Soil organic carbon stock variability in the Northern Gangetic Plains of India: interaction between agro‐ecological characteristics and cropping systems

Soil organic carbon (SOC) content and its spatial distribution in the Northern Gangetic Plain (NGP) Zone of India were determined to establish the cause–effect relationship between agro‐ecological characteristics, prevailing crop management practices and SOC stock. Area Spread Index (ASI) approach was used to collect soil samples from the NGP areas supporting predominant cropping systems. Exponential ordinary kriging was found most suitable geo‐statistical model for developing SOC surface maps of the NGP. Predicted surface maps indicated that 43.7% area of NGP had 0.5–0.6% SOC, while the rest of the area was equally distributed with high (0.61–0.75%) and low (< 0.5%) SOC content levels. Averaged across cropping systems, maximum SOC content was recorded in Bhabar and Tarai Zone (BTZ), followed by Central Plain Zone (CPZ), Mid‐Western Plain Zone (MWPZ), Western Plain Zone (WPZ) and South‐Western Plain Zone (SWPZ) of the NGP. The SOC stock was above the optimum threshold (> 12.5 Mg/ha) in 97.8, 57.6 and 46.4% areas of BTZ, CPZ and MWPZ, respectively. Only 9.8 and 0.4% area of WPZ and SWPZ, respectively, had SOC stock above the threshold value. The variation in SOC stock was attributed largely to carbon addition through recycling of organic sources, cropping systems, tillage intensity, crop or residue cover and land‐use efficiency, nutrient‐use pattern, soil texture and prevailing ecosystem. Adoption of conservation agriculture, balanced use of nutrients, inclusion of legumes in cropping systems and agro‐forestry were suggested for enhancing SOC stock in the region.     

山区区域特色产业的选择与培育——以铜仁市为例

阐述了山区区域特色产业的概念和内涵,分析了铜仁市特色产业的现状及存在的问题,并提出了特色产业发展的思路及对策。铜仁市应从科学规划,人才引进,品牌培育及多方融资等方面促进特色产业的发展。     

Abrupt temperature change and a warming hiatus from 1951 to 2014 in Inner Mongolia,China

An abrupt temperature change and a warming hiatus have strongly influenced the global climate.This study focused on these changes in Inner Mongolia, China. This study used the central clustering method, Mann-Kendall mutation test and other methods to explore the abrupt temperature change and warming hiatus in three different temperature zones of the study region based on average annual data series.Among the temperature metrics investigated, average minimum temperature(Tnav) shifted the earliest,followed by average temperature(Tnv) and average maximum temperature(Txav). The latest change was observed in summer(1990 s), whereas the earliest was observed in winter(1970 s). Before and after the abrupt temperature change, Tnav fluctuated considerably, whereas there was only a slight change in Txav.Before and after the abrupt temperature change, the winter temperature changed more dramatically than the summer temperature. Before the abrupt temperature change, Tnav in the central region(0.322°C/10 a)and west region(0.48°C/10 a) contributed the most to the increasing temperatures. After the abrupt temperature change, Tnav in winter in the central region(0.519°C/10 a) and in autumn in the west region(0.729°C/10 a) contributed the most to the temperature increases. Overall, in the years in which temperature shifts occurred early, a warming hiatus also appeared early. The three temperature metrics in spring(1991)in the east region were the first to exhibit a warming hiatus. In the east region, Txav displayed the lowest rate of increase(0.412°C/a) in the period after the abrupt temperature change and before the warming hiatus,and the highest rate of increase after the warming hiatus.     

