Building resilience to drought in desertification-prone savannas in Sub-Saharan Africa: The water perspective

Securing sustainable livelihood conditions and reducing the risk of outmigration in savanna ecosystems hosted in the tropical semiarid regions is of fundamental importance for the future of humanity in general. Although precipitation in tropical drylands, or savannas, is generally more significant than one might expect, these regions are subject to considerable rainfall variability which causes frequent periods of water deficiency. This paper addresses the twin problems of “drought and desertification” from a water perspective, focusing on the soil moisture (green water) and plant water uptake deficiencies. It makes a clear distinction between long‐term climate change, meteorological drought, and agricultural droughts and dry spells caused by rainfall variability and land degradation. It then formulates recommendations to better cope with and to build resilience to droughts and dry spells. Coping with desertification requires a new conceptual framework based on green‐blue water resources to identify hydrological opportunities in a sea of constraints. This paper proposes an integrated land/water approach to desertification where ecosystem management supports agricultural development to build social‐ecological resilience to droughts and dry spells. This approach is based on the premise that to combat desertification, focus should shift from reducing trends of land degradation in agricultural systems to water resource management in savannas and to landscape‐wide ecosystem management.     

Assessment of <Emphasis Type="Italic">Gmelina arborea</Emphasis> sawdust–cement-bonded rainwater storage tank

The performance of a mixture of a forest bye product and cement for the production of storage structure for harvested rainwater was assessed. Three mix ratios of Cement: Gmelina arborea sawdust 3.0:1.0 (specimen A), 2.5:1.0 (specimen B) and 2.0:1.0 (specimen C) were considered. Engineering properties and dimensional stability of the different mix-ratios were monitored from prototypes cylindrical pots and test billet specimens. Possible change in quality of stored rainwater, with time was monitored in all the three cases. Water quality parameters monitored include pH, hardness, total suspended solids, alkalinity, acidity and total dissolved CO₂. The tensile stress obtained were 110, 104, and 95 N/mm², while the compressive strength were 5,000, 3,000, and 2,000 kN for specimens A, B and C respectively. Accelerated aging test showed that sample A were more resistant to deformation, while specimen C were more susceptible to change in structure over time. Similarly, the values of tensile and compressive strength after accelerated aging test increased in the order of specimen A > B > C. Except in specimen C where significant differences in alkalinity and acidity were observed, there were no significant differences in quality of the water stored in the pots after 2 months of storage. The results indicate the suitability of the Gmelina arborea waste as an alternative in constructing water storage structures in rural communities.     

Dryland characteristics and its optimized eco‐productive paradigms for sustainable development in China

Dryland area occupies 37% of the national territory in China. Desertification and other disasters have limited dryland sustainable development. Here we overview the dryland characteristics and desertification status and introduce four regionally optimized eco‐productive paradigms for dryland sustainable development, i.e., the mountain‐oasis paradigm in arid desert; the small watershed‐based paradigm on the Loess Plateau; the integrated animal husbandry paradigm on the Inner Mongolia Steppe and the agro‐pastoral transitional region; and three circle paradigm on the Ordos Plateau. These paradigms are established on the basis of regional landscape patterns and their underlying material and energy flow rules, and different functional belts are determined and capitalized upon with the integrated consideration of regional biogeophysical processes, biogeochemical cycles and biogeosocial relations. These paradigms cannot cover all complex landscape types, but provide theoretical frameworks and practicable models for dryland sustainable development in China.     

The Coachella Valley Multiple Species Habitat Conservation Plan: A Decade of Delays

This article describes the history of the Coachella Valley Multiple Species Habitat Conservation Plan (CVMSHCP), in the Riverside County region of Southern California. When this collaborative biodiversity conservation planning process began, in 1994, local participants and supporters had numerous factors working in their favor. Yet, as of April 2007, nearly 13 years had passed without an approved plan. This is a common problem. Many multiple species habitat conservation plans now take more than a decade to complete, and the long duration of these processes often results in negative consequences. The CVMSHCP process became bogged down—despite strong scientific input and many political advantages—due to problematic relationships between the Plan’s local supporters, its municipal signatory parties, and officials from the state and federal wildlife agencies, particularly the regional office of the US Fish and Wildlife Service. This case study demonstrates the crucial importance of institutional structures and relationships, process management, and timeliness in habitat conservation planning. We conclude by offering several related recommendations for future HCP processes.     

Volunteer Macroinvertebrate Monitoring: Tensions Among Group Goals,Data Quality,and Outcomes

Volunteer monitoring of natural resources is promoted for its ability to increase public awareness, to provide valuable knowledge, and to encourage policy change that promotes ecosystem health. We used the case of volunteer macroinvertebrate monitoring (VMM) in streams to investigate whether the quality of data collected is correlated with data use and organizers' perception of whether they have achieved these outcomes. We examined the relation between site and group characteristics, data quality, data use, and perceived outcomes (education, social capital, and policy change). We found that group size and the degree to which citizen groups perform tasks on their own (rather than aided by professionals) positively correlated with the quality of data collected. Group size and number of years monitoring positively influenced whether a group used their data. While one might expect that groups committed to collecting good-quality data would be more likely to use it, there was no relation between data quality and data use, and no relation between data quality and perceived outcomes. More data use was, however, correlated with a group's feeling of connection to a network of engaged citizens and professionals. While VMM may hold promise for bringing citizens and scientists together to work on joint conservation agendas, our data illustrate that data quality does not correlate with a volunteer group's desire to use their data to promote regulatory change. Therefore, we encourage scientists and citizens alike to recognize this potential disconnect and strive to be explicit about the role of data in conservation efforts.     

