Meadow Steppe Research Articles

Energy balance and partitioning over grasslands on the Mongolian Plateau

Energy flux is a key component and driving factor in ecosystem processes and functions. Using 2015 datasets of eddy covariance, vegetation and meteorological measurements at four dominant ecosystems on the Mongolian Plateau, we analyzed the inter-site and seasonal variations and underlying biophysical controls on energy balance and partitioning in a meadow steppe (MDW), typical steppe (TPL), dry typical steppe (DRT) and shrubland (SHB). Vegetation dynamics dominated the energy partitioning. The growing season (May-Sept) net radiation (Rn) was 20% less at SHB due to higher bare soil coverage area than that at MDW. High vegetation cover and soil water content resulted in the highest latent heat (LE) at MDW, while sparse vegetation showed the highest sensible heat (H) at DRT among the four vegetation types. The Bowen ratios (β, H/LE) at TPL (1.68), DRT (1.44) and SHB (1.44) were an order of magnitude higher than that at MDW (0.14). At DRT and SHB, β had significantly negative feedback on canopy conductance (p < 0.05) and significantly positive feedback on vapor pressure deficit (VPD) (p < 0.05). We emphasized that the complex, interactive effects of vegetation types, ecosystem structures, and microclimate for the energy balance and partitioning.

Analysis of UAV lidar information loss and its influence on the estimation accuracy of structural and functional traits in a meadow steppe

• Canopy information loss of UAV lidar in grasslands is investigated. • Factors influencing UAV lidar information loss are analyzed. • UAV lidar information loss at canopy tops is more prevailing than at canopy bottoms. • UAV lidar can be used to extract grassland traits with a comparable accuracy to TLS. • Information loss at canopy tops greatly reduces the accuracy of grassland traits. Accurate quantification of grassland structural and functional traits is the foundation for grassland management and restoration. Light detection and ranging (lidar), especially the unmanned aerial vehicle (UAV) lidar, has been recognized as an accurate and effective technique for local to regional-scale vegetation structural and functional traits estimation. However, in grassland ecosystems, it is more likely to be influenced by UAV lidar information loss caused by dense vegetation canopies. In this study, we investigated how UAV lidar information loss may occur and how it may influence the estimation accuracy of grassland structural and functional traits by comparing it with terrestrial laser scanning (TLS) and field measurements in a meadow steppe of northern China. Five structural traits (i.e., mean vegetation height, maximum vegetation height, standard deviation of vegetation height, canopy cover, and canopy volume) and one functional trait (i.e., aboveground biomass) were estimated from the UAV lidar data and TLS data for evaluation. The results showed that TLS-derived structural and functional traits had a much higher accuracy than UAV lidar-derived traits. By comparing with TLS data, we found that UAV lidar data had a much more prevailing information loss at canopy tops than at canopy bottoms. The average height loss of UAV lidar at canopy tops reached over 0.30 m, and the average relative height loss reached over 49%, comparing to a value of 0.03 m and 6% at canopy bottoms. Maximum vegetation height, standard deviation, and the distance from the UAV lidar system to the ground were the three most influential factors on UAV lidar information loss at canopy tops, indicating the commonly seen sharp canopy tops of grasslands were prone to be missed by the UAV lidar system. UAV lidar information loss at canopy tops had a much stronger influence on the estimation accuracy of grassland structural and functional traits than that at canopy bottoms. With the decrease of information loss at canopy tops, UAV lidar can be used to extract grassland structural and functional traits with a comparable accuracy to TLS. Among the five grassland traits, aboveground biomass was the least influenced by UAV lidar information loss. This study is a very first evaluation on the UAV lidar information loss in grassland ecosystems and its influence on grassland structural and functional trait estimation, which can provide guidance for UAV lidar data collection and processing in future grassland applications.

Methods for Preserving Biodiversity of Meadow Steppes in the Middle Lena Valley

This article considers the results of the studies of the Agricultural and Ecological Group 6 lands of the Nam agricultural landscape conducted in the lower Lena valley under various nutrition regimens in natural steppificated meadows with content of steppe grasses of up to 52%. We established that steppe grasses react differently to fertilizers. Using various dosages of mineral and organic fertilizers helped increase the share of couch grass up to 74­93% while maintaining the share of steppe bluegrass at 14%, along with the mixed herbs including creeping sage at 24%. The combined use of organic and mineral fertilizers helps preserve steppe grasses, especially couch grass, up to 93% while preserving the steppe bluegrass up to 12% and mixed herbs up to 24%, which facilitates the hay fodder yield of up to 20 dt/ha.

Sensitivity of Green-Up Date to Meteorological Indicators in Hulun Buir Grasslands of China

