Grassland Management Research Articles

Spatial and temporal variation patterns of summer grazing trajectories of Sunit sheep

GPS is an important tool for real-time monitoring of individual livestock. Analysis of the spatial and temporal changes in the grazing trajectory of Sunit sheep provided a scientific basis for the rational use of Inner Mongolia desert grassland resources and optimal breeding of livestock. In this study, GPS collars were used to track Sunit sheep in the Inner Mongolia desert grassland. These data were combined with ground measurement data and spatial remote sensing data to investigate the spatial and temporal variation patterns of sheep grazing tracks. The results showed that the distance travelled by sheep in June was significantly different from that in July and August (p < 0.05). The effective daily foraging time was mainly concentrated in the time ranges of 7:00–10:00 and 15:00–18:00 in June and August, and in the time ranges of 7:00–9:00 and 16:00–19:00 in July, for more active grazing behavior in the morning and evening hours. The degree of nuclear density of foraging track points was significantly different from the edible forage biomass (p < 0.05), with the average daily walking distance negatively correlated with the total grass biomass (R2 = 0.49). Overall, the results of this study confirm that GPS-positioning technology can be applied to study the spatial and temporal variation patterns of sheep and suggest new strategies for more effective grassland management in this region.

UAV Assisted Livestock Distribution Monitoring and Quantification: A Low-Cost and High-Precision Solution.

Grazing management is one of the most widely practiced land uses globally. Quantifying the spatiotemporal distribution of livestock is critical for effective management of livestock-grassland grazing ecosystem. However, to date, there are few convincing solutions for livestock dynamic monitor and key parameters quantification under actual grazing situations. In this study, we proposed a pragmatic method for quantifying the grazing density (GD) and herding proximities (HP) based on unmanned aerial vehicles (UAVs). We further tested its feasibility at three typical household pastures on the Qinghai-Tibetan Plateau, China. We found that: (1) yak herds grazing followed a rotational grazing pattern spontaneously within the pastures, (2) Dispersion Index of yak herds varied as an M-shaped curve within one day, and it was the lowest in July and August, and (3) the average distance between the yak herd and the campsites in the cold season was significantly shorter than that in the warm season. In this study, we developed a method to characterize the dynamic GD and HP of yak herds precisely and effectively. This method is ideal for studying animal behavior and determining the correlation between the distribution of pastoral livestock and resource usability, delivering critical information for the development of grassland ecosystem and the implementation of sustainable grassland management.

Nitrogen addition and mowing had only weak interactive effects on macronutrients in plant-soil systems of a typical steppe in Inner Mongolia

Effective management of macronutrients is pivotal in the optimization and provisioning of ecosystem services in grassland areas, particularly in degraded grasslands. In such instances where mowing and nitrogen (N) fertilization have emerged as predominant management strategies, nutrient management is especially important. However, the precise effects of these concurrent practices on the distribution of macronutrients in plant-soil systems remain unclear. Here we evaluated the effects of 12 years of N addition (2, 10, and 50 g N m−2 year−1) and mowing on the concentrations and pools of six macronutrients (i.e., N; phosphorus P; sulfur S, calcium Ca, magnesium Mg, and potassium K) in three plant components (aboveground plants, litter, and belowground roots) at the community level and in the soil in a typical steppe in Inner Mongolia. Our results revealed that N addition generally raised the N concentration in the entire plant-soil system, regardless of whether plots were mowed. Higher N addition (10 and 50 g N m−2 year−1) also led to higher concentrations of P (+22%, averaging two N addition rates), S (+16%), K (+22%), Ca (+22%), and Mg (+24%) in plants but lower concentrations of these nutrients in the litter. Similar decreases in K (−9%), Ca (−46%), and Mg (−8%) were observed in the roots. In light of the observed increases in vegetation biomass and the lack of pronounced changes in soil bulk density, we found that the ecosystem N enrichment resulted in increased pools of all measured macronutrients in plants, litter, and roots (with the exception of Ca in the roots) while concurrently decreased the pools of P (−20%, averaging two higher N addition rates), S (−12%), K (−10%), Ca (−37%), and Mg (−19%) in the soil, with no obvious effect of the mowing practice. Overall, mowing exhibited a very limited capacity to alleviate the effects of long-term N addition on macronutrients in the plant-soil system. These findings highlight the importance of considering the distribution of macronutrients across distinct plant organs and the dynamic nutrient interplay between plants and soil, particularly in the context of long-term fertilization and mowing practices, when formulating effective grassland management strategies.