黄土残塬沟壑区不同林龄与坡向人工刺槐林生态系统服务协同关系

[目的] 通过权衡关系的研究探索不同林龄与坡向人工刺槐林多项生态系统服务间的差异及动态变化关系，为黄土残塬沟壑区人工刺槐林的经营管理提供理论依据。[方法] 按照不同林龄阶段和坡向共设置36个样地，对所选林分的涵养水源、土壤碳储量、土壤氮储量、年均生产力、生物多样性5个方面的生态系统服务进行测算，利用均方根偏差（RMSD）对该区人工刺槐林生态系统服务的权衡与协同关系进行研究，对生态系统服务与林分因子进行冗余分析。[结果] ①不同林龄、坡向人工刺槐林的生态系统服务差异显著（p<0.05）；随林龄增加，涵养水源量和年均生产力从幼龄林到中龄林增加达到最大值，随后逐渐减小；而生物多样性则呈先增后减趋势，在成熟林时期最高；土壤碳、氮储量随林龄增加呈逐渐增加趋势；阴坡的各生态系统服务价值均高于阳坡。②林龄是引起生态系统服务权衡关系变化的主导因子（p<0.05），坡向对生态系统服务权衡关系的影响不显著（p > 0.05），土壤碳固存与土壤氮固存呈协同关系，涵养水源与其他生态系统服务的权衡关系相比程度较高。③人工刺槐林5项生态系统服务与盖度、郁闭度、凋落物厚度呈现不同程度的正相关，与坡度呈现不同程度的负相关。[结论] 人工刺槐林生态系统服务在中龄林和过熟林时期权衡度高，不利于整体生态系统服务效益的发挥。应在中龄林时期引入耐旱灌木或乡土草本，在过熟林经营过程中，在满足涵养水源的前提下，合理控制林分密度，促进其他生态系统服务的作用，提高整体效益。     

淳化县渭北黄土高原花椒栽植管理技术

结合淳化县不同区域气候和地形地势等条件,提出了园地及优良品种选择、苗木处理与保护、栽植与定干等花椒栽植技术,以及地膜覆盖、施肥、整形修剪、中耕除草、病虫害防治等椒园管理技术。     

生物炭对黑土区土壤水分扩散与溶质弥散持续效应研究

为探究施用生物炭对黑土区坡耕地土壤水分扩散和溶质弥散的持续效应，于2016—2019年在1.5°、3°、5°的径流小区开展了生物炭持续效应试验，分析了单次施加生物炭对土壤容重、孔隙度、有机质含量、Boltzmann变换参数ξ、非饱和土壤水分扩散率D(θ)、非饱和土壤水动力弥散系数Dsh(θ)的持续作用。结果表明：土壤中单次添加生物炭后的4年内均可显著降低土壤容重、提高土壤孔隙度、增加土壤中有机质含量，且各指标变化率均随坡度增大、施炭年限延长而减小；坡度、年份、是否施用生物炭3个因素中，对土壤容重、孔隙度、有机质含量影响程度最大的均为是否施用生物炭；施用生物炭增大了ξ，且ξ随坡度增加、施炭后年限延长逐年减小。2016—2019年D(θ)与Dsh(θ)均随土壤含水率的增加而迅速增加。当土壤含水率小于等于042cm3/cm3时，生物炭抑制土壤水分扩散；当土壤含水率大于0.42cm3/cm3时，生物炭促进土壤水分扩散。当土壤含水率小于等于0.36cm3/cm3时，生物炭抑制土壤中NaCl溶液的弥散；当土壤含水率大于0.36cm3/cm3时，生物炭可以促进土壤中NaCl溶液的弥散。试验区θ处于0.20~0.35cm3/cm3，故施用生物炭对水分扩散、NaCl溶液弥散均具有抑制效果，且生物炭对水分扩散和溶液弥散抑制效果均随坡度增加、施炭后年限延长而减弱。     

Institutional performance and participatory paradigms: Comparing two groups of watersheds in semi-arid region of India

Watershed development programmes carried out in different agroclimatic conditions in India resulted in beneficial impact in terms of productivity enhancement and natural resources conservation, but less attention paid to institutional and participatory aspects. This paper explored the performance of various institutions regarding execution of watershed development programmes in semi-arid region of India. Recorded observations from documents maintained at watershed level and information collected through primary survey as well as focus group discussion with different types of stakeholders were used for analysis. The results indicated lacunae in participatory aspects during programme implementation process like monitoring activities, management of common property resources and equity. Gap in linkages and differential level of performance of various watershed level functionaries indicates the necessity for corrections in the structures and linkages pattern for sustainability of the infrastructure and institutions. The study also showed unequal priorities by the implementing agencies towards institutions, land and water resources development, production enhancement activities and fodder resources development as well as rationalities of technical, economic, financial, political and social aspects among the watersheds.     

