Semi-arid Northern Research Articles

Crotalaria juncea Genotype Biomass Accumulation in Northern Semi-Arid and Humid-Continental Climates

Crotalaria juncea Genotype Biomass Accumulation in Northern Semi-Arid and Humid-Continental Climates

Enhanced relationship between seasonal soil moisture droughts and vegetation under climate change over China

Climate change could intensify seasonal soil moisture droughts and subsequently degrade vegetation, but it can also facilitate vegetation growth with the rising temperature and CO2 concentrations. Therefore, the change of the vegetation-drought relationship under climate change remains elusive. Here, we investigate the effects of vegetation greening (i.e., increasing leaf area index (LAI)) on seasonal soil moisture drought trends by performing a set of land surface model simulations with the Conjunctive Surface-Subsurface Process model version 2 (CSSPv2), as well as the impact of seasonal soil moisture drought change on vegetation productivity via a statistical fitting model. Our results indicate that both the impact of increasing LAI on exacerbating seasonal droughts and the impact of increasing seasonal droughts on reducing vegetation productivity have been enhanced over China during 1961–2018. Specifically, increased LAI accounts for 48 % of the rising drought frequency through escalated evapotranspiration losses, with more pronounced effects in northern semiarid regions. The decrease in vegetation stomatal conductance caused by rising CO2 concentrations limits transpiration and alleviates 11 % of the increase in drought frequency, but it cannot fully offset the drought aggravation induced by increased vegetation water consumption under climate warming. Meanwhile, increased drought frequency and intensity have reduced the upward trend in vegetation productivity by 5 % over China, and by 8 % in water-limited northern regions. Our study shows the relationship between seasonal soil moisture droughts and vegetation over China has strengthened, indicating that vegetation greening will lead to increased water shortages and further impact vegetation growth and carbon sequestration. This challenges water resources management and environmental sustainability, especially in semiarid regions.

Optimistic growth of marginal region plantations under climate warming: Assessing divergent drought resilience.

Given the context of significant global warming and the intensification of extreme climate events in the last century, large-scale reforestation and afforestation have been recognized as effective strategies to mitigate the climate crisis. Since the 1970s, China has launched several afforestation programs aimed at regional ecological protection, playing an important role in reaching carbon neutrality by 2060. This study provided a detailed analysis of the growth suitability of the main planted conifers (Pinus sylvestris var. mongolica and Pinus tabulaeformis) and broadleaves (Populus spp., Robinia pseudoacacia) in the semi-arid northern China. We compared the radial growth trends of plantations and their responses to extreme droughts from 1980 to 2018. Growth of most plantations has significantly increased over time, but broadleaves showed recent growth reductions in the past decade, which may be related to tree age and reduced soil moisture. Nevertheless, under warmer climate scenarios, the growth of plantations is forecasted to continue increasing. Broadleaves showed a better post-drought recovery, probably linked to their anisohydric behavior, than conifers, which presented a better resistance to drought. Growth of conifers depended more on warmer temperature and better precipitation conditions during the growing season, whereas broadleaves mainly reacted to warm temperature. Additionally, pre-drought growth levels weakened resilience components, while post-drought precipitation compensated for drought-induced growth deficit. Growth and resilience were negatively related to tree age, while higher stand density reduced growth. This assessment and projections of growth and drought resilience indicate the sustainability of most plantations in semi-arid regions, but future warmer and drier conditions may lead to an uncertain future regarding forest health and reduce their carbon sink potential.

Synergistic Effects of Soil-Based Irrigation and Manure Substitution for Partial Chemical Fertilizer on Potato Productivity and Profitability in Semiarid Northern China.

