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91.
Clustering Timber Harvests and the Effect of Dynamic Forest Management Policy on Forest Fragmentation 总被引:1,自引:1,他引:0
Eric J. Gustafson 《Ecosystems》1998,1(5):484-492
To integrate multiple uses (mature forest and commodity production) better on forested lands, timber management strategies
that cluster harvests have been proposed. One such approach clusters harvest activity in space and time, and rotates timber
production zones across the landscape with a long temporal period (dynamic zoning). Dynamic zoning has been shown to increase timber production and reduce forest fragmentation by segregating uses in time without reducing the spatial extent of timber production. It is reasonable
to wonder what the effect of periodic interruptions in the implementation of such as strategy might be, as would be expected
in a dynamic political environment. To answer these questions, I used a timber harvest simulation model (HARVEST) to simulate
a dynamic zoning harvest strategy that was periodically interrupted by changes in the spatial dispersion of harvests, by changes
in timber production levels, or both. The temporal scale (period) of these interruptions had impacts related to the rate at
which the forest achieved canopy closure after harvest. Spatial dynamics in harvest policies had a greater effect on the amount
of forest interior and edge than did dynamics in harvest intensity. The periodically clustered scenarios always produced greater amounts of forest interior and less forest edge than did their never clustered counterparts. The results suggest that clustering of harvests produces less forest fragmentation than dispersed cutting alternatives,
even in the face of a dynamic policy future. Although periodic episodes of dispersed cutting increased fragmentation, average
and maximum fragmentation measures were less than if clustered harvest strategies were never implemented. Clustering may also
be useful to mitigate the fragmentation effects of socially mandated increases in timber harvest levels. Implementation of
spatial clustering during periods of high timber harvest rates reduced the variation in forest interior and edge through time,
providing a more stable supply of forest interior habitat across the landscape.
Received 19 September 1997; accepted 6 August 1998. 相似文献
92.
93.
Deirdre Howard-Wagner 《Ethnic and racial studies》2018,41(7):1332-1351
Thinking about the governance of Indigenous poverty as an economic, social and racial project, the paper offers a way of understanding the dynamics of Indigenous policy formation in Australia in the neo-liberal age as what Howard Winant first coined a racial formation. In providing this analysis, this paper sits alongside a small, but growing body of work that reveals the racialized effects of governing through poverty in the neo-liberal age. 相似文献
94.
Marian Wilson Samantha M. Riedy Maddy Himmel Ashley English Joshua Burton Sandra Albritton 《Chronobiology international》2018,35(6):849-852
ABSTRACTThis study assessed sleep quality, sleepiness and use of workplace break opportunities in 1285 health-care workers via an online questionnaire. Two hospitals were surveyed – one with and one without a fatigue mitigation policy. Across all respondents, 68.9% reported generally taking breaks of at least 30 min and 21.7% had access to a quiet place to rest, with no significant differences between hospitals. The presence of a fatigue mitigation policy was not associated with reduced sleepiness. However, accounting for hospital and shift characteristics, employees with access to a quiet place to rest while on break had significantly lower self-reported sleepiness scores. 相似文献
95.
DNA barcoding of economically important freshwater fish species from north‐central Nigeria uncovers cryptic diversity 下载免费PDF全文
Moshood K. Mustapha Chioma G. Nzeh Segun O. Oladipo Ifeanyi C. Nneji Agboola O. Okeyoyin Christopher D. Nwani Obih A. Ugwumba Adiaha A. A. Ugwumba Emmanuel O. Faturoti Yun‐yu Wang Jing Chen Wen‐Zhi Wang Adeniyi C. Adeola 《Ecology and evolution》2018,8(14):6932-6951
This study examines the utility of morphology and DNA barcoding in species identification of freshwater fishes from north‐central Nigeria. We compared molecular data (mitochondrial cytochrome c oxidase subunit I (COI) sequences) of 136 de novo samples from 53 morphologically identified species alongside others in GenBank and BOLD databases. Using DNA sequence similarity‐based (≥97% cutoff) identification technique, 50 (94.30%) and 24 (45.30%) species were identified to species level using GenBank and BOLD databases, respectively. Furthermore, we identified cases of taxonomic problems in 26 (49.00%) morphologically identified species. There were also four (7.10%) cases of mismatch in DNA barcoding in which our query sequence in GenBank and BOLD showed a sequence match with different species names. Using DNA barcode reference data, we also identified four unknown fish samples collected from fishermen to species level. Our Neighbor‐joining (NJ) tree analysis recovers several intraspecific species clusters with strong bootstrap support (≥95%). Analysis uncovers two well‐supported lineages within Schilbe intermedius. The Bayesian phylogenetic analyses of Nigerian S. intermedius with others from GenBank recover four lineages. Evidence of genetic structuring is consistent with geographic regions of sub‐Saharan Africa. Thus, cryptic lineage diversity may illustrate species’ adaptive responses to local environmental conditions. Finally, our study underscores the importance of incorporating morphology and DNA barcoding in species identification. Although developing a complete DNA barcode reference library for Nigerian ichthyofauna will facilitate species identification and diversity studies, taxonomic revisions of DNA sequences submitted in databases alongside voucher specimens are necessary for a reliable taxonomic and diversity inventory. 相似文献
96.
