Effect of Planting in Furrow and Whole Plasticfilm Mulching on Double Ridges on Improvement of Degraded Desert Grassland

[Objective] This study aimed to provide theoretical basis and technologies for the application of planting in furrow and whole plastic-film mulching on double ridges. [Method] The conventional method was used to re-seed the bunch Gramineous forage in the degraded desert grassland in Yanchi, Ningxia Hui Autonomous Region. Four kinds of conservation treatments, namely, ridging with black film mulching, ridging with transparent film mulching, ridging with no mulching and the flatplanting with no ridging and mulching were conducted to the forage to analyze the effects of each treatment on soil moisture and seedling growth. [Result] From July to November, the moisture contents of ridging with black film mulching, ridging with transparent film mulching, ridging with no mulching and the flatplanting were respectivery 9.88%, 9.24%, 8.75% and 8.13%, showing significant differences among the treatments; the survival rates of re-seeding forage were 96.2% , 93.4% , 45.6% and 28.3% , and the mulching treatment showed significant difference with the unmulching treatments in survival rate. The treatment with black film mulching showed great advantage that its moisture content on ridge top had the buffering effect of ＂load shifting＂, and the soil moisture content of black mulching treatment increased 21.5% than the flatplanting. Black film mulching also had the largest water supplement amount in soil below 1 m. Although mulching cost too much, its overall benefits were higher than that with no mulching. [Conclusion] This study lays the experimental basis for the application of planting in furrow and whole plastic-film mulching on double ridges in improving degraded grassland desertification.

Spatial pattern of soil organic carbon in desert grasslands of the diluvial-alluvial plains of northern Qilian Mountains

The soil properties in arid ecosystems are important determinants of vegetation distribution patterns. Soil organic carbon （SOC） content, which is closely related to soil types and the holding capacities of soil water and nutrients, exhibits complex variability in arid desert grasslands; thus, it is essentially an impact factor for the distri- bution pattern of desert grasslands. In the present study, an investigation was conducted to estimate the spatial pattern of SOC content in desert grasslands and the association with environmental factors in the diluvial-alluvial plains of northern Qilian Mountains. The results showed that the mean values of SOC ranged from 2.76 to 5.80 g/kg in the soil profiles, and decreased with soil depths. The coefficients of variation （CV） of the SOC were high （ranging from 48.83% to 94.67%）, which indicated a strong spatial variability. SOC in the desert grasslands of the study re- gion presented a regular spatial distribution, which increased gradually from the northwest to the southeast. The SOC distribution had a pattern linked to elevation, which may be related to the gradient of climate conditions. Soil type and plant community significantly affected the SOC. The SOC had a significant positive relationship with soil moisture （P〈0.05）; whereas, it had a more significant negative relationship with the soil bulk density （BD） （P〈0.01）. However, a number of the variations in the SOC could be explained not by the environmental factors involved in this analysis, but rather other factors （such as grazing activity and landscape）. The results provide important references for soil carbon storage estimation in this study region. In addition, the SOC association with environmental variables also provides a basis for a sustainable use of the limited grassland resources in the diluvial-alluvial plains of north- ern Qilian Mountains.

Effects of grazing on carbon and nitrogen in plants and soils in a semiarid desert grassland,China