Soil-based irrigation and the partial substitution of chemical fertilizers with manure are promising practices to improve water and nitrogen (N) use efficiency. We hypothesize that their combination would simultaneously benefit potato production, tuber quality and profitability. A two-year experiment was conducted in semiarid northern China to investigate the combined effects of three water treatments [rainfed (W0), soil-based irrigation (W1), conventional irrigation (W2)] and three N treatments [no N (N0), chemical N (N1), 25% manure substitution (N2)] on these indicators, and to perform a comprehensive evaluation and correlation analysis. The results showed that water and N treatments separately affected all indicators except vitamin C content. Compared to W2, W1 significantly increased water productivity by 12% and irrigation water use efficiency (IWUE) by 30% due to 10% lower evapotranspiration and 21% lower water use. However, W1 and W2 negatively affected crude protein content. Conversely, this was compensated by the combination with N1 and N2. There were slight differences between N1 and N2 for all indicators on average across water treatments, while under W1, N2 significantly increased leaf area index (LAI) and N recovery efficiency (REN) by 18% and 29.4%, respectively, over N1. Also, comprehensive evaluations showed that W1N2 performed best, with the highest tuber yield, profit and acceptable quality. This can be explained by the increase in LAI, IWUE and REN due to the positive correlations with tuber yield and net return. Consequently, soil-based irrigation combined with 25% manure substitution had complementary effects on tuber quality and synergistic effects on potato productivity and profitability.

The impact of community-led conservation models on women's nature-based livelihood outcomes in semi-arid Northern Ghana

With increasing human-induced environmental degradation, women's nature-based livelihood activities are threatened. In semi-arid northern Ghana, shea processing (i.e., shea butter, a derivative of shea nut from the shea tree), a vital women-dominated economic activity, is at risk as naturally occurring shea trees continue to decline in numbers and productivity. The decline of the shea tree's number and productivity and the ensuing biodiversity loss have sparked conservation efforts by governments and local communities. This includes community-led conservation models, which have recently gained traction in the Global South. Ghana implemented the Community Resource Management Areas (CREMA)—a community-led conservation model to improve biodiversity and ecosystem services, including shea trees conservation in response to climate change. Research has not explored the impacts of community-led conservation efforts on women’s nature-based livelihoods in Ghana. Using a mixed-methods approach involving surveys (n = 517) and focus group discussions (n = 8), this study explored shea productivity outcomes under CREMAs. Findings show that women residing in CREMAs had significantly better shea harvesting outcomes than those outside CREMAs (α = −53.725; P < 0.01). These findings demonstrate the potential for targeted conservation initiatives that are community-led, such as the CREMAs, to improve the conservation of economically significant naturally occurring trees like Shea. With the increasing impacts of climate change and environmental degradation, such models would be instrumental in achieving sustainable development goals like SDG5-gender equality, SDG10-reduced inequalities, SDG13-Climate action, SDG14-life below water, and SDG14-life on land.

Rainwater Harvesting System Analysis for Semi-Arid Climate: A Daily Linear Programming Model

Rainwater harvesting has proven to be an alternative water supply scheme for sustainable water management of regions with limited water resources. In this paper, a linear programming (LP) model with daily time steps, which minimizes a rooftop rainwater harvesting system (RWHS) cost, is developed and used to calculate the optimum RWH tank size. The developed LP model is applied to the semi-arid Northern Cyprus in the Eastern Mediterranean. The analysis is carried out for 33 sites which receive average annual rainfall ranging from 292 mm to 548 mm to evaluate the spatial effect of rainfall characteristic and the water cost on the financial feasibility and performance of the RWHS. At 29 out of 33 sites, RWHS investments are found to be financially feasible with discounted payback periods ranging from 12 to 28 years. The optimum RWH tank sizes are determined to be between 2 m3 and 6 m3 resulting in up to 20 % reliability with more than 50 m3 of average annual water savings per house. It is observed that the cost of water is a critical factor that affects the financial feasibility and water savings of a RWHS, especially in regions with limited rainfall. The comparison of the developed daily LP model with an LP model with monthly time steps demonstrates that the financial feasibility and the optimum tank size can only be assessed realistically when daily time steps are used. Finally, the sensitivity analysis shows that the discounted payback period is highly sensitive to the collector area.

