不同植被覆盖度沙垄土壤化学性质的空间分异

为了研究温带固定半固定沙漠土壤化学性质与地表植被的关系,本文以古尔班通古特沙漠西南缘莫索湾地区沙漠-绿洲过渡带为研究区,分别选取植被覆盖度为10%和15%的半固定沙垄及植被覆盖度为30%的固定沙垄。采集了各沙垄不同地貌部位的土壤样品,室内测试了土壤pH、电导率、有机质、全氮和全磷等指标。结果表明:①随着植被覆盖度下降,沙垄西坡、坡顶和东坡,土壤pH、电导率、有机质、全氮和全磷呈逐渐降低趋势;②不同地貌部位的分布格局各沙垄表现不一致,沙垄A和沙垄B的pH、电导率、有机质、全氮和全磷含量最大值均出现在垄间地,其他部位之间没有明显的规律,沙垄C的pH和电导率最大值出现在垄间地,而土壤养分含量在坡顶部位富集;③各沙垄不同土层土壤性质分布规律相对一致,土壤pH、电导率随着土层深度的增加呈上升的趋势,而土壤养分随着土层深度的增加而降低;④土壤化学性质空间分布异质性与植被的分布格局密切相关,相互影响,当植被覆盖度较高时,生物作用起主导作用,当植被覆盖度较低时,风蚀、地形等非生物因素作用加强,影响生物作用,植被对土壤颗粒和养分的拦截及富集作用逐渐减弱或消失。     

基于云模型的宁南山区小流域土壤养分综合评价

土壤养分受到各因素的综合影响,也是植被生长繁衍的基础.为了解宁南山区小流域土壤养分状况,文中基于260个采样点0 ～20cm土层实测数据,分析了土壤养分含量特征,选取pH值、电导率(EC)、有机质(SOM)、全氮(TN)、全磷(TP)、全钾(TK)、碱解氮(AN)、速效磷(AP)和速效钾(AK)作为评价指标,运用熵权法...     

水土保持植物——芨芨草对土壤养分影响的研究

以自然植被下土壤为对照，通过对芨芨草地土壤全氮，全磷、全钾、速效磷、钾、土壤有机质及阳离子交换量的测定，了解芨芨草对土壤养分的影响，结果表明，芨芨草对土壤有机质及全量养分影响不大，但能明显提高土壤速效养分的含量，并能提高土壤阳离子代换量及降低土壤pH值。     

毛乌素沙地南缘保护性耕作对土壤化学性质的影响

采用免耕(NT)、秸秆覆盖(SM)、覆膜(PM)和翻耕(CT)4种耕作措施,研究保护性耕作对毛乌素沙地南缘土壤化学性质的影响。结果表明,免耕和秸秆覆盖措施下表层0～20 cm土壤pH值低于覆膜、翻耕。免耕和秸秆覆盖措施下土壤有机质、碱解氮、速效钾和速效磷有明显的表层富集现象。随着耕作时间的变化,不同耕作措施下土壤有机质和速效钾都有所增加,免耕、秸秆覆盖、覆膜和翻耕有机质相对于试验开始前分别增加了33.0%、32.3%、31.1%和6.5%,而碱解氮和速效磷有下降的趋势,但保护性耕作条件下其下降率低于翻耕。保护性耕作不利于全氮的积累,经过3年试验后,免耕、秸秆覆盖和覆膜措施下的土壤全氮含量都低于翻耕。耕作措施对全磷的影响不大。说明保护性耕作是实现沙区农田生产力持续发展、保持土壤养分和防治土壤退化行之有效的措施。     

半干旱区流域土壤养分分布特征及其与地形、植被的关系

以小流域为单元,以典型横断面为代表,初步分析了黄土高原半干旱区中连川小流域坡顶、坡面和坡脚不同部位土壤养分分布特征及其与地形和植被的关系.结果表明,中连川流域土壤养分全量和速效态都匮乏.在开垦利用条件下,0～20 cm土层土壤有机碳、氮、磷、Olsen-P、硝态氮含量在不同坡位的高低顺序:坡面＜坡顶＜坡脚,显示了土壤养分坡脚富集、坡面和坡顶流失的特征.恢复地表植被后,土壤有机碳、氮的含量较相邻的农田显著提高.草本植被群落对土壤养分(0～20 cm)的积累促进作用高于灌木.     

