Infl uence of the slope aspect on the ectomycorrhizal fungal community of Quercus variabilis Blume in the middle part of the Taihang Mountains,North China

The slope aspect is one of the most critical topographic factors in mountainous areas.Little is known,however,about the eff ect of the aspect on the ectomycorrhizal(ECM)fungal community.Additionally,we know very little about the composition of ECM fungal communities associated with Quercus variabilis,which is widely distributed in East Asia.In this study,we compared the richness,community composition,and exploration types of ECM fungi associated with Q.variabilis between predominantly south-and north-facing slopes in the Taihang Mountain,North China for the fi rst time.DNA was extracted from the root tips of Q.variabilis,and Illumina MiSeq sequencing was used to identify ECM fungi.In total,168 operational taxonomic units belonging to 28 genera were detected,and the ECM community was found to be dominated by Russula,Inocybe,Tomentella,Scleroderma,and Cortinarius.Compared with the north-facing slopes,the ECM communities on the south-facing slopes had higher diversity.The community composition and exploration types were directly aff ected by the slope aspect.Also,the aspect-induced edaphic variables,such as total phosphorus,total nitrogen,total potassium,pH,and soil water content,were important sources of variation in ECM fungal richness and distributions of exploration types.Diff erent genera tended to be distributed in various slope aspects.Cenococcum,Genea,and Clavulina were signifi cantly enriched in north-facing slopes,while Geopora,Helvelosebacina,Scleroderma,Gyroporus,Astraeus,Boletus,Tricholoma,Hebeloma,Cortinarius and unclassifi ed Thelephoraceae were more abundant in south-facing slopes.Hydrophobic ECM fungi were obviously enriched in the south-facing slope,but there was no statistical diff erence between hydrophilic among the south-and north-facing slopes.Our study deepened our knowledge of the aspect-driven variation in ECM fungal communities associated with Q.variabilis.

Elevation, Slope Aspect and Integrated Nutrient Management Effects on Crop Productivity and Soil Quality in North-west Himalayas, India

On farm bio-resource recycling has been given greater emphasis with the introduction of conservation agriculture specifically withclimate change scenarios in the mid-hills of the north-west Himalaya region（NWHR）. Under this changing scenario, elevation, slope aspect and integrated nutrient management（INM） may affect significantly soil quality and crop productivity. A study was conducted during 2009-2010 to 2010-2011 at the Ashti watershed of NWHR in a rainfed condition to examine the influence of elevation, slope aspect and integrated nutrient management（INM） on soil resource and crop productivity. Two years of farm demonstration trials indicated that crop productivity and soil quality is significantly affected by elevation, slope aspect and INM. Results showed that wheat equivalent yield（WEY） of improved technology increased crop productivity by -20%-37% compared to the conventional system. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-17%. North aspect and higher elevation increased crop productivity by 15%-25% compared to south aspect and low elevation（except paddy）. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-15%. Irrespective of slope, elevation and cropping system, the WEY increased by -30% in this region due to INMtechnology. The influence of elevation, slope aspect and INM significantly affected soil resources（SQI） and soil carbon change（SCC）. SCC is significantly correlated with SQI for conventional（R2 = 0.65＊）, INM technology（R2 = 0.81＊） and for both technologies（R2 = 0.73＊）. It is recommended that at higher elevation.（except for paddy soils） with a north facing slope, INM is recommended for higher crop productivity; conservation of soil resources is recommended for the mid hills of NWHR; and single values of SCC are appropriate as a SQI for this region.

Effects of drought and slope aspect on canopy facilitation in a mountainous rangeland