The Impact of Village Savings and Loan Associations as a Financial and Climate Resilience Strategy for Mitigating Food Insecurity in Northern Ghana

In semi-arid Northern Ghana, smallholder farmers face food insecurity and financial risk due to climate change. In response, the Village Savings and Loan Association (VSLA) model, a community-led microfinance model, has emerged as a promising finance and climate resilience strategy. VSLAs offer savings, loans, and other financial services to help smallholder farmers cope with climate risks. In northern Ghana, where formal financial banking is limited, VSLAs serve as vital financial resources for smallholder farmers. Nevertheless, it remains to be seen how VSLAs can bridge financial inclusion and climate resilience strategies to address food insecurity. From a sustainable livelihoods framework (SLF) perspective, we utilized data from a cross-sectional survey of 517 smallholder farmers in northern Ghana’s Upper West Region to investigate how VSLAs relate to food insecurity. Results from an ordered logistic regression show that households with membership in a VSLA were less likely to experience severe food insecurity (OR = 0.437, p &lt; 0.01). In addition, households that reported good resilience, owned land, had higher wealth, were female-headed, and made financial decisions jointly were less likely to experience severe food insecurity. Also, spending time accessing the market increases the risk of severe food insecurity. Despite the challenges of the VSLA model, these findings highlight VSLAs’ potential to mitigate food insecurity and serve as a financially resilient and climate-resilient strategy in resource-poor contexts like the UWR and similar areas in Sub-Saharan Africa. VSLAs could contribute to achieving SDG2, zero hunger, and SDG13, climate action. However, policy interventions are necessary to support and scale VSLAs as a sustainable development and food security strategy in vulnerable regions.

Suitability of the shrub-steppe habitat of Eastern Washington for Halyomorpha halys (Hemiptera: Pentatomidae).

The invasive brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), has spread throughout most of Washington (WA) State since its detection in 2012. While it has emerged as a major agricultural and nuisance pest in the Pacific Northwest (PNW) west of the Cascade Mountains, pest pressure in the major tree fruit-growing areas in semi-arid northern and central WA State remains low. The reasons for this are unclear, although both biotic and abiotic conditions may be contributing factors. We evaluated the suitability of a common shrub-steppe/riparian corridor plant assemblage for supporting H. halys development from egg to adult in summer and fall through controlled feeding studies. Nymphs successfully completed development on this diet of PNW native plants, though it generally resulted in lower survivorship and adult weight and longer developmental times than a modified colony diet or a diet of known hosts from the eastern United States. These developmental data were used to parameterize stage-structured matrix models to predict the impact of diet and extreme heat events on H. halys population growth. The predicted net reproductive rate (R0) of H. halys was consistently and substantially reduced by a diet of PNW native plants, and heat shock imposed further severe reductions in R0. Our results suggest that the combined population effects of suboptimal plant host quality and regional heat waves may explain the lack of landscape-level H. halys pest pressure in semi-arid regions of the PNW.

Late Quaternary evolution of Daihai Lake in northern China and implications to the variation of the East Asian summer monsoon

Global warming over the past decades has resulted in desiccation of lakes in arid and semi-arid northern China. However, the mechanisms responsible for the sharp fluctuations in water levels for these lakes in this region are still unclear. The water level fluctuations in geological time can provide an analogue to better understand current lake levels’ response to global warming. In this study, a combination of quartz and feldspar luminescence dating techniques was applied to establish the chronologies of two sedimentary sequences related to lake level in the catchment of Daihai Lake, located on the fringe of the East Asian summer monsoon (EASM) domain. Our objective is to reconstruct the late Quaternary history of lake level fluctuations and provide the interpretations of their causes. The results indicate that two lake-level highstands existed during 130–120 ka and 8-4 ka, at least ∼38 m and 40 m above the current lake level, respectively. We interpret that the lake level variations on multiple timescales in the monsoonal marginal area have primarily been regulated by the EASM intensity and corresponding monsoonal precipitation, while temperature changes may have played a minor role. Moreover, a compilation of existing lake level data reveals that EASM intensity has a complex response to changes in Northern Hemisphere summer insolation on millennial-orbital timescales. Combining precipitation records in central and southern China, the character of rainfall across East Asia during MIS 5 exhibits a dominant tripolar pattern.

Responding to harvest failure: Understanding farmers coping strategies in the semi-arid Northern Ghana.

