Agro-pastoral Ecotone Research Articles

Nitrogen flow in food production and consumption system of Inner Mongolia from 2000 to 2020

Decoupled crop and livestock production caused serious disconnection of nitrogen utilization in agro-pastoral ecotone of northern China. In this study, we employed a material flow analysis approach to investigate reactive nitrogen (Nr) flow in the food production and consumption system in Inner Mongolia from 2000 to 2020. Results indicated that agricultural production system is the primary source of Nr input for the food consumption system. The environmental nitrogen load in Inner Mongolia has been increasing progressively, from 266 Gg in 2000 to 882 Gg in 2020, primarily due to the rapid increase in livestock farming and significant losses of nitrogen in feces and urine. Our results raise the attention to promote the close integration of farmland production and livestock system in the decoupled crop and livestock production system.

Habitat fragmentation reduced plant functional diversity in the agro-pastoral ecotone of Inner Mongolia

Habitat fragmentation reduced plant functional diversity in the agro-pastoral ecotone of Inner Mongolia

Conserving cropland resilience space in alpine agro-pastoral ecotones: A quantitative study of Qinghai Province

CONTEXTInfluenced by natural conditions, geographic location and socioeconomics, Qinghai Province is a typical alpine agro-pastoral ecotone; additionally, its food production system cannot cope with many risks, and exploring the suitability of resilient cropland spaces and rational utilization paths is of practical significance. OBJECTIVEThe objectives of this study are to explore the influencing factors of the resilience space of cropland in the alpine agro-pastoral ecotone and to establish a method to quantify the quantity and quality of resilience space. Finally, recommendations for the development and utilization of cropland resilience space and cropland protection in Qinghai Province are presented. METHODSThis study takes cropland system resilience as the theoretical basis and creates a conceptual model of the factors influencing cropland resilience space. The Cropland Resilience Space Index (CRSI) is constructed from the three factors of suitability, scale and aggregation and is used to quantify the spatial suitability of cropland resilience in Qinghai Province. RESULTS AND CONCLUSIONSThe results revealed that there are 441,000 ha of cropland resilience space in Qinghai Province, low values of the suitability factor are distributed mainly in the edge areas of the Kunlun Mountains and the Qilian Mountains, and the scale factor and aggregation factor are generally high in the west and low in the east. The average CRSI value in Qinghai Province is 0.445, and that in Haixi Prefecture is 0.469, which is higher than the average value. Priority should be given to the development of cropland resilience space in the eastern part of Dulan County and Golmud city based on utilization sustainability and ecological stability. SIGNIFICANCEThis research will help enrich research methods for the sustainable utilization of cropland and help promote the transformation of cropland protection policies from rigid to resilient. The quantitative results of the cropland resilience space in the alpine agriculture and animal husbandry intertwined zone can provide a reference basis for rationally formulating the policies of cropland protection and resilience space development and utilization.

Effects of different sand fixation plantations on soil properties in the Hunshandake Sandy Land, Eastern Inner Mongolia, China

Planting forests is an effective way to improve desertification. In order to elucidate the impacts of different vegetation types on soil development and restoration of degraded lands, we compared the properties of soils at different depths in three plantation forests in the Hunsandak Sandy Land in the Chinese agro-pastoral ecotone (Ulmus pumila, Pinus sylvestris var. mongolica, and Populus simonii). The results show that all three plantation forests were able to significantly improve the soil properties, and they resulted in soil nutrient enrichment in the surface layer. As the soil depth increased, the soil became progressively poorer in nutrients, the fine particle content decreased, and the bulk density and water content increased. The orders of the fractal dimension characterization and soil improvement effects of the different tree species were as follows: U. pumila > P. sylvestris var. mongolica > P. simonii. Compared with the bare sand, the soil bulk density under the U. pumila plantation was 19% lower; the soil water content was 74% higher; the soil organic matter, total N, P, and K were 336%, 207%, 106%, and 31% higher; the available N, P, and K were 41%, 125%, and 21% higher; and the clay and silt contents were 498% and 387% higher, respectively. The ranges of the soil fractal dimension were 1.67–2.08 for the bare sandy land and 2.14–2.32 for the planted forests. The soil fractal dimension was strongly correlated with the soil physicochemical properties, especially with the soil nutrients and fine particle content, which exhibited highly significant correlations (p < 0.01), and the correlation coefficients were all greater than 0.8. Therefore, we believe that U. pumila is a suitable sand-fixing plant species in this area. In addition, the soil fractal dimension can be used as an important reference index for characterizing soil properties in sandy areas.

