Payments for Ecosystem Services as a Framework for Community-Based Conservation in Northern Tanzania

Abstract:  Payments for ecosystem services (PES) are an increasingly promoted approach to conservation. These approaches seek to develop financial mechanisms that create economic incentives for the maintenance of ecosystems and associated biodiversity by rewarding those who are responsible for provision of ecological services. There are, however, few cases in which such schemes have been used as a strategy for conserving wildlife in developing countries and very few operational examples of such schemes of any sort in sub-Saharan Africa. In savannah ecosystems, large mammal populations generally depend on seasonal use of extensive areas and are widely declining as a result of habitat loss, overexploitation, and policies that limit local benefits from wildlife. Community-based conservation strategies seek to create local incentives for conserving wildlife, but often have limited impact as a result of persistent institutional barriers that limit local rights and economic benefits. In northern Tanzania, a consortium of tourism operators is attempting to address these challenges through an agreement with a village that possesses part of a key wildlife dispersal area outside Tarangire National Park. The operators pay the community to enforce voluntary restrictions on agricultural cultivation and permanent settlement in a defined area of land. The initiative represents a potentially cost-effective framework for community-based conservation in an ecologically important area and is helping to reconcile historically conflicting local and national interests relative to land tenure, pastoralist livelihoods, and conservation. Wider adaptation of payments for ecosystem services approaches to settings where sustaining wildlife populations depends on local stewardship may help address current challenges facing conservation outside state-protected areas in savannah ecosystems in sub-Saharan Africa and other parts of the world.     

Monitoring Urban Streams: Strategies and Protocols for Humid-Region Lowland Systems

Governmental mandates and public awareness have forcedprogressively smaller and less sophisticated agencies andorganizations to initiate stream monitoring programs,particularly in urban and urbanizing areas. Yet many of thesemonitoring efforts lack either a coherent conceptual frameworkor appropriately chosen methods, and they rely on monitoringtechniques that are simply infeasible for these institutionalsettings. We propose a monitoring strategy, and specificexisting monitoring protocols, that will be useful for themanagement and rehabilitation of streams in urbanizing watersheds.A monitoring strategy must be developed by 1) identifying the management question(s) being addressed, 2) determining theinstitional level of effort required (and available) toeffectively make particular kinds of measurements, and 3) identifying what specific parameters should and can be measured.Only a limited set of parameters show much utility orfeasibility in addressing the most common management questionsbeing faced by municipalities in urbanizing, humid-area regionsof the United States. These include measures of riparian canopy,bank erosion and bank hardening, and in-stream large woodydebris. With some additional expertise useful data can also beincluded on channel gradient, substrate composition, and pools.Nearly all of the other myriad parameters that have beenmeasured historically on rivers and streams show little apparentvalue in these watershed and institutional settings.     

The Relationship of Lithology and Watershed Characteristics to Fine Sediment Deposition in Streams of the Oregon Coast Range

Lithology is one of many factors influencing the amount, grain size distribution, and location of fine sediment deposition on the bed of mountain stream channels. In the Oregon Coast Range, 18 pool-riffle stream reaches with similar slope and intact riparian area and relatively unaffected by logjams were surveyed for assessment of fine sediment deposition. Half of the streams were in watersheds underlain by relatively erodible sandstone. The other half were underlain by a more resistant basalt. Channel morphology, hydraulic variables, particle size, relative pool volume of fine sediment (V*), and wood characteristics were measured in the streams. A significantly higher amount of fine sediment was deposited in the sandstone channels than in the basalt channels, as indicated by V*. Grab samples of sediment from pools also were significantly finer grained in the sandstone channels. Geographic information systems (GIS) software was used to derive several variables that might correlate with fine sediment deposition. These variables were combined with those derived from field data to create multiple linear regression models to be used for further exploration of the type and relative influence of factors affecting fine sediment deposition. Lithology appeared to be significant in some of these models, but usually was not the primary driver. The results from these models indicate that V* at the reach scale is best explained by stream power per unit area and by the volume of wood perpendicular to the flow per channel area (R² = 0.46). Findings show that V* is best explained using only watershed scale variables, including negative correlations with relief ratio and basin precipitation index, and positive correlations with maximum slope and circularity.     

Mapping Stream Habitats with a Global Positioning System: Accuracy,Precision, and Comparison with Traditional Methods

We tested the precision and accuracy of the Trimble GeoXT™ global positioning system (GPS) handheld receiver on point and area features and compared estimates of stream habitat dimensions (e.g., lengths and areas of riffles and pools) that were made in three different Oklahoma streams using the GPS receiver and a tape measure. The precision of differentially corrected GPS (DGPS) points was not affected by the number of GPS position fixes (i.e., geographic location estimates) averaged per DGPS point. Horizontal error of points ranged from 0.03 to 2.77 m and did not differ with the number of position fixes per point. The error of area measurements ranged from 0.1% to 110.1% but decreased as the area increased. Again, error was independent of the number of position fixes averaged per polygon corner. The estimates of habitat lengths, widths, and areas did not differ when measured using two methods of data collection (GPS and a tape measure), nor did the differences among methods change at three stream sites with contrasting morphologies. Measuring features with a GPS receiver was up to 3.3 times faster on average than using a tape measure, although signal interference from high streambanks or overhanging vegetation occasionally limited satellite signal availability and prolonged measurements with a GPS receiver. There were also no differences in precision of habitat dimensions when mapped using a continuous versus a position fix average GPS data collection method. Despite there being some disadvantages to using the GPS in stream habitat studies, measuring stream habitats with a GPS resulted in spatially referenced data that allowed the assessment of relative habitat position and changes in habitats over time, and was often faster than using a tape measure. For most spatial scales of interest, the precision and accuracy of DGPS data are adequate and have logistical advantages when compared to traditional methods of measurement.     

