while the effects of plants can extend several tens of centimeters into the sediments, there are no reports suggesting large-scale mobilization of metals by wetland plants.     

Size-selective harvesting alters life histories of a temperate sex-changing fish.

Selective mortality, whether caused naturally by predation or through the influence of harvest practices, initiates changes within populations when individuals possessing certain heritable traits have increased fitness. Theory predicts that increased mortality rates will select for changes in a number of different life history characteristics. For example, fishing often targets larger individuals and has been shown repeatedly to alter population size structure and growth rates, and the timing of maturation. For sex-changing species, selective fishing practices can affect additional traits such as the mature population sex ratio and the timing of sexual transformation. Using historical comparisons, we examined the effects of exploitation on life history characteristics of California sheephead, Semicossyphus pulcher, a temperate protogynous (female-male sex changer) labrid that inhabits nearshore rocky environments from central California, USA, to southern Baja California, Mexico. Recreational fishing intensified and an unregulated commercial live-fish fishery developed rapidly in southern California between the historical and current studies. Collections of S. pulcher from three locations (Bahia Tortugas, Catalina Island, and San Nicolas Island) in 1998 were compared with data collected 20-30 years previously to ascertain fishery-induced changes in life history traits. At Bahia Tortugas, where fishing by the artisanal community remained light and annual survivorship stayed high, we observed no changes in size structure or shifts in the timing of maturation or the timing of sex change. In contrast, where recreational (Catalina) and commercial (San Nicolas) fishing intensified and annual survivorship correspondingly declined, males and females shifted significantly to smaller body sizes, females matured earlier and changed sex into males at both smaller sizes and younger ages and appeared to have a reduced maximum lifespan. Mature sex ratios (female:male) increased at San Nicolas, despite a twofold reduction in the mean time spent as a mature female. Proper fisheries management requires measures to prevent sex ratio skew, sperm limitation, and reproductive failure because populations of sequential hermaphrodites are more sensitive to size-selective harvest than separate-sex species. This is especially true for S. pulcher, where different segments of the fishery (commercial vs. recreational) selectively target distinct sizes and therefore sexes in different locations.     

Structural marsh management effects on coastal fishes and crustaceans

Structural marsh management, using levees and water-control structures, is used in the coastal zone for many objectives, for example, to reduce marsh loss, to enhance waterfowl habitat, to revegetate open-water areas, and to reduce saltwater intrusion. The literature was evaluated to categorize structural marsh management and to determine some of its effects on fishes and crustaceans. Structural marsh management had positive effects on standing stock of most resident organisms and negative effects on marine-transient organisms. Emigration was negatively affected for both resident and marine-transient organisms. Techniques such as opening structures at critical migration times, designing structures that offer the greatest management flexibility, and using structures to create a flow-through system could reduce these impacts. More effort should be put into monitoring managed areas to determine if the objectives are being met and to evaluate the effects on fishes and crustaceans. Although frequent manipulation could reduce these impacts, the costs and problems incurred may outweigh the anticipated benefits.