Differences in background environment and fertilization method mediate plant response to nitrogen fertilization in alpine grasslands on the Qinghai-Tibetan Plateau

Grassland degradation threatens ecosystem function and livestock production, partly induced by soil nutrient deficiency due to the lack of nutrient return to soils, which is largely ascribed to the intense grazing activities. Therefore, nitrogen (N) fertilization has been widely adopted to restore degraded Qinghai-Tibetan Plateau (QTP) grasslands. Despite numerous field manipulation studies investigating its effects on alpine grasslands, the patterns and thresholds of plant response to N fertilization remain unclear, thus hindering the prediction of its influences on the regional scale. Here, we established a random forest model to predict N fertilization effects on plant productivity based on a meta-analysis synthesizing 88 publications in QTP grasslands. Our results showed that N fertilization increased the aboveground biomass (AGB) by 46.51 %, varying wildly among plant functional groups. The positive fertilization effects intensified when the N fertilization rate increased to 272 kg ha−1 yr−1, and decreased after three years of continuous fertilization. These effects were more substantial when applying ammonium nitrate compared to urea. Further, a machine learning model was used to predict plant productivity response to N fertilization. The total explained variance and mean squared residuals ranged from 49.41 to 75.13 % and 0.011–0.058, respectively, both being the highest for grasses. The crucial predictors were identified as climatic and geographic factors, background AGB without N fertilization, and fertilization methods (i.e., rate, form, and duration). These predictors with easy access contributed 62.47 % of the prediction power of grasses' response, thus enhancing the generalizability and replicability of our model. Notably, if 30 % of yak dung is returned to soils on the QTP, the grassland productivity and plant carbon pool are predicted to increase by 5.90–6.51 % and 9.35–10.31 g C m−2 yr −1, respectively. Overall, the predictions of this study based on literature synthesis enhance our understanding of plant responses to N fertilization in QTP grasslands, thereby providing helpful information for grassland management policies.Conflict of interest: The authors declare no conflict of interest.

Untangling the effects of climate variation and human interference on grassland dynamics in North China

AbstractClimatic and anthropogenic disturbances play pivotal roles in shaping the dynamics of grassland. Quantifying their impacts on grassland variation is essential to ensure sustainable grassland management. In this study, we employed the Thornthwaite Memorial and Carnegie–Ames–Stanford‐approach (CASA) models to investigate the spatiotemporal effects of these two variables on grassland variation in northern China from 2000 to 2016, using the net primary productivity (NPP) as a measure. Our findings reveal that approximately 25.92% of the grassland in northern China experienced degradation, while restored grasslands occupied 45% of the total grassland area. The average grassland actual NPP (ANPP) and human‐induced NPP decreased at rates of −0.60 and −5.62 gC m−2 a−1, respectively. Conversely, potential NPP exhibited an upward trend with an average increase of 2.27 gC m−2 a−1. Furthermore, grassland ANPP showed a projected increase in most parts of northern China. Climate change emerged as the primary driver for grassland restoration in Xinjiang, Qinghai, and Inner Mongolia, leading to an increase of 21582.79 Gg C in grassland NPP. In contrast, human activities were the dominant catalysts for grassland degradation, resulting in a reduction of 51932.3 Gg C in grassland NPP. Human‐induced grassland degradation was ubiquitous in northwest and northeast China. With the exception of slope grassland, climate change primarily influenced the restoration of most grassland types, while human activities were the primary cause of degradation. Our analysis indicated a strong correlation between temperature and grassland degradation, while precipitation played a pivotal role in grassland restoration in northern China. Human interference demonstrated both positive and negative impacts on grassland changes. In conclusion, the increase in precipitation and the implementation of ecological restoration plans have effectively promoted the restoration of grasslands in northern China.