Innovative Perspectives on Ecological Assessment in the Agro-Pastoral Ecotone of Inner Mongolia: An Integrated Evaluation and Forecast of Landscape and Ecological Risks and Drivers

The agro-pastoral ecotone of Inner Mongolia, one of China’s most ecologically vulnerable regions, requires careful evaluation and prediction of landscape ecological risks to improve its environment and support sustainable development. Our study built a model to assess the landscape ecological risks from 1990 to 2020 using land use data from Google Earth Engine. We examined the changes in landscape ecological risks and their driving factors through spatial autocorrelation analysis and geographic detectors. Future ecological risks from 2025 to 2040 were predicted using the multi-criteria evaluation-cellular automata-Markov model. Results revealed a declining trend in both disturbance and loss intensity across land use types, with the overall ecological risk index also decreasing. Higher risk areas were concentrated in the east and southwest, while lower risks were observed in the north and center. Temperature and precipitation are key natural factors, while the impact of Gross Domestic Product (GDP), a human factor, on ecological risk is increasing and surpassed natural influences in 2015 and 2020. In the future, the highest risk areas will remain in the southwest and northeast. This study provides detailed evidence and guidance for ecological safety and sustainable development in the agro-pastoral ecotone of Inner Mongolia.

Source identification of nitrate in groundwater of an agro-pastoral ecotone in a semi-arid zone, northern China: Coupled evidences from MixSIAR model and DOM fluorescence

In the extensive agro-pastoral ecotone of northern China, groundwater is a valuable resource, but it suffers from severe nitrate pollution. However, the extent of the contributions of agricultural and pastoral activities to nitrate accumulation in the groundwater of the region remains unclear. This study aimed to identify the main sources of groundwater nitrate in Chahannur Basin, a typical agro-pastoral ecotone in the semi-arid zone of northern China, using the MixSIAR model based on dual stable isotopes and dissolved organic matter (DOM) fluorescence. The hydrochemical and isotopic results showed that the groundwater has high concentrations of nitrate (up to 208.19 mg/L) with weak denitrification, and nitrate accumulation is mainly driven by mixed input from different sources. The MixSIAR model results indicated that the largest contributors to groundwater nitrate accumulation are manure & sewage, followed by soil nitrogen, chemical fertilizers, and atmospheric deposition. According to the DOM fluorescence characteristics, the groundwater is strongly affected by livestock and poultry waste, followed by soil humic substances. Moreover, the DOM fluorescence results further supported the MixSIAR model results based on the significant correlation between the contributions of nitrate sources and the percentages of fluorescent components, jointly confirming that the main source of nitrate in groundwater is manure and sewage, followed by soil nitrogen. These findings indicate that coupled evidences from the MixSIAR model and DOM fluorescence could be applied to identify the sources of nitrate in groundwater, and this coupling can provide valuable information for local authorities to achieve sustainable groundwater management.

