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

在农场简历资源上，再循环明确地与保存农业的介绍被给了更大的强调 withclimate 变化情形在西北 Himalaya 区域(NWHR ) 中间山。在这种变化情形，举起，斜坡方面和综合营养素下面，管理(INM ) 可以显著地影响土壤质量和庄稼生产率。研究处于一个 rainfed 条件在 NWHR 的 Ashti 分水岭在 20092010 ～ 20102011 期间被进行在土壤资源和庄稼生产率上检验举起，斜坡方面和综合滋养的管理(INM ) 的影响。二年农场示范试用显示庄稼生产率和土壤质量被举起，斜坡方面和 INM 显著地影响。结果证明改进技术的小麦等价物产量(WEY ) 与常规系统相比由 20%37% 增加了庄稼生产率。与豇豆和大豆玉米杂种由另一 8%17% 提高了产量。诺思方面和更高的举起与南方方面和低举起相比由 15%25% 增加了庄稼生产率(除了稻) 。与豇豆和大豆玉米杂种由另一 8%15% 提高了产量。不管斜坡，举起和收割系统， WEY 由于 INM 技术在这个区域增加了 30% 。举起，斜坡方面和 INM 的影响显著地影响了土壤资源(SQI ) 和土壤碳变化(SCC ) 。 SCC 显著地与 SQI 被相关为常规( R <啜class=“ a-plus-plus ”> 2 =0.65*)， INM 技术( R <啜class=“ a-plus-plus ”> 2 =0.81*)并且为两种技术( R <啜class=“ a-plus-plus ”> 2 =0.73*)。它被推荐那在更高的举起。(除了稻土壤) 与面对斜坡的北方， INM 为更高的庄稼生产率被推荐；土壤资源的保存为 NWHR 的中间的山被推荐；并且 SCC 的单个价值作为为这个区域的 SQI 适当。

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.

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。

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。

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。

坡度条件下不同长宽比矩形火源燃烧火焰贴地长度实验研究

利用可变角度实验台,改变斜坡角度(10°~50°)、热释放速率(12.3~24.6 kW)以及燃烧器长宽比(1~6),开展了一系列燃烧实验,研究了火焰贴地长度随这3个因素的演变规律.结果表明,随着斜坡角度、火源热释放速率及燃烧器长宽比的增加,火焰贴地长度增加.对于相同的坡度和火源热释放速率,随长宽比增大,贴地长度增幅范围在65%~105%之间.基于斜坡诱导压差与火羽流浮力共同作用的物理机制分析,并考虑到燃烧器长宽比对火焰卷吸行为的影响,提出了无量纲火焰贴地长度预测模型.

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.

陕南中低海拔山区植物物种多样性与海拔及坡向的关系

为了研究陕南中低海拔山区植物物种多样性与坡向、海拔之间的关系,在研究区内设置并选取了具有代表性的样方91处,统计分析了每150 m海拔区间内乔木层、灌木层、草本层物种多样性及其关系。结果表明:(1)研究区内共有维管束植物129科、312属、460种;阴坡乔木、灌木、草本植物的物种数均多于阳坡;相同坡向内草本植物的科、属、种数量最多,灌木次之,乔木最少。(2)除草本植物的H、D值外,其他层次物种多样性指数的变异系数阴坡均大于阳坡;阳坡海拔1250 m以上草本植物物种数逐渐降低,优势种逐渐显现;在阴坡,海拔500—650 m处草本植物物种数最多,而海拔1400—1550 m灌木的个体数量最多。(3)回归分析中,多样性指数与海拔之间大多能呈现较好的拟合效果。阴、阳坡向内乔木层的多样性指数均先降低再升高,海拔950 m以上,阴坡乔木层的H、M值大于阳坡,差异显著(P<0.05);而D、J值差异不显著。阴坡灌木层的H、J、M值在海拔800 m处呈现单峰格局;阳坡灌木层的H、M值在研究区域内单调升高,而J值与海拔之间没有很好的拟合效果。在研究区内,阳坡草本层的H、J、M值随海拔升高呈现先增加再降低趋势,而阴坡草本层各指数与海拔之间没有很好的拟合效果。(4)不同层次间相关性检验中,阳坡乔木层H值与灌木层的H、D、M为显著负相关(0.01<P≤0.05),乔木层的J值与灌木层的J值、灌木层的J值与草本层的J值为显著正相关(0.01<P≤0.05);阴坡灌木的多样性指数与草本层各指数(D值除外)多呈显著或极显著正相关;其他相关性均达不到显著水平。(5)阳坡的种间共同出现率的峰值位于海拔800—950 m、950—1100 m的两个区间内,最低值在海拔1100—1250 m、1250—1400 m两个区间内。阴坡的峰值海拔比阳坡峰值海拔高100—400 m,而最低值所处的海拔区间与阳坡相同。