Alteration of microbial carbon and nitrogen metabolism within the soil metagenome with grazing intensity at semiarid steppe

Grazing causes changes in microbiome metabolic pathways affecting plant growth and soil physicochemical properties. However, how grazing intensity affects microbial processes is poorly understood. In semiarid steppe grassland in northern China, shotgun metagenome sequencing was used to investigate variations in soil carbon (C) and nitrogen (N) cycling-related genes after six years of the following grazing intensities: G0, control, no grazing; G1, 170 sheep days ha−1 year−1; G2, 340 sheep days ha−1 year−1; and G3, 510 sheep days ha−1 year−1. Taxa and functions of the soil microbiome associated with the C cycle decreased with increasing grazing intensity. Abundances of genes involved in C fixation and organic matter decomposition were altered in grazed sites, which could effects on vegetation decomposition and soil dissolved organic carbon (DOC) content. Compared with the control, the abundances of nitrification genes were higher in G1, but the abundances of N reduction and denitrification genes were lower, suggesting that light grazing promoted nitrification, inhibited denitrification, and increased soil NO3− content. Q-PCR further revealed that the copies of genes responsible for carbon fixation (cbbL) and denitrification (norB) decreased with increasing grazing intensity. The highest copy numbers of the nitrification genes AOA and AOB were in G1, whereas copy numbers of the denitrification gene nirK were the lowest. A multivariate regression tree indicated that changes in C fixation genes were linked to changes in soil DOC content, whereas soil NO3− content was linked with nitrification and denitrification under grazing. Thus, genes associated with C fixation and the N cycle affected how C fixation and N storage influenced soil physicochemical properties under grazing. The findings indicate that grazing intensity affected C and N metabolism. Proper grassland management regimes (e.g., G1) are beneficial to the balances between ecological protection of grasslands and plant production in the semiarid steppe.

Grassland health assessment based on indicators monitored by UAVs: a case study at a household scale.

Grassland health assessment (GHA) is a bridge of study and management of grassland ecosystem. However, there is no standardized quantitative indicators and long-term monitor methods for GHA at a large scale, which may hinder theoretical study and practical application of GHA. In this study, along with previous concept and practices (i.e., CVOR, the integrated indexes of condition, vigor, organization and resilience), we proposed an assessment system based on the indicators monitored by unmanned aerial vehicles (UAVs)-UAVCVOR, and tested the feasibility of UAVCVOR at typical household pastures on the Qinghai-Tibetan Plateau, China. Our findings show that: (1) the key indicators of GHA could be measured directly or represented by the relative counterpart indicators that monitored by UAVs, (2) there was a significantly linear relationship between CVOR estimated by field- and UAV-based data, and (3) the CVOR decreased along with the increasing grazing intensity nonlinearly, and there are similar tendencies of CVOR that estimated by the two methods. These findings suggest that UAVs is suitable for GHA efficiently and correctly, which will be useful for the protection and sustainable management of grasslands.

Understanding the drivers of ecosystem multifunctionality in the Mongolian steppe: The role of grazing history and resource input