Evaluation and Optimization of Landscape Spatial Patterns and Ecosystem Services in the Northern Agro-Pastoral Ecotone, China

The alteration of landscape spatial patterns (LSPs) and ecosystem services (ESs) in watersheds can have detrimental effects on the local environment and community. However, a comprehensive understanding of the current state of LSPs and ESs in watersheds around Winter Olympic venues in China is limited. Here, we assessed current LSPs and ESs and developed optimization strategies for the Xigou watershed around Winter Olympic venues in the northern agro-pastoral ecotone of China. The results indicated that the main land use type was grassland in the Xigou watershed, and landscape types were relatively homogenous. All three ESs (water yield, sediment retention, and carbon storage) generally improved from 2004 to 2020. For ESs, there was the lowest total volume of water yield in 2004 (637.44 × 104 m3). But sediment retention (10.54 × 106 t, 18.13 × 106 t, 13.28 × 106 t, and 16.85 × 106 t) had an upward, then downward, then upward trend before and after ERP. Carbon storage grew steadily. Correlation analysis suggested that the three ESs were closely related to the landscape spatial indices of average patch area (AREA_MN), contagion index (CONTAG), and Shannon’s evenness index (SHEI). AREA_MN, CONTAG, and SHEI in the eastern part of the study area promoted sediment retention and carbon storage, while in the southwestern part of the study area, they inhibited water yield and sediment retention. The results suggest that improving sediment retention by optimizing land use and cover change (LUCC) and LSPs is the main approach to further enhance ESs in the study area. Our study suggests that the inclusion of multiple landscape pattern indices can provide a more comprehensive representation of regional ecosystem service.

How do household crop and livestock production adapt to extreme climatic events? —Insights from a typical agro-pastoral ecotone on the Qinghai[sbnd]Tibet Plateau

The increased threat of more frequent extreme climatic events (ECEs) poses significant challenges to household crops and livestock production, exacerbated by their weak adaptability. To explore ways to improve households’ adaptation awareness and behaviors, a typical agro-pastoral ecotone on the northeastern QinghaiTibet Plateau (QTP), Gonghe Sandy Land (GSL), was selected as the study area. This study analyses the impact of ECEs, and the adaptation measures taken by households, and innovatively includes the perception of government services from households in the factor system to identify the key driving mechanism of coping strategies. The results revealed that (1) 74.07 % of households experienced an extreme drought, and livestock production was 29.63 % more affected than crop production was; (2) households adopted different adaptation strategies with weather forecasts being the prevailing measure among households for crop (25.93 %) and livestock (42.33 %) production adaptation; and (3) different strategies are key to improving adaptive capacity. We found that production experience sharing, demographic and economic coordination, and early warning system and support by the government can increase farmers' awareness of adaptation strategies. While enhancing cognitive levels regarding measures, optimizing a household’s health, rationally allocating assets, and increasing timely and stable government services can improve adaptive behaviors. On the basis of these findings, this study provides recommendations from the perspective of human well-being, with the aim to achieving the SDGs, enhancing regional climate change adaptation capacity and ensuring the safety and efficiency of crop and livestock production in the QTP.

Optimizing Ridge–Furrow Rainwater-Harvesting Strategies for Potato Cultivation in the Drylands of Northwestern China: A Regional Approach

The arid and semi-arid region of Northwest China plays a significant role in potato production, yet yields are often hampered by drought due to limited precipitation and irrigation water. The ridge–furrow rainwater-harvesting technology is an efficient and widely used technique to relieve drought impact and improve crop yield by changing the micro-topography to harvest rainwater to meet the water demand of crops. An analysis of precipitation, water demand, and runoff data spanning 30 years guided the selection of suitable rainwater-harvesting methods tailored to meteorological conditions. The results showed that potato water demand exceeded precipitation in the region. The mulching approach performed best in the western arid region with the most significant increase in yield and water use efficiency (WUE) and was suitable for the western semi-arid region and the agro-pastoral ecotone. In the potato dryland farming areas, the water deficit increased from southeast to northwest. Specifically, northern Gansu, northern Ningxia, and midwestern Inner Mongolia experienced a water deficit of over 200 mm, and rainwater harvesting combined with irrigation was recommended. Conversely, regarding deficits below 200 mm in southern Gansu, Ningxia, and central Inner Mongolia, a 1:1 or 2:1 pattern of ridges could be applied, and mulching was needed only in the necessary areas. For the southern Qinghai, Shaanxi, and eastern Inner Mongolia regions, ridge–furrow rainwater harvesting could be replaced by flat potato cropping. In summary, rainwater harvesting addresses water deficits, aiding climate adaptation in Northwest China’s arid and semi-arid regions. The implementation of mulching and ridge–furrow technology must be location-specific.

