Survey Techniques of Grassland Plant Resources

Based on years of practice and survey methods of grassland resources at home and abroad, the technical problems that may occur in the survey process are analyzed, the preparatory work before survey, specific content of field survey and sample processing and analysis and specimen preparation are elaborated. Moreover, the announcements of major technical methods are also described in details.

History,Current Status and Trends of the Investigation for Grassland Plant Resources at Home and Abroad

The existing main problems in the investigation for grassland plant resources are found out by systematically analyzing the history, current status and de- velopment trends of the investigation for grassland plant resources at home and abroad. The paper cxploratively points out that the investigation for grassland plant resources should focus on integrated muhidisciplinary research in the future, ultimately realizing highly efficient utilization and sharing of information in grassland plant resources.

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.

Effects of Nitrogen Application on Plant Growth and Soil Inorganic Nitrogen Content in Alpine Grasslands

In order to further determine the nitrogen demand of plants in alpine grassland ecosystem,different nitrogen levels( 0,1,2,4,8,16,24,32 g/m2)were designed through field control to study the responses of different plant functional groups( grass,sedge and weed) to different nitrogen application levels in the aboveground biomass and soil inorganic nitrogen( nitrate nitrogen and ammonium nitrogen).The results showed that with the increase of nitrogen application rate,the aboveground biomass of different functional groups increased linearly,and the soil inorganic nitrogen content increased with the increase of nitrogen application rate,among which treatments N16,N24 and N32 increased significantly in soil nitrate nitrogen content( P < 0.05).The results showed that the optimal nitrogen content in alpine grasslands was 8 g/m^2,which could not only promote plant growth,but also effectively control soil nitrate nitrogen content.

Effects of converting natural grasslands into planted grasslands on ecosystem respiration： a case study in Inner Mongolia, China

With increasingly intensifying degradation of natural grasslands and rapidly increasing demand of high quality forages, natural grasslands in China have been converted into planted grasslands at an unprecedented rate and the magnitude of the conversion in Inner Mongolia is among the national highest where the areal extent of planted grasslands ranks the second in China. Such land-use changes（i.e., converting natural grasslands into planted grasslands） can significantly affect carbon stocks and carbon emissions in grassland ecosystems. In this study, we analyzed the effects of converting natural grasslands into planted grasslands（including Medicago sativa, Elymus cylindricus, and M. sativa＋E. cylindricus） on ecosystem respiration（F（eco）） in Inner Mongolia of China. Diurnal F（eco） and its components（i.e., total soil respiration（F（ts））, soil heterotrophic respiration（F（sh）） and vegetation autotrophic respiration（F（va））） were measured in 2012（27 July to 5 August） and 2013（18 July to 25 July） in the natural and planted grasslands. Meteorological data, aboveground vegetation data and soil data were simultaneously collected to analyze the relationships between respiration fluxes and environmental factors in those grasslands. In 2012, the daily mean F（eco） in the M. sativa grassland was higher than that in the natural grassland, and the daily mean F（va） was higher in all planted grasslands（i.e., M. sativa, E. cylindricus, and M. sativa＋E. cylindricus） than in the natural grassland. In contrast, the daily mean F（ts） and F（sh） were lower in all planted grasslands than in the natural grassland. In 2013, the daily mean F（eco）, F（ts） and F（va） in all planted grasslands were higher than those in the natural grassland, and the daily mean F（sh） in the M. sativa＋E. cylindricus grassland was higher than that in the natural grassland. The two-year experimental results suggested that the conversion of natural grasslands into planted grasslands can generally increase the F（eco） and the increase in F（eco） is more pronounced when the plantation becomes more mature. The results also indicated that F（sh） contributed more to F（eco） in the natural grassland whereas F（va） contributed more to F（eco） in the planted grasslands. The regression analyses show that climate factors（air temperature and relative humidity） and soil properties（soil organic matter, soil temperature, and soil moisture） strongly affected respiration fluxes in all grasslands. However, our observation period was admittedly too short. To fully understand the effects of such land-use changes（i.e., converting natural grasslands into planted grasslands） on respiration fluxes, longer-term observations are badly needed.

Effects of Grassland Caterpillars on Plant Community Structure of Alpine Kobresia Meadows and Soil Properties

[Objective] To investigate the relationship between the grassland caterpillar with different grades and the structure of alpine Kobresia meadow or soil feature. [Method] A total of 10 plots （20.00 m × 20.00 m） were chosen. In each plot, five smaller plots （5.00 m × 5.00 m） were randomly selected and six sample plots （0.25 m × 0.25 m） were then selected in each smaller plot. The biomass, vegetation height, grasslayer thickness, bare land area, soil moisture and total vegetation cover degree were determined. Data were analyzed statistically by Excel 2003 and SPSS 13.0 software. [ Result] There was a significant difference （P 〈 0.05） between the grassland caterpillars at different hazard grades and the structure of alpine Kobresia meadow or soil properties. [ Conclusion] With the increase of grassland caterpillar density, the plant community structure of alpine Kobresia meadows changes from sedge family-dominant community to the forbs-dominant community.