不同植被覆盖下子午岭土壤养分状况研究

以黄土丘陵沟壑区的子午岭次生林区为研究区域,研究了不同植被覆盖对土壤养分状况的影响。结果表明:不同植被类型覆盖下,土壤有机质含量为乔木>灌木>草本>农田>弃耕地。土壤全氮含量为乔木≥草本>灌木>农田≥弃耕地;全磷含量变化不大,其中农田土壤全磷含量最高;全钾含量为乔木>灌木>草本>农田>弃耕地;土壤碱解氮含量为乔木>灌木≈草本≥农田>弃耕地;速效磷含量为乔木≈灌木≈农田>草本>弃耕地;速效钾含量为乔木≥草本>灌木≥农田>弃耕地。由此可见,随植被演替阶段的提高,不同植被覆盖下土壤的养分含量逐渐升高。因此,在黄土高原丘陵区,坡地退耕还林,恢复植被,可以有效改善土壤养分状况。     

晋西黄土区不同退耕年限油松林草本多样性与土壤养分的关系

本文以晋西黄土丘陵沟壑区不同退耕年限(11 a、17 a、22 a、26 a)的油松林为对象,测定不同土层深度(0～60 cm)的土壤养分因子,采用冗余分析(RDA)、回归分析研究了林下草本植物多样性和土壤养分的变化及相互关系。结果表明:①不同退耕年限油松人工林下共出现8种植物,隶属于6科,8属;随着退耕年限的增加,草本层的物种多样性指数(Margalef、Patrick指数)、丰富度指数(Simpson、Shannon指数)、均匀度指数(Pielou指数)均有所减小,林下草本以万年蒿(Artemisia gmelinii)出现频率最大,其重要值为27;②0～60 cm土层的平均土壤有机质和全氮随退耕年限的增加有增加的趋势,具有表聚效应,土壤氨氮、pH、全磷随退耕年限的增加而减小,速效钾随着退耕年限的增加呈先减小后增加的趋势,速效磷变化与速效钾相反;有机质、全氮、pH、速效钾随着土层深度增加而减小;③冗余分析表明,林下草本多样性除了受土壤养分影响外,还受其他环境因素影响,土壤养分因子仅能解释41. 42%的草本多样性变化;油松人工林下草本层的丰富度指数、多样性指数以及均匀度指数与有机质、全氮均呈负相关,与pH、氨氮、全磷均为正相关;④回归分析表明,Patrick指数与有机质、pH、氨氮呈显著乘幂关系(R~2为0. 743、0. 708,P 0. 01),Margalef指数与有机质、全氮呈线性关系(R~2为0. 651、0. 719); Shannon指数与pH、氨氮均为线性关系(R~2为0. 539、0. 790); Simpson指数与有机质为线性关系(R~2为0. 672); Pilou指数与有机质、pH、全氮均表现为指数关系(R~2为0. 631、0. 515、0. 550)。因此可以看出土壤养分在一定程度上对草本多样性指数有一定的影响。     

仁用杏园不同土层土壤养分含量的测定

在陕北黄土丘陵沟壑区,对仁用杏园的土壤有机质、全氮、全磷、速效氮、速效磷、速效钾进行了测定。0～500cm土层的土壤有机质为3．368g／kg,全氮为0．268g／kg,全磷为0．536g／kg,速效氮为13．644mg／kg。速效磷为2．202mg／kg,速效钾为50．406mg／kg。陕北黄土丘陵沟壑区仁用杏园无论是浅层、根系集中分布层还是源层土壤,土壤养分含量均较低,满足不了仁用杏的正常生长与开花结实。     

甘肃省中部干旱区植被恢复对土壤养分变化的影响研究

通过对甘肃省中部干旱区植被恢复过程中不同退耕年限(0年、3年、6年和10年)的土壤养分及各养分间的相关性进行了分析,研究结果表明:1)不同退耕年限对安定区土壤养分除全钾外对有机质和其它氮磷钾养分均有极显著或显著影响。2)植被恢复过程中养分在土壤剖面的分布具有明显的层次性,各养分具有明显的表聚性。3)土壤有机质的变化与全氮、速效氮呈现出显著的相关性,与钾素和磷素的相关性较低。全磷与速效钾和氮养分相互间显著相关,与速效磷相关性较小。全钾与速效钾相关性也未达到显著水平。     

