Revealing regional regeneration projects in three small towns in Aotearoa—New Zealand     

Harvey C. Perkins  Michael Mackay  Deborah Levy  Malcolm Campbell  Nick Taylor  Raewyn Hills  Karen Johnston 《New Zealand geographer》2019,75(3):140-151

We discuss case studies of three South Island small towns: Ashburton, Timaru and Oamaru and their wider local authority jurisdictions, focusing on how local stakeholders are defining the issues facing these places and identifying, prioritising and investing in regeneration initiatives, sometimes with the support of central government and other external agencies. Our key finding is that small‐town regeneration is complex, demands a long‐term local collaborative approach, and significant investment in skills, information sharing and programme development, some of which needs to be provided by external, central government, agencies.  相似文献   

长石莼（缘管浒苔）（Ulva linza）原生质体再生与分化发育初步研究          下载免费PDF全文

陈群芳  汤文仲  冯子慧  霍元子  何培民 《海洋与湖沼》2011,42(3):397-403

采用细胞酶解技术获得长石莼（缘管浒苔）原生质体,再通过细胞培养观察原生质体再生以及各种分化发育途径。结果表明,长石莼（缘管浒苔）主要存在3种分化发育途径：1）部分原生质体可直接分裂形成有假根或无假根得单细胞苗。2）部分原生质体分裂成规则细胞团或不规则细胞团,最后形成苗簇。3）部分原生质体可发育为孢子囊／配子囊,其中部分...  相似文献   

Patterns and Cellular Mechanisms of Arm Regeneration in Adult Starfish Asterias rollestoni Bell     

FAN Tingjun  FAN Xianyuan  DU Yutang  SUN Wenjie  ZHANG Shaofeng  LI Jiaxin 《青岛海洋大学学报(英文版)》2011,(3):255-262

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Grazing as a driver for Populus euphratica woodland degradation in the semi-arid Aibi Hu region, northwestern China     

I. Säumel  D. ZicheR. Yu  I. KowarikD. Overdieck 《Journal of Arid Environments》2011,75(3):265-269

The endangered river plain woodlands of semi-arid Central Asia provide numerous ecosystem services. Previous studies have focused mainly on changes in water supply and salinity as the underlying mechanisms of Populus euphratica woodland’s decline. We tested whether vegetative regeneration of P. euphratica serves as an alternative pathway to propagation from seeds for reproduction in a degraded tree steppe in northwestern China and whether this method also works on grazed sites. We measured the effects of different grazing pressures on tree growth, survival, and vegetative regeneration. When subjected to high or moderate grazing pressure, P. euphratica populations failed to regenerate vegetatively, indicating recruitment limitation. A 25% increase of grazing pressure decreased the ramet density to 50% and the ramet height to 25%, as well as reducing the average age of ramets to one year. As overgrazing seriously limits the potential of natural recovery of P. euphratica a balance between livestock grazing and the regeneration of the Tugai forests is needed to sustain positive effects of increasing water tables and floods on tree vitality and regeneration. To restore population structure, and to support early vegetative regeneration long-term livestock management interventions to exclude livestock from degraded and recovered land need to be developed.  相似文献   

塔里木河下游人工胡杨林生态恢复过程的初步研究   总被引：8，自引：3，他引：5  

古丽努尔·沙布尔哈孜  尹林克  严成 《干旱区地理》2004,27(3):384-387

在以植物群落调查样地为基础,对塔里木河下游不同林龄人工胡杨林的物种丰富度、物种多样性指数、群落均匀度、生态优势度等进行了分析,同时对土壤理化性质在21a间的变化情况也作了详细分析。通过分析,表明人工胡杨群落随着发育年限的增加,群落物种丰富度,物种多样性指数和均匀度指数不断增长,而群落生态优势度逐渐降低,同时土壤理化性质不断改善。在此基础上,对塔里木河植被的演变趋势作一初步的探讨和估计,从而对塔里木河下游植被的生态恢复也具有重要意义。  相似文献   

海洋多毛类动物的再生演化     

张琳琳  翁洁羊  李倩 《海洋与湖沼》2021,52(2):450-467

再生是生物体丢失的组织或器官重新生长和修复的过程,是生物科学的本质问题之一。再生现象在生物界中广为分布,但不同生物的再生能力却存在着巨大差异。虽然近年来再生的分子和细胞机制取得了显著的研究进展,但驱动物种再生能力多样性形成的遗传机制尚不明确。海洋多毛类因其多样且快速演化的再生能力和简单线性的分节结构成为研究再生演化的极佳类群。本文首先从生态和演化生物学的角度综合分析了多毛类再生的特点、进一步总结细胞和分子来源以及再生性状多样性,然后分析了印太交汇区的海洋多毛类再生性状的特点以及外在多圈层因素对再生性状的潜在驱动效应,并就未来的发展趋势提出了建议。  相似文献   

Saguaro (Carnegiea Gigantea) Densities and Reproduction Over the Northern Sonoran Desert     