Aims Species composition and diversity of the mountainous rangelands are results of interactions between environmental severities,het-erogeneous topography and facilitative effects by nurse plants.This research was aimed to compare relative effects of these three envi-ronmental variables on the natural vegetation of a mountainous rangeland.For a more detailed understanding,effects of four dif-ferent nurse species were separately compared on the various plant growth forms and on two community plant responses(diversity and abundance).Methods A mountainous semiarid rangeland was selected in Baharkish,Quchan,Northeast of Iran.Density and canopy cover of all plant species were recorded under the canopy of four different shrubs and in open areas,in north and south-facing aspects,and in a normal and a drought year.Shannon diversity,total abundance(%cover)and the abundance of different growth forms were used as crite-ria for assessing effects of the environmental variables.Data were arranged in a factorial combination and analyzed by three-way analysis of variance using a GLM analysis.Important Findings(i)Drought,aspect and canopy created niche differentiation:annual forbs and shrubs were more affected by drought,whereas geophytes and grasses were more responsive to slope aspects.Effects of drought and slope aspect were more profound on species diversity,whereas that of canopy facilitation was stronger on plant abundance.(ii)Canopy facili-tation was dependent on severity of the abiotic factors and life history of interacting species.Canopy facilitation allowed for the persistence of only annual forbs,but it was disadvantaged during the drought year.Plant community responses to abiotic factors(slope and drought)were more dependent on the plant growth form,while responses to canopy facilitation were more dependent on the morphology and/or ecology of nurse shrubs.(iii)Effect of shrubs was dependent on their morphology and ecology:shrubs with larger canopy area and nitrogen fixation capa-bility increased,but those with allelopathic effects or a dense canopy structure decreased the diversity of the understory species.

Integration of aspect and slope in snowmelt runoff modeling in a mountain watershed

This study assessed the performances of the traditional temperature-index snowmelt runoff model(SRM) and an SRM model with a finer zonation based on aspect and slope(SRM + AS model) in a data-scarce mountain watershed in the Urumqi River Basin,in Northwest China.The proposed SRM + AS model was used to estimate the melt rate with the degree-day factor(DDF) through the division of watershed elevation zones based on aspect and slope.The simulation results of the SRM + AS model were compared with those of the traditional SRM model to identify the improvements of the SRM + AS model's performance with consideration of topographic features of the watershed.The results show that the performance of the SRM + AS model has improved slightly compared to that of the SRM model.The coefficients of determination increased from 0.73,0.69,and 0.79 with the SRM model to 0.76,0.76,and 0.81 with the SRM + AS model during the simulation and validation periods in 2005,2006,and 2007,respectively.The proposed SRM + AS model that considers aspect and slope can improve the accuracy of snowmelt runoff simulation compared to the traditional SRM model in mountain watersheds in arid regions by proper parameterization,careful input data selection,and data preparation.

Response of soil nutrients to terracing and environmental factors in the Loess Plateau of China

Terracing is a widely adopted agricultural practice in mountainous regions around the world that aims to conserve soil and water resources.Soil nutrients play a crucial role in determining soil quality,particularly in landscapes prone to drought.They are influenced by factors such as land-use type,slope aspect,and altitude.In this study,we sought to examine the impact of terracing on soil nutrients(soil organic content(SOC),total nitrogen(TN),nitrate-nitrogen(NO_(3)^(-)-N),ammonium nitrogen(NH_(4)^(+)-N),total phosphorus(TP),available phosphorus(AP),total potassium(TK),and available potassium(AK))and how they vary with environmental factors in the Chinese Loess Plateau.During the growing season,we collected 540 soil samples from the 0 to 100 cm soil layer across five major land-use types,different slope aspects,and varying altitudes.Additionally,a meta-analysis of literature data further corroborated the effective accumulation of soil nutrients through terracing in the Loess Plateau.Our findings are as follows:(1)Terraced fields,regardless of land-use type,showed a significant improvement in SOC and TN content.(2)Soil nutrient contents within terraced fields were predominantly higher on sunny slopes.(3)Terraces at lower altitudes are characterized by elevated SOC concentrations.(4)A meta-analysis of literature data pertaining to terracing and soil nutrients in this region confirmed the effective accumulation of soil nutri-ents through terracing.The elucidated outcomes of this study offer a profound theoretical underpinning for the accurate planning and management of terraces,the scientific utilization of land resources,and the enhancement of land productivity.