Temperature and precipitation are considered to be the most important indicators affecting the green-up date. Sensitivity of the green-up date to temperature and precipitation is considered to be one of the key indicators to characterize the response of terrestrial ecosystems to climate change. We selected the main grassland types for analysis, including temperate steppe, temperate meadow steppe, upland meadow, and lowland meadow. This study investigates the variation in key meteorological indicators (daily maximum temperature (Tmax), daily minimum temperature (Tmin), and precipitation) between 2001 and 2018. We then examined the partial correlation and sensitivity of green-up date (GUD) to Tmax, Tmin, and precipitation. Our analysis indicated that the average GUD across the whole area was DOY 113. The mean GUD trend was −3.1 days/decade and the 25% region advanced significantly. Tmax and Tmin mainly showed a decreasing trend in winter (p &gt; 0.05). In spring, Tmax mainly showed an increasing trend (p &gt; 0.05) and Tmin a decreasing trend (p &gt; 0.05). Precipitation showed no significant (p &gt; 0.05) change trend and the trend range was ±10 mm/decade. For temperate steppe, the increase in Tmin in March promotes green-up (27.3%, the proportion of significant pixels), with a sensitivity of −0.17 days/°C. In addition, precipitation in April also promotes green-up (21.7%), with a sensitivity of −0.32 days/mm. The GUDs of temperate meadow steppe (73.9%), lowland meadow (65.9%), and upland meadow (22.1%) were mainly affected by Tmin in March, with sensitivities of −0.15 days/°C, −0.13 days/°C, and −0.14 days/°C, respectively. The results of this study reveal the response of vegetation to climate warming and contribute to improving the prediction of ecological changes as temperatures increase in the future.

Grazing and Mowing Affect the Carbon-to-Nitrogen Ratio of Plants by Changing the Soil Available Nitrogen Content and Soil Moisture on the Meadow Steppe, China.

Common grassland management practices affect plant and soil element stoichiometry, but the primary environmental factors driving variation in plant C/N ratios for different species in different types of grassland management remain poorly understood. We examined the three dominant C/N stoichiometric responses of plants to different land uses (moderate grazing and mowing) in the temperate meadow steppe of northern China. Our results showed that the responses of the C/N ratio of dominant plants differed according to the management practice. The relative abundance of N in plant tissues increased due to increased soil NO3−, with a consequent decrease in plant C: N in the shoots of Leymus chinensis, but the C/N ratio and nitrogen concentration in the shoots of Bromus inermis and Potentilla bifurca were relatively stable under short-term moderate grazing management. Mowing reduced the concentration of soil NH4+, thus reducing the nitrogen concentration of the roots, resulting in a decrease in the root C/N ratio of Potentilla bifurca. Structural equation model (SEM) showed that the root C/N ratio was affected by both root N and soil inorganic N, while shoot C/N ratio was only affected by the soil inorganic N. Our findings provide a mechanistic understanding of the responses of plant C/N ratio to land use change. The species-level responses of plant stoichiometry to human-managed grasslands deserve more attention.

Productivity of natural phytocenoses of the Namsky agrolandscape in Yakutia under organic and mineral nutrition regimes

The results of the study of the productivity potential of natural phytocenoses of different species composition in the Namsky agrolandscape of the middle taiga subzone of the Republic of Sakha (Yakutia) are presented. The research was conducted in 2009-2016. The soils of the experimental plot are permafrost soils with a thin humus layer. The effect of mineral and organic fertilizers on the productivity of steppe meadows was studied. On herb-grass, wheatgrass, steppificated phytocenoses the following practices of organo-mineral nutrition of plants were used: control (no fertilizer); humus 20 t/ha; humus 20 t/ha once every 4 years + N60P60K60 annually; N30P30K30 annually; humus 20 t/ha annually. The optimum rates of organic and mineral nutrients to improve the productivity potential of natural steppe meadows have been established. The highest productivity potential in the Namsky agrolandscape was obtained with the combined application of organic and mineral fertilizers (humus 20 t/ha once every 4 years + N60P60K60 annually). On herb-grass and wheatgrass phytocenoses hay yield reached 23.0-24.1 c/ha. Yield per 1 ha of metabolizable energy was 27.0-22.4 GJ, fodder units 1472-1663, crude protein 336-371 kg. The content of digestible protein in 1 fodder unit in herb-grass was 92 g, in wheatgrass - 102 g. The annual application of mineral fertilizers at a dose of 60 kg/ha of the active substance provided a 2-fold increase in the productivity of natural phytocenoses, depending on agroclimatic conditions of the growing season. The influence of mineral fertilizers and their joint application with organic fertilizers on the yield of natural phytocenoses is statistically reliable, which indicates the possibility of regulating the productivity of steppificated phytocenoses.

Environmental changes and human activities over the last about 220 years revealed by the pollen record of Lake Lianhuan in Heilongjiang Province

