Dryland Regions Research Articles

NATURAL COVER SURROUNDING THE FARM FIELD REDUCES CROP DAMAGE AND PEST ABUNDANCE IN BRAZILIAN DRYLAND

ABSTRACT One of the major ecosystem services delivered to agriculture worldwide is the reduction of pests by natural enemies. However, the landscape composition affects multiple dimensions of pest control, and non-crop habitat surrounding farm fields shows variable responses across geographies. Here, crop damage and pest abundance were compared between local farms with two antagonistic land cover and land use aspects (1- High conservation, landscape with high structural complexity; 2- High degradation, landscapes with low complexity). The field data were collected at experimental guava orchards in the Cariri Paraibano, one of the driest regions in the Brazilian Caatinga. The results show that damage caused by orthopterans and their abundance was significantly smaller in the landscape with high structural complexity. Therefore, the results support the hypothesis that crop damage and pest abundance are smaller in landscapes with high structural complexity. Additionally, the results are very important for the dryland regions as they provide information about the relationship between landscape structure and crop damage plus pest abundance in a regional gap. As drylands are critically endangered in all American continents, sustainable agricultural landscapes with the application of natural cover restoration can help drylands to achieve sustainable development.

Effects of Automated Irrigation Systems and Water Regimes on Soil Properties, Water Productivity, Yield and Fruit Quality of Date Palm

Applications of modern micro-irrigation methods are inevitable for optimum water use due to the limitations imposed by irrigation water resource scarcity. Regardless of water shortages and associated challenges in dry areas, the irrigation of date palm trees consumes an excessive quantity of water annually using conventional irrigation methods. Therefore, the present study was designed to evaluate the effects of modern surface and subsurface micro-irrigation systems, i.e., subsurface drip irrigation (SSDI), controlled surface irrigation (CSI), and surface drip-irrigation methods (SDI), with different irrigation water regimes, i.e., 50%, 75%, and 100% irrigation water requirements (IWRs), on the yield and fruit quality of date palms (cv. Khalas) and water conservation in the dryland region of Al-Ahsa, Saudi Arabia. The effects of three irrigation methods and IWRs were studied on macronutrients and soil chemical properties at three depths (0–30, 30–60, and 60–90 cm), as well as on water productivity, yield, and the fruit quality of date palms. The study was carried out over two years and was designed using a two-factorial randomized complete block design (RCBD) with nine replications. The results indicated that electrical conductivity (EC) increased as the depth of the soil increased. The soil chemical properties did not change much in all experimental treatments, while soil pH values decreased with the soil depth from 0–30 to 60–90 cm. Although the maximum fruit yield (96.62 kg palm−1) was recorded when 100% irrigation water was applied in the SSDI system, other treatment combinations, such as SDI at 100% IWR (84.86 kg palm−1), SSDI at 75% IWR (84.84 kg palm−1), and CSI at 100% IWR (83.86 kg palm−1) behaved alike and showed promising results. Similarly, the highest irrigation water productivity (2.11 kg m−3) was observed in the SSDI system at 50% IWR, followed by the SSDI at 75% IWR (1.64 kg m−3) and 100% IWR (1.40 kg m−3). Fruit quality attributes were also promoted with the SSDI system at 75% IWR. Hence, the SSDI method at 75% IWR appeared to be an optimal choice for date palm irrigation in arid areas due to its positive impact on water conservation and fruit characteristics without affecting soil chemical properties.

Why Have Economic Incentives Failed to Convince Farmers to Adopt Drip Irrigation in Southwestern Iran?

Sustainable water usage is an important global concern and an urgent priority, especially in dryland regions such as Iran. The Iranian government is actively addressing the challenge of water scarcity by encouraging farmers to adopt new water application technology. Its main element to decrease water consumption is to encourage new irrigation systems, in particular drip irrigation. However, despite the benefits of drip irrigation technologies and the availability of generous government subsidies, adoption rates of the improved irrigation technology remain critically low among Iranian farmers. Therefore, this study seeks to determine what is limiting the uptake of improved irrigation technology in Iran. While it is well known that acceptance of new technology ultimately depends on multiple and interrelated factors, we examine those factors affecting farmers’ adoption from three theoretical perspectives in the adoption literature: farmers’ socio-economic characteristics, social capital, and technology characteristics. A cross-sectional survey was undertaken in Behbahan district in Khuzestan province in southwest Iran. The sample comprises 174 farmers who adopted drip irrigation in that region and 100 non-adopters who were located in the same region. Discriminant analysis reveals that a socio-economic approach is the strongest model to predict adoption of drip irrigation technology in the study area, followed by models of technical characteristics, and social capital. These results can help agricultural extension agents and policy-makers design appropriate and effective strategies that facilitate the adoption of drip irrigation at an increasing rate.