Exploring the Water-Soil-Crop Dynamic Process and Water Use Efficiency of Typical Irrigation Units in the Agro-Pastoral Ecotone of Northern China.

Groundwater resources serve as the primary source of water in the agro-pastoral ecotone of northern China, where scarcity of water resources constrains the development of agriculture and animal husbandry. As a typical rainfed agricultural area, the agro-pastoral ecotone in Inner Mongolia is entirely dependent on groundwater for agricultural irrigation. Due to the substantial groundwater consumption of irrigated farmland, groundwater levels have been progressively declining. To obtain a sustainable irrigation pattern that significantly conserves water, this study faces the challenge of unclear water transport relationships among water, soil, and crops, undefined water cycle mechanism in typical irrigation units, and water use efficiency, which was not assessed. Therefore, this paper, based on in situ experimental observations and daily meteorological data in 2022-2023, utilized the DSSAT model to explore the growth processes of potato, oat, alfalfa, and sunflower, the soil water dynamics, the water balance, and water use efficiency, analyzed over a typical irrigation area. The results indicated that the simulation accuracy of the DSSAT model was ARE < 10%, nRMSE/% < 10%, and R2 ≥ 0.85. The consumption of the soil moisture during the rapid growth stage for the potatoes, oats, alfalfa, and sunflower was 7-13% more than that during the other periods, and the yield was 67,170, 3345, 6529, and 4020 kg/ha, respectively. The soil evaporation of oat, potato, alfalfa, and sunflower accounted for 18-22%, 78-82%; 57-68%, and 32-43%, and transpiration accounted for 40-44%, 56-60%, 45-47%, and 53-55% of ETa (333.8 mm-369.2 mm, 375.2 mm-414.2 mm, 415.7 mm-453.7 mm, and 355.0 mm-385.6 mm), respectively. It was advised that irrigation water could be appropriately reduced to decrease ineffective water consumption. The water use efficiency and irrigation water use efficiency for potatoes was at the maximum amount, ranging from 16.22 to 16.62 kg/m3 and 8.61 to 10.81 kg/m3, respectively, followed by alfalfa, sunflowers, and oats. For the perspective of water productivity, it was recommended that potatoes could be extensively cultivated, alfalfa planted appropriately, and oats and sunflowers planted less. The findings of this study provided a theoretical basis for efficient water resource use in the agro-pastoral ecotone of Northern China.

Short‐term grazing reduced community stability by decreasing community‐wide asynchrony and dominant species stability

AbstractThe effects of grazing on natural grasslands' plant composition, diversity, and productivity depend on the intensity of grazing. Besides grazing intensity, animal composition is also important. However, whether and how sheep grazing intensity affects the temporal biomass stability of plant communities is unclear. Here, we conducted a 5‐year grazing experiment to evaluate the effects of four grazing intensities on community biomass stability and the underlying mechanisms. Our results showed that the higher grazing intensity significantly decreased community biomass stability, community‐wide asynchrony, functional groups asynchrony, dominant species stability, and species dominance, but did not affect species richness. The results of structural equation modeling revealed that grazing decreased community biomass stability by decreasing dominant species stability and community‐wide asynchrony, which was attributable to the reduction in plant functional group asynchrony. Our results highlight the importance of functional group composition and dynamics in predicting the changes in community function in sheep grazing grassland ecosystems. Under continuous seasonal grazing conditions, the sustainable function and human services of grasslands in the agropastoral ecotone might decrease in the future.