Winter Foraging Plants of Domestic Sheep in Hulunbeir Grassland

Winter food constitution and favorite level of domestic sheep were studied with the microhistological analysis technique of feces in Hulunbeir Grassland. some problems were inquired into, such as the quality state of local herbage resource, improvement of pasture, rational use of herbage, etc. The results showed that the staple food of domestic sheep in winter was Gramineae, which made up 73.3 percent of the total foraging species. Fabaceae was second, 11.6 per cent. Composite took third place, 7.4 per cent. The proportion of other species were very small.

黄河源区高寒退化草地空间分布特征

为了解黄河源地区“黑土滩”退化草地的空间分布规律和分布的关键地形特征,利用2019年黄河源区玛沁县、河南县、泽库县遥感影像解译数据,结合实地调查,分析高寒“黑土滩”型退化草地空间分布特征。结果表明:黄河源区“黑土滩”型退化草地海拔为3500~4000m,且在海拔3700~3800m时退化最严重;从坡向分析来看,“黑土滩”型退化草地主要发生于阳坡、半阳坡,从坡度分析来看,“黑土滩”型退化草地主要发生于缓坡地和滩地。聚类分析发现研究区草地类型为阳坡极度退化草地、半阳坡重度退化草地、阳坡-滩地轻度退化草地、半阳坡轻度退化草地、湿地轻度退化草地、阴坡未退化草地等6类。随着退化程度的加剧,植被盖度、地上生物量减少;同一土层的全氮、全磷、碱解氮、速效磷、有机质含量在湿地轻度退化草地和阴坡轻度退化草地中最高,阳坡极度退化草地最低,且差异显著(P<0.05);丰富度指数、多样性指数、均匀度指数以及土壤速效钾含量在重度、轻度退化草地较高,湿地轻度退化草地显著最低。阳坡极度退化草地全钾含量、鼠害破坏率和鼠洞数最高,湿地轻度退化草地全钾含量最低,与阳坡极度退化草地差异显著(P<0.05);湿地轻度退化草地和阴坡轻度退化草地均无鼠类活动。

西藏高寒草原湿润度梯度下植物群落特征空间格局及其驱动因子

西藏高原是中国高寒生态系统类型和生物多样性均聚集的区域之一,其中以高寒典型草原和高寒草甸草原为主生态系统类型,但其系统活力、组织力和恢复力均较弱,容易受到全球气候变化的影响,表现出极强的脆弱性。目前青藏高原草地生态系统植物群落分布状况与其变化规律以及对各种环境因子的反应研究多集中于站点尺度或样带尺度,但研究结果尚有较大的不确定性。研究于西藏地区沿着不同的湿润度梯度选择14处高寒草原区样地,通过植物群落调查、土壤理化性质分析,探索草本植被群落空间格局对气候因子响应特征及其主要驱动因子,其结果为青藏高原天然草地保护和可持续利用提供基础科学数据支撑。结果表明:(1)研究区内依据湿润度分区可分为干旱区、微干区、微润区和湿润区4类;研究区1971—2021年的气候数据分析发现,北部的干旱程度在逐渐减轻,而南部在1991—2010阶段干旱化趋势逐渐加强,整个研究区的湿润度指数均在下降;(2)植物群落调查发现不同植物功能群的变化各有差异,莎草科地上生物量随湿润度增加而增加,杂类草地上生物量呈现单峰趋势,而其他植物功能群无明显规律;湿润度较高的微润区间植物群落的Shannon-Wiener指数、Simpson指数、丰富度指数、均匀度指数均高于其他湿润度区间;(3)土壤理化性质分析发现高湿润度区域的土壤含水量、全氮、硝态氮、铵态氮、速效磷含量均为最高;对各环境因子与植物群落特征指标进行相关性、主成分分析后构建结构方程模型,发现直接影响西藏高寒草原植物群落特征变化因子为湿润度,土壤含水量和土壤pH,且都表现为显著的负效应(P<0.05),同时湿润度对土壤含水量和土壤全量养分产生了显著的正向影响(P<0.05),进而影响着西藏高原高寒草原不同植物功能群的分布、多样性、地上生物量。