Grazing can modulate the feedback between vegetation and soil nutrient dynamics（carbon and nitrogen）,altering the cycles of these elements in grassland ecosystems.For clarifying the impact of grazing on the C and N in plants and soils in the desert grassland of Ningxia,China,we examined the plant biomass,SOC（soil organic carbon）,total soil N and stable isotope signatures of plants and soils from both the grazed and ungrazed sites.Significantly lower aboveground biomass,root biomass,litter biomass and vegetation coverage were found in the grazed site compared to the ungrazed site,with decreases of 42.0%,16.2%,59.4% and 30.0%,respectively.The effects of grazing on plant carbon,nitrogen,？15N and ？13C values were uniform among species.The levels of plant carbon and nitrogen in grasses were greater than those in the forbs（except for the carbon of Cynanchum komarovii and Euphorbia esula）.Root 15 N and 13 C values increased with grazing,while the responses of root carbon and nitrogen to grazing showed no consistent patterns.Root 15 N and 13 C were increased by 79.0% and 22.4% in the grazed site compared to the ungrazed site,respectively.The values of SOC and total N were significantly lower in the grazed than in the ungrazed sites for all sampling depths（0–10 and 10–20 cm）,and values of SOC and total N at the surface（0–10 cm） were lower than those in the deeper soils（10–20 cm）.Soil ？15N values were not affected by grazing at any sampling depth,whereas soil ？13C values were significantly affected by grazing and increased by 19.3% and 8.6% in the soils at 0–10 and 10–20 cm,respectively.The soil ？13C values（–8.3‰ to –6.7‰） were higher than those for roots（–20.2‰ to –15.6‰） and plant tissues（–27.9‰ to –13.3‰）.Our study suggests that grazing could greatly affect soil organic carbon and nitrogen in contrast to ungrazed grassland and that grazing appears to exert a negative effect on soil carbon and nitrogen in desert grassland.

Altitude pattern of carbon stocks in desert grasslands of an arid land region

For estimating the altitude-distribution pattern of carbon stocks in desert grasslands and analyzing the possible mechanism for this distribution, a detailed study was performed through a series of field vegetation surveys and soil samplings from 90 vegetation plots and 45 soil profiles at 9 sites of the Hexi Corridor region, Northwestern China. Aboveground, belowground, and litter-fall biomass-carbon stocks ranged from 43 to 109, 23 to 64, and 5 to 20 g/m2, with mean values of 80.82,44.91, and 12.15 g/m2, respectively. Soil-carbon stocks varied between 2.88 and 3.98 kg/m2, with a mean value of 3.43 kg/m2 in the 0–100-cm soil layer. Both biomass-and soil-carbon stocks had an increasing tendency corresponding to the altitudinal gradient. A significantly negative correlation was found between soil-carbon stock and mean annual temperature, with further better correlations between soil-and biomass-carbon stocks, and mean annual precipitation. Furthermore, soil carbon was found to be positively correlated with soil-silt and-clay content, and negatively correlated with soil bulk density and the volume percent of gravel. It can be concluded that variations in soil texture and climate condition were the key factors influencing the altitudinal pattern of carbon stocks in this desert-grassland ecosystem. Thus, by using the linear-regression functions between altitude and carbon stocks, approximately 4.18 Tg carbon were predicted from the 1,260 km2 of desert grasslands in the study area.

Aboveground net primary productivity and soil respiration display different responses to precipitation changes in desert grassland

Precipitation(PPT)changes affect both aboveground vegetation dynamics and belowground carbon cycling processes,particularly in arid and semiarid regions.However,it remains unclear how extreme PPT variation can affect soil carbon sequestration potential.A 3-year PPT manipulation experiment with five levels(±40%,±20%and ambient PPT)was conducted in a desert grassland of western Loess Plateau.Aboveground net primary productivity(ANPP)and soil respiration(Rs)were measured to examine whether the responses of ANPP and Rs to PPT changes displayed a double asymmetry model.The ANPP was more sensitive to extreme drought than extreme wet treatments in wet and dry years,which displayed a negative asymmetric model.The change in ANPP was mainly due to the direct effect of PPT change,and plant density variation also exerted some influence in the dry year.In contrast,Rs displayed a positive asymmetry response to PPT change in dry year.This may be ascribed to enhanced autotrophic respiration due to the enhanced positive responses of plant growth and ANPP to wet treatments as well as stronger birch effect of rainfall events on heterotrophic respiration.The saturating response of Rs to extreme drought(−40%PPT treatment)was also found in the dry year.Nevertheless,the response of Rs to PPT change displayed a negative asymmetry model in wet years.The contrasting models for ANPP and Rs in response to altered PPT regime suggest that extreme wet or dry treatments may increase soil C pools effluxes toward debt in this desert grassland.

