草本植物根系对边坡浅层稳定性影响研究

为研究草本植物根系对边坡浅层稳定性的影响,在假设滑坡体为长方体的条件下,通过对植物根系加固边坡的力学原理进行分析,推导了植物根系对边坡浅层稳定性的安全系数公式,并计算分析了坡度、滑坡体尺寸以及根土面积比对边坡稳定性的影响。结果表明:随着边坡坡度及滑坡体尺寸的增加,边坡的稳定系数将减小。并且,植物护坡的坡体安全系数要大于无防护坡体的安全系数。随着根-土面积比的增大,坡体的稳定系数逐渐增加,说明植物根系能增加边坡的稳定性。     

松嫩草原盐碱土过氧化物酶活性及其与肥力因素的关系

2007年5-9月,对松嫩草原盐碱土过氧化物酶活性及肥力因素进行测定,为改良利用盐碱草地提供理论依据。结果表明:研究样地内过氧化物酶活性变化范围较大,8月份变异系数最高;随着植被盖度的增加,酶活性呈现逐渐降低的趋势;在植被生长季内酶活性5月较高,而在8月较低;过氧化物酶活性和全氮呈显著负相关;和速效磷、全盐、pH值有显著的正相关关系;和其他肥力因素相关性因月份而异。主成份分析结果表明可以用过氧化物酶活性作为盐碱土肥力变化的指示指标。     

Salinity an Environmental “Filter” Selecting for Plant Invasiveness? Evidence from Indigenous Lepidium alyssoides on Chihuahuan Desert Shrublands

A better understanding of site-specific factors such as soil salinity that regulate plant invasions is needed. We conducted a 3-mo greenhouse study to evaluate the salinity responses of three local maternal sources of Lepidium alyssoides, which is an indigenous species shown to aggressively colonize disturbed shrubland sites in the southwestern United States, including those affected by high salinity and sodicity. Results indicated that there were little or no population effects on plant evapotranspiration (ET), growth, and tissue Na and Cl concentrations. Significant reductions in seedling growth and ET were largely independent of various isosmotic saline irrigation solutions that included NaCl, Na₂SO₄, and CaCl₂, each at ? 0.1 MPa and ? 0.2 MPa, suggesting that ET and growth were controlled by solution osmotic potential. The combined Na and Cl concentrations in leaves were 9–10% of dry weight with no visible sign of injury. However, increasing leaf mortality and abscission as a proportion of total leaf production was observed in the high-salt treatments (? 0.2 MPa), with a combined Na and Cl concentration reaching 16% with high NaCl. Under saline conditions, considerable foliage salt loads of this species could deposit high-salt litter to potentially alter a landscape to its own favor and to the detriment of other salt-sensitive species. Results of this study add to a limited quantitative database on site-specific salinity factors governing plant invasions by showing the potential for these populations to behave invasively under saline conditions and, thus, potential for soil salinity assessment to predict incipient populations. However, due to its halophytic traits and indigenous status, L. alyssoides may alternatively provide ecosystem services to salinized shrublands of the arid and semiarid southwestern United States.     

三江源区高寒草原土壤湿度变化特征及与气候因子的关系

利用青海省三江源区兴海县牧业气象站1999-2016年高寒草原土壤湿度、牧草生育期资料,分析了高寒草原土壤湿度的年、季变化特征以及牧草生长季不同生育期土壤湿度的变化特征及与气候因子的关系。结果表明:高寒草原0-10、10-20、20-30、30-40和40-50 cm土壤湿度均随年际延长呈增加趋势,春季除40-50 cm土层外,其他各层土壤湿度均随年际延长呈显著增加趋势(P<0.05)。高寒草原牧草生长季的土壤相对湿度随年际延长呈显著上升趋势(P<0.05),且与生长季降水量之间呈极显著正相关关系(P<0.01)。随着气候变化,牧草抽穗、开花、成熟和枯黄期的土壤相对湿度随年际延长呈显著增加趋势(P<0.05)。牧草抽穗期、枯黄和全生育期的土壤湿度与气温呈显著负相关关系(P<0.05)。高寒草原牧草生长季土壤湿度的增加有利于草地植被生长。     