Spatial Variation of Top Soil Moisture in Semi-Arid Agro-Pastoral Ecotone and Its Response to Spatial Driving Factors: A Case Study in the Sanggan River Basin, China

Spatial Variation of Top Soil Moisture in Semi-Arid Agro-Pastoral Ecotone and Its Response to Spatial Driving Factors: A Case Study in the Sanggan River Basin, China

Effect of ecological restoration on evapotranspiration and water yield in the agro-pastoral ecotone in northern China during 2000–2018

Evapotranspiration (ET) and water yield (WY) play a crucial role in sustaining available water resources, and are greatly affected by climate and anthropogenic activities. The agro-pastoral ecotone in northern China (APENC) has been undergoing ecological restoration projects since 2000 to rehabilitate ecosystem services such as food production and water availability. Previous studies have primarily accessed the combined effect of vegetation greening and climate change on ET. However, the independent influences of these factors, particularly land use/cover change (LUCC) and vegetation greening on both ET and WY remain poorly understood. In this study, we systematically investigated the effect of LUCC, vegetation greening, and climate change scenarios on regional ET and WY variations from 2000 to 2018 in the APENC using a coupled carbon and water model. Results showed a significant increase in the mean annual ET, with a trend of 5.8 mm/y while the WY had a statistically insignificant trend of −0.6 mm/y from 2000 to 2018. Areas with significant increases in ET and decreases in WY mainly occurred in the southeastern part of the APENC. Vegetation greening induced by ecological restoration had a more pronounced impact on ET variation than climate change, while LUCC resulted in relatively minor changes in ET in the APENC. The variations in WY were primarily influenced by changes in precipitation, the increase in precipitation effectively offset the decrease in WY caused by vegetation greening. These findings provide valuable information to policy/decision markers for sustainable management of large-scale ecological restoration programs in dry regions.

Coupled zoning and spatial heterogeneity of human activities and natural endowments based on self-organizing map and random forest: A case study of the agro-pastoral ecotone in Gansu, China

Regional zoning is an important way for humans to understand geographical space，but the existing research on regional zoning focuses on natural conditions, ignoring the interdependent characteristics of human and nature, and the driving mechanism of regional differentiation is not sufficiently explained. In this study, using algorithms such as self-organizing feature map, clustering quality index, structural similarity index measure (SSIM) and random forest, the human activity (HA)–natural endowment (NE) coupled zoning in the agro-pastoral ecotone in Gansu, China (AEGC), was conducted to explore the driving mechanism of regional differentiation. Results show the following: (1) The HA-NE coupled zoning has the best clustering effect when implementing the partitioning scheme with a classification number of 4. Accordingly, the AEGC can be divided into four regions with significant differences between HAs and NEs. (2) From the perspective of spatial distribution, HA–NE coupled zoning, climate zoning, geographic zoning, and vegetation zoning are similar, whereas HA zoning is different. The results of SSIM showed that HA–NE coupled zoning takes all types of factors into consideration (SSIM mean 0.708), and the zoning results are better than single type zonings. HAs have strong independence (SSIM mean 0.576), and geographic conditions are closely related to all other factors (SSIM mean 0.671). (3) Elevation is the most important driver of regional differentiation in the AEGC, with a contribution degree of 22.36%; other important drivers include land use intensity, precipitation, and normalized difference vegetation index, with contribution degree distributions of 17.38%, 16.34%, and 15.79%. Furthermore, the dominant factors of regional differentiation in each sub-region are different. This study emphasizes that regional characteristic factors and uneven spatial distribution factors are important drivers of regional differentiation, and land use intensity has become an important force influencing geographic space. Policy recommendations for zonal governance are made based on the inherent conditions of different regions. This study may provide a reference for scientific regional zoning and cognitive regional differentiation.