通过²¹⁰Pb测年建立年代标尺，利用黑龙江省连环湖阿木塔泡高分辨率的孢粉记录，探讨了研究区约220年的环境变化与人类活动.研究表明，1790—1820 AD期间，植被类型可能是以禾本科为主的草甸草原植被，沙地类型以固定沙地为主，气候相对较凉湿或环境几乎不受人类活动的破坏，湖泊营养较丰富.1820—1930 AD期间，草甸草原植被中禾本科和菊科植物比例下降，藜科和蒿属植物比例增加，固定沙地减少、半固定沙地逐渐增加，气候逐渐变干或可能伴随人类破坏环境的活动增强，湿地面积减少.1930—1980 AD期间，针叶乔木松树比例有所增加，草甸草原植被中菊科植物比例是220年来最高的，藜科植物也略有增加，而禾本科和蒿属植物比例下降，推测此阶段固定沙地持续减少，半固定沙地扩张到220年以来面积最大，指示气候进一步变干且伴随着人类活动对自然环境的破坏强度增加，湖泊湿地面积进一步减少.1980—2000 AD期间，草原植被中藜科植物的比例是220年以来最高的，流动沙地面积明显增加，湖泊湿地面积锐减，结合气象数据，得出此期的植被变化是由人类大范围围湖造田以及湿地水田化等活动导致的.2000—2010 AD期间，研究区周围以桦木/鹅耳枥属和栎属为主的落叶阔叶乔木比例增加，草原植被中藜科和菊科植物比例是220年以来最低的，揭示流动沙地和半固定沙地面积明显减少，结合气象数据，认为此期孢粉组合揭示的植被变化主要受人类退耕还草还林，种植桦木/鹅耳枥属、榆属等阔叶植物以及在八支干渠建闸引水至连环湖等活动的影响.;Based on the chronology established through the ²¹⁰Pb dating and the high-resolution pollen record of Amutapao in Lake Lianhuan, Heilongjiang Province, the environmental changes and human activities over the last about 220 years in the study area were discussed. The results showed that during 1790-1820 AD, the vegetation type was probably meadow steppe dominated by Poaceae, and the sandy type was mainly fixed sand. The climate was relatively cool and wet or the environment was hardly damaged by human activities, and lake was of relatively high nutrition. During 1820-1930 AD, the proportion of Poaceae and Compositae plants in the meadow steppe decreased, while that of Chenopodiaceae and Artemisia plants increased. The area of the fixed sand decreased, and the area of the semi-fixed sand gradually increased. The climate gradually became dry or it may be accompanied by the increased human activities, and the wetland area decreased. During 1930-1980 AD, the proportion of coniferous tree Pinus increased, and the proportion of Compositae plants in the meadow steppe was the highest in the past 220 years, and the proportion of Chenopodiaceae plants also increased slightly, while the proportion of Poaceae and Artemisia plants decreased. It is speculated that the fixed sand continued to shrink during this period, and the semi-fixed sand expanded to the largest area for the last about 220 years. It indicates that the climate became further dry and with the increased human activities, and the area of the wetland further decreased. During 1980-2000 AD, the proportion of the Chenopodiaceae plants in the steppe was the highest for the last about 220 years, the area of the mobile sand increased significantly, and the area of the wetland decreased sharply. Combined with the meteorological data, it was concluded that the vegetation changes in this period were caused by human activities such as large-scale lake reclamation and wetland paddy field. During 2000-2010 AD, the proportion of deciduous broad-leaved trees dominated by Betula/Carpinus and Quercus around the study area, and the proportion of Chenopodiaceae and Compositae plants in the steppe was the lowest in the last about 220 years, revealing a significant decrease in the areas of mobile sand and semi-fixed sand. Combined with the meteorological data, it is considered that the vegetation changes during this period revealed by the pollen assemblage were mainly influenced by humans returning farmland to grassland and forest, planting broad-leaved trees such as Betula/Carpinus and Ulmus et al., and building sluices in eight main canals to divert water to Lake Lianhuan.

青藏高原两种高寒草地植被变化及其水温驱动因素分析

高寒草甸和高寒草原作为青藏高原两种重要植被类型，研究其植被变化与气候变化相关性，有助于为青藏高原两种高寒草地生态系统应对全球气候变化管理提供参考。以位于同纬度的三江源高寒草甸和阿里高寒草原为研究对象，基于植被净初级生产力（Net Primary Productivity，NPP）变化表征植被变化，利用NPP数据和气象数据，分别分析两地2000-2017年植被NPP、降水和气温时空变化差异；利用Sen+Mann-Kendall趋势检验，研究两种高寒草地气候与植被净初级生产力变化趋势；以县域统计年鉴牛羊肉产量表征放牧强度，研究放牧活动对高寒草地植被变化的影响；通过Pearson相关和偏相关分析方法，分别研究降水和气温对两种高寒草地植被NPP变化影响差异。研究结果表明：（1）2000-2017年三江源高寒草甸和阿里高寒草原区年平均气温以0.085℃/a和0.084℃/a的趋势上升，降水以平均每年3.87 mm和2.23 mm的趋势增加，高寒草甸区变暖变湿速率较高寒草原区快。（2）三江源高寒草甸和阿里高寒草原植被NPP均呈现由东南向西北逐渐降低空间格局；2000-2017年高寒草甸区57.7%植被NPP呈现上升趋势，而高寒草原区50.96%植被NPP呈现上升趋势，高寒草甸植被NPP增长趋势较高寒草原明显。（3）三江源高寒草甸和阿里高寒草原两种草地植被变化受放牧影响不大，受气候变化影响较大。（4）三江源高寒草甸大部分植被NPP增长与气温呈显著正相关而与降水呈显著负相关，高寒草甸植被NPP主要受温度调控，而阿里高寒草原植被NPP受降水和温度的双重调控。;Alpine meadow and alpine steppe are two important vegetation types on the Qinghai-Tibet Plateau. Studying the correlation between vegetation change and climate change in alpine meadow and alpine steppe is helpful to provide reference for the management of the two alpine grassland ecosystems on the Qinghai-Tibet Plateau in response to global climate change. In this study, the alpine meadow of the Three-River Headwaters Region and the alpine steppe of Ali located in the same latitude were taken as the research objects. Vegetation changes were characterized based on the changes of Net Primary Productivity (NPP) of vegetation. Based on NPP data and meteorological data, the spatial and temporal variations of NPP, precipitation and air temperature between 2000 and 2017 were analyzed. Sen+ Mann-Kendall trend test was used to study the change trend of climate and vegetation net primary productivity in two alpine grasslands. The effects of grazing activities on the vegetation change of alpine grassland were studied by using the yield of beef and mutton in county statistical yearbooks. Through Pearson correlation and partial correlation analysis, the variation trend of precipitation and air temperature on vegetation NPP and the difference of precipitation and air temperature on NPP of two alpine grasslands were studied respectively. The results show that:(1) from 2000 to 2017, the annual average temperature in Three-River Headwaters Region alpine meadow and Ali alpine steppe increased at 0.085℃/a and 0.084℃/a, and the annual average precipitation increased at 3.87 mm and 2.23 mm, respectively. The warming and wetness rate in the alpine meadow was faster than that in the alpine steppe. (2) The NPP of the alpine meadow in the Three-River Headwaters Region and the alpine steppe in Ali showed a decreasing spatial pattern from southeast to northwest. From 2000 to 2017, the NPP of 57.7% of alpine meadow vegetation presented an upward trend, while that of 50.96% of alpine steppe vegetation showed an upward trend. The NPP of alpine meadow vegetation increased more obviously than that of alpine steppe. (3) The alpine meadow in the Three-River Headwaters Region and the alpine steppe in Ali region were less affected by grazing and more affected by climate change. (4) The NPP growth of most alpine meadow vegetation in the Three-River Headwaters Region was significantly positively correlated with air temperature and negatively correlated with precipitation. The NPP of alpine meadow vegetation was mainly regulated by temperature, while the NPP of alpine steppe vegetation in the Ali region was controlled by both precipitation and temperature.