Enhanced Ecosystem Services in China’s Xilingol Steppe during 2000–2015: Towards Sustainable Agropastoralism Management

Ecosystem services (ESs) provided by dryland regions are very vulnerable to environmental dynamics and management transformation, and it is still unclear how these services will be affected by the combined effects of accelerated climate variability and land-use changes at a regional macro level. In this study, the status, patterns and trends of ESs provided by the Xilingol steppe were quantitatively evaluated, and the impact of climate and land-use change on ESs were discussed. The results showed that favorable climatic conditions and the implementation of ecological policies had a substantial positive impact on regional vegetation restoration during 2000–2015. As a result of the vegetation greening, water retention and carbon sequestration increased significantly at rates of 16.01 m3 ha−1 and 1.75 g C m−2 yr−1, respectively. Soil loss caused by wind erosion, an ecosystem disservice, decreased significantly at a rate of −0.57 t ha−1 yr−1. Although several environmental factors had differing impacts on the ESs changes in the subregions, including the meadow, typical and desert steppes, the main factors that contributed to the enhancement of overall ESs benefits were the climatic humidification and the reduced grazing pressure in the entire study area. The above conclusion shows that, in the era of climate change, the implementation of sustainable farming–pastoral strategies can realize a “win-win” situation between ecological restoration and socioeconomic development in arid and semi-arid steppes.

Biophysical regulations of transpiration and water use strategy in a mature Chinese pine (Pinus tabulaeformis) forest in a semiarid urban environment

AbstractUrban trees and forests provide multiple ecosystem services for urban dwellers. However, forest water use for these benefits has become one of the critical concerns in dryland regions where water is limited. Negative forest water use impacts could be reduced by selecting tree species with low rates of transpiration. However, the possible changes of urban tree transpiration and its biophysical controls are still unclear. This study monitored the sap flow of a 58‐year‐old Chinese pine (Pinus tabulaeformis) plantation in a semiarid urban environment of northern China. Soil moisture played an important role in stand transpiration (Ec). Ec had a strong positive relationship with vapour pressure deficit (VPD) and solar radiation (Rs) when soil water was sufficient. In addition, the sensitivity of leaf stomata to VPD was not related to leaf and branch water potential. Under soil water stress, Ec was significantly reduced by 63.1% (p < 0.001) and was weakly related to VPD and Rs. Canopy conductance (gc) was reduced (p < 0.001) by 74.3% due to leaf stomatal closure, and the sensitivity of leaf stomata to VPD was significantly increased (p < 0.05) with increasing leaf and branch water potential. Wind speed had no significant effects on Ec. P. tabulaeformis tended to be isohydric with a relatively constant midday leaf water potential (i.e. −2.46 to −2.92 MPa) and strong stomatal regulation as a function of soil water stress. However, slopes (0.53–0.56) of the linear relationship between m (dgc/dlnVPD) and reference canopy conductance were significantly lower than the widely recognized 0.6 (p < 0.001). Therefore, urban tree transpiration drivers and forest impacts need to be clarified to better understand the proper tradeoff between water consumption and ecological services for urban areas.

Consistent effects of vegetation patch type on soil microbial communities across three successional stages in a desert ecosystem

