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191.
192.
Community-level resource management efforts are cornerstones in ensuring sustainable use of natural resources. Yet, understanding how community characteristics influence management practices remains contested. With a sample size of ≥725 communities, we assessed the effects of key community (i.e., socioeconomic) characteristics (human population size and density, market integration, and modernization) on the probability of occurrence of fisheries management practices, including gear, species, and spatial restrictions. The study was based in Solomon Islands, a Pacific Island country with a population that is highly dependent on coastal fisheries. People primarily dwell in small communities adjacent to the coastline dispersed across 6 island provinces and numerous smaller islands. We used nationally collected data in binomial logistic regression models to examine the likelihood of management occurrence, given socioeconomic context of communities. In contrast to prevailing views, we identified a positive and statistically significant association between both human population size and market integration and all 3 management practices. Human population density, however, had a statistically significant negative association and modernization a varied and limited association with occurrence of all management practices. Our method offers a way to remotely predict the occurrence of resource management practices based on key socioeconomic characteristics. It could be used to improve understanding of why some communities conduct natural resource management activities when statistical patterns suggest they are not likely to and thus improve understanding of how some communities of people beat the odds despite limited market access and high population density. 相似文献
193.
Increasingly intensive strategies to maintain biodiversity and ecosystem function are being deployed in response to global anthropogenic threats, including intentionally introducing and eradicating species via assisted migration, rewilding, biological control, invasive species eradications, and gene drives. These actions are highly contentious because of their potential for unintended consequences. We conducted a global literature review of these conservation actions to quantify how often unintended outcomes occur and to elucidate their underlying causes. To evaluate conservation outcomes, we developed a community assessment framework for systematically mapping the range of possible interaction types for 111 case studies. Applying this tool, we quantified the number of interaction types considered in each study and documented the nature and strength of intended and unintended outcomes. Intended outcomes were reported in 51% of cases, a combination of intended outcomes and unintended outcomes in 26%, and strictly unintended outcomes in 10%. Hence, unintended outcomes were reported in 36% of all cases evaluated. In evaluating overall conservations outcomes (weighing intended vs. unintended effects), some unintended effects were fairly innocuous relative to the conservation objective, whereas others resulted in serious unintended consequences in recipient communities. Studies that assessed a greater number of community interactions with the target species reported unintended outcomes more often, suggesting that unintended consequences may be underreported due to insufficient vetting. Most reported unintended outcomes arose from direct effects (68%) or simple density-mediated or indirect effects (25%) linked to the target species. Only a few documented cases arose from more complex interaction pathways (7%). Therefore, most unintended outcomes involved simple interactions that could be predicted and mitigated through more formal vetting. Our community assessment framework provides a tool for screening future conservation actions by mapping the recipient community interaction web to identify and mitigate unintended outcomes from intentional species introductions and eradications for conservation. 相似文献
194.
Caitlin E. Andrews Sandra H. Anderson Karin van der Walt Rose Thorogood John G. Ewen 《Conservation biology》2022,36(4):e13892
Conservation translocation is a common method for species recovery, for which one increasingly frequent objective is restoring lost ecological functions to promote ecosystem recovery. However, few conservation translocation programs explicitly state or monitor function as an objective, limiting the ability to test assumptions, learn from past efforts, and improve management. We evaluated whether translocations of hihi (Notiomystis cincta), a threatened New Zealand passerine, achieved their implicit objective of restoring lost pollination function. Through a pollinator-exclusion experiment, we quantified, with log response ratios (lnR), the effects of birds on fruit set and seed quality in hangehange (Geniostoma ligustrifolium), a native flowering shrub. We isolated the contributions of hihi by making comparisons across sites with and without hihi. Birds improved fruit set more at sites without hihi (lnR = 1.27) than sites with hihi (lnR = 0.50), suggesting other avian pollinators compensated for and even exceeded hihi contributions to fruit set. Although birds improved seed germination only at hihi sites (lnR = 0.22–0.41), plants at sites without hihi had germination rates similar to hihi sites because they produced 26% more filled seeds, regardless of pollination condition. Therefore, although our results showed hihi improved seed quality, they also highlighted the complexity of ecological functions. When an important species is lost, ecosystems may be able to achieve similar function through different means. Our results underscore the importance of stating and monitoring the ecological benefits of conservation translocations when functional restoration is a motivation to ensure these programs are achieving their objectives. 相似文献
195.