宁夏引黄灌区盐化土壤微生物区系及其指示意义

为了有效防治土壤盐渍化的进一步发展,采用平板稀释法和常规土壤化学性质测定方法,对宁夏惠农不同程度盐渍化土壤微生物区系及其动态变化,土壤化学性质、养分含量及其与土壤微生物的相关关系进行了研究。结果表明：在盐渍化土壤区域,随着盐渍化程度的增加,土壤pH和碱化度以轻度盐渍化土壤最高,且20～40 cm土层高于0～20 cm。不同程度盐渍化土壤养分含量、细菌、真菌和放线菌数量均表现为随着盐渍化程度的加重,而呈现逐渐降低的趋势,即轻度＞中度＞重度,且0～20 cm土层显著高于20～40 cm。细菌、真菌和放线菌数量在不同采样时间上表现为6月＞8月＞9月。土壤微生物区系与土壤养分含量之间相关关系明显,细菌、真菌、放线菌数量除与土壤全钾含量之间没有达到显著水平外,与土壤有机质、全氮、全磷、碱解氮、有效磷、速效钾含量之间均达到显著或极显著正相关关系（P<0.05或P<0.01）。因此,土壤微生物区系可以作为评价盐化土壤质量恢复及演变过程的生物指标。     

随机抽样必要样本容量的确定方法及其应用

在随机抽样中,常通过样本均值来估计总体均值,而样本容量的选择是估算样本均值的关键。以统计理论为基础,并结合半干旱区科尔沁沙地的土壤含水量、有机质、氮、磷和钾含量;植物种组成与植被高度、盖度及密度等历史数据集,得到了这些生态指标在随机抽样中的必要样本容量和确定方法。分析结果表明：当这些指标的变异系数不超过相应的变异系数时,① 沙地农田土壤有机质、全氮、速效氮、全磷、有效磷和速效钾含量的必要样本容量在7~15之间;② 沙质草地和固定沙丘植被高度、盖度、密度和植物种数的必要样本容量分别为11, 8, 28和15;③ 固定沙丘和半固定沙丘0~30 cm土壤含水量的必要样本容量分别为32和12。这为今后在该区域或者类似地区研究这些指标,对样本容量的合理选取有一定的指导作用和参考价值。     

民勤黑果枸杞形态学特征与土壤因子的关系

通过对民勤绿洲外围4种不同立地类型黑果枸杞群落物种组成、生长特征、土壤因子等的调查,分析不同立地类型土壤因子对黑果枸杞生长的影响。结果表明:①不同立地类型黑果枸杞群落物种结构简单,共出现12科24属28种,存在多个单属单科单种现象,多为适应干旱盐碱化的藜科、蒺藜科植物,无乔木和高大灌木,黑果枸杞在不同立地类型中优势地位明显。②黑果枸杞群落丰富度指数砾石地高于盐碱地、覆沙地及固定或半固定沙丘地(P<0.05);多样性指数砾石地高于盐碱地,盐碱地高于覆沙地及固定或半固定沙丘地(P<0.05)。③不同立地类型黑果枸杞密度表现为:盐碱地>覆沙地>固定或半固定沙丘地>砾石地。株高表现为:固定或半固定沙丘地>盐碱地>覆沙地>砾石地。冠幅表现为:固定或半固定沙丘地>盐碱地>砾石地>覆沙地。④土壤速效钾、有效磷、全磷及有机质含量均为盐碱地显著高于其他3个立地类型(P<0.05),全钾、全氮含量在4种不同立地类型之间差异性不显著(P>0.05)。不同土层中土壤因子变化规律不同。⑤土壤水分随土层深度的增加变化趋势不同,砾石地和固定或半固定沙丘地中土壤含水率随土层深度的增加而增加,覆沙地随土层深度的增加呈现波动变化,盐碱地随土层深度的增加变化不大。⑥黑果枸杞的生长状况和形态学特征株高、冠幅等受土壤水分、土壤氮、磷、钾及有机质等土壤因子的影响和制约,且10~20 cm土层深度土壤因子影响最为密切。     