Predicting the comprehensive driver of ecosystem multifunctionality is crucial for effective grassland management. However, the underlying biotic and abiotic mechanisms of ecosystem multifunctionality under global change and land use remain poorly understood. In this study, a 3-year field experiment was conducted in a semi-arid steppe in Inner Mongolia to investigate the relative importance of different biotic and abiotic factors in regulating aboveground ecosystem multifunctionality (AEM) and belowground ecosystem multifunctionality (BEM) in response to resource input after long-term grazing. The experiment involved three grazing intensities (1.5 low, 4.5 moderate, and 9.0 high sheep/ha) with a 7-year difference in grazing history. Precipitation (W) and nitrogen deposition (N) were manipulatively increased during the growing season. The study focused on exploring the effects of various biotic factors (e.g. species richness, functional diversity, plant functional groups) and abiotic factors (e.g. soil environment variables) on AEM and BEM. The results revealed asymmetric responses of AEM and BEM to resource input. Resource input enhanced AEM, but not BEM. However, increasing grazing intensity substantially reduced BEM, though we noted that AEM and BEM decreased the most under moderate grazing. Interestingly, the study found consistent responses of single ecosystem functions and ecosystem multifunctionality to resource input across the three grazing blocks. Structural equation modeling (SEM) analysis indicated that species richness primarily enhanced AEM, while soil environment played a major role in promoting BEM across different grazing history intensities and the whole grazed system. Multiple biotic and abiotic factors with varying relative importance in different grazing history scenarios controlled AEM and BEM. Species richness exhibited a strong influence on AEM and BEM, but within a narrow effect threshold range, whereas soil environment had a lesser effect size but a wider threshold range. This study provides the first evidence that grazing history and resource enrichment jointly regulate AEM and BEM. The findings highlight the importance of considering biodiversity conservation, soil health, and land use history in management practices aimed at maintaining ecosystem multifunctionality under climate change and human activities scenarios.

Grazing mediates the biodiversity effects on multifunctionality in grasslands

AbstractBiodiversity loss by grazing pressure has threatened multiple ecosystem functions simultaneously (ecosystem multifunctionality, EMF) in grasslands. Therefore, detecting the relation between EMF and biodiversity under human intervention would provide guidance on the optimization of sustainable grassland management. However, little is known about how grazing effects grassland EMF by mediating biodiversity under different grazing intensities. Here, species and functional diversity were investigated along a longitudinal gradient in Inner Mongolia grassland, and its EMF was quantified comprehensively on six ecosystem functions by an averaging approach, threshold approach and multiple threshold approach to assess the impact of grazing intensity on EMF. There was a significantly lower average EMF index and above‐ground biomass under heavy grazing (HG) than under light grazing (LG). The threshold approach‐based EMF and average EMF index were positively related to species diversity and functional diversity, and species diversity was a stronger driver of EMF than functional diversity. Compared with LG, the slope of the positive relation between EMF and species diversity significantly weakened by 40%–86% under moderate grazing (MG) and decreased by 30%–100% under HG, and reversed to a negative relation between functional diversity and EMF under HG. Additionally, species diversity was more negatively influenced by soil pH and sand content, while functional diversity was more negatively influenced by grazing intensity, indicating that functional diversity was more sensitive to intensive grazing. This study highlights the role of grazing intensity for driving multiple ecosystem functions, and reinforces the significance of managing both species diversity and functional diversity for sustaining productive functional grasslands.

Climate change and management intensity alter spatial distribution and abundance of P mineralizing bacteria and arbuscular mycorrhizal fungi in mountainous grassland soils

In mountainous grasslands management adaptations are required to maintain soil functions. We investigated climate change (CC) and management effects on the abundance and potential activity of microbiota catalyzing the major steps of P transformation which are still unknown in these grasslands.Soil samples were taken from intact plant-soil mesocosms managed extensively or intensively (two vs. five mowing and slurry applications, respectively). These mesocosms were previously translocated from high to lower altitudes to simulate two CC scenarios (CC1: +1 °C warming and mean annual precipitation (MAP) of 1347 mm and CC2: +3 °C warming and MAP of 956 mm), while control mesocosms (CC0) were relocated at their original site (6 °C and MAP of 1400 mm). Specific marker genes for P-solubilization (gcd), P-mineralization (phoN, phoD, phnX and appA), P-uptake (pitA and pstS), total bacteria and arbuscular mycorrhizal fungi (AMF) were quantified by quantitative real-time PCR. Spatial distributions of phosphatase activities were analyzed in situ by zymography analysis and total organic C, N and P contents were measured.Gene abundances and enzymatic activities were comparable for both managements under CC0, except for phytase-harboring (appA) microbiota which decreased under intensive management. The abundance of microbiota which catalyzes organic P (Po) mineralization (phoN and appA) and those harboring quinoprotein glucose dehydrogenase (gcd) for P solubilization significantly dropped by interacting effects of CC2 and extensive management. The same effect was found for microbes harboring specific P transporters (pitA and pstS). Under intensive management, microbiota catalyzing Po mineralization (phoN and appA), and alkaline phosphatase activities tended to increase in CC2. Noteworthy, the AMF abundance was reduced at 0–5 cm soil depth under CC. Our results suggest that CC and extensive management reduced microbial P solubilization, mineralization and uptake, while management intensification may increase P availability, which leads to shifts in nutrient stoichiometry and decreased AMF abundance.