气候变化和人为活动在宁夏草地变化中的相对作用

PDF HTML阅读 XML下载 导出引用 引用提醒 气候变化和人为活动在宁夏草地变化中的相对作用 DOI: 10.5846/stxb202105191307 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 宁夏自然科学基金项目（2018AAC03277）；宁夏农业高质量发展和生态保护科技创新示范项目（NGSB-2021-14-03，NGSB-2021-15-01）；陕西省教育厅项目（20JK0760） Assessment of relative effects of climate change and human activities on grassland dynamic in Ningxia Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:气候变化和人为活动是草地生态系统退化或恢复过程中的两大驱动因素。选取植被净初级生产力（NPP）为衡量指标，利用改进的Carnegie-Ames-Stanford Approach （CASA）模型、Thornthwaite Memorial模型以及残差趋势法分别计算了宁夏草地实际净初级生产力（ANPP）、潜在净初级生产力（PNPP）和人为活动影响的生产力（HNPP）及其变化趋势，定量评估了2001-2019年气候变化和人为活动在宁夏4种类型草地（温性草甸、温性草原、温性荒漠草原和温性草原化荒漠）动态变化中的相对作用。结果表明，2001-2019年宁夏草地实际净初级生产力增加的面积占宁夏草地总面积的97.84%；全区草地潜在净初级生产力均表现为增加趋势，表明气候变化有利于植被恢复。草地恢复过程中，气候变化引起的草地恢复面积占草地恢复总面积的61.68%，气候变化和人为活动共同作用引起的草地恢复面积占38.32%；人为活动是导致草地退化的绝对主导因素。4种类型草地动态变化的驱动因素存在差异，气候变化是促进温性草甸（68.94%）和温性草原化荒漠（70.51%）恢复的主导因素，气候变化和人为活动共同作用是促进温性草原恢复的主导因素（62.30%），温性荒漠草原的恢复是气候变化和人为活动共同作用的结果（97.93%）。水热条件好转，尤其是降水增加是宁夏草地恢复的主导气候因子，生态保护政策的实施是促进草地恢复的主要人为因素，对草地的不合理利用是导致草地退化的主要人为因素。 Abstract:Climate change and human activity are two main factors driving vegetation dynamics during grassland recovery or degradation. In this study, the net primary productivity (NPP) was selected as the index, the improved Carnegie-Ames-Stanford Approach (CASA) model and Thornthwaite Memorial model were used to estimate actual net primary productivity (ANPP) and potential net primary productivity (PNPP) determined by climatic conditions, respectively. The residual trend analysis (RESTREND) method was applied to analyze the residuals of potential and actual net primary productivity and further identify non-climatic effects on vegetation dynamics in four types of natural grassland, including meadow steppe, warm steppe, desert steppe and warm steppe desert of Ningxia. Results showed that the ANPP in 97.84% of the grassland increased from 2001 to 2019 generally. The PNPP of the whole region presented an increasing trend, revealing that climate change had a positive effect on vegetation recovery across the study area. During the grassland restoration, 61.68% of the recovered grassland resulted from climate change, while 38.32% of the recovered grassland from the combined effects of climate change and human activity. Anthropogenic activities were considered as the absolutely dominant influencing factor for vegetation degradation. The driving factors of vegetation dynamic showed differences in the four types of grassland. Climate change was the dominant factor for the recovery of warm meadow (68.94%) and warm steppe desert (70.51%). The combined effects of climate change and human activities were the main factors for the recovery of warm steppe (62.30%). The recovery of warm desert steppe resulted from the combined effects of climate change and human activities (97.93%). The improvement of hydrothermal conditions, especially the increases in precipitation, was the main influencing factor for grassland restoration in Ningxia. The implementation of ecological protection policies produced significantly positive effects on the restoration of grassland, and the unreasonable occupation of grassland was the main anthropogenic factor leading to grassland degradation. 参考文献 相似文献 引证文献

. Productivity changes of wetland and grassland ecosystems along a latitudal gradient