Farmers coping strategies against harvest failures have implication for future adaptation to such shocks. Previous studies on farmers' vulnerability and response to shocks have emphasized on adaptation, at the expense of their coping to such shocks. Using a survey data from 299 farm households in northern Ghana, this study has analyzed farmers' coping strategies against harvest failure, and the drivers of the choice and intensity of the coping strategies. The empirical results show that most of the households used liquidation of productive assets, reduction in consumption, borrowing from family and friends, diversification of livelihoods, and migration to cities for off-farm jobs as coping measures in response to harvest failure. The empirical results from a multivariate probit model indicate that the choice of coping strategies is influenced by farmers' access to radio, net value of livestock produced per man-equivalent (ME), experience of yield loss in the previous year, farmers' perception about the fertility status of their crop fields, access to credit, distance to market, farm-to-farmer extension, location of the respondent, cropland per ME, and access to off-farm income. Empirical results from a zero-truncated negative binomial regression model also indicate that the number of coping strategies adopted increases with the value of farm implements, access to radio, farmer-to-farmer extension and being located in the regional capital. It however decreases with the age of the household head, number of family members abroad, a positive perception about the fertility status of crop fields, access to government extension services, distance to market, and access to off-farm income. Limited access to credit, radio, and markets renders farmers more vulnerable and pushes them to adopt more costly coping strategies. In addition, an increase in income earned from secondary livestock products decreases incentive for farmers to adopt liquidation of productive assets as coping strategy after a harvest failure. Policy makers and stakeholders could make smallholder farmers less vulnerable to harvest failure by enhancing their access to radio, credit, off-farm income and market, promotion of farmer-to-farmer extension, implementing measure to improve the fertility of crop fields in the study area, and enhancing farmers' engagement in the production and selling of secondary livestock products.

A new approach to assessing natural capital consumption inequities from a nonlinear perspective

The rate of decline in ecosystem services has been exacerbated by inefficient and inequitable natural resource use and management. This study analyzes the natural capital stock and outflow in the Arid and Semi-Arid Northern Region of China (ASRNC) from 2000 to 2020. The Gini coefficient and coefficient of variation are used in the equity assessment of natural capital consumption. Over-appropriation of natural capital is a prerequisite for the inequitable distribution of natural resources, and all variables were accounted for through a geographic probe. Since most of the variables in this study have a nonlinear relationship, an in-depth analysis was conducted using NARDL. The results show that (1) natural capital flow occupancy generally shows an upward and downward trend and peaks in 2015. Natural capital stock occupancy was on a linear upward trend over the study period, rising from 14.580hm2/cap to 18.272hm2/cap. Depletion of natural capital is increasing and construction land has become the land type that leads to deep footprint changes (2) A city's consumption of natural capital matches its ecological carrying capacity to contribute to economic growth. However, the Gini coefficient for the depth of the ecological footprint from 2000 to 2020 is on a fluctuating upward trend. It reached its maximum in 2020 (1.457), indicating that the inequitable use of natural capital stock is increasing. (3) In the long run, population density and urbanization rate have different adverse effects on utilizing natural capital stock. In addition, the equity of planted forest area on natural capital use is heterogeneous in the long and short term. There is a negative effect of planted forest area on natural capital stock under long-term development. The study helps to judge the equity of regional consumption of natural capital and provides a scientific basis for the harmonious development between socio-economic systems and ecosystems.