高寒草地四种植物叶片化学计量学特征及其对坡度的响应

本研究以高寒草甸和高寒灌丛共有物种黑褐苔草(Carex atrofusca Schkuhr Riedgr.)、黄花棘豆(Oxytropis ochrocephala Bunge.)、冷地早熟禾(Poa crymophila Keng.)、乳白香青(Anaphalis lactea Maxim.)为研究对象,比较分析四种植物叶片碳(Carbon, C)、氮(Nitrogen, N)、磷(Phosphorus, P)含量差异及其随坡度变化的变化趋势。结果表明:高寒草甸植物叶片C,N含量、C/N比值种间差异显著,高寒灌丛植物叶片N,P含量,C/N,C/P,N/P比值种间差异显著;高寒灌丛乳白香青叶片C/N,C/P比值和黄花棘豆叶片C/P,N/P比值显著高于高寒草甸;随着坡度增大,两种草地类型所有植物叶片C含量和N/P比值均无显著变化趋势;高寒草甸黑褐苔草和黄花棘豆叶片N含量显著减少,C/N比值显著增大;高寒灌丛乳白香青叶片P含量显著减少,C/P比值显著增大。两种草地类型植物叶片化学计量特征对坡度的响应差异说明了植物适应环境策略的多样化。

锡林郭勒草原不同植物群落特征与土壤养分特性研究

为了揭示不同草原亚型的植被特点和土壤养分特征,探明物种多样性与土壤养分之间的相互关系,本研究以内蒙古锡林郭勒草原为研究区,通过野外采样、室内化验、冗余分析等方法对草甸草原、典型草原和荒漠草原三种草原亚型的植物群落特征、土壤养分特性及其相互关系进行分析。结果表明,(1)植物群落的生物量(W)、丰富度指数(M)、多样性指数(H′)和优势度指数(D)均表现为草甸草原>典型草原>荒漠草原,均匀度指数(J)在荒漠草原数值最高。(2)土壤钾含量在典型草原中最高,其他土壤养分含量均在草甸草原中最高;速效氮、速效钾、有机质和全氮含量在不同草原亚型中差异显著(P<0.05),全磷和全钾含量差异不显著。(3)草甸草原中对植物群落特征影响最大的是速效氮含量,作用最小的是全磷含量;典型草原中对植物群落特征影响较大的是速效氮、速效磷含量,作用较小的是速效钾含量;荒漠草原中全磷含量对植物群落特征影响较大,全钾含量对植物群落特征的作用较小。综上,在草甸草原和典型草原的植被保护中,应注重氮元素的投入,而对荒漠草原,应注重磷元素的控制。

牦牛和藏羊放牧对青藏高原高寒草地植物群落氮库的影响

放牧是青藏高原高寒草地最主要的利用方式,牦牛和藏羊是青藏高原最常见的放牧家畜,家畜通过采食植物地上部分会使地上生物量减少,进而对植物群落氮库产生影响。本研究依托青海省高寒草地-家畜系统适应性管理技术平台的放牧试验样地,探讨不同家畜类型放牧对高寒草地植物群落氮库的影响。研究结果表明:未放牧处理下高寒草地地上生物量为180.0 g·m^(-2),藏羊单独放牧显著降低了植物群落地上生物量。对未放牧处理下不同功能群氮素含量的研究发现:豆科植物(26.4 mg·g^(-1))>杂类草(17.0 mg·g^(-1))>禾草(12.9 mg·g^(-1))≈莎草(11.8 mg·g^(-1))。放牧显著增加了禾草和莎草氮含量,对杂类草氮含量影响较小。放牧对群落水平植物地上部分氮含量的影响变化小于对各功能群的变化影响,因为植物群落具有稳定性。当高寒草地植物群落处于放牧压力下,会从土壤中获取更多的氮以维持生长,放牧会进一步加剧青藏高原高寒草地植物生长的氮限制。

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。

基于文献计量学可视化放牧对植物种群影响的研究历程

草地在维持生物多样性,保护生态环境等方面具有重要意义,但不合理的放牧活动伴随气候因子的扰动可能对草地系统产生不可逆的消极影响。植物种群是构成群落并形成生产力的基本要素,系统地认识放牧对植物种群影响的研究脉络对进一步发挥草地生态系统的生态意义和经济效益具有重要作用。因此,本文基于文献计量学,通过CiteSpace软件对国内外有关放牧对植物种群影响的相关文献进行统计,就发文趋势及分布,研究主题及演变方向,研究特点与不足,未来创新与突破进行探讨。结果表明:1999~2022年国内外发文量随时间均呈逐渐增加趋势。在WOS数据库,我国发文量在全球国家中排名第4,中国科学院在全球机构排名第2;我国学者发文量以王德利、侯扶江等较高,且均为近些年(2020~2022年)发表;有关放牧对植物种群影响研究主要发表在Journal of Applied Ecology,Journal of Ecology等生态学领域的期刊。CNKI数据库中,主要发文机构具有地域性,其中内蒙古自治区内的机构在国内占一定优势;相关研究多在《中国草地学报》《草地学报》发表。国际上主要关注植物种群的动态、保护、生长、响应等种群特征指标,而国内聚焦多样性、生态系统、高寒草甸等大范围、系统性的指标。总体而言,我国有关放牧对植物种群影响的发文量较美国总体偏低,虽然近年(2019~2022年)发文量逐渐增加,但发文机构单一,发文期刊分散,研究范围具有局限性。因此,加强地区合作,深化研究层次,形成突破点可能是提升我国在该领域影响力的有效途径。