The aim of the study. Analysis of changes in the productivity of dwarf shrub-moss-lichen, pine-dwarf shrub-sphagnum and sedge-sphagnum and grass ecosystems along the latitudinal gradient. Methodology. For a number of bog and grass ecosystems located along a latitudinal gradient from 65 to 50° N in the range of longitudes from 63 to 95° E the stocks of live and dead, aboveground and belowground phytomass, as well as the values of aboveground (ANP), belowground (BNP) and total production (NPP) were analyzed. The data are given for 45 ecosystems grouped into 12 types from forest-tundra mires to desert steppes. The vegetation of ecosystems is represented by bog one (mosses, shrubs and grasses) to the steppe (mesoxerophytic and xerophytic grasses). Since the spread of data on stocks and production for individual ecosystems is large, we present averaged data for ecosystem types. Main results. The largest stock of green phytomass was obtained for floodplain meadows (7 t/ha), the smallest stock was found in the desert steppes (0.8 t/ha). The stock of dead aboveground phytomass was maximal in the fens of the forest-steppe zone (10 t/ha) and minimal in the oligotrophic hollows of boreal bogs (0.3 t/ha). The stock of living belowground organs decreases along a latitudinal gradient from 20 (true steppes) to 3 t/ha (desert steppes), whereas the stock of dead belowground organs decreased from 79 (fens of the forest-steppe zone) to 4 t/ha (in the ryams of the middle taiga and desert steppes). Above-ground production was estimated as highest in the fens of the forest-steppe zone (12), decreasing along the latitudinal gradient down to the desert steppes (1 t/ha per year). Belowground production in all types of ecosystems studied was higher than the above-ground one, ranging from 45 (fens of the forest-steppe zone) to 3 t/ha per year (mires in the forest-tundra). The NPP value in some of the studied ecosystems varied from 57 (fens of the forest-steppe zone) to 5 t/ha per year (mires in the forest-tundra). The BNP/ANP ratio averaged over ecosystem types was maximal in the desert steppes (5.9) and minimal in floodplain meadows (1.9). In the range of latitudes 56-52°N, where steppe meadows, meadow steppes and true steppes located, the NPP, averaged over these ecosystems, varied from 22 to 24 t/ha per year. These ecosystems the most fertile soils of the region, i.e. meadow chernozem and ordinary chernozem (Phaeozems) were developed. To the north and south of this area, the NPP value decreases: to the north due to the lack of heat, and to the south due to lack of moisture. Conclusions. In the biotic cycle in mires differs from that in meadows and steppes by the annual sequestration of a part of the carbon influx in the forming peat. This amount of carbon sequestration is about 10% of the NPP of the wetland ecosystem. In the climax grass ecosystems, the carbon influx is equal to its outflux. These ecosystems are acting as gas exchangers between plants, soil and atmosphere. In contrast to grasslands, wetlands are acting as carbon accumulators that lower the CO2 in the air.

Структура, разнообразие и продукция леймусовых сообществ (Leymus chinensis ((Trin.) Tzvel.) южной части Восточного Забайкалья

The study of the steppe gramineous communities with Leymus chinensis (Trin.) Tzvel as a monodominant that vegetate on different soil types of meadow and haloxerophytic steppe and steppe floodplain grasslands within the southern part of Eastern Transbaikalia was performed for the first time. Species composition of Leymus communities is represented by 21 families, 45 genera and 62 species, accounted for 11,3% halophytes, 29% – halotolerant, and 59,7% – glycophytes. Multispecies families are Asteraceae (19), Poaceae (11), and Rosaceae (5). Artemisia (9) and Potentilla (4) are multispecies genera, each of Heteropappus, Poa, and Carex genera had 2 species, and the rest are single-species.L. chinensis as edificator mainly formed the projective cover of communities (40- 80%) that is determined by the soil and ecological conditions of its growth. The community dominant has been established to belong to the forest-steppe group, to be a xeromesophyte, of Central Asian type of areal and represented by long-rhizome biomorphs. It is the positive feature for the effective use of mineral fertilizers. The similarity between communities is in the range of weak to medium due to the significant part of single-species families and genera. Leymus communities are attributed mainly to steppe complex with different variants of xerophytes of Asian type of areal. The main part of biomorphs is represented by rhizomatous species, and the share of perennials is also significant. The similarity between communities was evaluated as weak – medium due to a large number of single-species families and genera. Primary production of L. chinensis communities was estimated to be high (2105-3189 g/m2 per year). The contribution of L. chinensis and each of its components (stems, leaves, ears) separately to the above-ground mass, as well as the role of other species (cereals, sedges, legumes, forbs), united in the group of forbs, was determined first. An assessment of the seasonal rag accumulation, depending on the soil and ecological conditions is given. The largest part of ears in aboveground phytomass was noted only in two communities (4 and 5). The coefficient of seed productivity had the maximum value (52-58%) in descriptions 3 and 4, in the rest – 7,5-14%, caused by adaptation of the species to the long-term climate change, due to increased reserves of nutrients that provide energy for vegetative growth and reproduction, reducing the generative. The underground phytomass consist of 84-94% of the total productivity. Depending on the soil-ecological conditions, the excess of underground phytomass over above-ground varies within 1:5-15. In perspective, the development of a system of rational use and mineral fertilizers application of that increase and improve the productive process in the soil-plant system is required to increase and preserve the productive longevity of Leymus communities in Eastern Transbaikalia.