AbstractDesertification is a worldwide problem caused by climate change and human activity in dryland regions. In China, approximately 27% of the land surface is desertified. In these desertified ecosystems, aboveground interactions are known to greatly affect ecological succession, but belowground soil microbial communities are relatively unstudied. It is not yet clear how these communities change with different vegetation patch types (e.g., shrub vs. grass) across successional stages in dryland ecosystems. In this study, we assessed the effects of shrub patches (dominated by Artemisia ordosica) and grass patches on soil microbial community diversity, soil environment, and soil substrates across three successional stages (mobile, semi‐mobile, and fixed dunes) in a sand dune ecosystem in the Kubuqi Desert, China. Microbial alpha diversity, as indicated by the Shannon index or operational taxonomic unit (OTU) richness, was not affected by patch type but increased with successional stages. Patch type‐ or successional stage‐induced changes in soil bacterial and fungal alpha diversity were mainly associated with soil organic carbon. Unlike alpha diversity, soil microbial beta diversity was greatly affected by successional stage and patch type. The Mantel test revealed that changes in soil bacterial beta diversity were mainly associated with soil organic carbon, and changes in soil fungal beta diversity were mainly associated with soil organic carbon and soil pH. Microbial OTU richness responded more strongly to the successional stage than the microbial Shannon index, indicating that microbial OTU richness can be used as an indicator of successional status in desert ecosystems. The consistent differences in microbial beta diversity between shrub and grass patches across the three successional stages indicate that shrubs significantly influence soil microbial communities in desert ecosystems.

Impact of low cost interventions through frontline demonstrations on crop productivity and profitability of small and marginal farmers under dryland conditions

Introduction of drought tolerant varieties of maize and wheat resulted in significantly higher additional yield of 35.6 and 32.5 percent, respectively over the years. The rainwater management through ex situ and in situ techniques also proved to be crucial interventions for enhancing the crop productivity of small and marginal farmers in dryland regions. The lifesaving irrigation to wheat through harvested water gave 46.8% higher yield, while the in situ moisture conservation techniques resulted in 7.7% (summer ploughing), 10% (sowing across the slope) and 11.3% (ridge sowing) additional maize yield compared to farmers’ practice. The farm mechanization also improved the yield (20.3%), operational and economic efficiency of the farm operations and reduced the labour cost. Hence, from the present study, it was concluded that the adoption of these low cost interventions can improve the crop productivity with better economic returns and enable them to cope with weather aberrations in these dryland regions.

Understanding farming systems and their economic performance in Telangana, India: Not all that glitters is gold

Farming systems are transitioning from a subsistence orientation to market orientation in response to changing food demands, technologies, and policies. In India's dryland regions, watershed development, among several other initiatives, has been a critical driver of these transitions, but their outcomes are poorly understood. The present paper investigates the characteristics and economic performance of current farming systems in a region in Telangana, India, that has undergone a rapid transition from subsistence orientation to market orientation. We surveyed 3006 farms, followed by a farm-economics study involving 75 households belonging to the three major farming systems. The gross margin was low for all systems but most inadequate for the crop-without-livestock system, highest for the crop-with-small-ruminants system, and intermediate for the crop-with-dairy system. Economic risks and natural-resource scarcity threaten the sustainability of current farming systems, and the reassessment of watershed development policies is recommended.

Seed germination requirements of an Australian semi-arid floodplain

Plants that occur on floodplains in dryland regions often use floods to disperse and germinate seeds, which establish during and following flooding events. Acacia stenophylla (river cooba) is a perennial tree, common in the riparian habitats of the Murray–Darling Basin, Australia. The aims of this study were to (1) determine the relationship between seed germination and seedling establishment of A. stenophylla and hydrological conditions, (2) determine the buoyancy of its seeds and, hence, ability to disperse by hydrochory and (3) provide recommendations on the hydrological requirements for A. stenophylla recruitment. Seedling recruitment data collected between 2014 and 2020 on the floodplain of the lower Lachlan River were compared with time since flooding. In a glasshouse experiment, seeds of A. stenophylla within their pods and with their pods removed were exposed to one of five experimental treatments (rainfall, soaked soil, and inundated for 20 and 40 days), over a period of 50 days. A. stenophylla germinated during and following flooding and following high rainfall. Seeds in pods floated for 8 days. A. stenophylla establishes during and following flooding and requires 1 month of flooding followed by flood recession to maximise seed germination. This research contributes to our broader understanding of the reproductive biology of one of the less studied Acacia species.

