Mobility in pastoral systems: Dynamic flux or downward trend?

Several interdependent strategies have allowed pastoralists to survive for centuries in patchy and unpredictable low-productivity environments while sustaining their resource base: mobility, diversity, flexibility, reciprocity and reserves. Recent decades have witnessed curtailed mobility due to agricultural expansion into rangelands, the establishment and enforcement of political and administrative boundaries, the usurpation of local institutional control and disruption of local practices, increased labour costs, and the development of stationary goods and services. Pastoralists have responded by becoming sedentary, diversifying or intensifying their production strategies, leaving the herding sector, or adapting and transforming their practices and institutions. While these trends may be significant, an historical precedence of ebbs and surges in mobility indicates they may not be new or unidirectional. Emerging political trends and technologies may provide an opportunity for pastoral populations to maintain or increase their mobility in the future, but will the customary pastoral institutions that support sustainable practices still be viable, or will new, viable institutions emerge? These institutions are often subtle, contextual, and norm-based; 'invisible' and easily dismantled or replaced by more authoritarian regimes. There is relatively little understanding of how they work or how to support them. Without them, the trend may be towards open access or privatization.     

The effectiveness of incentives in protected area management: An empirical analysis

Incentive approaches are believed to be indispensable for effective conservation and successful management in protected areas. However, the actual effectiveness of these approaches is still debatable. We carried out a case study in Wolong Biosphere Reserve (WBR), the largest reserve for the giant panda (Ailuropoda melanoleuca), to evaluate the effectiveness of incentives. We obtained data from government documents and statistics, interviews and surveys on the employment status of public sector and industries. Results indicated that government-paid community-based conservation projects provided the most widespread and direct economic incentives. The conservation sector and several industries including hotels, hydropower and tourism have directly raised the employment level of local communities. The hotel industry, driven by the development of tourism, has been the most effective means of increasing local employment. However, the problem of immigrants attracted by the improved economic situation in WBR should be considered in the management plans. Suggestions for WBR management include development of quality ecotourism, vocational education for local young adults and new policies encouraging employment of local labour, both in the reserve and outside. Lessons learned from this research are constructive for the management of other protected areas.     

Rain forest dwellers' livelihoods: income generation,household wealth and NTFP sales,a case study from Xishuangbanna,SW China

Through annual in-depth household questionnaire interviews of 60% of households in Daka and Baka villages from 1998 to 2004, we explored wealth-related differences and similarities in the sale of NTFPs of tropical rain forest fringe dwellers in Xishuangbanna, SW China. Contribution of different NTFPs to cash income and different seasonal access to NTFPs between Baka and Daka were analysed. There were significant differences in income and role of NTFPs per household between Baka and Daka related to different access to: NTFPs in forests, labour and market sales in different seasons. In Baka, the ranking of NTFP income was: fungi, wild vegetables, bamboo shoot in 2000 and 2001. Differences in gender and generational involvement in NTFP sales was also examined. For example, households without a son, as well as those with a female householder depended more on income from NTFPs and less on income from rubber than other households. Resource use patterns between relatively wealthy and poor households were also analysed. Wealthy households sold 2.50 ± 0.50 types while poor households sold 2.08 ± 0.26 NTFPs. The Gini coefficient of gross income per household for Baka in recent years was 0.393, increasing to 0.414 without NTFPs. The Gini coefficient of gross income for Daka in recent years was 0.291, increasing to 0.292 without NTFPs, showing the different role of NTFPs in mitigating wealth inequality in the two villages.     

Integrated effects of slope aspect and land use on soil nutrients in a small catchment in a hilly loess area,China

This study addressed the integrated effect of slope aspect and land use on soil nutrients in a loess hilly catchment in the western Loess Plateau of China. Soil samples were collected from five land-use types: wasteland, cropland, woodland, shrubland and abandoned cropland, at two depths (0–20 and 20–40 cm) in the middle slope position of both north-facing and south-facing slopes. Soil nutrient changes and the relationships between soil nutrients and slope aspect were investigated, based on statistical analysis and expert knowledge. Soil organic matter, total N, total P, nitrate nitrogen and available K of the 0–20 cm soil layer differed significantly between land uses and slope aspects. Soil nutrients in the north-facing slope were better than in the south-facing slope. Revegetation has an enrichment effect, especially on soil organic matter, total N, total P, nitrate nitrogen and available K. Planting of trees, shrubs and grasses could improve soil fertility and favours a policy of revegetation and sustainable land use in the hilly loess area of China. Conversion of slope farmlands into more sustainable land uses, such as shrubland or grassland is a cost-efficient way to achieve soil conservation and ecological restoration. Terracing and the use of agro-techniques for soil conservation, such as furrow-ridging tillage and leaving crop residues on fields, can increase the input of C to soils. Growing crops in rotation with alfalfa and beans could be a promising choice for the sustainability of agriculture and the environment.     