Assessing ecosystem service dynamics and drivers for sustainable management in the Agro-pastoral ecotone of northern China: A spatiotemporal analysis

To achieve regional ecological management and sustainable socio-economic development, it is essential to comprehend the intricate and interdependent relationships among various ecosystem services. The Agro-pastoral ecotone of northern China is a typical ecologically vulnerable area. There is limited research on managing multiple ecosystem services to maximize supply based on understanding the complex relationships among ecosystem services. This study used the InVEST model to quantify habitat quality (HQ), soil conservation (SC), carbon sequestration (CS), and water yield (WY) in the Agro-pastoral ecotone of northern China in 2000, 2010, and 2020 at the 5 km grid and county scales. Their trade-off and synergistic effects were explored using Spearman correlation analysis and the Geographically Weighted Regression (GWR) model. In addition, self-organizing mapping was employed to identify ecosystem service bundles at two scales, whereas the geodetector was employed to determine the primary social-ecological drivers of ES. Finally, management strategies are proposed based on the research results to promote regional ecological sustainability. The results indicate that: (1) The four ESs exhibited an increasing trend during the study period. Except for WY, the other three ES demonstrated a similar spatial distribution while remaining relatively stable over time; (2) there is a synergistic effect between CS, HQ, and SC, whereas WY-related ES show trade-off effects; (3) six ES bundles were identified at the 5 km grid scale, and four ES bundles were identified at the county scale; (4) precipitation is a major driving factor for WY and an important driving factor for CS, HQ, and SC. In summary, natural factors have a greater impact on ES than socio-economic factors. Based on the differences in ecosystem service bundles and drivers at different scales, and in conjunction with China’s existing environmental policies, corresponding ecological management strategies were proposed, potentially providing a reference for sustainable development of the Agro-pastoral ecotone in northern China.

Livelihood transformation of farmers and herdsmen in the agro-pastoral ecotone from the perspective of ecological protection: a case study of the Tianzhu Tibetan Autonomous County, China

Livelihood transformation of farmers and herdsmen in the agro-pastoral ecotone from the perspective of ecological protection: a case study of the Tianzhu Tibetan Autonomous County, China

Impact of Soil Factors on the Yield and Agronomic Traits of Hemerocallis citrina Baroni in the Agro-Pastoral Ecotone of Northern China

The ecologically fragile agro-pastoral ecotone in northern China is characterized by relatively poor arable land quality. Yunzhou District in Datong City, which is situated within this transitional zone, boasts over 600 years of Hemerocallis citrina Baroni cultivation. Exploring the effects of soil physicochemical properties on daylily yield and related agronomic traits is essential for enhancing the ecological and economic value of dominant crops in ecologically fragile areas. Therefore, in this study, we focused on the daylily, a characteristic cash crop that is grown in the agro-pastoral ecotone in Yunzhou District. Physicochemical property measurement and yield estimation were performed using soil samples collected from 37 sites, with Spearman’s correlation analysis, one-way analysis of variance with multiple comparisons, path analysis, and stepwise regression analysis used to analyze the generated data. The results showed the following: (1) The pathway analysis of daylily yield with each agronomic trait showed that the BN and PH directly affected the yield of daylily with direct pathway coefficients of 0.844 and 0.7, respectively, whereas the SN indirectly affected the yield of daylily through the BD and PH, with indirect pathway coefficients of 0.827 and 0.566, respectively. (2) A total of four principal components were extracted for the soil factors, of which SMC, ST and BD had large loadings on PC1; OM, TN and pH had large loadings on PC2; AK had large loadings on PC3; and AP had large loadings on PC4. (3) From the principal component regression and stepwise regression, it can be seen that SMC is the most critical factor affecting the yield of daylily, as well as the related agronomic traits, and the results also show that yield prediction was affected by OM, ST, and AK, while BN was influenced by OM and ST, and SN and PH were influenced by AP. Comparing the goodness of fit and significance of the two models, it can be concluded that the stepwise regression model is the optimal model for this study.