Dissolved oxygen sag analysis for a settling fields overlapping type multi-wastewater-outfall

The classical Streeter–Phelps models for Dissolved oxygen (DO) sag do not account for a significantly settleable portion (about 10% in treated to about 60% in the untreated wastewater discharged) of the total biochemical oxygen demand (BOD) inputs into rivers through wastewater outfalls, and therefore, they can not be used to predict the DO sag to any accuracy and rationality. The author’s rationally composited model for an accurate prediction of stream BOD, accounting for near linear removal of settleable BOD as well as simultaneous exponential decay of the non-settleable BOD, is used to predict the DO sag resulting from a multi-wastewater-outfall system, wherein the settling fields of some of the outfalls interfere and overlap. An illustrative case example has been presented to demonstrate use of the models evolved under varying locations of the multi-wastewater-outfalls. A universal and integrated PC based computer program can also be evolved for the computation of the overall resultant DO sag to confirm the manually computed DO sag.     

A Rapid Method to Score Stream Reaches Based on the Overall Performance of Their Main Ecological Functions

A method was developed to score the ecological condition of first- to third-order stream reaches in the Auckland region of New Zealand based on the performance of their key ecological functions. Such a method is required by consultants and resource managers to quantify the reduction in ecological condition of a modified stream reach relative to its unmodified state. This is a fundamental precursor for the determination of fair environmental compensation for achieving no-net-loss in overall stream ecological value. Field testing and subsequent use of the method indicated that it provides a useful measure of ecological condition related to the performance of stream ecological functions. It is relatively simple to apply compared to a full ecological study, is quick to use, and allows identification of the degree of impairment of each of the key ecological functions. The scoring system was designed so that future improvements in the measurement of stream functions can be incorporated into it. Although the methodology was specifically designed for Auckland streams, the principles can be readily adapted to other regions and stream types.     

Use of Standardized Visual Assessments of Riparian and Stream Condition to Manage Riparian Bird Habitat in Eastern Oregon

The importance of riparian vegetation to support stream function and provide riparian bird habitat in semiarid landscapes suggests that standardized assessment tools that include vegetation criteria to evaluate stream health could also be used to assess habitat conditions for riparian-dependent birds. We first evaluated the ability of two visual assessments of woody vegetation in the riparian zone (corridor width and height) to describe variation in the obligate riparian bird ensemble along 19 streams in eastern Oregon. Overall species richness and the abundances of three species all correlated significantly with both, but width was more important than height. We then examined the utility of the riparian zone criteria in three standardized and commonly used rapid visual riparian assessment protocols—the USDI BLM Proper Functioning Condition (PFC) assessment, the USDA NRCS Stream Visual Assessment Protocol (SVAP), and the U.S. EPA Habitat Assessment Field Data Sheet (HAFDS)—to assess potential riparian bird habitat. Based on the degree of correlation of bird species richness with assessment ratings, we found that PFC does not assess obligate riparian bird habitat condition, SVAP provides a coarse estimate, and HAFDS provides the best assessment. We recommend quantitative measures of woody vegetation for all assessments and that all protocols incorporate woody vegetation height. Given that rapid assessments may be the only source of information for thousands of kilometers of streams in the western United States, incorporating simple vegetation measurements is a critical step in evaluating the status of riparian bird habitat and provides a tool for tracking changes in vegetation condition resulting from management decisions.     

Instream Flow Science For Sustainable River Management1

Abstract: Concerns for water resources have inspired research developments to determine the ecological effects of water withdrawals from rivers and flow regulation below dams, and to advance tools for determining the flows required to sustain healthy riverine ecosystems. This paper reviews the advances of this environmental flows science over the past 30 years since the introduction of the Instream Flow Incremental Methodology. Its central component, Physical HABitat SIMulation, has had a global impact, internationalizing the e‐flows agenda and promoting new science. A global imperative to set e‐flows, including an emerging trend to set standards at the regional scale, has led to developments of hydrological and hydraulic approaches but expert judgment remains a critical element of the complex decision‐making process around water allocations. It is widely accepted that river ecosystems are dependent upon the natural variability of flow (the flow regime) that is typical of each hydro‐climatic region and upon the range of habitats found within each channel type within each region. But as the sophistication of physical (hydrological and hydraulic) models has advanced emerging biological evidence to support those assumptions has been limited. Empirical studies have been important to validate instream flow recommendations but they have not generated transferable relationships because of the complex nature of biological responses to hydrological change that must be evaluated over decadal time‐scales. New models are needed to incorporate our evolving knowledge of climate cycles and morphological sequences of channel development but most importantly we need long‐term research involving both physical scientists and biologists to develop new models of population dynamics that will advance the biological basis for 21st Century e‐flow science.     

基于属性理论的长株潭城市群生态系统健康评价

城市生态系统是一种高度人工化的自然-社会-经济复合生态系统,其健康状况直接影响到城市的可持续发展。针对城市生态系统健康评价标准的不确定性问题,在构建评价指标体系的基础上,提出了基于属性理论的城市生态系统健康评价模型及评价方法。以长株潭城市群为研究区域,运用该模型和方法对其生态系统健康进行了综合评价。评价结果表明：长株潭城市群的生态系统现状属于一般健康类,其中自然生态子系统对区域整体健康状况有较大影响,评价结果与实际情况大体吻合。通过对各子系统层的健康度分析,识别了健康限制因素,并提出了相应的调控措施。采用属性理论方法开展城市生态系统健康评价,能较好地识别系统层综合健康状况和子系统层的健康状况,具有一定的实用价值,其评价结果为促进城市生态建设,有效实施生态系统健康管理提供了科学依据。