尕海地区弃耕地土壤可溶性盐分测定

１９９０～１９９３年在柴达盆地尕海地区弃耕地进行土壤可溶性盐分测定，测定结果，该地区土壤盐分组成为氯化物－硫酸盐和硫酸盐－氯化物，大部分地区耕层盐分含量小于１０ｇ．ｋｇ＾－１，少部分盐荒地表层含盐量高达７０ｇ．ｋｇ＾－１，牧草生长季节中，土壤盐分含量最低期在６月份。     

放牧方式对青藏高原高寒草地土壤节肢动物群落结构和多样性的影响北大核心CSCD

土壤节肢动物作为土壤生态系统的重要组成部分,对于周围环境的变化十分敏感,可作为环境变化的"指示剂"。放牧作为青藏高原地区高寒草地的主要利用方式,不仅影响土壤理化性质,同时会对生物多样性产生影响,进而影响到以土壤为主要生存场所的土壤节肢动物。为了明确不同放牧家畜及其混合比例对青藏高原高寒草地土壤节肢动物群落结构及多样性的影响,于2020年7月在青海省海北州海晏县西海镇"高寒草地-家畜系统适应性管理技术平台",设置中等放牧强度下牦牛单牧(YG)、藏羊单牧(SG)、牦牛藏羊1∶2混合放牧(MG1∶2)、牦牛藏羊1∶4混合放牧(MG1∶4)和牦牛藏羊1∶6混合放牧(MG1∶6)5个放牧样地,以无放牧(CK)为对照样地,采集0~5 cm、5~10cm、10~15 cm的土样,利用干漏斗法(Tullgren法)分离土壤节肢动物,并进行鉴定统计。结果表明:1)试验样地分离得到的土壤节肢动物优势类群为螨总科(Acaroidae)和甲螨总科(Oiibatida),分别占土壤节肢动物总捕获量的36.67%和41.14%,且在0~5 cm土层数量最多,具有表聚性;2)不同放牧方式对土壤节肢动物的组成、群落结构、密度及多样性存在不同的影响。与对照相比,放牧降低了土壤节肢动物优势类群螨总科的组成比例,而增加了甲螨总科的组成比例;无放牧样地与其他放牧方式样地土壤节肢动物群落结构存在明显差异;土壤节肢动物丰富度指数、多样性指数、类群数均表现为藏羊单牧放牧样地较高,而均匀度指数与之相反;3)土壤节肢动物均匀度指数与土壤全氮、全碳、速效钾呈显著负相关(P<0.05或P<0.01),而与有机质、pH呈显著正相关(P<0.05或P<0.01);土壤节肢动物丰富度指数与土壤pH呈显著负相关,而与土壤全氮、速效氮、有机质呈显著正相关;土壤节肢动物多样性指数与土壤pH呈显著负相关,而与土壤全氮、速效氮、速效磷、有机质呈显著正相关;土壤节肢动物平均密度、总类群数与土壤pH呈显著负相关,而与土壤全氮、速效氮、速效钾、有机质呈显著正相关;4)土壤全氮、全磷、全碳、速效氮、速效磷在藏羊单牧放牧样地较高;速效钾、有机质在无放牧样地最高;pH、土壤含水量在牦牛藏羊1∶6混合放牧样地最高。综上所述,在青藏高原高寒草地生态系统,藏羊单牧对于土壤节肢动物密度、群落组成以及群落多样性的提高具有正向作用。     

The influences of reseeding date and mowing prior to reseeding on establishment of alfalfa in Leymus chinensis meadows北大核心CSCD