97.
京津冀城市群区域产业协同的政策格局及评价 总被引:1,自引:0,他引:1
产业协同发展是京津冀区域协同发展的三个重点领域之一,科学合理的产业协同政策是加快实现这一发展目标的重要保障。通过对京津冀城市群区域产业协同政策事件的系统梳理,从区域、省际和城际3个尺度解读了产业协同政策的格局及其演进过程,并从新区域主义的管治视角进行了评价。研究认为:(1)京津冀产业协同发展进入了快速发展的机遇期,协同政策极大地推动了区域内跨地产业合作和城市间产业联系,有助于提高城市群整体竞争力;(2)不同空间尺度的产业协同政策关注的重点、发展的方向、演化的特征不同,当前城市间的产业协同政策与区域协同发展目标的关系不明确,产业协同对生态环境的改善尚不显著,亟需加强研究和统筹协调;(3)受城市行政区等级关系和竞争关系的影响,京津冀产业协同政策与市场调节无法实现高度契合统一,与新区域主义的管治理念并不相符,影响科学合理协同政策的制定与实施。研究对当前京津冀区域产业协同发展推进及其政策制定有重要的参考意义。 相似文献
98.
Translocations,conservation, and climate change: use of restoration sites as protorefuges and protorefugia 下载免费PDF全文
David W. Braidwood Mark A. Taggart Melanie Smith Roxane Andersen 《Restoration Ecology》2018,26(1):20-28
High levels of human activity have affected the quality and usability of the natural landscape, leading to habitat degradation, loss of connectivity between sites, and reduced chances of long‐term survival for individual species. In line with conservation policy, ecological restoration practitioners try to improve degraded sites by means of reestablishing species lost from these sites, thereby returning ecological functionality and maintaining biological diversity. It may appear difficult to integrate the long‐term potential impacts of climate change within restoration strategies. However, more refined climate projections and species distribution models provide us with better understanding of likely scenarios, enabling us to consider future proofing as an integral part of the design of restoration sites, aiding plant conservation. We believe that it is possible to go one step further with a closer integration of restoration and conservation objectives. We introduce the novel concepts of “protorefuges” and “protorefugia”—restoration sites that threatened species can be translocated to, where the restoration design can be specifically adapted to help reduce the decline of threatened species at the leading and trailing edges (respectively) of bioclimatic envelope shifts. This is particularly relevant for nuclear decommissioning sites, which may be free from human activity for decades to centuries. 相似文献
99.
The SER Standards: a globally relevant and inclusive tool for improving restoration practice—a reply to Higgs et al. 下载免费PDF全文
George D. Gann Tein McDonald James Aronson Kingsley W. Dixon Bethanie Walder James G. Hallett Kris Decleer Donald A. Falk Emily K. Gonzales Carolina Murcia Cara R. Nelson Alan J. Unwin 《Restoration Ecology》2018,26(3):426-430
In response to a critique by Higgs et al., this article clarifies the content and intent of the Society for Ecological Restoration's (SER) International Standards for the Practice of Ecological Restoration. Higgs et al. expressed concern that the SER Standards are not sufficiently underpinned by principles and risk disenfranchising some practitioners by narrowing what qualifies as ecological restoration. To demonstrate that these concerns are unfounded, we discuss the policy context and principles on which the Standards are based, its organizational structure, the innovative and inclusive approach used for development, and highlight significant errata by Higgs et al. 相似文献
100.
Coupling Input‐Output Tables with Macro‐Life Cycle Assessment to Assess Worldwide Impacts of Biofuels Transport Policies 下载免费PDF全文
Audrey Somé Thomas Dandres Caroline Gaudreault Guillaume Majeau‐Bettez Richard Wood Réjean Samson 《Journal of Industrial Ecology》2018,22(4):643-655
Many countries see biofuels as a replacement to fossil fuels to mitigate climate change. Nevertheless, some concerns remain about the overall benefits of biofuels policies. More comprehensive tools seem required to evaluate indirect effects of biofuel policies. This article proposes a method to evaluate large‐scale biofuel policies that is based on life cycle assessment (LCA), environmental extensions of input‐output (I‐O) tables, and a general equilibrium model. The method enables the assessment of indirect environmental effects of biofuels policies, including land‐use changes (LUCs), in the context of economic and demographic growth. The method is illustrated with a case study involving two scenarios. The first one describes the evolution of the world economy from 2006 to 2020 under business as usual (BAU) conditions (including demographic and dietary preferences changes), and the second integrates biofuel policies in the United States and the European Union (EU). Results show that the biofuel scenario, originally designed to mitigate climate change, results in more greenhouse gas emissions when compared to the BAU scenario. This is mainly due to emissions associated with global LUCs. The case study shows that the method enables a broader consideration for environmental effects of biofuel policies than usual LCA: Global economic variations calculated by a general equilibrium economic model and LUC emissions can be evaluated. More work is needed, however, to include new biofuel production technologies and reduce the uncertainty of the method. 相似文献