施肥和补播对不同坡向斑块化退化高寒草甸生物量和物种多样性的影响

探索黄河源区斑块化退化高寒草甸有效的人工修复措施,对促进退化高寒草甸生态修复具有重要意义。本研究通过设置不同有机肥施用量与不同禾草补播量的交互处理试验,分析斑块化退化高寒草甸不同坡向草地生物量和物种多样性的变化特征,以期筛选出适合该地区有效恢复的施肥量与补播量的最优组合。结果表明:(1)施肥和补播处理均可提升斑块化退化高寒草甸植物地上和地下生物量,但对植物物种多样性的促进效果不明显;(2)施肥和补播处理对草地生物量和多样性的影响因阳坡和阴坡坡向不同而存在差异;(3)分布在阳坡滩地的斑块化退化高寒草甸适宜修复措施为添加有机肥150 g/m^(2)+补播牧草(垂穗披碱草0.75 g/m^(2)+青海中华羊茅0.375 g/m^(2)+青海冷地早熟禾0.375 g/m^(2)),阴坡滩地适宜修复措施为补播垂穗披碱草1.5 g/m^(2)+青海中华羊茅0.75 g/m^(2)+青海冷地早熟禾0.75 g/m^(2);(4)在斑块化退化高寒草甸修复过程中,阳坡和阴坡草地的生物量与物种多样性之间总体呈现相反的关联性。研究结果表明斑块化退化高寒草甸的生态修复需要考虑坡向环境的影响。

基于MODIS数据的2003—2020年西南地区林火随地形因子的动态变化

云南、贵州、四川、重庆为代表的西南地区是我国第二大天然林区,是我国林火灾害最严重地区之一。研究气候变化下该地区林火分布的地形变化规律,可为天然林应对气候变化提供科学依据。基于2003—2020年MODIS火点数据MCD14DL,结合地理高程数据DEM和历史气候数据,运用数理统计、核密度分析和M-K趋势检验,研究气候变化下西南地区林火与地形因子的统计关系及变化趋势。研究表明:(1)2003—2020年西南林火总体呈下降趋势,下降率为42次·a^(-1)。春、冬季为林火高发期。空间上总体呈现从云南南部到四川北部逐步减少的格局,林火分布多集中在哀牢山、横断山脉以及攀枝花等地。(2)2003—2020年平均来看,林火与海拔、坡度呈单峰型关系,分别在海拔1400—1600 m、坡度15—20°达到峰值;阳坡最多,半阴半阳坡最少。(3)气候变化下,林火出现“转移”现象。海拔600—1200 m内相对湿度和降水的增加致使林火在该海拔显著减少、在高于1400 m的中高海拔区间增加;年均温的升高导致林火从坡度20—25°“抬升”到35°以上。气候变化下,西南林火出现向高海拔、高坡度转移现象,致使高海拔、高坡度可燃性屏障减弱。

坡向对道路边坡生物土壤结皮组成和发育特征的影响

坡向是影响温带干旱半干旱区生物土壤结皮生长的关键因素,但是以往研究对坡向的划分比较简单粗略。陕西省榆林市横山区一处具有360°坡向的道路边坡上自然生长着生物土壤结皮,以15°坡向为间隔,研究该道路边坡不同坡向生物土壤结皮组成(藓、藻结皮分盖度)、发育特征指标(结皮厚度、苔藓株高、生物土壤结皮叶绿素a含量)、结皮层含水率和抗剪强度的差异以及成因。结果表明:(1)在南北向上,315°—30°区间内的混合生物结皮以藓结皮为主、藻结皮次之;75°—225°区间内的混合生物结皮以藻结皮为主、藓结皮次之。(2)在东西向上,生物土壤结皮的组成和发育呈现非对称性。混合生物结皮中藓结皮分盖度、结皮层含水率和生物土壤结皮叶绿素a含量在西向(225°—315°)平均分别是东向(45°—135°)的3.31、2.82倍和2.55倍,发育程度总体表现为西向优于东向。(3)当以藻结皮为主时,结皮层含水率低于3.8%,以藓结皮为主时,结皮层含水率高于7%。提出了道路边坡生物土壤结皮在不同方向上组成和发育特征的差异性规律和可能的成因,有助于生物土壤结皮生态修复工程中不同方向上藻、藓的精准配置。