Community Differentiation and Ecological Influencing Factors along Environmental Gradients: Evidence from 1200 km Belt Transect across Inner Mongolia Grassland, China

In this work, we conducted a 1200 km belt transect for field survey in typical and meadow steppes across Inner Mongolia Plateau in 2018. The field investigation, laboratory soil analysis, and quantitative ecology methods were utilized to explore the differentiation characteristics of the plant community, and their relationships with ecological factors. The results showed that a total of 140 vascular plants within 108 quadrats mainly comprised of Asteraceae, Poaceae, Rosaceae, and Fabaceae. Two-way Indicator Species Analysis (TWINSPAN) revealed eight vegetation typologies: I: Stipa sareptana var. krylovii + Dysphania aristata, II: Stipa grandis + Leymus chinensis, III: Stipa sareptana var. krylovii + Leymus chinensis, IV: Stipa grandis + Cleistogenes squarrosa, V: Stipa grandis + Carex duriuscula, VI: Stipa baicalensis + Leymus chinensis, VII: Carex pediformis + Stipa baicalensis, VIII: Leymus chinensis + Elymus dahuricus. Detrend Correspondence Analysis (DCA) confirmed the above eight vegetation typologies and indicated a relatively small variation. Redundancy analysis (RDA) revealed that the spatial differentiation characteristics in the typical steppe were chiefly driven by precipitation, while the influencing factor in the meadow steppe was soil nutrients, followed by temperature and precipitation. The contrast between typical and meadow steppes revealed that the spatial distribution of typical steppe was influenced by precipitation, while the contribution of heat and water in the meadow steppe was equal. The conclusion revealed that the temperature and precipitation conditions coupled with soil nutrients shaped the spatial differentiation characteristics of temperate steppe vegetation in the Inner Mongolia grassland. Therefore, this study advanced our knowledge of the spatial patterns of temperate steppe along longitude and latitude gradients, providing scientific and theoretical guidance for the biodiversity conservation and sustainable ecosystem management of the Inner Mongolia grassland.

Нові дані щодо видів рослин для території Харківської області та Національного природного парку «Гомільшанські ліси»

The discovery of a new species for the flora of Kharkiv Oblast — Galium praeboreale Klokov (Rubiaceae) — is reported along with records of eight more species that have not been registered before in the Homilshanski Lisy National Nature Park and its vicinites: Euphorbia subtilis Prokh. (Euphorbiaceae), Carex tomentosa L. (Cyperaceae), Tragopogon podolicus (DC.) Artemcz. (Asteraceae), Arctium nemorosum Lej. (Asteraceae), Galeopsis ladanum L. (Lamiaceae), Centaurea apiculata Ledeb., C. pseudomaculosa Dobrocz. (Asteraceae), and Muscari neglectum Gus. ex Ten. (Hyacinthaceae). Phytocoenotic conditions of the investigated habitats are described. A description of the M. neglectum population is given. Literature data and materials of the herbarium of V. N. Karazin Kharkiv National University (CWU) are analysed in regard to the distribution of the identified species in the flora of Kharkiv Oblast. It is established that since the second half of the 20th century there have been no data on records of E. subtilis, C. tomentosa, T. podolicus, A. nemorosum, C. apiculate, and C. pseudomaculosa confirmed by herbarium collections. The species E. subtilis, T. podolicus, C. tomentosa, and G. praeboreale were found in the territory of Homilshanski Lisy National Nature Park. The first two species occur in phytocoenoses of natural meadows, whereas the other two occur in phytocoenoses of both natural and steppe meadows in the floodplain of the Siverskyi Donets River. In the territory of the national park, A. nemorosum was found on a forest path and on the edge of an oak forest on the right bank of Siverskyi Donets River, whereas G. ladanum occurs in ruderal vegetation of glades and forest roads of the sandy terrace on the left bank of the river. The species C. apiculata, C. pseudomaculosa, and M. neglectum were found only outside the park. Both species of Centaurea occur on grassy slopes, in ruderal vegetation at the bottom of an old clay quarry, on sides of dirt roads in south-western outskirts of the town Zmiiv, as well as on grassy slopes between the town Zmiiv and the village Haidary. A population of M. neglectum was also found in the south-western outskirts of Zmiiv. On a grassy slope planted by a forest strip, 115 generative individuals were found on an area of about 0.25 ha.

Divergences of soil carbon turnover and regulation in alpine steppes and meadows on the Tibetan Plateau

The grasslands of the Tibetan Plateau store approximately 2.5% of global soil organic carbon (SOC) and considerable soil inorganic carbon (SIC) and have the potential to become a vast carbon source or sink as climate change progresses. However, the soil carbon (C) sequestration mechanisms that occur across large-scale natural gradients remain unclear. Here, humic substances (HS) were utilized to trace soil C turnover at 0–20 cm, and we compared divergences among three main grassland types (alpine meadow, alpine steppe, and artificial plantation) using structural equation modeling (SEM). The results showed that the alpine meadows sequestered the most soil C (63.99 ± 4.41 g kg−1 SOC and 4.11 ± 0.63 g kg−1 SIC), sequestering 2–3 times more than the alpine steppe ecosystems (19.78 ± 1.98 g kg−1 SOC and 9.21 ± 0.66 g kg−1 SIC). The alpine steppe and artificial plantation regions have strong C sink potential due to their low C/N ratios (P < 0.05). Importantly, SIC played an important role in the alpine steppes, accounting for nearly 26–37% of soil C. The ratios of recalcitrant HS to SOC were estimated as 46.50%, 65.09%, and 78.17% in the alpine meadow, alpine steppe, and artificial plantation ecosystems, respectively, indicating that SOC in the alpine meadow was the most sensitive to climate change. Fulvic acid (FA) accounted for 50.86% of SOC in the 0–20-cm interval, contributing most to the formation of SOC in all vegetation types. In addition, in contrast to climatic controls on soil C turnover in the alpine meadow, climate conditions rarely controlled C turnover in the alpine steppe. Moreover, sand and silt were the main soil minerals involved in C turnover in alpine meadow and alpine steppe ecosystems, respectively. Our study improves understanding of the mechanism by which soil C sinks form on the Tibetan Plateau under warming and wetting conditions.