This research studied the effects of sowing date and cutting prior to sowing on establishment of the leguminous forage,alfalfa（Medicago sativa）,in a lightly degraded Leymus chinensis meadow and investigated the sowing date×cutting interaction. The factorial experiment comprised four sowing dates（May 1,June 1,July 1,August 1）and cutting treatment（cut or uncut）prior to sowing,and evaluated the establishment performance of alfalfa and the ecological mechanisms related to establishment. It was found that soil moisture during emergence of alfalfa was the greatest when sowing occurred on July 1,and clipping prior to sowing significantly decreased the plant height of L. chinensis during emergence and seedling growth of alfalfa. There was a significant sowing date×cutting interaction effect on alfalfa establishment. Clipping prior to sowing significantly increased the emergence percentage of alfalfa through reducing the plant height of L. chinensis and associated above-and below-ground competition,and the seasonal soil moisture change resulted in a 20% higher（P<0. 05）alfalfa emergence rate when sowing occurred on July 1. With cutting,the number of surviving alfalfa seedlings and seedling survival rate were greatest（83 plants· m−2 and 53%,respectively）when sowing occurred on July 1. For later sowing,owing to the shortened growing time,the development and overwintering survival rates of alfalfa seedlings were significantly reduced. Cutting prior to sowing significantly increased the overwintering rate of alfalfa seedlings through improving their development. In the cutting treatment,the number of overwintered alfalfa seedlings（22 plants·m−2）when sowing was on July 1 was significantly higher than for other reseeding dates. In the second year,a botanical composition measurement showed that clipping prior to reseeding significantly increased the alfalfa biomass within the meadow,and the alfalfa biomass was significantly greater than in other treatments when sowing occurred on July 1 after cutting. Cutting prior to sowing also significantly increased the crude protein content of forage. Based on these research results,normal production practice should include cutting when alfalfa is sown into L. chinensis meadow. Combined with cutting,a sowing date around July 1 is the most favorable for the establishment of alfalfa. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

盐渍化草地根际土壤理化性质对降水改变和氮添加的响应

为揭示盐渍化草地根际效应及其对降水改变和氮添加的响应,对增水、减水和氮添加及其交互处理下晋北盐渍化草地根际和非根际土壤理化性质进行分析。研究发现：与对照相比,减水及减水+氮添加显著提高了土壤交换性Na⁺含量,氮添加提高了非根际土壤208.1%的硝态氮和105.3%的无机氮含量（P<0.05）;增减降水与氮添加交互对根际和非根际土壤理化性质均无显著影响;根际土壤pH值比非根际低0.25个单位,铵态氮、硝态氮、有机酸、氨基酸、全碳和全氮含量分别比非根际高412.0%,81.4%,37.5%,22.4%,37.3%和43.6%（P<0.05）;主成分分析发现根际和非根际土壤理化性质对水、氮交互处理的响应具有明显差异。表明盐渍化草地植物具有较强的根际效应,但其对增加降水及水、氮交互的响应不敏感,结果可为预测未来降水变化和大气氮沉降增加情境下盐渍化草地根际效应和土壤理化性质变化提供理论依据。     

甘南高寒草甸草原不同海拔土壤理化性质分析

对甘肃夏河高寒草甸不同海拔梯度的土壤理化性质分异规律进行了研究,以期探究土壤理化性质与海拔之间的关系。结果表明:除0~10cm土层电导率外,其余各土层土壤理化指标均与海拔呈显著相关(P0.05),其中,含水量、有机质含量均随海拔升高而升高,且随土壤深度增加而降低;pH随海拔升高呈先降低后升高的势态;0~10cm表层土壤全氮含量随海拔升高显著增加(P0.05),10~30cm土层全氮含量随海拔的升高先缓慢下降后平缓上升。因此,对于该区域草甸生态系统的管理与利用,不但考虑植被类型及状况,也需关注不同海拔梯度的草地土壤理化特性。     

4种野生早熟禾对土壤酸碱性的生理响应

以甘肃省境内采集的4种野生早熟禾为材料,设8个pH处理(3、4、5、6、7、8、9、10),探讨土壤pH对其生理特性的影响机制以及适宜生长的土壤pH,以期为早熟禾属草坪的养护管理和野生早熟禾的引种驯化提供依据。结果表明,随pH增大,4种野生早熟禾相对膜透性,游离脯氨酸(F-Pro)、可溶性糖(SS)和丙二醛(MDA)含量及过氧化物酶(POD)活性均呈先减小后增大的趋势,可溶性蛋白(SP)含量和超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性均呈先增大后减小的趋势;草地早熟禾(Poa pratensis)、一年生早熟禾(P.annua)和小药早熟禾(P.micrandra)在pH为7时,硬质早熟禾(P.sphondylodes)在pH为6时受到的伤害最小,是其最适宜生长的pH。