Effect of Long-Term Burning and Mowing Regimes on Ant Communities in a Mesic Grassland

Ecological disturbance is fundamental for grassland management and the maintenance of its biodiversity. Fire and grazing are the primary habitat disturbances influencing the structure and composition of grassland ecosystems, both acting to remove grass biomass. Little is known about the effects of such grass biomass removal on grassland ants, an ecologically dominant faunal group. Our study assesses the response of ant communities to long-term experimental burning and mowing treatments in a South African mesic grassland. The study’s main objectives were (i) to assess the effect of frequency and season of burning and mowing on ant species richness and composition and (ii) to identify indicator species associated with the various grassland management treatments. The experiment included two fully crossed fire treatments: frequency (annual, biennial, and triennial) and season (late winter and after spring rains), along with annual mowing and an undisturbed control. Ants were sampled using pitfall traps in 27 plots, comprising 18 burnt, 6 mown, and 3 controls. The mean species richness in the burnt plots (22.38 ± 3.71) was far higher than in the control (23 ± 2.0) or mown (21.0 ± 2.28) plots. However, the total richness (combining plots) did not vary among treatments. Four of the nine most common species showed a statistically significant response to experimental treatment, but there were no significant treatment effects on overall species composition. Three indicator species (IndVal &gt; 70%) were identified for the control plots, and detector species (IndVal 50–70%) were identified for annual, biennial, and triennial burning treatments. Our findings demonstrate that ant communities in this grassland system are highly resilient to burning and mowing, and that fire promotes diversity at the plot scale. Our identified indicator and detector species can be used as a focus for ongoing monitoring of biodiversity change in our grassland system, including in response to woody expansion.

Virtual fencing systems: balancing production and welfare outcomes

Virtual fencing systems are having rapid commercial uptake. A geographical navigation satellite system (GNSS)-locating collar provides sound warning alerts to each animal when in close proximity to virtual fencelines set on the stock manager's app. These are followed by an electric shock if the animal proceeds forward, but no further shock/warnings when reversing or turning away. Many research reports show that through associative learning, the livestock quickly understand the system and adapt to virtual paddocks with low numbers of electric shocks. Escapees usually return to the main group quickly. Practical applications for extensive systems include keeping stock away from danger areas which would be difficult or expensive to fence. Combining physical inspections, more easily achieved through live locations, with virtual inspections offers opportunities to improve stock management, though there are risks that the number of physical inspections may decrease. Highly flexible and rapidly modified grassland management, together with other combined sensors for health and reproduction, provide opportunities for further farm management gains.

Light grazing reduces gaseous nitrogen emissions from temperate grassland soils during freeze‒thaw cycles: An intact core incubation study