近55年来河西地区干旱时空演变特征及其与ENSO事件的关系

根据河西地区14个气象站点1961-2015年的逐月气象观测资料，基于SPEI指数采用Mann-Kendall趋势检验法、反距离加权插值(IDW)等方法分析了近55年来河西地区年代际、四季干旱及空间变化特征，并探讨了ENSO 事件与该区干旱的关系。结果表明：在年代际变化上，自20世纪90年代以来河西地区干旱次数增多、干旱程度加重。季节时间变化上，河西地区春、夏、秋季均呈干旱化趋势，春季干旱化趋势最为突出，夏季次之，冬季略呈变湿趋势。空间变化上，整个河西地区春季均呈干旱化趋势，而且大部分地区的春旱趋势极为显著，其中春旱趋势最显著的地方是金塔；冬季整个研究区趋于湿润化。各季节干旱高频区分别集中在：春季在金塔、民勤地区，夏季在河西西北部，秋季在河西中东部及西部的安西—玉门一线，冬季在101°E以西的河西地区。河西地区秋季SPEI与SSTA指数的相关性最为显著，春季次之，夏季最弱。ENSO事件发生强度与河西地区SPEI影响因子的多项式拟合关系表明，ENSO事件强度对温度的影响高于降水；其中在ENSO暖事件(厄尔尼诺事件)发生年份，气温有明显的上升趋势；在ENSO冷事件(拉尼娜事件)发生年份，少数年份降水有所增加，对气温的影响较弱。     

艾纳香脱氢酶基因家族的生物信息学分析

采用RT-PCR和RACE（Rapid amplification of cDNA ends）技术,从艾纳香（Blumea balsamifera (L.) DC.）叶片中克隆到4条编码艾纳香脱氢酶（BbADH1、BbADH2、BbADH3、BbADH4）基因的cDNA序列,并对4条核苷酸及其编码的氨基酸序列进行生物信息学分析。结果显示:4条艾纳香脱氢酶序列开放阅读框均在900 bp左右,蛋白质等电点（pI）值在5.0~9.0之间,含量最多的氨基酸为亮氨酸（Leu）,最少的为色氨酸（Try）,具有明显的疏水区和亲水区,N端未发现信号肽,且无跨膜区;同源性比对结果显示,艾纳香BbADH蛋白与其他植物中ADH蛋白具有高度的相似性,且具有脱氢酶的特征功能域;系统发育分析表明,艾纳香（B. balsamifera (L.) DC.）BbADH1和BbADH3同处于一个分支,且与胡杨（Populus euphratica Oliv.）PeADH物种亲缘关系较近,而艾纳香BbADH4和BbADH2处于不同分支,且分别与葡萄（Vitis vinifera）VvADH和烟草（Nicotiana tabacum）NtADH物种亲缘关系较近。     

东北黑土区坡耕地斜坡垄作与顺坡垄作土壤侵蚀的对比分析

斜坡垄作是东北黑土区最普遍的垄作方式之一，但当前关于斜坡垄作对坡耕地土壤侵蚀的影响鲜见报道。为此，本研究基于室内模拟试验，设计2个降雨强度（50和100 mm/h）以及2种垄作方式（斜坡垄作和顺坡垄作），分析东北黑土区坡耕地斜坡垄作与顺坡垄作坡面土壤侵蚀的差异。结果表明：（1）在50和100 mm/h降雨强度下，斜坡垄作断垄前坡面侵蚀速率分别是顺坡垄作的0.46%和0.35%；但在45 min的降雨过程中，由于斜坡垄作发生断垄现象，造成50和100 mm/h两种降雨强度下斜坡垄作坡面侵蚀速率分别是顺坡垄作的1.24和1.03倍。（2）斜坡垄作径流强度和侵蚀速率随降雨历时的变化均从断垄开始发生突变。在50和100 mm/h降雨强度下，随着降雨历时的变化斜坡垄作断垄前的径流强度和侵蚀速率值均低于顺坡垄作,其平均径流强度分别为顺坡垄作的8.42%和3.75%、平均侵蚀速率分别为顺坡垄作的0.46%和0.35%，但斜坡垄作断垄后坡面径流和侵蚀速率明显增大，其平均径流强度分别为顺坡垄作的1.33和1.47倍、平均侵蚀速率分别是顺坡垄作的2.03和1.62倍。（3）在50和100 mm/h降雨强度下，斜坡垄作断垄前坡面径流量和侵蚀量存在显著的线性关系（P<0.01），而断垄后两者的相关关系则不显著（P>0.05）；而顺坡垄作在两种降雨强度下坡面径流量和侵蚀量存在显著的线性关系。（4）在两种降雨强度下斜坡垄作坡面90%以上的径流泥沙均来自断垄后。因此，提高垄丘稳定性和防止断垄现象发生，是减少斜坡垄作坡面土壤侵蚀的关键所在。