AN IMPROVED METHOD FOR AN ECO-CLIMATIC ZONATION AND ITS APPLICATION AS ZONES IN ARID GRASSLANDS,SEMIDESERTS AND DESERTS

The method was developed for a Range Management Handbook of Kenya and the pre-liminary results published 1991. Now it is improved to a stage ready for international discus-sion.1. Main moisture Zones are defined by a specified sum of monthly moistureindices:

Response of Grassland Vegetation to Air Temperature and Precipitation in Minqin Desert Region

[ Objective] This paper aims to analyze response characteristics of desert grassland vegetation to climate change. [ Method] The responses of grassland vegetation in desert region to air temperature/precipitation changes were analyzed by phenological observations since 1974, observation data conceming vegetation samples and meteorological data during the same period. The changing trend significance was denoted by linear trend line and its regression significance. The interrelation between the two variables was indicated by correlation coefficients. Data were analyzed by the software SPSS 13.0. [Result] （1） The rising rate of annual average temperature in the Minqin desert area since 1961 was greater than both the global level and Ghina＇s level over the past century. （2） Desert plants＇ response to temperature changes were mainly displayed as the advance of spring phenology, the delay of autumn phenology and the extension of growing duration. Plants＇ main response to precipitation changes was that vegetation coverage and pure coverage were decreasing along with precipitation reducing. （3） Both the vegetation coverage and pure coverage mainly had a positive correlation with the annual precipitation. Plant density mostly had a positive correlation with the precipitation in September. （4） The impact of rising temperature on plant phenology in spring was greater than that in autumn. [ Conclusion] The effects of temperature changes on desert grassland plants were the advance of spring phenology, the delay of autumn phenology, the extension of growing season and longer plant growing period than that in other reports. The responses of desert grassland vegetation to precipitation changes were that both vegetation coverage and pure coverage were decreasing along with precipitation reducing, and plant density fluctuated along with precipitation change.

2010–2020年塔里木盆地南部荒漠草地凋落物回收量月动态数据集

中国科学院新疆策勒荒漠草地生态系统国家野外科学观测研究站(以下简称“策勒站”)地处塔里木盆地南缘,南依昆仑山,北临我国最大的塔克拉玛干沙漠。具有植被群落简单,土壤有机质积累缓慢等特点。凋落物是该区域重要的养分来源。基于对策勒站荒漠植物群落的长期定位观测,通过对不同植物凋落物器官(枝、叶、果)分组,本文整理统计得到2010–2020年塔里木盆地南部荒漠草地凋落物的回收量月动态数据,同时记载了观测场群落以及土壤养分的年度变化情况。数据的产生严格遵照CERN生物观测规范执行,数据的审核及质量控制由台站与分中心质控人员共同完成。本数据集以期为深入研究塔里木盆地南部荒漠草地凋落物动态变化提供基础数据,为了解和评估极端干旱荒漠生态系统养分循环过程提供理论支撑。

退化荒漠草地恢复对土壤有机碳及其驱动因子的影响

揭示中国北方退化荒漠草地土壤有机碳分布积累对草地恢复的响应规律和驱动机制,可为科学治理退化草地、阐明草地恢复的土壤碳汇效应提供科学依据。以鄂尔多斯高原不同恢复阶段(流动沙地、恢复前期、恢复中期和恢复后期)的退化草地为研究对象,分析了0—10 cm,10—20 cm和20—40 cm的土壤有机碳对草地恢复的响应,并采用多种统计方法分析土壤有机碳的驱动因素。结果表明:(1)草地恢复显著增加了不同深度的土壤有机碳(P<0.05),恢复后期可使0—10 cm、10—20 cm和20—40 cm土壤有机碳分别增加8.28倍、6.44倍和9.46倍。(2)不同深度土壤有机碳的驱动因素不同:植被盖度和植物多样性共同控制0—10cm土壤有机碳的积累,而下层土壤(10—20 cm和20—40 cm)有机碳积累受到养分限制(土壤氮素)的影响,并且这种影响会随着土壤深度的增加而加强。研究结果可为合理恢复退化草地提供理论依据,同时还为通过草地恢复促进土壤碳循环以实现双碳目标提供了证据。