《自然地理学》2013,34(6):505-518

Casual observations suggest that saguaro populations are densest in southeastern Arizona, although data have not been collected and no study has been done to address this topic. In addition, the topic of reproductive density has similarly never been addressed. Saguaro reproductive output is directly related to the number of adult individuals and the number of branches in the area. Thirty saguaro populations over their U.S. range were sampled to consider two variables: population density and reproductive stem density. Stepwise regression using climate and vegetation (e.g., availability of nurse plants) to predict density yielded tree + Ambrosia cover and maximum July precipitation. Nurse cover, however, is also influenced by summer rain. The partial correlation results suggest that high saguaro densities are linked with high quality nurse cover (i.e., not Larrea tridentata) in addition to summer rainfall. Total cover and mean annual precipitation are the best predictors of reproductive stem density. Mean annual precipitation may be a good predictor of reproductive stem density, because population density is linked with summer rain while branching is linked with winter rain. The plots were also divided into climatic regions. One-way ANOVA shows that the northeast (high winter precipitation) and west (dry) have lower saguaro densities than the southeast (high summer precipitation), while the northeast and southeast both have very high reproductive stem densities relative to the west. The warmer west is less susceptible to periodic freezing mortality, while previous work has shown that the southeast generally regenerates more successfully. Thus in the colder northeast, which is also outside of the primary summer rain and best nurse plant belt, low density populations seem to be maintained only with high reproductive density.  相似文献   

Climatic Controls of Saguaro (Carnegiea Gigantea) Regeneration: A Potential Link With El Niño     

《自然地理学》2013,34(6):465-475

Saguaro cacti establish periodically in cohorts during years that are climatically favorable. Determining the establishment year is complicated by age-height relationships that vary considerably from site to site and require extensive data collection. Estimations of age-height relationships for only a few locales have thus limited the ability of researchers to estimate age in other populations, and consequently to relate periods of regeneration to climate. We collected data for 254 saguaros in the arid western portion of the species' range and employed a recently developed site-specific technique for estimating saguaro age to reconstruct the population structure at this locale. Second, we used discriminant analysis to determine which climate variables best predict regeneration years. We found that above-average temperatures in November coupled with concurrent high soil moisture levels, conditions typically associated with El Niño years, are associated with years characterized by high regeneration. Accordingly, these results suggest that El Niño events may be related to years of favorable regeneration for saguaros.  相似文献   

Packed‐Column of Granular Activated Carbons for Removal of Chemical Oxygen Demand from Industrial Wastewater     

Sawanya Laohaprapanon  Marcia Marques  Fabio Kaczala  William Hogland 《洁净——土壤、空气、水》2013,41(3):244-250

In the present study, chemical oxygen demand (COD) removal by packed‐columns of activated carbon (AC) derived from two different materials (coal activated carbon, CAC and wood activated carbon, WAC) is reported as part of an on‐site wastewater treatment system for handling small volumes of wastewater generated at wood‐floor industries for which there are no proper on‐site treatment options available in the market. The performance of the sorbents, the effect of bed depth (0.19 and 0.57 m) and volumetric load (0.10 and 0.24 m h^?1) on the breakthrough curve of sorption systems were studied. The results indicated the feasibility of using both ACs to treat these wastewaters. At the bed depth (0.57 m), volumetric load (0.24 m h^?1), and 30% breakthrough, CAC and WAC showed treatment capacity of 40.5 L kg^?1 in 250 h and 23.8 L kg^?1 in 63 h, respectively. This indicated that CAC requires longer retention times to reach a performance similar to WAC. The experimental data was fit into the bed depth‐service time model showing that under the same conditions, CAC had higher maximum sorption capacity (N₀) than WAC. Moreover, thermal regeneration at 500°C temperature could be a cost‐effective procedure since the reuse of spent AC through such regeneration process for further treatment could still achieve 90% of the initial sorption capacity, reducing then costs for the use of new sorbents and also the need for waste disposal.  相似文献   

What is the Meaning of ‘Social Mix’? Shifting perspectives in planning and implementing public housing estate redevelopment     

Kathy Arthurson  Iris Levin  Anna Ziersch 《The Australian geographer》2015,46(4):491-505

This paper unravels a variety of perspectives about the concept of social mix, drawing on a case study of the implementation of a redevelopment project in Melbourne. The first part provides a theoretical overview of two internationally predominant academic debates around policy interpretations of this concept, namely social mix as a means for promotion of social inclusion; and as a state-led form of gentrification. These two arguments are usually presented as one, with social inclusion and reductions of concentrations of disadvantage one side of the ‘social mix policy’ coin, and state-led gentrification the other. This paper contributes to the national and international literature on public housing estate regeneration and social mix policies through exploring the question of whether these two ideas about social mix were shared by different stakeholders as the ‘messy’ process of redevelopment unfurled. Interviews were conducted with public tenants, homeowners and homebuyers, private renters and local service providers at the Carlton Housing Estate to explore the diverse perspectives of various stakeholder groups as estate design and implementation shifted. The study identified that as a result of the global financial crisis and the developers exerting pressure on government there was a gradual move away from perceiving social mix as a policy tool for encouraging social inclusion at Carlton, between public housing tenants and private residents, towards a different form of social mix and inclusion. Contrary to intentions, the revised form of social mix at Carlton was perceived as a means to harness market capital and attract higher income residents to the inner city.  相似文献