黄土陡坡人工植被下土壤表层的水文效应

[目的]探讨栽植坡度、坡向对绿化陡坡土壤表层水文效应的影响,为黄土陡坡植被恢复过程中水资源的有效利用提供科学依据。[方法]在干旱半干旱区选择46°~55°和56°~65°两个陡坡级的阴坡、半阴坡、阳坡、半阳坡4种坡向绿化8 a的乔灌木陡坡,测定0—40 cm土层的土壤基本性状、持水量和渗透性能,分析各土壤因子和地形因子的关系。[结果]①坡度和坡向立地因子之间交互作用对0—40 cm土层土壤容重、质量含水量、总孔隙度、最大持水量有显著影响(p<0.05),对0—20 cm土层土壤毛管孔隙度、毛管持水量有显著影响(p<0.05),其他因子影响均不显著(p>0.05)。②不同坡度间,最大持水量表现为:46°~55°>56°~65°陡坡;平均渗透速率则表现为:56°~65°>46°~55°陡坡;同时不同坡向间,最大持水量表现为:阳坡(522.42 t/hm^(2))>半阳坡(505.03 t/hm^(2))>阴坡(502.27 t/hm^(2))>半阴坡(496.15 t/hm^(2));土壤平均渗透速率表现为阳坡(0.79 mm/min)>半阳坡(0.59 mm/min)>阴坡(0.42 mm/min)>半阴坡(0.30 mm/min)。③双因素方差分析表明,坡度级和坡向的双因素交互作用对陡坡的水文特征影响最大。[结论]46°~55°陡坡的土壤基本性状优于56°~65°陡坡,而阳坡和半阳坡的水源涵养能力高于阴坡和半阴坡。

地形对高寒草地土壤水文特征的影响

为更加合理地利用高寒地区的水资源,有效保护和恢复高寒地区植被,在甘肃连城国家级自然保护区选取不同地形(坡向、坡位)条件下的高寒草地作为研究对象,探讨不同地形条件下高寒草地0~30 cm土层土壤水文特征的变化规律。结果表明:随着土层深度增加,不同地形条件下高寒草地土壤含水量降低,土壤容重增大;从不同坡向来看,阴坡土壤含水量高于阳坡,土壤容重则相反;从不同坡位来看,坡下部土壤含水量和土壤容重高于坡上部。土壤总孔隙度、毛管孔隙度和非毛管孔隙度均为阴坡大于阳坡、坡上部大于坡下部,三者均表现为阴坡上部最高。不同地形条件下,高寒草地的土壤持水能力大小为阴坡>阳坡,坡上部>坡中部>坡下部。土壤初始入渗率(0.47~5.90 mm·min^(-1))高于稳定入渗率(0.08~1.36 mm·min^(-1))和平均入渗率(0.09~1.54 mm·min^(-1)),不同地形条件下,高寒草地的土壤渗透率表现为阳坡>阴坡,坡上部>坡中部>坡下部。地形(坡向、坡位)对高寒草地的土壤水文特征有不同程度的影响,因此,在甘肃连城国家级自然保护区对高寒草地生态系统进行生态保护与恢复、可持续发展建设的过程中,应充分考虑地形与土壤水文特征的相互关系。

坡向对三江源区3种栽培植物生长及光合特征的影响

坡向作为主要地形因子,影响植物的生长和光合特征。本研究以果洛州达日县两种坡向(阴坡、阳坡)、3种栽培植物[青海草地早熟禾(Poa pratensis‘Qinghai’)、垂穗披碱草(Elymus nutans)和发草(Deschampsia cespitosa)]为对象,监测分析不同坡向不同植物的生长及光合特征,筛选出不同植物适宜的生境,为三江源区“黑土山”植被修复提供科学依据。结果显示:1)发草生长特性(株高、叶长、茎粗、叶面积和地上生物量)为阴坡显著高于阳坡(P<0.05),垂穗披碱草的比叶面积、地下生物量为阳坡显著高于阴坡(P<0.05),青海草地早熟禾的所有生长指标在坡向间无显著差异(P>0.05)。2)青海草地早熟禾的蒸腾速率(T_(r))、气孔导度(G_(s))为阳坡显著高于阴坡(P<0.05);垂穗披碱草的胞间CO_(2)浓度(C_(i))为阴坡显著高于阳坡(P<0.05);发草的C_(i)、G_(s)为阳坡显著高于阴坡(P<0.05)。研究结果表明,发草适宜在阴坡生长,阳坡生境利于青海草地早熟禾光合作用,垂穗披碱草在阳坡种植有利于其生长。