2005-2020年中国干旱半干旱区典型草地和荒漠生态系统植被地上生物量数据集

植被生物量是全球碳循环的重要组成部分,是陆地生态系统与大气之间碳交换的重要环节,是定量研究全球气候变化与草地、荒漠生态系统之间的反馈调节作用等的基础。中国干旱半干旱区的草地、荒漠生态系统是重要的碳库类型,本文选取中国生态系统研究网络(Chinese Ecosystem Research Network,CERN)中位于中国干旱半干旱区的2个草地生态系统观测研究站(海北站、内蒙古站)和5个荒漠生态系统类型观测研究站(鄂尔多斯站、阜康站、临泽站、奈曼站、沙坡头站)的典型生态系统,对其按照CERN生态系统长期观测规范开展长期观测获取的植被地上生物量的2005–2020年间生长季的月动态实测数据进行了收集整理与质量控制,并开展了样方原始调查数据到样地尺度观测数据的统计计算,生成了植被地上生物量数据集,可为中国干旱半干旱区草地和荒漠生态系统对全球气候变化响应及植被保育与可持续发展等研究提供地面观测数据支撑。

放牧、氮添加对荒漠草原植物和土壤碳氮的影响

为了探究放牧和氮添加对内蒙古荒漠草原植物—土壤碳、氮循环的影响,在禁牧(UG,0只羊单位·hm^(-2))和重度放牧(HG,1.74只羊单位·hm-2)样地进行氮添加处理,各处理水平为:对照(CK,0 g·m^(-2)·a^(-1))、低氮(LN,5 g·m^(-2)·a^(-1))、中氮(MN,10 g·m^(-2)·a^(-1))和高氮(HN,20 g·m^(-2)·a^(-1))。通过对短花针茅(Stipa breviflora)叶片和土壤全碳(Total carbon, TC)、全氮(Total nitrogen, TN)、稳定碳同位素(Stable carbon isotopes, δ13C)、稳定氮同位素(Stable nitrogen isotopes, δ15N)及土壤有机碳(Soil organic carbon, SOC)、速效氮(Available nitrogen, AN)的测定分析,结果表明:放牧显著增加土壤TC、TN和AN含量(P<0.05);放牧使短花针茅叶片δ13C,δ15N值显著减小(P<0.05);氮添加使短花针茅叶片δ15N值显著减小(P<0.05)。放牧和氮添加在一定程度上均加速了短花针茅和土壤的养分循环,同时氮添加对短花针茅的氮吸收及分馏效应有一定影响,对退化草地恢复起重要作用。

凋落物添加对蒿类荒漠草地土壤碳氮磷含量及其化学计量特征的影响

为探究凋落物添加对土壤养分及化学计量比的影响,本研究采用梅森瓶室外培养法,探求凋落物添加种类及添加量对蒿类荒漠草地0~10 cm土壤有机碳(SOC)、全氮(TN)、全磷(TP)及其化学计量比的影响,发现茎叶混合促进了凋落物分解,但同一添加物各添加量间分解速率无显著差异。添加5 g和7.5 g叶后土壤SOC较对照分别增加10.4%,15.2%(P<0.05)。土壤TN随叶添加量增加呈上升趋势,较CK增加11.9%~18.4%(P<0.05),而茎、茎叶混合依次仅在5 g、7.5 g添加量时显著减少7.9%、增加37.8%(P<0.05)。2.5 g茎叶、5 g茎和7.5 g叶添加后土壤TP较CK依次增加9.8%,14.4%,7.2%(P<0.05)。凋落物添加后土壤C∶N,C∶P,N∶P分别为2.46~3.63,12.40~16.17,3.47~5.60,且SOC与C∶P、TN与N∶P均呈正相关,而TN与C∶N除添加叶外均呈显著负相关。因此,凋落物分解有利于蒿类荒漠土壤养分的恢复,尤其是叶凋落物的分解是其土壤碳氮短期补充的重要来源。