低温弱光条件下毒死蜱对黄瓜的毒性效应及油菜素内酯的调控作用

农药在使用中可能对农作物产生药害作用,而在低温弱光的亚适宜条件下,设施作物对农药暴露的应激响应可能具有特殊性。同时,作为一种新型植物激素,油菜素内酯在亚适宜条件下是否能够缓解农药的药害作用的研究有限。以典型的设施作物黄瓜为受试生物,通过人工气候箱模拟低温弱光的亚适宜条件,在毒死蜱(浓度分别为0.3和1mmol·L-1)暴露1、3和7d后,以实时荧光定量PCR对黄瓜叶片中光合作用基因(psaB、psbA和rbcL)、抗氧化系统相关基因(cAPX、DHAR、GR、CAT和GPX)、防御和应激相关基因(PAL、HPL、ADC和HSP70)的转录水平进行检测,阐明其毒性效应。并对比24-表油菜素内酯的预处理组,探讨油菜素内酯如何调控作物对农药胁迫的响应。结果表明,在低温弱光条件下,毒死蜱暴露抑制了黄瓜叶片中上述大部分基因的转录,而24-表油菜素内酯预处理后其转录水平显著上升,表明24-表油菜素内酯可有效且持续地缓解毒死蜱的药害效应。     

Dechlorination of 2,2＇,4,4＇,5,5＇-hexachlorobiphenyl by thermal reaction with activated carbon-supported copper or zinc

Activated carbon （AC）-supported copper or zinc made from ion exchange resin （IRCu-C and IRZn-C） have an increased metal load of 557.3 mg·g^-1 and 502.8 mg·g^-1 compared to those prepared by the traditional method involving impregnation with AC and copper （II） citrate or zinc citrate solution （LaCu-C and LaZn-C） of 12.9 mg·g^-1 and 46.0 mg·g^-1 respectively. When applied to decompose 2,2＇,4,4＇,5,5＇-hexachlorobiphenyl at 250 ℃, IRCu-C achieved higher activity of 99.0% decomposition efficiency than LaCu-C of 84.7%, IRZn-C of 90.5% and LaZn-C of 62.7%. When the reaction temperature rose to 350 ℃, all the four kinds of reactants can decompose PCB- 153 with efficiency above 90%. Further, X-ray photoelec- tron spectroscopy characterization of IRCu-C before and after the reaction indicated transformation of 19.1% of Cu atoms into Cu^2＋, illustrating that Cu is the active ingredient or electron donor promoting the decomposition of PCB- 153. The mechanism underlying this process differs from a traditional H donor. However, there is no significant change on the surface of IRZn-C before and after the reaction, suggesting that Zn acts as catalyst during the process of PCB-153 decomposition.     

Dissipation of polycyclic aromatic hydrocarbons and microbial activity in a field soil planted with perennial ryegrass

Dissipation and plant uptake of polycyclic aromatic hydrocarbons (PAHs) in contaminated agricultural soil planted with perennial ryegrass were investigated in a field experiment. After two seasons of grass cultivation the mean concentration of 12 PAHs in soil decreased by 23.4% compared with the initial soil. The 3-, 4-, 5-, and 6-ring PAHs were dissipated by 30.9%, 25.5%, 21.2%, and 16.3% from the soil, respectively. Ryegrass shoots accumulated about 280 μg·kg^-1, shoot dry matter biomass reached 2.48 × 10⁴ kg·ha^-1, and plant uptake accounted for about 0.99% of the decrease in PAHs in the soil. Significantly higher soil enzyme activities and microbial community functional diversity were observed in planted soil than that in the unplanted control. The results suggest that planting ryegrass may promote the dissipation of PAHs in long-term contaminated agricultural soil, and plant-promoted microbial degradation may be a main mechanism of phytoremediation.     

Sources of primary production supporting food webs in an arid coastal embayment

Penaeid shrimp can be useful ecological indicators of linkages between shallow tropical coastal habitats, acting as integrators of carbon and nitrogen sources due to their generalist feeding habits and their mobility between habitats and with tidal cycles. In the current study, the contribution of mangrove, seagrass and microbial mat to the nutrition of two penaeid shrimp species, Penaeus semisulcatus and Metapeneus ensis, in a shallow arid embayment in the Arabian Gulf was assessed through a combination of analysis of stomach contents and dual carbon and nitrogen stable isotope signatures. Shrimp tissue stable isotope signatures identified seagrass as a major source of carbon and nitrogen for both species, contributing 21–38?% (1–99?‰). Microbial mat was also detected as a significant nutritional source for early-stage Metapenaeus affinis postlarvae (1–27?%). However, mangroves were not identified as a significant source, with the range of results including the possibility of a zero contribution. Moreover, the greatest possible contribution of mangroves as source of carbon was less than for the other primary producers. This may be due the high salinity and wide temperature range limiting mangrove productivity as well as the low export of dissolved and particulate organic material out of the mangroves due to low rainfall.     

2,4-D二甲胺盐对莲草直胸跳甲生存和繁殖的影响

为探究除草剂在防治喜旱莲子草(Alternanthera philoxeroides)的过程中对其天敌昆虫的影响,采用不同浓度的2,4-D二甲胺盐浸叶处理的喜旱莲子草饲喂莲草直胸跳甲,连续饲喂7d后,考察了莲草直胸跳甲的繁殖、存活和发育情况。结果表明,2,4-D二甲胺盐可显著降低莲草直胸跳甲成虫的取食量,且抑制作用随药剂浓度升高和取食时间延长而显著增强;较高浓度(1.72～3.44g·L~(-1))的2,4-D二甲胺盐还会导致莲草直胸跳甲雌成虫存活率和产卵量的明显降低,卵孵化率、幼虫存活率和蛹羽化率也显著降低。可见,高浓度(1.72～3.44g·L~(-1))的2,4-D二甲胺盐对莲草直胸跳甲的生长发育和繁殖有显著不利影响,在防治喜旱莲子草时,应将2,4-D二甲胺盐的施用浓度控制在0.22～0.86g·L~(-1)内。