Decrease in Carabid Beetles in Grasslands of Northwestern China: Further Evidence of Insect Biodiversity Loss.

Simple SummaryLong-term studies on insect diversity trends are rare, especially in steppe ecosystems. To gain insights into carabid beetle diversity trends in steppe grasslands, we analyzed data on carabids from a trapping study that ran for 12 years in the grasslands of northwestern China. We found that species abundance and richness declined over time. The results of this study suggest that precipitation may play a role in changing species dynamics. This study emphasizes the urgent need to protect carabid communities in steppe ecosystems.Ground-dwelling beetles are important functional components in nutrient-poor grasslands of middle temperate steppe ecosystems in China. Here, we assessed the changes in ground beetle (Coleoptera: Carabidae) communities in the grasslands of northwestern China over 12 years to improve the management and conservation of beetles all over the world. The Generalized Additive Model (GAM) was applied to estimate the changes in carabid beetle communities in two regions: a desert steppe (Yanchi region), and a typical steppe and meadow steppe (Guyuan region). During the 12-year investigation, a total of 34 species were captured. We found that species abundance and richness per survey declined by 0.2 and 11.2%, respectively. Precipitation was the main factor affecting the distribution of carabid beetles. A distinct decline in carabid beetle species in the Yanchi region indicated that they may be threatened by less precipitation and loss of habitat, which could be due to climate change. Overall, species richness was stable in the Guyuan region. It is necessary to estimate and monitor the changes in carabid beetle communities in a temperate steppe of northern China and to protect them. Extensive desertification seriously threatens the distribution of carabid beetles. Future research should develop methods to protect carabid beetle communities in temperate steppes in China.

The Restoration Potential of the Grasslands on the Tibetan Plateau

While the alpine grassland ecosystems on the Tibetan Plateau (TP) have generally improved in recent years, some grasslands still suffer from varying degrees of degradation. Studying the restoration potential (R) of the grasslands on the TP is crucial to the conservation and restoration of its alpine grassland ecosystems. Few studies have assessed the restoration value of the alpine grasslands on the TP. We attempt to estimate the actual (ANPP) and potential net primary productivity (PNPP) of the grasslands on the TP. On this basis, we defined R as the “gap” between the current and highest achievable levels of restoration of a grassland. Then, R estimates were yielded for the alpine grasslands on the TP, which we used to analyze the restoration value of these grasslands. Specifically, based on the meteorological data for the period 2001–2019, in conjunction with remote-sensing imagery acquired by a moderate-resolution imaging spectroradiometer for the same period, the Carnegie–Ames–Stanford approach model was selected to produce ANPP estimates for the grasslands on the TP. Then, the Thornthwaite memorial model, the principle of similar habitats, and the Chikugo model, were employed to generate PNPP estimates for these grasslands. In addition, the R of these grasslands was then assessed based on the difference between their PNPP and ANPP. The main results are summarized as follows. (1) A multiyear mean R of 332.33 g C·m–2 (81.59% of the ANPP) was determined for the grasslands on the TP over the period 2001–2019. A notable spatial distribution pattern of high Rs in the southwestern, eastern and middle parts of the TP, and low Rs in the northwestern part of the TP were also identified. Most of the grasslands in areas such as the southern part of Nagqu, the southwestern part of Ngari, Xigaze, Garze Tibetan Autonomous Prefecture, Aba Tibetan and Qiang Autonomous Prefecture, Gannan Tibetan Autonomous Prefecture, Huangnan Tibetan Autonomous Prefecture, Haibei Tibetan Autonomous Prefecture, Guoluo Tibetan Autonomous Prefecture and Yushu Tibetan Autonomous Prefecture were found to have high restoration value. (2) Grasslands with a stable R account were the highest proportion (76.13%) of all the grasslands on the TP, followed by those with a decreasing R (19.62%) and those with an increasing R (4.24%). Grasslands with an increasing R were mainly concentrated in the southern part of Xigaze, and parts of Yushu Tibetan Autonomous Prefecture, Guoluo Tibetan Autonomous Prefecture and Garze Tibetan Autonomous Prefecture. (3) Analysis based on the local conditions of the TP revealed a high restoration value for three types of grassland (i.e., alpine meadows, mountain meadows, and temperate meadow steppes), the grasslands distributed at altitudes of 3000–4000 m, and the grasslands located in the warm temperate zone. The results of this study are expected to provide scientific and theoretical support for the formulation of policies and measures aimed at conserving grasslands, as well as restoring ecosystems and degraded grasslands on the TP.

