宁夏银川平原沙化土地不同人工林土壤质量评价

沙化土地土壤贫瘠、生产力低,人工植被恢复是重要的土壤改良措施。为研究宁夏银川平原沙地不同人工林栽植对土壤的影响,以银川腹部沙地银川植物园沙化土壤恢复区的2017年3月种植的文冠果(Xanthoceras sorbifolium)和欧李(Cerasus humilis)人工林地为研究对象,以邻近的长期撂荒地为对照,对土壤质量进行了研究。2020年7—8月采集土样并测定了土壤物理、化学、生物学等20个指标作为土壤质量评价的总数据集,方差分析筛选出差异显著性的9个指标作为重要数据集指标,采用主成分分析法和Norm值建立土壤质量评价指标最小数据集(MDS),利用线性和非线性两种评分方法计算土壤质量指数(SQI)。结果表明：与长期撂荒地相比,银川平原沙化土壤恢复区人工文冠果、欧李林地的土壤理化性质较好,土壤砂粒百分比减少、粉粒和黏粒百分比有所增加,pH降低;有机质、全氮、全磷、全钾等主要养分指标提高,蔗糖酶、脲酶、纤维素酶等主要生物酶活性也高于撂荒地,筛选出的研究区土壤质量评价MDS指标为土壤粉粒百分比和全磷。2种评价方法下,文冠果和欧李人工恢复林地的SQI高于撂荒地,但提高不显著(P>0...     

韧性城市研究综述——基于城市复杂系统视角

在全球气候变化与持续城市化的背景下,增强城市韧性是提升城市应急管理能力,实现城市系统可持续发展的重要途径。明确城市韧性的内涵、核心要素及相互作用机理,开展城市系统韧性测度与城市系统模拟,对提升变化环境下城市系统恢复力与韧性水平,缓解变化环境对城市系统运行稳定性冲击压力具有重要意义。基于文献与资料分析,全面解析韧性城市核心概念与各国韧性城市建设、管理与研究实践。此外,研究从城市复杂系统视角探究变化环境对城市系统影响机制、测度方法与系统模拟路径。研究为韧性城市理论、方法与实证研究提供了参考,并为我国韧性城市建设实践提供决策依据与政策建议。     

变化环境下火干扰研究进展

火是地球系统的重要过程,也是一种剧烈的环境干扰因素。火是生态系统变化的驱动力和催化剂,调节着生态系统的结构和功能,同时反馈给气候系统。近年来,世界多个国家相继爆发了历史上罕见的极端火事件,使得火干扰、气候变化和人类活动之间的相互作用关系得到了空前的关注。主要从3个方面回顾了变化环境下火干扰研究的进展,包括(1)火干扰的时空格局;(2)火干扰的驱动机制;(3)火干扰的生态效应。概括起来,遥感技术的发展使得火监测精度不断提高,对火时空格局的刻画由过去侧重火燃烧面积单一因素转向具有多重属性的火干扰体系。气候变化和人类活动共同决定着火干扰的分布格局、频率和强度,考虑气候的季节性能够提高火干扰的预测能力。火干扰调节着生态系统的草木平衡,对于生物多样性和生境的维持非常重要。此外,火干扰通过生物质燃烧释放的大量温室气体影响大气组成和空气质量,同时通过改变地表状况和陆-气相互作用来影响气候系统。正确理解气候-植被-火之间的相互作用和反馈机制有助于未来火干扰体系的预测。随着高温、大风、干旱等极端气候事件增多,未来全球大部分区域火发生的风险增加,但是人类活动可能会使火和气候之间的关系发生解耦。可持续的火管...     

黄河流域生态安全屏障防风固沙时空变化及驱动因素

黄河流域是我国重要的生态屏障和经济区,防风固沙服务及其驱动机制的研究对于筑牢黄河流域生态安全屏障具有重要意义。基于修正土壤风蚀模型(RWEQ)定量评估黄河流域2000—2018年防风固沙服务时空变化,采用相关分析和地理加权回归模型(GWR)从社会、气候、土壤、植被、地形等角度探究各驱动因素对黄河流域防风固沙服务影响的空间异质性。结果表明：(1)2000—2018年黄河流域土壤风蚀模数与单位面积防风固沙量分别以0.04 t hm^-2 a^-1和0.14 t hm^-2 a^-1的速率下降,而防风固沙保有率和植被覆盖度则分别以0.05%·a^-1和0.26%·a^-1的速率上升。(2)黄河流域土壤风蚀以微度(<2 t hm^-2 a^-1)和轻度(2—25 t hm^-2 a^-1)为主,共占研究区面积的96.28%。土壤风蚀在空间分布呈现西北高东南低的特点,而防风固沙服务高值则主要分...     