Improving dryland seedling recruitment using fungicide seed coatings

Abstract The success of seed‐based restoration in dryland regions of the world is often low or sporadic, with most mortality occurring between germination and emergence. Fungal pathogenesis is one process that may reduce seedling emergence and limit restoration success. Our objective was to determine whether fungicide seed coatings constitute an economically viable strategy for increasing emergence by reducing fungal pathogenesis and mortality. We performed an experiment across two sites and three years, using bluebunch wheatgrass (Pseudoroegneria spicata) as a model species. We found that fungicide coatings increased germination by 8.8% and emergence by 54.0% on average compared to the control. A cost analysis indicated that the fungicide coating was economically viable with an average estimated effective cost reduction of 18.8% under the study conditions. There was a strong interaction (P < 0.001) between the effects of the fungicide coating, site and year on emergence. The fungicide coating increased emergence compared to the control in five of the six sites and years, with the effect ranging from a 33.7% decrease (P = 0.042) to a 150.9% increase (P = 0.004). The observed interaction was likely related to the effect of the hydrothermal microsite environment on disease severity. In the site and year that the fungicide coating performed worse than the control, prolonged periods of exceptionally low soil moisture may have reduced disease severity through a variety of individual and community scale mechanisms. Overall, these results indicate that fungicide seed coatings have the potential to improve dryland restoration efforts.

Environmental and canopy conditions regulate the forest floor evapotranspiration of larch plantations

Integrated forest-water management focusing on forest-water coordination is an important way to alleviate water use conflicts among forests and other sectors in vast dryland regions. Forest floor evapotranspiration (FE), which is an important component of forest evapotranspiration, accounts for a large proportion of the water consumed in arid forests. Elucidating how environmental and canopy conditions impact FE has important significance for guiding integrated forest-water management in a changing environment.

Poplar trees do not always act as a water pump: Evidence from modeling deep drainage in a low-coverage-mode shelterbelt in China

Large-scale afforestation can combat desertification, provide ecosystem services, and mitigate climate change. However, it can also have negative effects on the hydrological cycle and water budget, and thus on water security in dryland regions depending on the afforestation strategy used. Currently, the effects of different afforestation strategies on soil moisture dynamics, evapotranspiration (ET), and water budget at the stand scale are unclear. In this study, we investigated the water budget in two poplar stands, one planted using a low-coverage-mode shelterbelt (LCMS) strategy and the other planted using a conventional strategy (control). Deep drainage (DP), as an indicator of water budget, was estimated using a Hydrus-1D model calibrated with the observed soil moisture at different soil depths (across 0–200 cm) during the growing seasons in 2016, 2017, and 2019. The average DP in the LCMS stand was 107.0–149.6 mm, accounting for 36.5–42.4% of the rainfall occurring during the growing seasons, which was slightly higher than that in the control stand containing younger trees at a higher density. However, DP was more spatially heterogenous in the LCMS stand compared with in the control stand. Specifically, in the LCMS stand, the inter-canopy DP was 195.3–237.5 mm, accounting for 66.6–69.7% of the rainfall, whereas the under-canopy DP was only 18.7–65.0 mm, accounting for 6.4–18.4% of the rainfall during the corresponding period. Structural equation modeling indicated that, on a daily scale, soil moisture had the greatest effect on DP, followed by precipitation and soil saturated hydraulic conductivity. Other climate factors (global radiation, air temperature, vapor pressure deficit and wind speed) and vegetation structure parameters (leaf area index and rooting depth) affected ET, which had a significantly negative relationship with DP. These results help explain the effects of plantation strategy on the water budget, with important implications for artificial forest management, ecological restoration, and protection of local water resources in water-limited environments.

Assessing impact of dry spells on the principal rainfed crops in major dryland regions of India

The dry spells and rainfall deficit within crop season, play vital role in determining productivity of rainfed crops. Dry Spell Index (DSI) was formulated to quantify cumulative impact of dry spells during kharif season (Jun-Sep) on major rainfed crops of India. District-wise variability of DSI were analyzed across rainfed regions of India using rainfall data of 1636 stations. Comparison of DSI with Standardized Precipitation Index (SPI), hitherto, a widely used drought index showed that, central and eastern Karnataka, northern Rajasthan and western Gujarat are becoming wetter in terms of total seasonal rainfall as indicated by SPI, and becoming drier in terms of total dry spell duration within the season as per DSI. The impact of DSI on yield of major rainfed crops viz., cotton, groundnut, maize, pearl millet, pigeon pea and sorghum were estimated. The analysis showed that, the impact of dry spells integrated in form of the DSI on yields of six major rainfed crops was higher in comparison to total rainfall indicated by SPI for six major rainfed crops in India. Groundnut and pearl millet crops experienced higher duration of dry spells in comparison to other crops. The productivity of all the crops was significantly influenced by DSI across more than 65% growing regions. The yield loss was about 75–99% in 24% of sorghum, 23% of groundnut and 13% of pearl millet and it was about 50–74% in 44% of cotton, 24% of groundnut, 17% of maize, 16% each of pearl millet & sorghum and 12% of pigeon pea growing regions. We also found that by minimizing the cumulative impact of dry spells, yield can be increased twice in more than 55%, 49% and 42% areas of pearl millet, pigeon pea and groundnut growing regions, respectively. This study will help developing adaptation strategies to sustain crop production in rainfed regions of India.