Adapting to Climate Change in the Semi-Arid Northern Kenya

Climate change in the semi-arid northern Kenya is evidenced by increasing frequency and duration of severe droughts. The effects are devastating with the region experiencing massive loss of livestock, total crop failures and increased levels of hunger and starvation resulting in near collapse of livelihood sources which is mainly pastoralism. This study investigated the most appropriate drought adaptive strategies that pastoralists in the semi-arid northern Kenya depend on to subsist. Data was collected from the counties of Garissa, Samburu, Turkana, Isiolo, Marsabit, West Pokot, Laikipia and Baringo where drought is persistent. The study used a cross-sectional design where past and current data was obtained through face-to-face and telephone interviews from purposively sampled respondents and observations. Document information collected supplemented the information obtained from the respondents. The pastoralists embrace adaptive strategies that are easy, accessible and affordable. The traditional adaptive strategies such as food preservation and herd composition and management predominate. These strategies are preferred because of their ease of implementation and also culturally acceptable. With increasing drought severity and other factors like increase in population growth, there has been decline in grazing areas limiting transhumance activities. This has stemmed the adoption of non-pastoral activities such as crop farming, craftwork, poultry keeping, petty trade and dependence on external assistance. The traditional adaptive strategies play a key role in surviving the droughts. Due to their pastoral nature, the non-pastoral sedentary practices do not fit their lifestyles and are less practiced especially by men but taken up much better by women who are left at home. Therefore, efforts to enhance pastoral resilience in the semi-arid areas should strengthen the traditional practices as well as capacity building on the non-pastoral activities.

Cold-water pollution impacts on two ‘warm-water’ riverine fish: interactions of dam size and life-history requirements

Context Temperature regulates most ecological processes in freshwater ecosystems. Anthropogenic changes to natural thermal regimes, especially cold water released from stratified impoundments (cold-water pollution, CWP), is a widespread and major threat to fish populations globally. Aims Because mitigation options for CWP are often expensive, we aimed to provide robust ecological evidence to inform expenditure. Methods We modelled population responses to CWP remediation for two warm-water fish species (Murray cod and golden perch) downstream of two impoundments (Copeton and Pindari dams) in the semi-arid northern Murray–Darling Basin, Australia. Key results Predicted populations of both species were severely affected by CWP at both sites; however, impacts were species- and site-specific. Effects were greater on golden perch than Murray cod because of their higher temperature requirements for spawning. Predicted spawning opportunities decreased by 77–100% for golden perch and by 38–92% for Murray cod. The larger Copeton Dam had greater impacts than did the smaller Pindari Dam. Conclusions Remediation of CWP can help restore populations and meeting the needs of golden perch may benefit a range of other species. Implications Globally, CWP is a serious threat to warm-water fishes that may compromise and even nullify other restoration efforts. However, restoration may be impeded by current low abundances, angler harvest and restrictions to fish passage.

Effects of Returning Different Organic Materials in Combination with Inorganic Fertilizers on the Diversity of Eukaryotic Microorganisms in Semi-Arid Northern China

Soil eukaryotic microorganisms are important to biodiversity, and returning different kinds of organic materials to the field could improve the biodiversity of soil eukaryotic microorganisms. However, no detailed research has been conducted in the northern China semi-arid area in returning the different organic materials to the field and determining the status of eukaryotic microorganisms. Therefore, we explored the effects of various organic materials returning to the soil in combination with inorganic fertilizer on the diversity and community structure of eukaryotic microorganisms in Shanxi province, China. Soil samples were collected from five different fertilization treatments: chemical fertilizer (F), chemical fertilizer + cattle manure (FM), chemical fertilizer + straw (FS), chemical fertilizer + pig manure (FC) and control without fertilizers (CK). High-throughput sequencing was applied to analyze the eukaryotic diversity and community structure. Results showed that the dominant eukaryotic microorganisms among soil samples were Fungi, Viridiplantae, Metazoa and Protist. Although α-diversity was not significantly different among the five treatments, principal coordinate analysis and permutational multivariate analysis of variance illustrated significant differences (p &lt; 0.001) in β-diversity of eukaryotic microorganism under treatments with different organic materials. Redundancy analysis showed that the soil properties, including total potassium, available nitrogen, available potassium and organic matter were the main factors attributed to eukaryotic microorganisms’ community structure in this region.