荒漠草原生长季不同时间尺度水热通量变化特征及其影响因子

荒漠草原水热通量变化特征及其影响因素分析对提高区域水热交换规律认识和了解其在气候变化中的作用具有重要意义。该研究基于内蒙古荒漠草原2018和2019年4—10月涡度相关系统与相应的环境因子观测资料,分析了荒漠草原不同时间尺度水热通量(感热通量(sensible heat flux,H)和潜热通量(latent heat flux,LE))及能量占比(H/LE)的变化特征及其环境因子调控机制。结果表明:1)H为该生态系统的主要能量消耗形式,且同一环境因子在不同生育期对H、LE、H/LE的影响存在差异;2)小时尺度上,H、LE呈单峰型变化,峰值均主要出现在12:00—14:00之间,且LE峰值出现时间较H滞后1~2 h。H的主要影响因素为平均风速(wind speed,Ws),相对湿度(relative humidity,RH)、饱和水汽压差(vaporpressuredeficit,VPD)和空气温度(airtemperature,Ta),相关系数(correlation coefficient,r)绝对值大小分别为Ws(0.72)>RH(0.66)>VPD(0.61)>Ta(0.38)。LE的主要影响因素为Ta、VPD、地面温度(soil temperature,Ts)和降雨(precipitation,P);3)日尺度上,H、LE呈明显的季节变化,H的主要影响因素是RH、Ws、Ts、Ta、P和VPD,LE主要影响因素为RH、Ws、Ts和Ta;4)月尺度上,H、LE近似呈单峰型变化,夏季能量消散方式以LE为主,H的主要影响因素为RH、Ws和VPD,其中VPD正效应最强(r=0.75),P对LE的正效应最强(r=0.75),而RH对H/LE的负效应最强(r=-0.76)。研究结果有利于准确理解多时间尺度下荒漠草原H和LE对环境因子的响应,同时可为草原生态功能区的植被恢复、生态环境保护提供理论依据和技术支撑。

封育对荒漠草原真菌群落的影响

【目的】评估封育对荒漠草原真菌群落的影响,并阐述真菌群落在土壤中的作用。【方法】采用野外调查取样的方法,以封育14年的荒漠草原和相邻自由放牧荒漠草原为研究对象,基于内转录间隔区(ITS)技术与液质联用(LC-MS)技术研究封育对荒漠草原真菌群落的影响。【结果】封育增加了荒漠草原子囊菌门(Ascomycota)的相对丰度,降低了担子菌门(Basidiomycota)、被孢霉门(Mortierellomycota)和unclassified_k__Fungi的相对丰度,显著改变了真菌群落的β多样性。此外,封育处理下土壤养分含量和植物生物量高于放牧处理。封育处理下真菌群落的内部联系更加紧密,主要关系为相互竞争,而放牧处理下真菌群落内部关系主要是互利共生。真菌群落与土壤总钾及植物生物量之间相关性较强。土壤差异真菌群落多与代谢物显著正相关。【结论】封育改变了荒漠草原真菌群落丰富度,增加了植物地上与地下部分生物量。