不同坡向落叶松人工林林分生长模型差异的研究

本文利用红石林业局2016年森林资源调查小班数据库,对落叶松人工林不同坡向的林分生长模型进行了构建,并分析了模型参数差异。结果表明:不同坡向落叶松人工林公顷株数、公顷蓄积量、平均胸径和年龄等主要林分因子差异较小。落叶松人工林林分生长模型为理查德方程,不同坡向模型参数a差异显著,参数b和参数c差异不显著。阳坡、半阴半阳坡和阴坡模型参数a分别为207.7、207.6和181.5,参数b均为0.0513,参数c均为2.7616。

黄土丘陵区撂荒年限和坡向对灌丛生物量及丰富度的影响

为研究撂荒年限和坡向对草地植物灌丛地上生物量及丰富度的影响,本研究以黄土丘陵区不同坡向4个主要撂荒年限(12 a, 20 a, 30 a和42 a)草地作为研究对象,分析其草地灌丛地上生物量及丰富度的变化。结果表明,撂荒草地物种丰富度、植物群落地上生物量、灌丛地上生物量及其百分比随撂荒年限的增加而增加,峰值多集中出现在30 a阳坡草地,分别达到:10.5种·m^(-2),133.20 g·m^(-2)和50.15 g·m^(-2),阴坡草地灌丛地上生物量百分比在42 a占比最高,达到51.68%;阳坡草地群落地上生物量及物种丰富度高于阴坡草地;但阳坡草地灌木和半灌木地上生物量低于阴坡草地,且阳坡撂荒草地群落灌木和半灌木物种数目百分比随撂荒年限的增加而降低,12 a占比最高达28.57%。撂荒年限与群落地上生物量、灌木和半灌木地上生物量、物种丰富度之间均存在正相关关系,坡向不同引起植物群落灌丛数量和生物量的变化。

矿山排土场边坡植被恢复过程中土壤团聚体稳定性机制

以矿山排土场边坡为对象,应用Le Bissonnais法(LB法)分析不同坡向、坡位和恢复年限对土壤团聚体稳定性的影响,研究团聚体破坏机制。结果表明,在LB法的快速湿润、慢速湿润和预湿后扰动3种处理下,排土场边坡土壤粒径以>2 mm团聚体为主。土壤团聚体稳定性从坡上到坡下逐渐增强,阴坡好于阳坡,随着恢复年限增加而增强。根据相对糊化指数和相对机械破碎指数,黏粒膨胀对土壤团聚体的破坏较小,而消散和机械外力作用是团聚体破坏的主要原因。所以,应降低暴雨及耕作等外力对土壤团聚体的破坏作用,提高土壤结构的稳定性,促进矿山生态恢复。

定植方式以及坡向与坡位对女贞幼树生长的影响

以2年生女贞截干苗为造林用苗,采取正栽和斜栽2种定植方式进行造林,4个半月后调查2种定植方式下不同坡位和坡向女贞幼树的树高、地径、新梢数、新梢长、萌芽位高等,分析定植方式以及不同定植方式下坡向与坡位对女贞幼树生长的影响;同时,分析女贞幼树各生长指标的相关性。结果显示:定植方式对女贞幼树的新梢数和萌芽位高均有极显著影响,对其树高、地径、新梢长的影响均不显著。斜栽的女贞幼树新梢数极显著多于正栽的,其萌芽位高极显著低于正栽的。以正栽方式定植,坡向与坡位对女贞幼树的树高、地径、新梢长均有极显著影响,对其新梢数、萌芽位高的影响均不显著;相同坡位,南坡的女贞幼树树高与胸径均大于东坡的;相同的坡向,下坡较上坡更利于女贞幼树的树高和新梢生长;山顶平坡最利于其地径生长和分枝。以斜栽方式定植,坡向与坡位对女贞幼树树高、新梢数、新梢长、萌芽位高均有极显著影响,仅对其地径无显著影响;相同坡位,东坡的女贞幼树树高与胸径均大于北坡的;相同的坡向,下坡较上坡更利于女贞幼树的树高和新梢生长;东坡上坡和山顶平坡均利于女贞幼树分枝和萌芽位高的降低,且东坡上坡和山顶平坡的女贞幼树新梢数和萌芽位高的差异均不显著。在2种定植方式下,女贞幼树的新梢数与树高均呈极显著正相关,与地径呈显著或极显著正相关;新梢长与地径呈显著或极显著正相关;萌芽位高与树高均呈极显著正相关,与新梢数均呈极显著负相关,与地径和新梢长相关均不显著。