金沙江下游典型库区消落带植被恢复模式

消落带植被分布、生活型、多样性的调查研究显著促进了消落带植被恢复技术的进步,然而相邻两梯级库区消落带植被分布的差异以及植被群落特征的年际变化并不明确。此外,金沙江下游部分区域表现出一定的干热特征,其影响下的消落带植被群落特征有待深入了解。基于2019年和2021年向家坝和溪洛渡库区消落带植被调查结果,分析表明：(1)金沙江下游消落带按照下垫面特性主要分为硬岩型、软岩型、松软堆积型3种类型,坡度平缓的松软堆积型消落带是植被恢复的主要类型;(2)整体上,消落带优势植被类型是一年生和多年生草本,单优势种、少优势种群落较为普遍,两个库区消落带优势种重要值差异显著,植被生活型较少;(3)向家坝、溪洛渡库区消落带在分别经历6次和8次周期性水淹后,消落带植被分布与群落物种多样性特征变化不显著,表明消落带植被群落结构相对稳定。综上说明向家坝、溪洛渡两个相邻的梯级库区消落带植被恢复需要以灌草为主,且具有不同的潜在恢复模式,因此需要对应采取不同的恢复策略。研究对于科学指导金沙江下游梯级水电站库区消落带植被恢复具有重要意义。     

环境中富啡酸对小麦吸收利用亚硒酸钠及其毒性的影响

利用小麦水培安验,研究了从土壤中提取的富啡酸（Ｆｕｌｖｉｃａｃｉｄ,ＦＡ）对亚硒酸钠生物有效性及毒性的影响。结果表明,富啡酸对小麦吸收利用亚硒酸钠有明显的影晌,并且对高浓度亚硒酸钠的毒性有一定的抑制作用,富啡酸可提高小麦对硒胁迫的生态适应性。     

中国主要五针松群落学特征及其生物量的研究

本文根据现有的文献资料,系统地分析了中国五针松的分布．群落学特征,按不同分布区、不同群落类型探讨了中国五针松的群落生物量和年净生产量及在群落的不同层次上的分布．比较分析了不同分布区五针松的年干物质累积速度（ＮＰ／Ｂ）．结果表明：１１５─１３５ａ生的阔叶红松林群落生物量在９７．０９─１２０．５１ｔ／ｈｍ￣２之间,年净生产量在８．６９８─１０．３４ｔ／ｈｍ￣２．ａ之间,年净生产量长白山山脉沙松、鹅耳枥红松林＞小兴安岭南坡枫桦、水曲柳红松林＞小兴安岭北坡云杉、冷杉红松林;３０─３６ａ生的华山松林群落生物量在７８．７５─９４．７３ｔ／ｈｍ￣２之间,年净生产量在４．９９３─５．５３７ｔ／ｈｍ￣２．ａ之间,年净生产量贵州山地常绿阔叶华山松林＞秦岭中山地阔叶华山松林＞甘肃小陇山针阔叶华山松林．ＮＰ／Ｂ值：长白山山脉的阔叶红松林＞小兴安岭山脉的阔叶红松林;秦岭中山地阔叶华山松林＞甘肃小陇山针阔华山松林＞贵州中山地常绿阔叶华山松林．     

Integrative assessment of Western Himalayas streams using multimeric index

Multimeric index based on fish composition was used to assess integrity of shallow and wadeable streams of lower Himalayas in temperate and subtropical ecoregions. Streams were surveyed for biotic and abiotic sampling during base flow periods in pre and post monsoon seasons in 2007 and 2008. Twenty three metrics were computed based on taxonomic richness, trophic composition, habitat preferences, abundance, stress tolerance and species origin attributes of 19 fish species. Candidate metrics were analyzed for efficiency to discriminate degraded sites from non-degraded and redundancy analysis, which sorted 71% of omnivore individuals (excluding intolerant species), 40% of intolerant individuals, 44% of herbivore individuals (excluding benthic species), abundance and 44.5% of non-native individuals as potential metrics. IBI values at forest, agriculture and urban zones were ranged between (max–min) 9.9–3.22, 6.18–2.49 and 4.43–0.69 respectively. Results suggested that poor ecological conditions in streams were generally related to drainage of urban sewage and habitat fragmentation while agriculture land use seems to have moderate impact on ecological integrity of the streams. Less urbanized upstream with grasslands and forests as land use, showed excellent to good ecological integrity of the streams. Proposed index was able to distinguish varying degrees of human impact on ecological integrity of streams and thus index could be used as valuable tool for bioassessment of regional flowing water resources.     

Climate sensitivity of conifer growth doesn’t reveal distinct low–high dipole along the elevation gradient in the Wolong National Natural Reserve,SW China

Recent climate warming is usually hypothesized to cause tree growth decline in the semi-arid regions where forests are particularly vulnerable to warming induced increases of water deficit. But there is still a large knowledge gap of climate warming effects on tree growth of cold temperate forest in the sub-humid region. Here we assess how climate warming has affected tree growth in the Wolong National Natural Reserve, Southwestern China, where recent warming might not cause tree growth decline because of the cold-humid climatic conditions. Tree-ring data from four co-dominant coniferous species (Larix potaninii var. macrocarpa, Tsuga chinensis, Abies faxoniana and Juniperus saltuaria) along an elevation gradient (from 2700 m to 3700 m) all imprinted temperature signals, and were both positively and significantly correlated with instrumental record of temperature data during the analyzed period of 1954–2010. Furthermore, the rising temperature since 1980 induced pervasive tree growth increases and stronger temperature signals for the coniferous species along the elevation gradient. The tree-ring chronology recorded a strong coherence with instrumental temperature since 1980 and was successful to keep up with the pace of climate warming rate. If climate warming continues, further increases in forest growth could be expected, and the terrestrial carbon sink will be strengthened for the local forest ecosystem in the future.