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《山地学报》2017,(5)
近几十年来,气候变暖、大气CO_2浓度升高和干旱对陆地生态系统的影响引起了广泛关注。杨树是世界各国普遍种植的木本植物,研究其对环境变化的响应具有重要的理论和实践意义。本文采用Meta分析(Meta analysis)方法定量总结了增温、大气CO_2浓度升高、干旱对杨树生理生态特性的影响。通过Web of Science、中国知网等中英文数据库检索,共收集了34篇原始文献,获得690个独立样本。结果表明:(1)增温显著提高了杨树的高增长(+78.32%)、叶面积(+58.23%),促进了地上生物量(+89.59%)和叶生物量的积累(+71.69%),显著降低了杨树的水分利用效率(-22.61%)和碳同位素(-5.51%);(2)CO_2浓度升高显著提高了杨树的叶面积(+49.65%)和光合速率(+22.53%),以及根生物量(+72.36%),显著降低了杨树的气孔导度(-17.21%);(3)干旱显著提高了杨树的根冠比(+38.95%)和水分利用效率(+34.52%),显著降低了杨树的叶面积(-148.53%),以及总生物量(-70.81%)。从本文收集的文献来看,单独研究大气CO_2浓度升高、增温或干旱对杨树生理生态特性影响的文献较多,关注两两交互或三者协同作用对杨树生理生态特性影响的文献很少,这些环境因子的交互作用对杨树生理生态特性的影响研究应加强。 相似文献
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<正> 地处甘肃东部的平凉地区是杨树分布的中心地带。杨树曾是该地区人工林主要树种和木材生产重要来源。然而近年来杨树生产发展受到了诸多因素制约,尤其是黄斑星天牛危害导致杨树生产力急遽下降,进而出现了“全面砍伐,五年内不准再栽杨树”的决策,使杨树大有断种绝迹之势。为此,对平凉地区杨树将如何发展进行探讨和研究非常必要。 相似文献
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云南气候环境变化对辣木种植产业的影响研究 总被引：1，自引：0，他引：1
以适宜辣木种植的气候环境条件为基础,采用云南各气象台站1959-2012年逐月的气象观测资料和数据,分析研究了云南气候环境变化对辣木种植产业的影响.得到的结果为：云南适合大面积推广种植辣木,但在不同的区域推广种植辣木,其气候环境的适应性差异则是比较显著的.因此,云南辣木种植产业的健康推进和理性发展,要以市场经济规律为基础,根据云南气候环境变化的时空特征和规律来进行科学合理的规划、引导和实施. 相似文献
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洞庭湖湿地柳属木本植物变化趋势及成因 总被引：1，自引：0，他引：1
柳属(Salix)植物是洞庭湖湿地唯一的原生木本植物,对湿地生态系统功能的维护具有重要意义,而以往研究大多关注草本植物,缺乏对木本植物的认识。本研究通过2008年5月和2013年11月的洞庭湖湿地大面积调查,揭示洞庭湖湿地柳属木本植物的变化趋势。结果表明,洞庭湖湿地柳属木本植物主要分布于东洞庭湖,其次是南洞庭湖,分布形式为小面积点状分布和大面积带状分布。2008年5月,洞庭湖湿地柳属木本植物分布区的面积为993.7 hm2,2013年11月减少至192.9 hm2。2008年5月,洞庭湖湿地柳属木本植物以原生型植物为主,2013年11月,其以种植型植物为主。在2008~2013年间,柳属木本植物呈现分布面积急剧减少、原生型植物减少、种植型植物增加的变化趋势,业已成为本地区的濒危物种。2013年11月,各柳属木本植物分布点的乔木层特征差异明显,树高为4.37~15.2 m,胸径为3.63~68.71 cm,原生型植物树高和胸径明显大于种植型植物。在原生型植物区,林下优势植物主要为短尖薹草(Carex brevicuspis);在种植型植物区,林下优势植物主要为芦苇(Phragmites australis)、荻(Miscanthus sacchariflorus)和短尖薹草。水位降低、淹水时间缩短、水质下降与大面积种植杨树等是导致洞庭湖湿地柳属木本植物退化的主要原因。 相似文献
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《资源与生态学报(英文版)》2021,(4)
宽城传统板栗栽培系统位于京津冀水源涵养功能区。传统板栗栽培系统以农林复合为特征,有研究表明相比于单一板栗种植模式,复合种植具有更好的生态效益。但当前当地农户大多以单一板栗种植为主。通过生态补偿,可以激励农户转变板栗经营方式,达到传承中国重要农业文化遗产、并提高生态效益的目的。本文引入偏好系数修正机会成本,通过访谈及发放问卷等调查方法,获取宽城地区农户单一板栗种植、板栗–栗蘑复合种植、板栗–小米复合种植以及板栗–养鸡复合经营投入产出状况与劳动力外出务工收入,通过分析和测算,得到结果如下:(1)尽管三种复合模式的净收入较高,但其经济投入比单一板栗种植模式多,单位投资的回报率低;(2)宽城地区青壮年劳动力外出务工的平均收入高于当地种植业,因此当地板栗复合种植生产模式具有较高的机会成本;(3)研究结果表明板栗–养鸡复合经营模式无需补偿,板栗–栗蘑复合种植模式至少需要补偿1608.5USD ha~(–1) yr~(–1),对板栗–小米复合种植模式最低需要补偿198.3 USD ha~(–1) yr~(–1),才可以保障农户获得其创造的全部价值,从而激励农户恢复传统的农林复合生产模式,实现经济和生态效益的双赢并传承农业文化遗产。 相似文献
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水稻种植过程中,常具有浓厚的环境适应的特征。分布在不同地貌区的壮族是典型的稻作民族,已充分意识到所在地区气候、土壤等自然地理环境对水稻种植的深刻影响。为适应自然地理环境,发挥最大的生产效益,山居壮族多选择种植生长期较长、耐寒、耐肥的粳稻为主;在平原丘陵地区的壮族则以种植生长期短的籼稻居多;为适应岩溶山区干旱少水、不利于灌溉的环境,当地壮族则多种陆稻,但由于陆稻口感不佳以及所在地区人地关系由宽趋紧,导致陆稻在壮族种植结构中的地位不断下降。此外,壮族在生活中对水稻用途的定位,也影响到水稻品种的选择与种植。 相似文献
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疏勒河流域双塔灌区种植结构变化及其原因 总被引：3，自引：0，他引：3
基于1996-2010年双塔灌区各乡（镇）农作物类型、种植面积、供水定额、用水定额、作物单产及价格等资料,探讨了气候变化背景下农业种植结构调整原因及其影响。结果表明：研究区2010年作物种植面积较1996年增长2.3倍,其中粮食作物种植面积减少,经济作物和其他作物种植面积增加,农作物总产值和单位产值均明显提高,说明当地种植结构调整优化在产生经济效益方面效果明显。当地种植结构调整主要受自然条件、政策指导、历史根源、农民意愿、市场调节、灌溉供水条件等多方面因素的影响,其中自然条件中的水资源供应状况主要影响作物种植面积,其他因素影响作物种植类型。通过种植结构调整,当地农业产值在增长同时,用水紧张现象较以前有所缓解,地表水基本可以满足农田灌溉需求,减少了对地下水的使用,从而对保护当地生态具有重要意义。 相似文献
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Social capital has the potential to influence the success of biodiverse carbon plantings in the face of uncertainty amongst rural landholders about the need or efficacy of efforts to address climate change through tree planting. We conducted 17 face-to-face semi-structured interviews with landholders in Victoria, Australia who voluntarily participate in biodiverse carbon plantings on their land, focusing in particular on the role of social capital for understanding how ‘early adopters' can advocate for programs locally. The interviews revealed the importance of social networks and the profound impact of trusted peers on the diffusion of carbon planting schemes. These social capital dimensions are especially important for shaping ongoing participation and the ways in which participants become active agents in trusted relationships that influence the participation of others. Our results suggest that the positive impact of social networks can counteract doubts about the validity of climate adaptation responses such as carbon planting, and enable landholders to connect the program with their existing stewardship motivations. The ability for early adopters of the program to demonstrate the physical materialisation of their plantings to others was vital to this process. We propose that targeting champions and trusted peers in local communities could accelerate the proliferation of biodiverse carbon planting schemes. 相似文献