Transforming livestock productivity through watershed interventions: A case study of Parasai-Sindh watershed in Bundelkhand region of Central India

CONTEXTGlobal experiences reveal the positive impact of watershed-based interventions in improving livelihoods and environmental security. In the drylands, increasing forage resources and improving livestock productivity is a critical challenge. OBJECTIVESThe overarching aim of this paper is to analyse the impact of watershed-based interventions on livestock population, productivity, fodder resources, and biomass availability. The paper describes the interrelationship between land, water, crop, and livestock and how the gap in forage deficit can be bridged through a range of watershed interventions. METHODSThe study was undertaken in the Parasai-Sindh watershed of Central India between 2011 and 2016. A 300-year-old defunct haveli (a traditional rainwater harvesting structure) was renovated and nine check dams along the drainage line were constructed. Nearly 25,000 running-meters of field bunds were constructed. Large fields (2-3 ha) were divided into relatively smaller plots (0.3–0.5 ha) to reduce runoff velocity. The impact of watershed interventions on water availability, livestock productivity, forage yield, and income was studied through hydrological monitoring, primary household survey and principal component analysis (PCA) biplot and hierarchical clustering. RESULTS AND CONCLUSIONSThe watershed interventions enhanced groundwater availability leading to greater fodder availability, 22% increase in livestock population (ACU) and a 120% increase in milk production over a period of five years. The bovine population recorded a surge of 193% (cattle) and 32% (buffalo) over this period. Mean dry matter (DM, fodder) availability also increased from 10 t/household/year to 16.7 t/household/year owing to improved water availability. Groundnut (rainy season) and wheat (post rainy season) contributed significantly as forage resources. There was an annual forage demand of 5560 t DM for a livestock population of 2175 ACU in 2011 and of 6770 t DM for a livestock population of 2650 ACU in 2016. Annual forage biomass availability was estimated at 4219 t DM in 2011 and 6977 t DM in 2016. There was a deficit of 1341 t DM (24%) in 2011 which turned into a 3% surplus of 210 t DM in 2016 through watershed-based interventions. With increased cropping intensity and milk production, average annual household income increased from US$ 1325 to US$ 2430 over the five-year period. SIGNIFICANCEThis case study clearly illustrates the impact of watershed-based interventions on livestock population, productivity, forage resources, and biomass availability to bridge the gap in forage deficit. Its findings serve as a guide to widely scale up watershed-based interventions for improved water and biomass availability, and livestock productivity in semi-arid and dryland regions.

Framework for integrated Ecosystem Services assessment of the costs and benefits of large scale landscape restoration illustrated with a case study in Mediterranean Spain

To prevent landscape degradation and the continuing loss of biodiversity and ecosystem services, decisions regarding landscape restoration should be based on their ‘true’ costs and benefits (i.e. broader welfare effects), including all externalities (positive and negative). In this paper, we present a framework consisting of nine steps to analyze, quantify and, where possible, monetize and capture the effects of changes in land use and management on the true costs and benefits. To illustrate this framework we applied it to large scale landscape restoration in a dryland region in SE Spain that is facing serious land degradation. Based on fieldwork involving several farms and expert interviews between 2017 and 2019, and additional literature review, we compared the costs and benefits, using the so-called Social- or Integrated Cost-Benefit Analyses (i-CBA) approach, of three land use systems: a multi-functional sustainable land use system (MFU) with those of almond monoculture under conventional management (CM) and under sustainable land management (SLM). Our study demonstrates that conventional financial CBA favors short-term, usually non-sustainable, land use. Using i-CBA gives a more realistic insight in the true welfare effects of landscape restoration. Our analysis also shows that a transition from conventional monoculture to multi-functional sustainable land use at the farm-level is only financially feasible when all externalities are accounted for and compensated. Our integrated approach enables the identification of opportunities and mechanisms to optimize multifunctional land use and capture the ‘full value’ of landscape restoration through so-called blended financing mechanisms. Eventually, sustainable land management can then become the norm rather than the exception because it is both financially more profitable for the private land owner and economically, environmentally and socially more beneficial to the community and society as a whole.