大兴安岭南段蒙古栎粗根非结构性碳对不同坡向的响应

在半干旱区,掌握树木根部碳储存规律对探究水分胁迫影响地上、地下器官碳分配机制至关重要。本研究以蒙古栎(Quercus mongolica)为研究对象,在2021年(湿润年)、2022年(干旱年)、2023年(正常年)的生长季每月采集不同坡向(阳坡、半阳坡、阴坡)蒙古栎粗根样本,测定非结构性碳(Non-Structural Carbohydrate,NSC)及其组分(可溶性糖、淀粉)含量并分析其动态变化规律。结果表明:(1)粗根NSC组成以淀粉为主,粗根NSC及其组分含量随5月、6月、7月、8月、9月的顺序递增且差异显著(P<0.05)。(2)NSC含量及淀粉含量随湿润年、正常年、干旱年的顺序递增;不同坡向淀粉含量随阳坡、半阳坡、阴坡的顺序递减,且二者均差异显著(P<0.05)。(3)通过对粗根NSC及其组分影响的主导因素分析,坡向因素影响大,反应了粗根NSC对潜在蒸散量梯度反应敏感。研究结果有助于理解干旱环境下地下器官对树木生长碳分配的调节机制。

冀北山地桦木林土壤细菌群落特征对坡向的响应

为了揭示冀北山地桦木林土壤细菌群落特征对坡向的响应规律,以冀北山地阴坡、半阴坡和半阳坡桦木林土壤为研究对象,采用高通量测序技术,分析了土壤细菌群落结构和多样性。结果表明:细菌群落组成主要包含41门、107纲,其中优势细菌门为变形菌门和酸杆菌门;土壤细菌群落α多样性指数在坡向间存在显著差异,阴坡>半阴坡>半阳坡;土壤含水量、容重、硝态氮和氨态氮均影响细菌微生物群落的结构组成,其中,土壤含水量与多种细菌门存在显著相关性,且与细菌α多样性存在极显著的正相关性。综上所述,不同坡向桦木林土壤细菌群落结构和多样性呈现出一定的变化规律,坡向和土层深度变化引起的土壤含水量变化是该地区桦木林土壤细菌群落结构和多样性差异的主要因素。

不同立地条件对黎蒴生长的影响研究

在不同海拔、不同坡位、不同坡向、不同坡形以及不同坡度等立地条件下进行了黎蒴造林试验,通过分析4年生黎蒴林分生长情况,对粤东地区黎蒴适宜生长的立地条件进行了研究。结果表明,不同海拔梯度对黎蒴林分生长影响显著,海拔<100 m时,黎蒴生长最好;随着坡位的上升,黎蒴平均树高、平均胸径和平均冠幅逐渐减小,下坡黎蒴生长最好;东北坡、北坡黎蒴生长情况明显优于南坡;生长于沟谷的黎蒴平均树高、平均胸径和平均冠幅显著高于山脊;当坡度<40°时,黎蒴的生长情况较好,当坡度>40°时,黎蒴生长情况较差。在粤东地区黎蒴造林中,立地条件宜选择海拔小于100 m、下坡、阴坡、沟谷及坡度小于40°。

宁夏南部山区植被覆盖度变化及其地形因子相关性分析

以宁夏南部山区为研究区,基于Landsat影像,运用改进的像元二分模型估算1996、2008和2018年3个时相的植被覆盖度,用数字高程模型提取坡度、坡向等地形因子,分析研究区植被覆盖度的变化以及与地形因子的相关性。结果表明:研究期间,研究区植被覆盖度呈现显著增加,尤以高植被覆盖度为甚。总体来看,高程在2400 m以下的植被覆盖度随高程增加呈现上升趋势;随坡度增加,植被覆盖度呈现上升趋势;1996和2018年2个年份的植被覆盖度在各坡向差异不大,但是2008年植被覆盖度有较明显的差异,变化趋势为阴坡>半阴坡>半阳坡>阳坡。

基于Landsat8的凤永高速地表温度反演

在隧道建设过程中,高地温热害会影响机械设备效率和施工进度,还会恶化作业环境、对人员安全造成威胁,因此,精准识别地热异常区对隧道建设非常重要。热红外遥感是用遥感的方法探测地球表面的温度,以此为基础利用遥感技术反演地表温度愈发可靠。以云南省凤永高速凤庆-领岗地隧道为研究区域,采用Landsat8影像数据,运用大气校正法对研究区进行地表温度反演,再利用DEM数据制作地形坡向文件,按阳坡、阴坡分布提取地表温度,结合地质构造对地表温度异常进行分析,圈定地热异常区。