基于无人机遥感影像和面向对象技术的荒漠草原植被分类

探究适合荒漠草原植被遥感分类方法,明确荒漠草原地区植物物种类型及其分布状况,可以提高荒漠草原精细化生物多样性监测能力,对于荒漠草原的保护管理与生态可持续发展均具有重要意义。以贺兰山东麓洪积扇荒漠草原典型植被短花针茅、松叶猪毛菜、刺旋花、斑子麻黄为研究对象,利用无人机遥感影像,采用面向对象的分类回归树(classification and regression tree,CART)、K最邻近(K-nearest neighbor,KNN)、随机森林(random forest,RF)和支持向量机(support vector machine,SVM)分类方法,结合特征优选算法对影像特征进行优选,在此基础上选择最优特征进行荒漠草原植被精细化分类研究。结果表明:1)特征优选能够有效提高分类精度,应予以充分利用,当选取的特征组合为贡献度大于1.00%时,分类精度最高;2)基于无人机遥感影像挖掘的植被光谱、纹理特征,结合面向对象分类方法能有效实现贺兰山东麓荒漠草原典型植被精细化分类,其中RF分类精度最高,分类总体精度达到87.77%,Kappa系数为0.79。研究结果可为荒漠草原植被分类研究提供参考,对荒漠草原生物多样性保护管理与生态可持续发展均具有重要意义。

陇中温性荒漠4种草地型土壤有机碳组分及碳库活度变化特征

为明确陇中温性荒漠不同草地型土壤有机碳(Soil organic carbon,SOC)各组分分布状况,本研究以陇中温性荒漠为对象,分析了4种草地型(盐爪爪型,红砂型,珍珠猪毛菜型,合头藜型)SOC、易氧化有机碳(Readily oxidisable organic carbon,ROC)、可溶性有机碳(Dissolved organic carbon,DOC)、颗粒有机碳(Particulate organic carbon,POC)、矿物结合态有机碳(Mineral-bound organic carbon,MOC)、惰性有机碳(Non-labile carbon,NLC)的含量和分配比例及碳库活度(Carbon pool activity,CA)的差异性变化。结果表明:SOC,ROC,POC,MOC,NLC,CA和ROC分配比例盐爪爪型草地显著高于其他草地型;在SOC及其组分中,POC可作为评估陇中温性荒漠草地型变化对SOC库影响的良好指标;SOC组分和CA与有效磷和速效钾含量呈正相关关系。盐爪爪型草地可作为提高陇中温性荒漠SOC及组分含量的优选类型,今后应加强对盐爪爪型草地的保护,改善土壤质量,稳定土壤碳库。

祁连山北麓荒漠草原5种优势植物生物量与土壤养分特征

为明晰荒漠草原优势植物的植物生物量与土壤养分关系,研究选取祁连山北麓肃北区域荒漠草原骆驼蓬(Peganum harmala)、狗尾草(Setaria viridis)、中华羊茅(Festuca sinensis)、碱茅(Pucci-nellia distans)和冰草(Agropyron cristatum)5种优势植物,测定该其生物量和根际土壤养分,探究其植物生物量分配及其与土壤养分间的关系。结果表明:(1)5种优势植物间总生物量和根冠比差异显著(P<0.05),骆驼蓬总生物量最高,碱茅最低。多年生的骆驼蓬、碱茅、中华羊茅和冰草植物生物量大部分集中在地下,一年生的狗尾草植物生物量大部分集中在地上,不同植物间根冠比大小为:碱茅>冰草>中华羊茅>骆驼蓬>狗尾草。(2)5种植物根际土壤有机碳、碱解氮、速效钾、全氮、全磷、全钾及其化学计量特征均存在显著差异(P<0.05),5种植物根际间土壤碳氮比大小为碱茅>狗尾草>冰草>骆驼蓬>中华羊茅。(3)不同植物生物量、根冠比及土壤养分变异性不一致,骆驼蓬、狗尾草和中华羊茅的根际土壤全钾与碱茅和冰草的根际土壤含水量等均为弱变异,而土壤养分及其化学计量特征为中等变异。5种优势植物的生物量与根际土壤碱解氮和全钾呈正相关性(P<0.05)。可见荒漠草原生态系统中植物生物量分配和根际土壤养分在生活史和物种间的差异较大,今后应根据不同优势植物养分需求,合理施肥来修复退化的荒漠生态系统。