PSXII-11 Evaluation of Yellow-Flowered Subspecies Falcata Alfalfa to Purple Flowered Medicago Sativa for Northern Plains: Productivity, Nutrient Profile, and in Vitro True dry Matter Digestibility

Abstract The protein content and nitrogen fixation capabilities of alfalfa (Medicago sativa L.) make it valuable in cropland and rangelands. However, the semi-arid Northern Great Plains climate negatively affects stand establishment and persistence. Falcata alfalfa (Medicago sativa subs. Falcata) produces adventitious shoots from roots, improving stress and drought resistance. This study compared production and forage quality for yellow- flowered falcata alfalfa (FAL) to a conventional alfalfa (var. Vernal [MSP]). Plots were established as randomized complete block design with four replications. Each cultivar was seeded in 2019 as a monoculture. In 2020, two harvests were made and sampled. Dry matter yield (DMY) and nutritive value of alfalfa were determined. Results showed first cut DMY was 4,228±361 and 3,442±720 kg/ha for the FAL and MSP, respectively. Results for forage quality for first harvest indicate that FAL alfalfa had greater (P &amp;lt; 0.05) ash (10.36 vs. 9.85 %), lignin (7. 86 vs. 7. 14 %), acid detergent fiber (ADF: 38.4 vs. 33.4%), neutral detergent fiber (NDF: 45.4 vs. 39.0 %) but less crude protein (CP; 18.7 vs. 21.2 %, DM basis), total digestible nutrients (TDN: 59.2 vs. 55.5%), non- fiber carbohydrates (NFC; 186 vs. 164), sugar (8.4 vs. 7.0 %), in vitro true dry matter digestibility after a 48-h incubation (IVTDMD48: 58.6 vs. 55.8%), compared with FAL. However, for the second harvest, DMY was 2,837±361 kg/ha for FAL, which had greater CP (20.4 vs. 19.4%), similar ADF (35.4 vs. 35.0), NDF (42.7 vs. 41.8 %), and IVTDMD48 (65.6 vs. 64.0%), but lower lignin (7.68 vs. 7.84%) and TDN (58.1 vs 58.9%) than MSP which yielded 2546 ±515 kg/ha. Falcata had greater nutritive value at second cutting and greater yield compared with Medicago but generally differed little for quality, suggesting falcata can be a viable alternative legume for Northern Plains.

The Optimum Calcium Concentration for Seedling Growth of Mongolian Pine (Pinus Sylvestris Var. Mongolica) Under Different Soil Types in Northern Semi-Arid Areas of China

Mongolian pine, as one of the major tree species of the Three-North Shelterbelt Project in the northern semiarid region of China, is very important for ensuring ecological and environmental security. Ca, as an imperative mineral element for plant development and a second messenger, partakes in photosynthesis and affects the growth of plants. However, the optimal calcium concentration for its growth in different soil types is still unclear. In this study, fifteen treatments with combinations of three different soils (e.g., sandy soil, cinnamon soil, dark brown soil) and five calcium concentration gradients (e.g., 0, 100, 200, 400, and 800 mg∙kg-1) were conducted to investigate this effect by measuring the indices of growth, biomass, photosynthetic pigment, gas exchange rate, photosynthates, chlorophyll fluorescence parameters and water use efficiency (iWUE) based on a pot experiment. The results showed that the optimal calcium concentration of Mongolian pine seedlings in sandy soil and cinnamon soil was 0–100 mg∙kg-1, and the optimal calcium concentration of Mongolian pine seedlings in dark brown soil was 100–200 mg∙kg-1. In other words, the results showed that there was an optimal calcium concentration for the growth of Mongolian pine seedlings, and the optimal calcium concentration was different under different soil types. And if the calcium concentration in the soil was too high, it would have an inhibitory effect on Mongolian pine seedlings, low calcium concentration maybe don’t work. The addition of an appropriate amount of exogenous calcium could promote the growth of Mongolian pine seedlings in different soil types. The plant height, basal diameter and biomass of Mongolian pine seedlings all increased significantly after applying an appropriate amount of calcium (p &amp;lt; 0.05); the addition of an appropriate amount of exogenous calcium could promote the photosynthetic characteristics of Mongolian pine seedlings in different soil types. Under sandy soil and cinnamon soil, the peaks for Pn, Gs, Tr, accumulation of soluble sugar and starch of Mongolian pine seedlings occurred at 0–100 mg∙kg-1, and the decreasing trend of the Fv/Fm value was significant in the case of exceeding 200 mg∙kg-1 (p &amp;lt; 0.05), indicating that the growth of Mongolian pine seedlings was affected when calcium concentrations higher than 200 mg∙kg-1 were applied. Moreover, under dark brown soil, the peaks for Pn, Gs, Tr, and accumulation of soluble sugar and starch of Mongolian pine seedlings occurred at 100–200 mg∙kg-1; similarly, the growth of Mongolian pine seedlings was affected when calcium concentrations higher than 200 mg∙kg-1 were applied. Compared with the treatment without calcium, after applying an appropriate amount of exogenous calcium, the water use efficiency of Mongolian pine seedlings in different soil types was significantly improved, though it was significantly reduced at 800 mg∙kg-1 (p &amp;lt; 0.05).