Livestock grazing and soil freeze‒thaw cycles (FTCs) can affect the biogeochemical processes of nitrogen (N) and gaseous N (N2O, NO, and N2) emissions from grassland soils. However, the effect of grazing intensity on soil gaseous N emissions during FTCs and the underlying mechanisms are not clearly understood. In this intact core incubation study, soil gaseous N emissions during two FTCs were simultaneously quantified from temperate grasslands that included grazing exclusion (GE), light grazing (LG), and heavy grazing (HG) in Inner Mongolia. Additionally, the abundance of N cycle-related functional genes and the main soil characteristics were determined to better understand the drivers of gaseous N emissions. The results showed that N2 emissions dominate the gaseous N loss from all investigated soils during FTCs, with cumulative N2 exceeding NO and N2O emissions by factors of 47–135 and 71–161, respectively. Increased soil moisture during thawing promoted N2 and N2O emissions from all three sites, except for N2O at the LG site. However, no obvious NO emission peak was observed from all investigated soils during FTCs. Soil C and N availability and aeration changed by grazing regulated soil N2O fluxes, while the abundances of key functional genes generally did not show significant correlations with gaseous N emissions. Moreover, compared to the GE and HG sites, LG substantially decreased the soil N2O and total gaseous N emissions during FTCs, suggesting that light grazing rather than long-term grazing exclusion could be a promising measure to reduce gaseous N losses during spring thaw. Our results highlighted the importance of the simultaneous determination of all kinds of gaseous N emissions during FTCs for closing the ecosystem N balance and developing appropriate strategies for grassland management.

Responses of carbon cycling and soil organic carbon content to nitrogen addition in grasslands globally

Understanding how N addition status (i.e., duration, rate, and form of N addition) impacts carbon (C) cycling has great implications for C storage prediction and grassland management. We examined 257 studies related to C cycling in grasslands and obtained a dataset of 1073 observations for meta-analysis. N addition significantly increased plant C input (plant above-ground biomass +49.1%, below-ground biomass +16.6%; litterfall biomass +17.4%; dissolved organic carbon +16.4%) across natural grasslands globally. For C loss processes, N addition enhanced litter decomposition by 9.2% and decreased soil respiration by 1.1%. In topsoil, microbial biomass C was reduced by 8.7% and soil organic C (SOC) content was increased by 3.1%. For C fluxes, N addition increased gross primary productivity and ecosystem respiration by 24.7% and 11.7% respectively, leading to negative net ecosystem exchange. These results indicated that grasslands were C sinks under N addition. Besides climate, the duration of N addition was the most important factor affecting C cycling. The response of SOC to N addition increased with time but weakened after a decade, associated with accumulative effects of N-induced soil acidification. N addition at any rate or form increased SOC content in temperate grassland/meadow while the effects in other grasslands depended on N addition status. There were higher SOC contents and the lowest net ecosystem exchange at low rates of N addition. Therefore, N addition should be limited to under 60 kg N ha−1 yr−1 to increase plant production and SOC content in grasslands globally and to maintain soil function as a C sink. More attention should be paid to the effects of the duration of N addition and soil acidification on C cycling to improve theoretical models or to help with grassland management practices and policies.

For a Better Quality of Beef: The Challenge from Growing Livestock on Limited Grasslands with a Production-Consumption Balance Perspective.

The growing population, the transition dietary towards animal-based products, and the preference for the brand of grass-feeding livestock are bringing increasing pressure on natural grasslands, especially for dry-land areas. The Xilingol League of China is famous for its free-range livestock product, however, overgrazing and herders' benefits damage are always serious issues for this semi-arid grassland region. This study focuses on the relationship between the supply of natural grassland and the consumption of free-range livestock in the Xilingol League, and this study employed the grassland carrying capacity as the index to judge the sustainability states and its trends of the local grass-feeding system. Satellite data production of net primary production was used for grassland production, statistical livestock data and the consumption model were used for actual forage consumption, and empirical key informant interview data were used to obtain a more comprehensive understanding. The results show that: (1) the natural grassland carrying capacity of the Xilingol League fluctuated, showing improvement from 2000 to 2021; (2) the grassland management needs to be more diversified in different regions with different natural conditions; and (3) while the demand for free-range, high-quality beef is increasing, attention should be paid to the carrying capacity of natural pastures and more consideration should be taken of the benefits of balancing the livelihood of herders, policy strategies, and the customers' preferences. Potential ways of doing this include employing technologies to improve livestock production, and further exploring and promoting the economic value of the free-range livestock and the geographical indication to get the economic-ecological win-win situation. The research framework and results would be beneficial to reveal the potential threats in pastoral areas and provide support for the optimization of the regional grass-feeding breeding system, especially in middle-income countries.