Biocrust succession improves soil aggregate stability of subsurface after “Grain for Green” Project in the Hilly Loess Plateau, China

Soil aggregate stability is often used as the key indicate to evaluate soil degradation or soil erodibility. Numerous studies have indicated that biological soil crusts (biocrusts) can stabilise the soil surface by increasing the aggregate stability. In the end of the 20th century, the “Grain for Green” ecological project was implemented in most areas of the Loess Plateau, leading to the widespread distribution and succession of biocrusts in the open spaces between vascular plants in the abandoned farmlands. However, the effects of biocrust succession on the soil aggregate stability of subsurface remain poorly explored. Thus, to determine how biocrust succession affect subsurface soil aggregate stability, we investigated a cropland and 5 abandoned farmlands sites that have developed over three to 30 years in the Loess Plateau region of China. Then we measured the amounts of water stable aggregates of subsurface soil underlying different successional stage biocrusts (bare soil, cyanobacterial crust, cyanobacteria-moss mixed crust, and moss crust) by using wet-sieving method, and summed the mass fraction of soil remaining on each sieve after sieving multiplied by the mean aperture of the adjacent mesh (mean weight diameter) to characterise the soil aggregate stability. In addition, we analysed the complex correlations among age of farmland abandonment, biocrust succession, soil organic matter, clay fraction, and aggregate stability using structural equation modelling (SEM). The results are as follows: (1) the mean weight diameter (MWD) in the subsurface soil increased with the biocrust succession. The MWD in the 0–2-cm soil layer beneath moss crusts was 2.33 mm, 7.3 times as much as that of cropland sites. (2) The later successional stage biocrusts (mixed crust and moss crust) improved the deeper soil aggreggate stability compared with the early successional stage biocrusts. The MWD in 0–2-cm layer of the cyanobacterial crust was significantly higher than those of the lower layers, while MWDs in 0–2-cm and 0–5-cm layers of the later successional stage biocrust were significantly higher than that of 5–10-cm layer. (3) The SEM results confirmed that in the 0–5-cm layer, biocrust succession indirectly improved the stability of aggregates by increasing soil organic matter (SOM). There was a highly significant linear relationship between MWD of 0–5-cm layer and biocrust succession parameter (moss biomass) (R2 = 0.35, P = 0.002). In the 5–10-cm layer, the SOM still significantly influenced the aggregate stability, but the biocrusts had no significant effect on the SOM in this layer. The results suggest that biocrusts should be considered a crucial factor in soil stability and be used as an effective rehabilitative tool for restoring lands in dryland regions.

Farmers’ Attitude towards the Climate-Resilient Technologies of NICRA Project in Anantapur District

Climate change has been perceived with high emphasis from the beginning of this century. Since it directly impacts the ecosystem and agriculture especially over the farmers of dryland regions. The research study has been conducted to assess the farmers’ attitude towards climate-resilient technologies of the National Initiatives on Climate Resilient Agriculture (NICRA) project by farmers of Anantapur district of Andhra Pradesh. The sample consists of 60 farmers as beneficiaries from NICRA villages and 60 farmers as nonbeneficiaries from non-NICRA villages were selected randomly. The ex-post facto research design was used in the study. The results of the study showed that more than half of the beneficiaries (51.67 %) and 48.33 per cent of non-beneficiaries had a medium level of favorableness towards climate-resilient technologies of the NICRA project. From the above findings, this is concluded that both beneficiaries and non-beneficiaries of the NICRA project have a positive favourable attitude towards climate-resilient technologies which is considered as a precursor for adoption of those technologies by the farming community. Hence the results of this research study may help extension organizations for good training and implementation of climate-resilient technologies of National Innovations on Climate Resilient Agriculture (NICRA).