Grazing Reduces the Soil-Atmosphere Exchange of Greenhouse Gases During Freeze-Thaw Cycles in Meadow Steppes in Inner Mongolia

Both livestock grazing and soil freeze-thaw cycles (FTCs) can affect the soil-atmosphere exchange of greenhouse gases (GHGs) in grasslands. However, the combined effects of grazing and FTCs on GHG fluxes in meadow steppe soils remain unclear. In this study, we collected soils from paired grazing and enclosed sites and conducted an incubation experiment to investigate the effect of grazing on soil GHG fluxes in the meadow steppes of Inner Mongolia during three FTCs. Our results showed that FTCs substantially stimulated the emissions of soil N2O and CO2 and the uptake of CH4 in the meadow steppes. However, compared with enclosure treatments, grazing significantly reduced the cumulative N2O, CO2 and CH4 fluxes by 13.3, 14.6, and 26.8%, respectively, during the entire FTCs experiment. The soil dissolved organic carbon (DOC) and nitrogen (DON), NH4+-N and NO3–-N, significantly increased after three FTCs and showed close correlations with N2O and CO2 emissions. Structural equation modeling (SEM) revealed that the increase in NO3–-N induced by FTCs dominated the variance in N2O emissions and that DOC strongly affected CO2 emissions during thawing periods. However, long-term grazing reduced soil substrate availability and microbial activity and increased soil bulk density, which in turn decreased the cumulative GHG fluxes during FTCs. In addition, the interaction between grazing and FTCs significantly affected CO2 and CH4 fluxes but not N2O fluxes. Our results indicated that livestock grazing had an important effect on soil GHG fluxes during FTCs. The combined effect of grazing and FTCs should be taken into account in future estimations of GHG budgets in both modeling and experimental studies.

A Warm Tea: The Role of Temperature and Hydroperiod on Litter Decomposition in Temporary Wetlands

Increasing global temperature and changes in the precipitation regime affect the global carbon cycle by altering the process of organic matter decomposition. Temporary aquatic systems are especially susceptible to climate change. We hypothesized that water availability and temperature affect the early and late stages of decomposition of litter differently and determine the decomposition rates according to litter type. We conducted two decomposition experiments using green (Camellia sinensis L.) and mint (Mentha piperita L.) tea in commercial bags. In the laboratory experiment, we incubated the bags at two contrasting temperatures (4 and 15°C) and in three simulated hydroperiods (M: moist, MS: submerged after 14 days, S: submerged). A field experiment was carried out in winter and spring in nine temporary wetlands (meadows) along a precipitation gradient (from forest to steppe ecosystems) in the Argentinean Patagonia. Water stimulated the leaching of soluble substances in the S treatment and was the conducting factor in early decomposition stages. Temperature stimulated tea decomposition in advanced stages, and both water and temperature exerted a different response depending on the litter type. In the field experiment, mass loss in meadows was determined by the hydroperiod condition, both in winter and spring. Detritus type was the controlling factor in steppe meadows, but on forest meadows water level stimulated both litter types, and temperature increased decomposition. Under the expected increase of temperature and decrease of precipitations in future climate scenarios, organic matter accumulation would increase in steppe meadows and decomposition would be higher in forest meadows.

Phosphorus addition promotes Nitrogen retention in alpine grassland plants while increasing N deposition

Nitrogen (N) and phosphorus (P) are common limiting nutrients affecting plant growth in alpine ecosystems. Anthropogenic activities significantly increase N input in ecosystems, thereby increasing P limitation when in excess. The increase of N input and P limitation may affect N retention, which is a critical ecosystem function. To understand how ecosystem N retention and N loss respond to N and P addition, this study investigated the effects of N and P addition on NH3 volatilization, N2O emissions, and N pools of plants and soil in two alpine grasslands (alpine meadow and alpine steppe). The results showed that P addition (with or without N) increased N retention, mainly by promoting plant N uptake, underlining the importance of P availability in N retention in the QTP alpine grassland ecosystems while increasing N deposition. N addition without P showed neutral effects of N retention of plant, soil and microbes, and N addition (with or without P) showed positive effects on gaseous losses of N. N loss through NH3 volatilization and N2O emissions was quite low (less than 1%), suggesting that N gaseous loss was not a significant pathway of N loss from the alpine grassland ecosystems. These results were meaningful for estimating the impacts of N retention and N loss under future N deposition scenarios in alpine grassland ecosystems in the QTP.

Driving factors and their interactions of carabid beetle distribution based on the geographical detector method

The decline of insect diversity has received widespread attention as a serious ecosystem problem worldwide. Accurately learning the driving factors of insect decline is difficult because of the complex multitrophic and environmental interactions involved. The scientific interpretation of the factors driving insect distribution is essential to understanding biological systems and the effects of changed environment. Generally, insect distributions result from the interactions of different factors, therefore, understanding how multi-factor interactions effect of carabid distribution is beneficial. Carabid beetles are indicator species in the steppes of northwestern China. Previous studies have focused on the main driving factors of carabid beetle occurrence separately, ignoring the interactions between drivers. Using the Geographical Detector method, a new method of spatial statistics, the interactive influences of 15 variables on carabid beetle distribution were quantified at three steppes in the Ningxia Hui Autonomous region, of northwestern China. The results showed that carabid beetle distribution in the steppes was primarily driven by annual average precipitation (q=0.55). Among the interactions of factors, precipitation ∩ Altitude (q=0.719) was the strongest, followed by precipitation ∩ plant biomass (q=0.677 ), and precipitation ∩ pH value (q=0.677). The areas with the greatest risk of carabid beetle decline are the desert steppe and northern parts of the meadow steppe. This study shows that the Geographical Detector approach was successful for analyzing the driving forces of carabid beetle distribution. Our study also offers a new method for understanding the interactions between different drivers of other animal distributions more broadly.