Yield of lucerne-grass mixtures did not differ from lucerne pure stands in a multi-site field experiment

Changing climatic conditions in north-western Europe require adaptations in management of ley grassland, requiring new grass-legume mixture designs in response to increased variability in precipitation and warmer summers. Evaluation of lucerne (Medicago sativa L.)-grass swards with the grasses cocksfoot (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.), which are potentially more tolerant to summer water shortage, have yet to be evaluated under the agro-climatic conditions of north-western Europe. We tested these grasses in three-species swards and binary lucerne grass swards and compared them against pure stands and a standard lucerne-grass mixture. The study was conducted in eight environments resulting from the combination of four soil sites during the two full main production years 2020 and 2021 with an annual precipitation range of 416–839 mm. Swards were harvested three to five times annually and the accumulated herbage dry matter (DM) and nitrogen (N) yields, as well as species proportions were recorded. We found an average yield of 11.1 t DM ha-1 and no significant differences in herbage DM yields between lucerne pure stands and the different mixture swards. This pattern was stable irrespective of environmental conditions, but in general herbage yield and aboveground N yield were affected by precipitation amount. Swards with cocksfoot had a greater grass proportion than those with tall fescue. The N yield of lucerne-grass swards was lower and declined as the grass proportion increased, and reached on average 353 kg N ha-1. The maximum N yield of lucerne pure stands was 547 kg N ha-1. Species mixtures yielded higher than expected from the pure stands (net mixture effect, NE) pointing at overyielding. Consequently, synergistic interspecific interactions occurred but did not lead to transgressive overyielding. The results indicate that the inclusion of grass species with tolerance to water shortage into lucerne-based swards offers the potential to diversify grasslands without losses of agronomic potential, at least during the first two main production years.

UAV Monitoring Topsoil Moisture in an Alpine Meadow on the Qinghai–Tibet Plateau

Soil moisture is one of the most critical soil components for sustained plant growth and grassland management. Unmanned aerial vehicles (UAVs) are gradually replacing manual labor in various aspects of grassland management. However, their potential for monitoring soil moisture in grasslands remains largely unexplored. High vegetation coverage and frequent rainfall in the Tibetan Plateau pose a challenge for personnel working in alpine meadows. To explore the potential of UAV technology for soil moisture detection in these areas, we conducted a rainfall reduction experiment in Maqu County, China to understand the relationships among soil moisture, vegetation coverage, and visible-light images captured using UAVs. The findings indicated a significant correlation between topsoil moisture and the brightness values in visible-light images acquired by UAVs (p &lt; 0.0001). These results demonstrated that visible-light brightness, vegetation coverage, rainfall reduction, and aboveground biomass can be utilized for estimating the topsoil moisture using these images (y = −0.2676 × Brightness + 0.2808 × Vegetation coverage −0.1862 × Rainfall reduction + 0.1357 × Aboveground biomass + 37.77). The model validation worked well (E = 0.8291, RS = −3.58%, RMA = 10.38%, RMSE = 3.5878, Pearson’s r = 0.9631, PSI = 0.0125). This study further addresses the problem of topsoil moisture measurement in flat areas of mesoscale moist alpine meadows and is expected to facilitate the widespread adoption of UAV use in grassland ecology research.

Grazing regulates soil N cycling of annual pastures by enhancing soil N turnover in arid climate condition