Effect of Aspect on Climate Variation in Mountain Ranges of Shennongjia Massif, Central China

The aim of this study was to better understand the mechanisms of regional climate variation in mountain ranges with contrasting aspects as mediated by changes in global climate. It may help predict trends of vegetation variations in native ecosystems in natural reserves. As measures of climate response, temperature and precipitation data from the north, east, and south-facing mountain ranges of Shennongjia Massif in the coldest and hottest months(January and July), different seasons(spring, summer, autumn, and winter) and each year were analyzed from a long-term dataset(1960 to 2003) to tested variations characteristics, temporal and spatial quantitative relationships of climates. The results showed that the average seasonal temperatures and precipitation in the north, east, and south aspects of the mountain ranges changed at different rates. The average seasonal temperatures change rate ranges in the north, east, and south-facing mountain ranges were from –0.0210℃/yr to 0.0143℃/yr, –0.0166℃/yr to 0.0311℃/yr, and –0.0290 ℃/yr to 0.0084℃/yr, respectively, and seasonal precipitation variation magnitude were from –1.4940 mm/yr to 0.6217 mm/yr, –1.6833 mm/yr to 2.6182 mm/yr, and –0.8567 mm/yr to 1.4077 mm/yr, respectively. The climates variation trend among the three mountain ranges were different in magnitude and direction, showing a complicated change of the climates in mountain ranges and some inconsistency with general trends in global climate change. The climate variations were significantly different and positively correlated cross mountain ranges, revealing that aspects significantly affected on climate variations and these variations resulted from a larger air circulation system, which were sensitive to global climate change. We conclude that location and terrain of aspect are the main factors affecting differences in climate variation among the mountain ranges with contrasting aspects.

不同坡向坡位对枫香树生长的影响

本研究选择浙江省临海市不同坡向和坡位的15年生枫香树人工林样地,研究坡向和坡位对枫香树生长的影响。结果显示,阳坡枫香树生长量高于阴坡,表现在树高、胸径、冠幅和单株材积均明显大于阴坡;无论阳坡还是阴坡,下坡枫香树生长量均优于中坡。采用Weibull函数可以较好地拟合枫香树径阶分布,不同处理林分都还处于发育阶段,尚未形成稳定的径级结构。总体来看,应选择阳坡和下坡等条件较好的立地种植枫香树,以获得更佳的生长效果。

坡地“常全影”空间属性与坡度及坡向相关性分析

夏热地区为室外公共空间的人群活动构建“常全影”空间十分有利,但不同坡度和坡向明显影响“常全影”空间的平面形态和大小,故须探明其相互之间的关联性特征,以便促进坡地“常全影”空间的有效构建。以广州地区、常见典型长方体建筑构影体为例,运用Eoctect软件的日照阴影模拟及可界定的“常全影”空间,揭示了长方体建筑构影体在坡面上所构的“常全影”空间在其形态、方位及面积大小与不同坡度、坡向之间的关联性特征,并阐明其在日期和时段上的差异性。以期为夏热地区城区中的坡地“常全影”空间构建,提供科学依据和有效指引。

广东省高程异常坡度坡向分析

为了确定高程异常的空间变化情况,更好地指导全球导航卫星系统高程测量、数字高程基准维持等生产实践,提出利用数字高程模型(digital elevation model,DEM)理论研究似大地水准面的坡度、坡向等形态特征方法,建立高程异常与水平距离和方位之间的联系。对广东省DEM,以及不同精度、分辨率的似大地水准面提取坡度、坡向后进行了重分类和统计分析比较。结果表明,广东省似大地水准面坡度、坡向上都存在一个主要数值,不同于普通DEM特征;整体上以坡度0.0020°,沿坡向297°逐渐下降;该方向上高程异常值变化率约3.49 cm/km;似大地水准面的坡度、坡向与其分辨率和精度都密切相关;坡度值受分辨率的影响更大,受精度的影响较小;分辨率的粗略化会降低其坡度值。