Divergent Causes of Terrestrial Water Storage Decline Between Drylands and Humid Regions Globally

AbstractDeclines in terrestrial water storage (TWS) exacerbate regional water scarcity and global sea level rise. Increasing evidence has shown that recent TWS declines are substantial in ecologically fragile drylands, but the mechanism remains unclear. Here, by synergizing satellite observations and model simulations, we quantitatively attribute TWS trends during 2002–2016 in major climate zones to three mechanistic drivers: climate variability, climate change, and direct human activities. We reveal that climate variability had transitory and limited impacts (<20%), whereas warming‐induced glacier loss and direct human activities dominate the TWS loss in humid regions (∼103%) and drylands (∼64%), respectively. In non‐glacierized humid areas, climate variability generated regional water gains that offset synchronous TWS declines. Yet in drylands, TWS losses are enduring and more widespread with direct human activities, particularly unsustainable groundwater abstraction. Our findings highlight the substantive human footprints on the already vulnerable arid regions and an imperative need for improved dryland water conservation.

Distribution of soil organic carbon and nitrogen under reduced nitrogen application in the Guanzhong plain of China#

AbstractBackgroundThe problems of soil quality degradation and environmental pollution caused by excessive use of nitrogen fertilizer seriously affect sustainable development of agriculture.AimsWe investigated the effects of reduced nitrogen application with simultaneous full straw return on carbon input, aggregate size distribution, aggregate‐associated organic carbon and total nitrogen (TN), soil organic carbon (SOC) stock, SOC fractions, and crop yield.MethodsA long‐term field experiment was performed in the dryland region of Guanzhong. The study involved three nitrogen fertilizer (NF) amounts: 337.5 (conventional NF, CNF), 286.4 (15%NF reduction, 15%RNF), and 236.3 (30%NF reduction, 30%RNF) kg N ha–1 y–1 with full straw return.ResultsCompared with CNF, 30%RNF increased the content of soil organic carbon by 5.7% and increased maize yield by 13.1%, under straw return conditions. The 30%RNF + straw application treatment promoted the formation of large macro‐aggregates more effectively than CNF application. The 30%RNF + straw treatment significantly increased SOC by 10.6% and 4.7%, respectively, in large and small macroaggregates relative to conventional NF. Moreover, the 30%RNF + straw treatment resulted in a significant increase in the SOC content in the density fractions of mineral soil organic matter (mSOM) for both small and large macro‐aggregates. This treatment also resulted in a significant increase in the content of TN in the mSOM and density fractions of particulate matter that had coarse and fine intra‐aggregates of the large macro‐aggregates.ConclusionFull straw return with reduced nitrogen (N) application could be a promising option to improve the structure of soil aggregates, soil organic carbon, and nitrogen sequestration.

Navigating local environment and scientific knowledge in dryland social-ecological systems through linking ecological policy-household interactions with land surface dynamics

As the Earth enters the Anthropocene, the system complexity and site-specificity of dryland social-ecological systems (SESs) presents new challenges for realizing the target of land degradation neutrality (LDN) in drylands. The valuable local environmental and scientific knowledge (LESK) of dryland SESs is crucial for adaptive governance but remains scarce. Here, we proposed an analytical framework to understand the LESK in relation to the mechanisms of ecological policy-household interactions and ecological performance of resource systems. According to this framework, we explored LESK by linking land surface dynamics and investigations of policy and households in a typical dryland region, Minqin. We reported that ecological policy contributed to significant socio-ecological benefits, including increased water resources, land desertification reduction, and natural vegetation restoration. However, there exist conflicting aspects, demonstrated by the encroachment of agricultural land, which increases the land degradation risk of oasis. These results implied that top-down ecological policy and bottom-up household responses caused both positive and negative LDN outcomes, which can be attributed to collective and conflicted actions between the self-interest orientation of multiple stakeholders. By investigating households, we found that education-induced economic need was one of the major drivers for the conflicted actions on the policy of agricultural land reduction. Therefore, we proposed a series of adaptive measurements to balance short-term economic concerns and long-term LDN. This study also highlighted that navigated LESK should be considered for future sustainable management and ecosystem modeling.