晋北干旱区盐碱地柽柳形态特征及其与土壤养分的关系

【目的】研究困难立地植被地上和地下部分对环境胁迫的响应,探讨植物叶、根形态对不良环境的适应策略,是逆境生理生态学研究的有效途径,可为困难立地造林及管理提供科学依据。【方法】以30年生柽柳Tamarix chinensis人工纯林为研究对象,分析其比叶面积(SLA)、细根比根面积(SRA)和比根长(SRL),并对0~60 cm不同土壤层次的全N、全P、速效K、Na、Mg、Ca、Zn、Fe、Cu等营养元素进行含量测定,研究盐碱地植物柽柳地上及地下部分形态特征及其与盐碱地土壤养分垂直分布格局的相关性。【结果】1)在晋北干旱区重度盐碱胁迫下的柽柳SLA显著高于轻度和中度胁迫(F=3.301,P=0.041);SRA在重度盐碱胁迫下高于轻度和中度胁迫,与轻度胁迫差异显著(F=0.154,P=0.015);SRL在不同盐碱胁迫等级下无显著差异(F=0.808,P=0.632),但在重度盐碱胁迫下其值明显高于轻度和中度胁迫。2)土壤全N含量表现为浅层高于深层,且重度胁迫盐碱含量明显低于轻度胁迫,全P、Cu含量在不同盐碱胁迫及不同土壤深度差异均不显著,速效K、Fe含量在不同盐碱胁迫下表现出完全不同的分布格局,Na含量在不同盐碱胁迫下差异显著,Mg、Ca、Fe含量在15~60 cm土壤表现出重度盐碱胁迫高于轻度和中度盐碱胁迫土壤,Zn含量在不同盐碱胁迫间差异不显著。3)不同的土壤营养元素对柽柳叶、根形态特征的作用机制不同,土壤速效K与柽柳SLA、SRA和SRL均呈显著正相关关系(P<0.05),Zn与柽柳SRA、SRL呈显著负相关关系(P<0.05),土壤全P和Fe含量与SRL呈显著正相关关系(P<0.05),其中以30~45 cm土壤养分含量与柽柳形态特征的关系最为密切,此土壤深度全N含量与SLA、SRA和SRL均呈显著负相关关系(P=0.038,0.019,0.006)。【结论】研究结果可为树种立地适应性评价、该区域植被恢复以及生态环境改善提供理论参考。     

小麦热激蛋白转录因子C家族基因的结构及其在干旱胁迫中的表达

小麦热激蛋白转录因子在热胁迫和耐热性产生的过程中发挥重要作用。为进一步了解小麦热激蛋白转录因子C亚家族,本研究采用全基因组信息保守结构域比对和进化聚类分析,共鉴定了24个小麦TaHsfC基因,并对TaHsfC亚家族成员染色体定位、基因结构、亚细胞定位、对应蛋白质的氨基酸特点、基因表达进行了分析。结果表明,24个TaHsfCs主要分布在5条染色体上,其中A基因组中有7个,B基因组中9个,D基因组中有6个,另外两个所在染色体位置不清楚。TaHsfCs含有0～2个内含子,其中 TaHsfC1亚族基因含有1～2个内含子, TaHsfC2亚族基因则含有0～1个内含子。聚类分析表明,小麦TaHsfC成员共分为 TaHsfC1和 TaHsfC2两个亚族。24个TaHsfCs成员全部定位于细胞核。在15%PEG模拟干旱条件下,干旱敏感品种矮抗58和耐旱品种晋麦47中有10个TaHsfC基因显著上调表达,其中 TaHsfC2亚族基因的表达量上调倍数均高于 TaHsfC1亚族基因(其中 TaHsfC2j和 TaHsfC2k未在晋麦47中检测到表达量)。本研究可为探索小麦热激蛋白转录因子C家族基因在小麦抗旱中的分子机制提供一定的理论支撑。     

茂兰自然保护区森林景观格局变化分析

本文以2011年和2017的森林调查成果化数据为基础,依据不同优势树种组,采用景观格局指数法,从组成结构、斑块特征、景观异质性和空间分布4方面分析2011年和2017年茂兰自然保护区的森林景观格局及其变化。结果表明：林地面积增加了654.08 hm²；森林优势树种数量从15种增加至30种；景观面积(CA)最大的均为阔叶混交树种组,增加了1286.33hm²；斑块平均大小(MpS)最大的均为阔叶混交树种组,增加了471.80 hm²；面积加权的平均形状指数(AWMSI)和面积加权的平均分形指数(AWMPFD)最大值均为阔叶混交树种组；景观斑块边缘密度(ED)最大值均为阔叶混交树种组；阔叶混交树种组的平均最小距离(ENN)减少。从2011年2017年研究区的主要优势树种组阔叶混交树种组得以保护,这与人为干扰的减少有关。     

巨菌草在动物饲养和生态改善领域的应用研究进展

巨菌草具有适应性广、抗逆性强、根系发达、营养含量丰富、产量高等特点,近年来在动物饲养和生态改善领域得到了广泛应用。本文综述了近年来巨菌草在动物饲养和生态改善领域的最新研究应用进展,对其存在的问题进行讨论,并对其发展前景提出了建议,以期为巨菌草的开发利用提供参考。     

Changes in the relationship between species richness and belowground biomass among grassland types and along environmental gradients in Xinjiang,Northwest China