放牧对草地植物影响的研究进展

草地是我国草地畜牧业发展的基础,也是生态系统的重要组成部分。放牧是草地利用的主要方式,是人为干扰草地最主要的因素,对草地生态系统服务功能有重要影响。通过放牧对草地植物影响的相关文献,分析放牧对植物群落及其多样性、组织力、生物量、根系等方面的影响,以期为研究草地合理利用和退化草地的治理提供一定参考。当前由于不合理的放牧造成了草地的退化,制约了草地经济的发展,下一步应结合施肥、补播、松耙等草地管理技术,加大对划区轮牧、季节放牧以及合理载畜量等方面的研究。

基于深度学习方法荒漠草原典型植物花朵计数

草原植物花朵计数可以帮助我们了解草原植物的生长状况、繁殖能力、群落结构等信息,通过人工计数方法获取草原上不同物种花朵丰度是一个费时费力的过程。本研究基于深度学习目标检测方法,在鄂尔多斯荒漠草原上10个样地和50个样方上开展检测模型训练、评估和应用。从YOLOv7的3个模型整体表现来看,YOLOv7-E6E的F1-sorce和mAP@0.5均可达到0.7以上,具有较高的识别精度。从YOLOv7的3个模型在5种花朵检测的表现来看,YOLOv7-X、YOLOv7-E6E模型在北芸香、蒙古韭、细叶韭的检测上mAP@0.5高于0.8,而3个模型中仅有YOLOv7-E6E在蒺藜、兔唇花的mAP@0.5超过0.6。从模型在50个样方的花朵计数应用来看,YOLOv7-E6E模型花朵计数的总体正确率为0.91,能满足这5种草原开花植物检测和计数的需要。综上所述,通过深度学习花朵快速计数可以提高样方尺度花期植物调查效率,但为满足大规模物种调查和计数的任务需求,仍需扩大样本量和不断改进模型结构,以提高模型植物花朵检测的整体性能。

不同施肥方式对草甸草原植物群落生长及土壤紧实度的影响

【目的】为研究不同施肥方式对草甸草原植物群落生长及土壤紧实度的影响。【方法】通过设置不施肥(CK)、常规肥(CG)和中微量肥(ZW)三个处理,开展不同施肥处理对草甸草原植物的株高、生物多样性、生物量和土壤紧实度影响的试验。【结果】研究结果表明:CG处理和ZW处理均能够增加植物群落平均高度,其中CG处理能够显著提升植物群落平均高度,较CK对照增高了61.77%;CG处理和ZW处理均增加了草地植物群落的Simpson优势度指数、Shannon-Wiener指数、Margalef丰富度指数、Pielou均匀度指数,施肥提高了草地植物群落的丰富度;ZW处理显著降低了草甸草地收获季的鲜重,与其他处理之间植物干重并无显著性差异,但ZW处理能够提高植物的干鲜比;不同施肥处理均降低0~30 cm土层的土壤紧实度,但各土层间存在一定差异。【结论】施肥能够改善草甸草地状况,能够增加草地群落高度,提高植物群落的多样性指数,增加草地植物的干鲜比,改善土壤紧实度。

我国草地植物根际促生菌种类及其作用研究进展

植物根际促生菌(plant growth promoting rhizobacteria,PGPR)具固氮、溶磷、解钾、分泌植物内源激素等优点。本文综述了草地主要PGPR种属及促生特性,PGPR菌剂在草地牧草生长和土壤肥力改善中的积极效应及对草地植物抗逆性的作用,并分析了PGPR促进牧草生长的过程及机理,为未来PGPR在草地生产中的应用提供理论基础。PGPR对草地促进效应表现在:分泌内源激素,调节牧草内源激素水平,促进牧草生长和营养元素吸收,改善牧草品质;促进土壤元素向有效态转化,使土壤养分处于活跃态,改善土壤理化性质;分泌铁载体和ACC脱氨酶,增强牧草抗逆性等。未来PGPR在草地生产中的应用方向主要为:拓宽PGPR获取途径,加快PGPR生产的微生物肥料替代化肥进程,筛选改善草地土壤质量的PGPR菌肥种类,筛选综合抗逆性强的PGPR。

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。