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上海城市建成环境对居民通勤方式选择的影响 总被引：14，自引：2，他引：12
伴随中国快速城市化与机动化进程,私人汽车拥有量不断增长,由此引起的交通拥堵和环境问题已成为制约中国城市可持续发展的难题。基于上海市区的居民通勤问卷调查数据,采用多项Logit模型检验了街道尺度城市建成环境对于居民通勤方式选择的影响,结果表明,在控制了其他因素后,提高居住地的人口密度、土地利用混合度与十字路口比重,可以减少小汽车通勤方式的选择,而就业地建成环境对居民通勤方式选择影响相对较弱;建成环境对通勤方式选择的影响会因个体的社会经济异质性而不同。这些结论为通过优化土地利用规划来优化居民通勤结构的城市交通和城市规划政策提供了启示。 相似文献
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近70年来兰州城市气温的变化 总被引：15，自引：3，他引：12
利用兰州市70年来的气温记录,采用城郊对比的方法定量的研究了城市化对兰州气温的影响。在分析了年平均气温和各特征气温的相关性的基础上,利用主成分分析的方法提取气温变化的主控制因子——低温控制因子、高温控制因子。利用两个控制因子的城郊对比,定量的揭示了城市化对城市气温变化的影响。任何区域气候变化不仅有城市化等人为因素的影响,而且带有大范围的气候背景的影响,所以在讨论城市发展对气温的影响之前,首先通过滑动T-检验研究了兰州市气温变化的大的趋势,得出兰州城市气温的11年变化周期,对于这一现象初步认为这于太阳的黑子活动的周期性有关。 相似文献
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Using survey and interview data gathered from educators and educational administrators, we investigate school and community impacts of unconventional gas extraction within Pennsylvania's Marcellus Shale region. Respondents in areas with high levels of drilling are significantly more likely to perceive the effects of local economic gains, but also report increased inequality, heightened vulnerability of disadvantaged community members, and pronounced strains on local infrastructure. As community stakeholders in positions of local leadership, school leaders in areas experiencing Marcellus Shale natural gas extraction often face multiple decision-making dilemmas. These dilemmas occur in the context of incomplete information and rapid, unpredictable community change involving the emergence of both new opportunities and new insecurities. 相似文献
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Rachel Winterton Andrew Butt Bradley Jorgensen John Martin 《The Australian geographer》2019,50(1):111-128
Within the policy and academic literature, the impact of rural retirement migration (RRM) on community sustainability has been questioned. This qualitative study investigated the perceived impact of retirement migration on rural social sustainability from a local government perspective. Focus groups were conducted with local government senior managers and community services staff (n = 39) across six rural local government areas in one Australian state. Data were analysed against the three components of rural social sustainability (equity, community and rurality) proposed by Jones and Tonts [1995. “Rural Restructuring and Social Sustainability: Some Reflections on the Western Australian Wheatbelt.” Australian Geographer 26: 133–140]. While RRM is perceived to benefit rural community capacity to facilitate or maintain equity, community and rurality, it also presents challenges for local government. Participants suggested that capacity to facilitate equity, community and rurality in contexts of RRM was impacted by uncertainty around future impacts of RRM on population ageing, increasing advocacy and expectations of older in-migrants, and the impact of RRM on rural heterogeneity. These issues required local governments to think critically about how to accommodate and manage the needs and expectations of older in-migrants, while mediating potential impacts associated with RRM. 相似文献
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《Urban geography》2013,34(7):616-638
This article presents new methods for comparative analysis of patterns of gross population density, and employs them in five Canadian metropolitan areas. By comparing changes in levels and patterns in the 1971-2001 period, assessments are made of the macro-level impacts of policies relating to densification and re-densification, and of how such impacts vary by city size. Three comparative techniques are employed. The first uses location quotients to map densities for census tracts in urbanized areas. A second approach defines central and peripheral density clusters, and analyzes their mapped patterns. The third method employs local indices of spatial autocorrelation (LISA) to detect locally significant "hotspots," particularly suburban outliers of higher density. Results suggest that in the suburbs homogenously low-density areas are in decline, while both high-density and heterogeneous areas are increasingly evident. 相似文献