科尔沁沙地坨甸交错区土壤水分的空间变异规律

科尔沁沙地沙丘-草甸相间地区,地貌形态多样、土地利用类型众多,从而导致土壤水分空间分布的复杂性。通过对科尔沁沙地典型沙丘-草甸相间地区的调查取样与试验分析,运用统计学理论和方法,研究土壤水分的空间变异性及其空间分布规律。结果表明：水平方向上,土壤水分总体表现为草甸地大于沙丘地,过渡带介于两者之间。就草甸地而言,植物生长越好,其土壤水分越高,保水持水性能也越好;沙丘地则与之相反,植被最稀疏的流动沙丘,其土壤含水量大于半流动半固定沙丘与固定沙丘,且有良好的储水条件。垂向上,高覆盖草甸、低覆盖草甸和农田（草甸）土壤含水量在地表下0～40 cm波动最大,40～160 cm随深度增加而递增;流动沙丘、半流动沙丘和固定沙丘土壤含水量随深度增加呈微弱加大趋势。林地、撂荒地、农田（沙丘）变化程度居中。从空间分布看,研究区中东部土壤水分偏大,且向南北两侧区域递减。     

Biological soil crust distribution in Artemisia ordosica communities along a grazing pressure gradient in Mu Us Sandy Land,Northern China

This study investigated the distribution pattern of biological soil crust (BSC) in Artemisia ordosica communities in Mu Us Sandy Land. Three experimental sites were selected according to grazing pressure gradient. In each experimental site, the total vegetation cover, A. ordosica cover, BSC cover, litter-fall cover, BSC degree of fragmentation, BSC thickness and soil properties were investigated in both fixed and semi-fixed sand dunes and simultaneously analyzed in the laboratory. The results showed that at the same grazing pressure, BSC cover and composition were significantly affected by the fixation degree of sand dunes. In addition, BSC cover in the fixed sand dunes was 83.74% on average, whereas it is proportionally dominated by 28% mosses, 21% lichens, and 51% algae. Meanwhile, BSC cover in the semi-fixed sand dunes was 23.54% on average, which is proportionally dominated by 6.3% mosses, 2.5% lichens, and 91.2% algae. Fine sand, organic matter, and total nitrogen (N) contents in the fixed sand dunes were all significantly higher than those in the semi-fixed sand dunes. Litter-fall cover decreased along the grazing pressure gradient, whereas BSC fragmentation degree increased. Fine sand content decreased along with the increase of grazing pressure, whereas medium sand content increased in both fixed and semi-fixed dunes. The organic matter and total N contents in the no grazing site were significantly higher than those in light and normal grazing sites. However, there were no significant differences between the light and normal grazing sites. In addition, there were also no significant differences in BSC thickness between the light and normal grazing sites in the fixed sand dunes. However, a significant decrease was observed in both BSC cover and thickness in the normal grazing site. The BSC in the semi-fixed dunes was more sensitive to disturbance.     

Scale dependence of plant species richness and vegetation-environment relationship along a gradient of dune stabilization in Horqin Sandy Land,Northern China

Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still lacking. In this study, we measured the plant species richness, soil properties and altitude across four spatial scales(1, 10, 100 and 1,000 m2) at three different dune stabilization stages(mobile dune, semi-fixed dune and fixed dune) in Horqin Sandy Land, Northern China. We also examined the relationships between plant species richness, community composition and environmental factors along the gradient of dune stabilization. Our results showed that plant species richness increased with the increase of spatial scales in each dune stabilization stage, as well as with the increase of dune stabilization degrees. Canonical correspondence analysis(CCA) showed that plant distribu- tions in the processes of dune stabilization were determined by the combined environmental gradient in relation to soil organic carbon(SOC), total nitrogen(TN), carbon/nitrogen(C/N), pH, electrical conductivity(EC), soil water content(SWC), fine sand(FS), very fine sand(VFS), silt and clay(SC), and altitude. Plant species richness was significantly and positively correlated to SOC and TN in mobile dune, and significantly and positively correlated to SOC, TN, C/N, VFS and SC in semi-fixed dune. However, no significant correlation between plant species richness and environmental factors was observed in fixed dune. In addition, plant species richness in different dune stabili- zation stages was also determined by the combined gradient of soil properties and altitude. These results suggest that plant species richness has obvious scale dependence along the gradient of dune stabilization. Soil resources depending on dune habitats and environmental gradients caused by dune stabilization are important factors to de- termine the scale dependence of species diversity in sand dune ecosystems.     