Multiple Soil Health Assessment Methods for Evaluating Effects of Organic Fertilization in Farmland Soil of Agro-Pastoral Ecotone

The incorporation of organic fertilizer is an important practice to improve the sustainability and productivity of crop production and decrease environmental pollution from crop-livestock systems in global agriculture. However, establishing an evaluation dataset is still the main challenge for quickly and effectively assessing the effect of management measures on farmland soil health. Hereby, we developed a minimum dataset (MDS) using three methods (network analysis (NA), random forest analysis (RF), and principal component analysis (PCA)). Based on MDS and two scoring functions (nonlinear (NL) and linear scoring curve (L)), the SHI (soil health index framework) was constructed to assess soil health conditions under four fertilization treatments (no fertilization, CK; only chemical fertilizer, NPK; only cow manure, MF; 50% chemical fertilizer + 50% cow manure, NPKM) in the northern ecotone of China. The results showed that the MDS-based on SHIs were positively correlated with each other and SHI-TDS (total dataset), verifying the consistency of soil health assessment models. Higher R2 was observed in the fitting of SHIs based on NA and TDS, which suggested that nMDS (minimum dataset based on network analysis) could represent most of the information in the TDS. The SHI-NL-nMDS (based on network analysis and nonlinear scoring curve) has the highest ability of sensitivity and accuracy, which indicates that compared with PCA and RF, the SHI based on NA can better embody farmland sol ecosystem functions. In addition, crop yield was significantly positive relative to SHI (soil health index). The incorporation of cow manure and chemical fertilizer improved soil health and increased crop yield. These results indicate that network analysis was a reliable technology for determining the minimum dataset in the evaluation of farmland soil health, and incorporating livestock manure could improve soil health and crop yield in this study area.

Habitat loss weakens the positive relationship between grassland plant richness and above-ground biomass.

Habitat loss and fragmentation per se have been shown to be a major threat to global biodiversity and ecosystem function. However, little is known about how habitat loss and fragmentation per se alters the relationship between biodiversity and ecosystem function (BEF relationship) in the natural landscape context. Based on 130 landscapes identified by a stratified random sampling in the agro-pastoral ecotone of northern China, we investigated the effects of landscape context (habitat loss and fragmentation per se) on plant richness, above-ground biomass, and the relationship between them in grassland communities using a structural equation model. We found that habitat loss directly decreased plant richness and hence decreased above-ground biomass, while fragmentation per se directly increased plant richness and hence increased above-ground biomass. Fragmentation per se also directly decreased soil water content and hence decreased above-ground biomass. Meanwhile, habitat loss decreased the magnitude of the positive relationship between plant richness and above-ground biomass by reducing the percentage of grassland specialists in the community, while fragmentation per se had no significant modulating effect on this relationship. These results demonstrate that habitat loss and fragmentation per se have inconsistent effects on BEF, with the BEF relationship being modulated by landscape context. Our findings emphasise that habitat loss rather than fragmentation per se can weaken the positive BEF relationship by decreasing the degree of habitat specialisation of the community.

Habitat loss weakens the positive relationship between grassland plant richness and above-ground biomass

Habitat loss and fragmentation per se have been shown to be a major threat to global biodiversity and ecosystem function. However, little is known about how habitat loss and fragmentation per se alters the relationship between biodiversity and ecosystem function (BEF relationship) in the natural landscape context. Based on 130 landscapes identified by a stratified random sampling in the agro-pastoral ecotone of northern China, we investigated the effects of landscape context (habitat loss and fragmentation per se) on plant richness, above-ground biomass, and the relationship between them in grassland communities using a structural equation model. We found that habitat loss directly decreased plant richness and hence decreased above-ground biomass, while fragmentation per se directly increased plant richness and hence increased above-ground biomass. Fragmentation per se also directly decreased soil water content and hence decreased above-ground biomass. Meanwhile, habitat loss decreased the magnitude of the positive relationship between plant richness and above-ground biomass by reducing the percentage of grassland specialists in the community, while fragmentation per se had no significant modulating effect on this relationship. These results demonstrate that habitat loss and fragmentation per se have inconsistent effects on BEF, with the BEF relationship being modulated by landscape context. Our findings emphasise that habitat loss rather than fragmentation per se can weaken the positive BEF relationship by decreasing the degree of habitat specialisation of the community.