2001-2021年内蒙古荒漠草原水分利用效率时空变化特征及影响因素研究

水分利用效率(Water use efficiency,WUE)是表征水碳过程的重要指标,对研究生态脆弱区水碳耦合规律及其响应因素具有重要意义。基于总初级生产力(GPP)、蒸散发(ET)、气温、降水量和土壤水分系统分析了2001—2021年内蒙古荒漠草原WUE的时空变化特征,讨论了影响WUE变化的因素。结果表明:(1)内蒙古荒漠草原2001—2021年WUE平均值0.877 g C·mm^(-1)·m^(-2),空间变化范围在0.35~2.42 g C·mm^(-1)·m^(-2)。(2)预测其未来变化趋势发生转变的区域占比较大(约占69.00%),这些区域WUE未来变化趋势容易逆转。(3)空间上超过60.00%研究区的WUE与降水量、ET、土壤水分呈现正相关,其中降水量与WUE正相关最为明显(正相关区域占比约91.00%,通过显著性检验P<0.05区域占比约30.00%)。(4)WUE与气温总体呈现负相关,负相关区域占比超过60.00%。(5)气候变化在内蒙古荒漠草原WUE变化中起主要作用。内蒙古荒漠草原WUE受多种因素影响,研究结果可为气候变化背景下荒漠草原地区WUE研究提供参考。

长期放牧对内蒙古荒漠草原土壤不同组分有机磷含量的影响

探究长期放牧对荒漠草原土壤不同组分有机磷含量的影响,对干旱半干旱草地生态系统的合理利用和地力提升具有重要意义。本研究依托于乌兰察布市四子王旗内蒙古农牧业科学院研究基地的长期放牧平台,设置4个不同放牧强度:轻度(Light grazing,LG)、中度(Moderate grazing,MG)、重度(Heavy grazing,HG)和对照(Control,CK),通过测定土壤理化性质、微生物群落特性,并利用Bowman-Cole磷分级体系测定不同组分有机磷含量,揭示不同组分有机磷对放牧强度的响应机制。结果表明:荒漠草原土壤有机磷组分占比情况为:中活性有机磷>活性有机磷>稳性有机磷。其中,活性有机磷含量随放牧强度增加显著增加,中活性有机磷含量随放牧强度增加显著降低,而稳性有机磷含量的差异未达显著水平。放牧通过改变土壤微生物和间接影响土壤有机质来调控活性有机磷含量;放牧通过改变土壤磷养分间接调控中活性有机磷含量。综上,长期放牧对荒漠草原不同组分有机磷含量的影响存在差异,可通过提高微生物代谢底物养分缓解放牧导致的磷资源短缺,这将有助于提高土壤养分有效性从而维持草地生态功能的可持续利用。

放牧干扰下荒漠草原植物功能群数量特征与输沙量的关系

[目的]分析放牧干扰下草地群落及功能群数量特征变化与草地土壤风蚀间的关系,阐明草地不同功能群对草地侵蚀过程的影响,为荒漠草原合理放牧利用及保护提供理论依据。[方法]以内蒙古短花针茅荒漠草原为研究对象,采取完全随机试验设计设置对照、中度和重度3个不同的放牧处理,对不同处理下的草地输沙量和功能群特征进行研究。[结果]①随放牧强度增加,各功能群内物种高度、盖度和地上生物量基本呈下降态势。适当放牧能显著提高Simpson优势度指数和Shannon-Wiener多样性指数。②各放牧处理间的草地输沙量差异显著,不同输沙高度处的草地输沙量变化规律均为HG>MG>CK,同一放牧处理下,随输沙高度上升输沙率显著降低。③各功能群高度、盖度与输沙量均存在指数负相关关系,其中多年生禾草和多年生杂类草的高度变化对输沙量的影响更显著。各功能群的地上生物量与输沙量存在负相关指数关系,其中多年生禾草的生物量与输沙量的拟合程度最高。[结论]过度放牧会显著影响功能群特征并降低草地的防风固沙能力,建议放牧强度控制在中度及以下。