地形对凉山州夏季降雨的影响研究

利用地面区域自动站降水、GMTED2010高程、ERA5再分析等资料,通过三阶反距离平方权差分、卷积计算等求出地形、降雨指标,分析凉山州夏季(5一10月)降雨、地形特征及其复杂地形对降雨的影响。结果表明:凉山州复杂地形下降雨空间分布不均匀,总降雨量1100mm以上大值区及强降雨主要分布在河谷流域,雨日100d以上的大值区主要分布在东部山区;坡向、坡度对大雨及以上量级的强降雨都有显著影响,对中雨及以下降雨影响不明显。高精度坡度、坡向地形指标有助于在凉山州这种复杂地形下更好地评估强降雨过程的雨量,提高灾害预警质量,特别是在地形多样、对降雨敏感的河谷流域作用更加明显。

格氏栲天然林群落结构特征及多样性分析

为了解不同立地条件下格氏栲天然林群落结构与物种多样性之间的耦合关系,对福建三明格氏栲自然保护区内不同坡位、坡向下格氏栲群落进行研究。结果表明,试验区共记录到植被94种,隶属于47科75属。乔木层个体生长状况在下坡位阳坡较好,灌草层的盖度随坡位的升高而降低,坡向对更新层植被生长影响较大。下坡位林下物种多样性指数更高,且乔木层植被生长特征值越大,林下植被物种多样性指数越大。冗余分析(RDA)表明,群落物种多样性的高低同时受到地形因子和群落结构的影响。与单因素方差分析结果一致,相比于坡向,坡位对群落结构和多样性的影响更大。

青藏高原东缘岷江冷杉径向生长对升温响应分异的坡向和海拔差异

【目的】研究气候变化背景下青藏高原东缘典型优势树种岷江冷杉的分异现象与坡向和海拔的空间关联,揭示该地区岷江冷杉发生分异的原因和响应机制。【方法】采用树木年轮方法,在青藏高原东缘米亚罗林区岷江冷杉4个主要分布坡向(东北、北、西北、西)的3个海拔梯度(3650、3800和3950 m)采集875根岷江冷杉的树芯,去除生长趋势后建立12个基于地形点位的岷江冷杉标准年表。利用回归分析方法研究岷江冷杉径向生长与增温的分异现象,应用Pearson相关分析和滑动相关分方法分析1955—2019年岷江冷杉径向生长与气候因子的相关性及其动态变化。【结果】1)4个坡向林线岷江冷杉径向生长均未发生分异,西坡未出现分异,北坡、西北坡中低海拔和东北坡低海拔均与增温趋势表现出分异。2)在5个发生分异的样点中,中低海拔北坡和低海拔西北坡岷江冷杉的径向生长与生长季(6月)降水呈显著负相关(P<0.05);中海拔北坡和西北坡分别与前一年9月降水和10月温度呈显著负相关(P<0.05);低海拔北坡与4月和9月温度呈显著负相关(P<0.05)。3)1955—2019年,中海拔北坡岷江冷杉径向生长与前一年9月和6月降水的负相关关系趋于显著(P<0.05);低海拔北坡与4月和9月温度的负相关关系趋于显著(P<0.05),与6月降水的负相关关系趋于显著(P<0.05);中海拔西北坡与前一年10月温度保持稳定的显著正相关关系(P<0.05);低海拔西北坡与6月降水的负相关关系趋于显著(P<0.05),与6月温度的显著负相关关系趋于不相关;低海拔东北坡与前一年9、10和12月,当年1、5和9月温度的负相关关系均趋于显著(P<0.05)。【结论】相比偏阳的东北坡和西坡,岷江冷杉出现分异现象的海拔分别在北坡和西北坡更低。岷江冷杉的分异现象与前一年生长季末和当年非生长季的干旱胁迫密切联系。未来气候变化背景下,低海拔岷江冷杉的生长响应具有不确定性,但林线岷江冷杉的径向生长将受益于增温。