Agroforests can play an important role in biodiversity conservation in complex landscapes. A key factor distinguishing among agroforests is land-use history – whether agroforests are established inside forests or on historically forested but currently open lands. The disparity between land-use histories means the appropriate biodiversity baselines may differ, which should be accounted for when assessing the conservation value of agroforests. Specifically, comparisons between multiple baselines in forest and open land could enrich understanding of species’ responses by contextualizing them. We made such comparisons based on data from a recently published meta-analysis of the effects of cocoa (Theobroma cacao) agroforestry on bird diversity. We regrouped rustic, mixed shade cocoa, and low shade cocoa agroforests, based on land-use history, into forest-derived and open-land-derived agroforests and compared bird species diversity (species richness, abundance, and Shannon's index values) between forest and open land, which represented the 2 alternative baselines. Bird diversity was similar in forest-derived agroforests and forests (Hedges’ g* estimate [SE] = -0.3144 [0.3416], p = 0.36). Open-land-derived agroforests were significantly less diverse than forests (g* = 1.4312 [0.6308], p = 0.023) and comparable to open lands (g* = -0.1529 [0.5035], p = 0.76). Our results highlight how land-use history determined the conservation value of cocoa agroforests. Forest-derived cocoa agroforests were comparable to the available – usually already degraded – forest baselines, but entail future degradation risks. In contrast, open-land-derived cocoa agroforestry may offer restoration opportunities. Our results showed that comparisons among multiple baselines may inform relative contributions of agroforestry systems to bird conservation on a landscape scale. 相似文献
196.
南水北调大型渡槽结构抗震安全性研究 总被引:1,自引:1,他引:1
阐述了南水北调中大型渡槽的抗震问题,分别介绍了基于常微分方程求解器(ODE)和有限元方法的大型渡槽动力计算模型、动力特性分析和设置铅芯橡胶支座(LRB)的隔震分析。研究表明,基于ODE求解器的解析和半解析方法有很好的精度和可靠性,可用于大型渡槽的初步设计。结合所得的研究成果,对南水北调的渡槽抗震提出了合理化建议。 相似文献
197.
198.
介绍了在传统SBR脱氮工艺的基础上 ,开发的用于处理COD和氮浓度较高的工业废水的两段SBR系统 (TSSBR) .根据传统SBR工艺在反应过程中 ,当COD不再被降解 ,而硝化反应又没有开始时 ,DO迅速大幅度升高以及pH曲线上出现的拐点 ,可以将COD降解与硝化反应分割开 ,先后在不同的反应器内进行 ,分别命名为SBR1和SBR2 ,避免高COD浓度对硝化反应的冲击 ,提高处理效率 .利用在线检测的DO、ORP和pH参数实时控制SBR1、SBR2各个生化过程的反应时间 ,解决了两段SBR系统的自动控制问题 ,可以使系统长期稳定运行 ,保证出水水质 ,节约能耗 .采用实时控制策略 ,并控制系统温度在 3 0℃左右 ,可将SBR2的硝化反应控制在亚硝酸型硝化结束 .采用该工艺处理石化废水 ,COD去除率达到 90 %~ 95 % ,3 0℃时的比硝化反应速率达到 0 3kg(NH4 N) (kg(MLSS)·d) ,出水已检测不出氨氮和硝态氮 相似文献
199.
200.
采用具有自由端的梳状中空纤维膜-生物反应器处理污水,考察了其膜污染控制性能.结果发现,如果将膜污染定义为恒压操作下的膜通量下降,膜组件b比膜组件a易获得更大的膜通量,具有更优异的抗污染效果.含膜组件b的MBR在温度为22~26℃,污泥浓度为7 500~10 500 mg/L,曝气量为200 L/h,抽停时间比为9 min/1 min,压力为0.02 MPa的条件下连续运行47 d,膜通量维持在4.0~8.0 L·(m2·h)-1,其间不需要任何水力或化学清洗.由于这种膜组件易充分发挥曝气的作用,不易污染,因而所需曝气量较小,并且当抽停时间比从12 min/1 min变化到6 min/1 min,膜通量差别不大.对膜的清洗试验表明,水力清洗+化学清洗+乙醇浸泡是最有效的清洗方法.水力清洗+化学清洗后,较之水力清洗,中空纤维膜表面上的胶团数目和面积大大减少,膜孔变得更加清晰. 相似文献