AbstractNitrogen is the second limited factor in arid regions. Little information is available on soil N cycling and availability under grazing in arid regions, which is required to evaluate land‐use management with respect to soil N availability and dynamics. In 2011, we established a rotational grazing field experiment in arid grassland. We conducted experiments to explore the effects of herbivores grazing on soil net N mineralization and N processes via changes in soil temperature, moisture, pH, and microbial biomass nitrogen (MBN) in 2016 and 2017. Our results showed that grazing did not alter soil N mineralization because higher soil moisture and soil MBN under grazing had positive and negative effects on soil N mineralization, thereby balancing soil N mineralization. Plant N uptake at the grazing plots was, nevertheless, 23% higher than that at the non‐grazing plots. These demonstrated that grazing potentially improved soil inorganic N availability and alleviated soil N limitation in arid regions. Soil nitrification was main pathway of N transformation in arid regions. Grazing improved soil accumulation of NO3− content, resulting in environmental problems (such as N2O emission and N leaching); however, grazing had a little effect (~15% increase) on soil N leaching and (~7% decrease) on N2O emission. These N processes reflect important mechanisms of resilience and ecosystem stability under grazing in an N‐limited environment. Our results provide an important perspective for grassland management, aiming to maintain soil N supplying capacity in annual pasture sustainably. Overall, our study suggests that grazing is an effective management practice for the sustainable usage of local grasslands, as it improves soil physicochemical and biological properties, which, in turn, increases N supply.

Grassland Carbon Change in Northern China under Historical and Future Land Use and Land Cover Change

Land use and land cover (LULC) change has greatly altered ecosystem carbon storage and exerted an enormous impact on terrestrial carbon cycling. Characterizing its impact on ecosystem carbon storage is critical to balance regional carbon budgets and make land use decisions. However, due to the availability of LULC data and the strong variability in LULC change, uncertainty remains high in quantifying the effect of LULC change on the historical and future carbon stock. Based on four historical LULC maps and one future LULC projection, this study combined the Land Use and Carbon Scenario Simulator (LUCAS) with a process-based CENTURY model to evaluate the historical and future LULC change and its impact on grassland carbon storage from 1991 to 2050 in northern China. Results showed that grassland experienced a drastic decrease of 16.10 × 103 km2 before 2005, while agriculture and barren land increased by 16.91 × 103 km2 and 3.73 × 103 km2, respectively. After that, grassland was projected to increase, agriculture kept steady, and barren land decreased. LULC change has resulted in enormous total ecosystem carbon loss, mainly in agro-pasture areas; the maximum 8.54% of carbon loss happened in 2000, which was primarily attributed to agriculture to grassland, forest to grassland, grassland to agriculture, and grassland to barren. Before 2000, the grassland net biome productivity was projected to be −15.54 Tg C/yr and −2.69 Tg C/yr with and without LULC change. After 2001, the LULC change showed a positive impact on the grassland carbon balance, and the region was projected to be a carbon sink. Ecological projects have made a significant contribution to grassland carbon storage. The paper provides a framework to account for the effects of LULC change on ecosystem carbon and highlights the importance of improving grassland management in balancing the grassland carbon budget, which is helpful to understand the regional carbon budget and better inform local land use strategies.

Abandoning grassland management negatively influences plant but not bird or insect biodiversity in Europe

AbstractGrasslands are globally distributed and naturally occurring; however, in Europe, most grasslands are anthropogenically created or altered by livestock grazing or mowing. Low‐intensity use and management have led to species‐rich communities in European grasslands. The intensification of crop production and livestock farming with stabling throughout the year has led to an abandonment of grasslands that are no longer economically profitable. In this study, we looked at the influence of grassland abandonment on biodiversity. We hypothesized that abandonment of grasslands decreases the overall biodiversity, but has different effects depending on the focal taxonomic group (i.e., vascular plants, insects, or birds). We also hypothesized that the type of management before abandonment, the type of grassland, and the time after abandonment would influence grassland biodiversity. We conducted a Web of Science search, with pre‐defined terms, to find articles that compared biodiversity of managed and abandoned grasslands in Europe. We screened the articles and included 39 studies in a subsequent meta‐analysis. We found that overall biodiversity was reduced after abandonment; however, the biodiversity reduction in the grasslands differed among taxonomic groups. Plant species diversity was significantly lower after abandonment (plant summary effect size: −0.25 [−0.34; −0.16]), whereas the diversity of insects and birds showed no significant trend, but a visual trend toward an increase. None of the other environmental variables (type of management, type of grassland, or the time after abandonment) had a significant influence on the biodiversity of the grasslands. We conclude that maintaining grassland management is crucial to support biodiversity conservation in European grasslands.