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Spatial disparities in the price of residential heating fuel may have considerable impacts on social well-being. Dependence on relatively expensive fuels in off-gas grid contexts may be linked to high rates of fuel poverty, making it a key policy issue. However, fuel prices in the off-grid sector have received relatively little research attention. This study investigates pricing structures within the heating oil market in Northern Ireland, a region with high rates of fuel poverty, using applied spatial analysis. The results indicate significant spatial variations in the price of heating oil at local level. High prices occur in remote rural areas and urban areas with high rates of gas heating. Prices appear to arise from a complex set of interacting factors related to local market structures, supply costs, market competitiveness and socio-economic factors which affect demand. This study makes a significant contribution to the literature on off-gas residential heating. Although further research is needed, the results presented here suggest that policy responses such as price regulation may have only limited impacts on fuel poverty levels, emphasizing the importance of maximising access to more affordable fuels (e.g. mains gas or renewables) as part of a sustainable energy solution. 相似文献
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Revealing the drivers and scale effects of water pollutant discharges is an important issue in the study of the environmental consequences during urban agglomeration evolution. It is also a prerequisite for realizing collaborative water pollutant reduction and environmental governance in urban agglomerations. This paper takes 305 counties in the Yangtze River Delta (YRD) as an example and selects chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) as two distinctive pollutant indicators, using the Spatial Lag Model (SLM) and Spatial Error Model (SEM) to estimate the drivers of water pollutant discharges in 2011 and 2016. Then the Multiscale Geographically Weighted Regression (MGWR) model is constructed to diagnose the scale effect and spatial heterogeneity of the drivers. The findings show that the size of population, the level of urbanization, and the economic development level show global-level increase impacts on water pollutant discharges, while the level of industrialization, social fixed assets investment, foreign direct investment, and local fiscal decentralization are local-level impacts. The spatial heterogeneity of local drivers presents the following characteristics: Social fixed assets investment has a strong promoting effect on both COD and NH3-N discharges in the Hangzhou-Jiaxing-Huzhou region and the coastal area of the YRD; industrialization has a promoting effect on COD discharges in the Taihu Lake basin and Zhejiang province; foreign direct investment has a local inhibitory effect on NH3-N discharge, and the pollution halo effect is more prominent in the marginal areas of the YRD such as northern Jiangsu, northern Anhui, and southern Zhejiang; local fiscal decentralization has a noticeable inhibitory effect on COD discharge in the central areas of the YRD, reflecting the positive impacts on improved local environmental awareness and stronger constraints of multilevel environmental regulations in the urban agglomeration. Therefore, it is recommended to guide greener development to reduce the water pollutant discharge; to embed an environmental push-back mechanism in the fields of industrial production, capital investment, and financial income and expenditure; and to establish a high-quality development pattern of urban agglomerations systematically compatible with the carrying capacity of the water environment. 相似文献