Blowing Smoke in Yellowstone: Air Quality Impacts of Oversnow Motorized Recreation in the Park

Snowmobile use in Yellowstone National Park has been shown to impact air quality, with implications for the safety and welfare of Park staff and other Park resource values. Localized impacts have been documented at several high-use sites in the Park, but the broader spatial variability of snowmobile emissions and air quality was not understood. Measurements of 87 volatile organic compounds (VOCs) were made for ambient air sampled across the Park and West Yellowstone, Montana, during 2 days of the 2002–2003 winter use season, 1 year before the implementation of a new snowmobile policy. The data were compared with similar data from pristine West Coast sites at similar latitudes. Backward trajectories of local air masses, alkyl nitrate-parent alkane ratios, and atmospheric soundings were used to identify the VOC sources and assess their impact. Different oversnow vehicle types used in the Park were sampled to determine their relative influence on air mass pollutant composition. VOCs were of local origin and demonstrated strong spatiotemporal variability that is primarily influenced by levels of snowmobile traffic on given road segments at different times of day. High levels of snowmobile traffic in and around West Yellowstone produced consistently high levels of benzene, toluene, and carbon monoxide.     

土壤锑污染对桑树的影响初探

运用盆栽实验和实验分析方法,研究了土壤锑(Sb)污染对桑叶品质的影响,揭示了桑树对土壤锑的耐性机制。在土壤中分别添加三价锑15mg/kg、40mg/kg、80mg/kg、120mg/kg、160mg/kg和300mg/kg,以植物生长指标及生理指标为测试指标,实验周期60d。实验结果表明,低浓度Sb处理(<40mg/kg)对桑树生长有促进作用;随着土壤Sb浓度增高(40—300mg/kg),它对桑树产生抑制效应。但当土壤锑浓度不超过160mg/kg时,桑树对土壤锑污染有一定的耐性,其耐性指数>0.8。土壤锑污染对桑叶叶绿素含量、淀粉含量和可溶性糖含量影响不显著,桑叶中的锑含量随土壤锑含量的增加而增多。     

Estimating Forest Ecosystem Evapotranspiration at Multiple Temporal Scales With a Dimension Analysis Approach1

Abstract:  It is critical that evapotranspiration (ET) be quantified accurately so that scientists can evaluate the effects of land management and global change on water availability, streamflow, nutrient and sediment loading, and ecosystem productivity in watersheds. The objective of this study was to derive a new semi‐empirical ET modeled using a dimension analysis method that could be used to estimate forest ET effectively at multiple temporal scales. The model developed describes ET as a function of water availability for evaporation and transpiration, potential ET demand, air humidity, and land surface characteristics. The model was tested with long‐term hydrometeorological data from five research sites with distinct forest hydrology in the United States and China. Averaged simulation error for daily ET was within 0.5 mm/day. The annual ET at each of the five study sites were within 7% of measured values. Results suggest that the model can accurately capture the temporal dynamics of ET in forest ecosystems at daily, monthly, and annual scales. The model is climate‐driven and is sensitive to topography and vegetation characteristics and thus has potential to be used to examine the compounding hydrologic responses to land cover and climate changes at multiple temporal scales.     

Effects of Flow Augmentations in the Snake River Basin on Farms Profitability1

Abstract: For over 10 years, several species of salmon have been identified as either threatened or endangered in the Snake River Basin of Idaho. The United States Bureau of Reclamation, in cooperation with the National Marine Fisheries Service, has proposed a variety of plans to increase stream flows in the Snake River Basin to facilitate movement by juvenile salmon smolts to the ocean. This research examines two of the flow augmentation plans proposed by the Bureau of Reclamation as well as two alternative plans, one founded purely on existing priority‐based water rights and another geared toward minimizing the effects of flow augmentations on farms profitability. Results from a basin‐wide model of agricultural production in the Snake River Basin, the Snake River Agricultural Model, present evidence that (1) older water rights are used towards production of less valuable crops, (2) flow augmentation scenarios have unequal effects on farms profitability across agricultural regions within the basin, and (3) irrigation water is valued from US$4 to US$59 an acre‐foot.     

Comparison of 85Kr and 3H Apparent Ground‐Water Ages for Source Water Vulnerability in the Collyer River Catchment,Maine1

Abstract: Apparent ground‐water ages as determined by the noble gas isotope ⁸⁵Kr and the water isotope ³H are compared. Refined gas extraction methodology at the wellhead permits efficient collection of Kr for ⁸⁵Kr isotope enrichment. ⁸⁵Kr isochrones elucidate areas of much younger ground‐water ages than ³H. Declining ³H activities in the catchment prevent its correlation with the youngest measured ⁸⁵Kr ages. Source water for most drinking water supplies in the Collyer River catchment is recharged within 40 years BP (2004). Mean‐age (τ) transport modeling suggests uncertainty of ground‐water ages is greatest in the central basin area.