艾比湖地区盐生植物群落土壤氮素的垂直分布特征

通过研究艾比湖地区9种盐生植物群落土壤剖面的氮素特征,揭示其影响因子。结果表明：① 干旱区荒漠中盐生植物的土壤理化性质差异显著(P＜0.05）。在整体上土壤氮素含量随土壤深度增加呈减小趋势,有效氮素形态为硝态氮。② 土壤氮素与土壤理化性质的相关性：全氮和碱解氮与有机质呈极显著正相关(P＜0.01）;碱解氮和全氮与pH、硝态氮和无机氮与电导率相关性不显著。③ 土壤中硝态氮的主要影响因素为铵态氮、碱解氮、全氮和有机质,其次是容重和含水量,最后是土壤pH和电导率,其他因素是通过影响土壤有机质的积累和分解对其起作用。     

Effect of sand-fixing vegetation on the hydrological regulation function of sand dunes and its practical significance

Soil water content is a key controlling factor for vegetation restoration in sand dunes. The deep seepage and lateral migration of water in dunes affect the recharge process of deep soil water and groundwater in sand dune ecosystems. To determine the influence of vegetation on the hydrological regulation function of sand dunes, we examined the deep seepage and lateral migration of dune water with different vegetation coverages during the growing season in the Horqin Sandy Land, China. The results showed that the deep seepage and lateral migration of water decreased with the increase in vegetation coverage on the dunes. The accumulated deep seepage water of mobile dunes (vegetation coverage<5%) and dunes with vegetation coverage of 18.03%, 27.12%, and 50.65% accounted for 56.53%, 51.82%, 18.98%, and 0.26%, respectively, of the rainfall in the same period. The accumulated lateral migration of water in these dunes accounted for 12.39%, 6.33%, 2.23%, and 7.61% of the rainfall in the same period. The direction and position of the dune slope affected the soil water deep seepage and lateral migration process. The amounts of deep seepage and lateral migration of water on the windward slope were lower than those on the leeward slope. The amounts of deep seepage and lateral migration of water showed a decreasing trend from the bottom to the middle and to the top of the dune slope. According to the above results, during the construction of sand-control projects in sandy regions, we suggest that a certain area of mobile dunes (>13.75%) should be retained as a water resource reservoir to maintain the water balance of artificial fixed dune ecosystems. These findings provide reliable evidence for the accurate assessment of water resources within the sand dune ecosystem and guide the construction of desertification control projects.     

科尔沁沙地不同植物群落土壤呼吸及环境因素分析

对科尔沁沙地固定、半固定和流动沙丘土壤呼吸的日进程、季节变化及其环境因素进行了测定分析.结果表明:1)土壤呼吸速率与植物群落生物量、土壤有机碳、全氮及粘粉粒含量之间存在显著的正相关关系;固定沙丘日平均土壤呼吸速率分别是半固定和流动沙丘的1.18和2.02倍.2)从固定、半固定到流动沙丘,土壤温度及近地表空气温度呈现增加...     

Species composition and diversity,and carbon stock in a dune ecosystem in the Horqin Sandy Land of northern China

In this study, we determined carbon allocation and carbon stocks in the plant-soil system of different dune ecosystems in northeastern China. We quantified the species composition, above- and below-ground biomasses, and carbon stocks of three dune types(i.e. active dunes, semi-stabilized dunes and stabilized dunes) and their corresponding inter-dune lowlands(i.e. interdune lowlands of active dunes, interdune lowlands of semi-stabilized dunes and interdune lowlands of stabilized dunes) in the Horqin Sandy Land. The results showed that the succession series on interdune lowlands of the Horqin Sandy Land confirmed differences in species composition of the various dune types. Aboveground carbon(AGC) on the interdune lowlands of semi-stabilized dunes(33.04 g C/m2) was greater(P<0.05) than that on the interdune lowlands of active dunes(10.73 g C/m2). At the same time, the different dune types did not show any significant differences(P>0.05) in belowground plant carbon(BGC). However, the percentage of plant BGC in interdune lowlands of active dunes(81.5%) was significantly higher(P<0.05) than that in the interdune lowlands of semi-stabilized dunes(58.9%). The predominant carbon pool in the study dune ecosystem was in the soil. It accounted for 95% to 99% of total carbon storage. Soil organic carbon(SOC) was at least 55% greater(P<0.05) in the interdunes than in the dunes. Stabilized dunes showed at least a 37% greater(P<0.05) SOC content than active dunes up to a 1-m soil depth. Meanwhile, SOC content of interdune lowlands of semi-stabilized dunes was greater(P<0.05) than that of interdune lowlands of active dunes only up to a 20-cm soil depth. The dune ecosystem showed a great potential to store carbon when interdune lowlands of active dunes were conversed to interdune lowlands of semi-stabilized dunes, which stored up to twice as much carbon per unit volume as interdune lowlands of active dunes.