The association between biodiversity and belowground biomass (BGB) remains a central debate in ecology. In this study, we compared the variations in species richness (SR) and BGB as well as their interaction in the top (0-20 cm), middle (20-50 cm) and deep (50-100 cm) soil depths among 8 grassland types (lowland meadow, temperate desert, temperate desert steppe, temperate steppe desert, temperate steppe, temperate meadow steppe, mountain meadow and alpine steppe) and along environmental gradients (elevation, energy condition (annual mean temperature (AMT) and potential evapotranspiration (PET)), and mean annual precipitation (MAP)) based on a 2011-2013 survey of 379 sites in Xinjiang, Northwest China. The SR and BGB varied among the grassland types. The alpine steppe had a medium level of SR but the highest BGB in the top soil depth, whereas the lowland meadow had the lowest SR but the highest BGB in the middle and deep soil depths. The SR and BGB in the different soil depths were tightly associated with elevation, MAP and energy condition; however, the particular forms of trends in SR and BGB depended on environmental factors and soil depths. The relationship between SR and BGB was unimodal in the top soil depth, but SR was positively related with BGB in the middle soil depth. Although elevation, MAP, energy condition and SR had significant effects on BGB, the variations in BGB in the top soil depth were mostly determined by elevation, and those in the middle and deep soil depths were mainly affected by energy condition. These findings highlight the importance of environmental factors in the regulations of SR and BGB as well as their interaction in the grasslands in Xinjiang.     

Impacts of water resource planning on regional water consumption pattern: A case study in Dunhuang Oasis,China

Water resources are critical for the existence and development of oases in endorheic basins. Thus, to enable sustainable development, it is fundamentally important to understand how to allocate and use these resources in a reasonable way. We therefore simulated and analyzed changes in water consumption pattern within the Dunhuang Oasis of China under three scenarios using a system dynamic model that corresponds to different water consumption pattern. This was done to assess the impacts of regional water resource planning (comprehensive planning of the rational use of water resource and protection of ecosystem services in the Dunhuang Basin) on water consumption pattern within the Dunhuang Oasis. The first of these, Scenario 1, is a baseline in which the status quo is maintained, while Scenario 2 incorporates the comprehensive effects of agricultural water-saving irrigation measures with an inter-basin water diversion project, and Scenario 3 focuses on ecological rehabilitation. In the baseline Scenario 1, the total water consumption within the Dunhuang Oasis increased progressively while agricultural water consumption remained extremely high and threatened overall ecological security. In contrast, Scenario 2 would decrease agricultural water consumption by almost 5.30×10⁷ m³ following the implementation of water-saving practices. The additional water allocated from an inter-basin water diversion project would play an important role in alleviating ecological strain on the oasis. Finally, in Scenario 3, the total irrigated land must be decreased to 20.6×10³ hm² by 2025 assuming that water supply for ecosystem restoration would be at least 50% of the total consumption. Although water resource planning plays a very important role in alleviating the ecological water crisis within the oasis, it is necessary to consider the suitable scale of oasis with regard to current water consumption pattern.     

基于产业发展的宁夏生态移民村庄规划探析

分析了宁夏生态移民安置模式与产业发展现状，提出了以产业发展规划为前提指导，融合于物质空间的村庄规划方法，并阐述了宁夏生态移民中以高效农业、加工业、观光农业为主导产业的村庄规划的具体内容与方法。     

生境对无芒雀麦幼穗分化进程及生殖格局的影响

以乌苏1号无芒雀麦为材料,设置2个生长环境（荒漠绿洲区、高海拔地带）,通过观测幼穗分化进程及开花习性,探究生境对无芒雀麦幼穗分化及生殖格局的影响。结果表明,无芒雀麦幼穗分化从分蘖期开始至抽穗期结束,分为初生期、伸长期、结节期、小穗原基分化期、小花原基分化期、雌雄蕊原基分化期、雌雄蕊形成期和完穗期8个时期。幼穗分化是从生长锥顶端第1枝梗原基与小花原基开始分化,相同小枝梗上原基与小花原基均是自下逐渐向上发育;整穗是从顶部向下逐渐开花,下部枝梗开花时间小于上部枝梗;小穗上的小花由下向上逐步开花。与荒漠绿洲区相比,高海拔地带的无芒雀麦幼穗分化时间晚,周期缩短,穗部赤霉素（GA）、脱落酸（ABA）及叶片可溶性蛋白含量相对较高,细胞分裂素（CTK）含量和种子千粒重较低,但高海拔地带单穗成熟种子粒数与单位面积内种子产量高,更适合无芒雀麦种子生产。     

苜蓿地撂荒过程中土壤-微生物-胞外酶及化学计量的变化

紫花苜蓿(Medicago sativa L.)作为优良修复草种在黄土高原广泛种植,然而随着农村人口迁移及土地利用变化,苜蓿人工草地大量弃置的问题已引起广泛关注。为研究苜蓿弃置草地土壤质量变化规律,本研究分析了不同弃置年限(0年、5年和10年)苜蓿草地土壤养分、微生物量、参与土壤碳氮磷(C,N,P)循环的胞外酶活性及其化学计量变化。结果表明：总体上,土壤和微生物C,N含量随弃置年限呈增加趋势,而C,N相关胞外酶活性和化学计量变化幅度较小;土壤和微生物P含量随弃置年限增加而显著降低,但P相关胞外酶活性及化学计量均有不同程度的增加。进一步分析发现：相较于其他土层,表层(0～20 cm)土壤C,N,P含量及其酶活性较高,其变化趋势与总体结果相似;亚表层土壤(20～40 cm)和(80～100 cm)深层土壤C,N,P含量及其酶活性呈先增后减趋势,且各指标较于表层土壤均降低40%～80%。相关分析表明弃置草地土壤由于P匮乏而逐步退化,可通过补施磷肥改善。