不同坡向微气候对‘霞多丽’葡萄果实品质的影响

【目的】探讨不同坡向微气候对葡萄生长和果实品质的影响,为建立优质的酿酒葡萄种植园提供参考依据。【方法】以酿酒葡萄品种‘霞多丽’为材料,对葡萄种植地南坡、东坡、北坡3个坡向的微气候因素进行监测,测定不同坡向‘霞多丽’的果实品质指标,将果实品质与微气候因子进行相关分析和多元逐步回归分析,研究地形对酿酒葡萄品质的影响。【结果】(1)葡萄种植园在2020年8月13日(晴天)和8月14日(阴天)太阳直射条件下东坡光照强度最强;7、8月(果实成熟期)的平均气温和平均湿度、地上150 cm月平均最高温度、地下10 cm土壤日最低温度和地下20 cm土壤日最高温度的变化趋势显著且均为南坡>东坡>北坡,而9月的微气候因子变化趋势不显著,南坡的温度和湿度高于北坡、东坡。(2)2020年和2021年‘霞多丽’可溶性固形物含量、还原糖含量、固酸比、糖酸比南坡最大,可滴定酸和总酚含量北坡最大。(3)7、8月(果实成熟期)空气湿度与‘霞多丽’果实的可滴定酸、单宁、总酚呈负相关,与百粒重、可溶性固形物、还原糖呈正相关;7、8月不同坡向果实微气候地上部温度与‘霞多丽’的百粒重、可溶性固形物、还原糖呈负相关;7、8月地下部温度与‘霞多丽’的百粒重、可溶性固形物呈负相关;7月地上50 cm日较差与‘霞多丽’的百粒重、可溶性固形物、还原糖呈负相关,与可滴定酸、总酚呈正相关;8-9月水热系数与‘霞多丽’果实的可滴定酸、固酸比、糖酸比呈极显著正相关;而9月微气候因子与‘霞多丽’果实的果实品质的关系不显著。(4)‘霞多丽’果实品质受地下部温度影响不显著,受气象因子(水热系数、平均温度、平均湿度)影响较大。【结论】葡萄种植园不同坡向微气候显著影响葡萄果实品质的形成,其互补效应对葡萄果实品质的影响更大;青铜峡产区酿酒葡萄最适合的坡向为南坡,其微气候温湿度高,更有利糖分积累,果实成熟度好更有利于酿造优质的葡萄酒。

三江源区建植“黑土山”人工草地对土壤性质的影响

本研究以三江源区阴阳坡天然(NG)、退化“黑土山”(BG)、人工(AG)高寒草地为研究对象,通过土壤性质的测定,探讨三江源区退化草地与人工草地土壤碳氮磷及生态化学计量特征。结果表明,阳坡BG样地全氮(Total Nitrogen,TN)含量、NG样地全钾(Total potassium,TK)含量显著高于阴坡;AG样地全磷(Total phosphorus,TP)含量阴坡显著高于阳坡;阴坡和阳坡土壤碳氮比(C∶N)、氮磷比(N∶P)和碳磷比(C∶P)均呈现NG>BG>AG的趋势。全氮含量整体呈NG<AG<BG;AG的速效氮(Available nitrogen,AN)、土壤有机碳(Soil organic carbon,SOC)含量显著高于BG和NG。三因素方差分析显示,除速效氮外,坡向显著影响了土壤其余各指标;草地群落显著影响了除速效钾(Available potassium,AK)和pH值以外的土壤性质;土层显著影响了土壤速效养分和土壤有机碳含量。因此,人工草地建植前期和管护后期需要适当补充速效肥料且需增加氮钾肥比例,才能有效改善退化草地土壤状况。

坡向对北亚热带大别山区不同马尾松林型土壤细菌群落的影响

土壤细菌作为土壤微生物的重要组成部分,在土壤生态系统中发挥着重要作用,作为北亚热带区典型的森林植被类型,马尾松针阔混交林在区域地带性植被恢复方面发挥着重要作用。探讨马尾松不同森林类型土壤细菌群落的组成结构和多样性特征是维护马尾松森林生态系统健康和稳定的关键。以北亚热带大别山区4种马尾松林型[马尾松(Pinus massoniana)纯林(pure forest,PF)、马尾松—麻栎(Quercus acutissima)混交林(Pinus mas-soniana-Quercus acutissima mixed forest,PQM)、马尾松—枫香(Liquidambar formosana)混交林(Pinus massoniana and Liquidambar formosana mixed forest,PLM)和马尾松—化香(Platycarya strobilacea)混交林(Pinus massoni-ana-Platycarya strobilacea,PPM)]为研究对象,分析不同坡向(阴坡和阳坡)下马尾松4种林型林地土壤细菌群落的组成及多样性变化规律,旨在为该区不同环境梯度下马尾松林的生产经营和生物多样性保护提供理论参考。结果表明:(1)马尾松4种林型林地共检测到36门107纲246目393科688属,其中土壤优势菌门为放线菌门(Actinobacteriota)、变形菌门(Proteobacteria)、酸杆菌门(Acidobacteriota)和绿弯菌门(Chloroflexi)。(2)3种马尾松针阔混交林土壤细菌丰富度和多样性在阴坡均显著高于马尾松纯林,且不同坡向变化为:阴坡>阳坡,而4种林型在阳坡差异不显著。(3)土壤含水量与土壤细菌门之间存在显著相关性,其中与细菌α多样性呈极显著正相关。综上,阳坡环境下,马尾松4种林型林地土壤细菌群落变化差异较小,相较于马尾松纯林,3种针阔混交林土壤细菌群落更易受不同坡向环境条件的变化而变化。坡向和林型变化引起的土壤含水量改变是导致北亚热带大别山区马尾松森林土壤细菌群落组成改变和多样性差异的主要因素。