Pollen–vegetation relationship based on lake surface sediments of arid and semi-arid northern China; considerations and limitations

In this paper, we investigated pollen assemblages of 92 lake center surface sediments of arid and semi-arid northern China to statistically disclose the pollen–vegetation relationships at the regional scale and explore considerations and limitations for lacustrine pollen-based reconstructions. As a result, the Principal component analysis (PCA), the Indicator species analysis, the Discriminate analysis (DA), the Random forest (RF), and the Supportive vector machine (SVM) generally reveal positive correlations between pollen assemblages and vegetation types or ecotones and suggests capabilities of pollen to represent regional vegetation and climate. However, the DA, RF, and SVM reveal that the samples of desert steppe, typical steppe, and meadow steppe cannot be differentiated by pollen assemblages, suggesting weaknesses to represent regional vegetation and climate. Mental test analyses of pollen assemblages and azonal vegetation of the dune desert and the Gobi desert yield better correlations than that of regional vegetation, suggesting that the pollen of azonal vegetation distort the regional pollen–vegetation relationships and thus weaken the capabilities to represent regional vegetation and climate. Our results present considerations and limitations for pollen-based past vegetation and climate reconstructions and provide references for interpretations of lacustrine fossil pollen records in arid and semi-arid northern China.

An improved method of using two-dimensional model to evaluate the carrying capacity of regional water resource in Inner Mongolia of China

The evaluation of regional water resource carrying capacity has been repeatedly conducted to provide a scientific basis for the local water resource management and the sustainable development, in particular in the water-limited regions. However, the definition of regional water resource carrying capacity and its evaluation method are still arguable. Through a case study of Inner Mongolia, located in the arid and semi-arid northern China, this paper developed an improved method to calculate regional water resource carrying capacity by the combination of the water supply-demand analysis and the S-shaped curve threshold analysis. The spatial and temporal patterns of the regional water resource carrying capacity in Inner Mongolia during 2000–2019 was evaluated at three scales, namely the province scale, the basin scale and the city scale. The results showed that the average regional water resource carrying capacity of the whole province was 0.25 (the full mark is 1.00); at the basin scale, the Yellow River Basin had the lowest regional water resource carrying capacity (0.17) among all the basins, showing that the utilization of the water resources was unreasonable; at the city scale, the average regional water resource carrying capacities in Hulunbuir and Xilingol were both over 0.25, while those in Alxa, BayanNur and Wuhai were below 0.1; Hulunbuir had 25.48 billion m3 water surplus, while BayanNur suffered from an average water deficit of 4.51 billion m3 from 2000 to 2019. This paper has provided a reasonable way to measure the regional water resource carrying capacity using an improved method by incorporating S-shaped curve threshold analysis, which may have a wider application for the clustering and optimization of regional water management. In addition, the spatial and temporal patterns of regional water carrying capacity are beneficial for policymakers in the implementation of the effective water usage.

Human pressures constrain Eurasian otter occurrence in semiarid Northern Africa

Populations inhabiting the periphery of species distribution ranges may experience suboptimal environmental conditions and higher vulnerability to anthropogenic pressures. Disentangling the role of natural and human-related factors and the relationships among them in these marginal areas is thus key to understand and prevent species declines and range reductions. We analysed Eurasian otter (Lutra lutra) occurrence patterns in relation to anthropogenic pressures and natural environmental gradients in Morocco, an area constituting the arid limit of the species’ global range. The probability of otter occurrence was higher as terrain ruggedness increased and at intermediate elevations, and lower in catchments exposed to higher anthropogenic pressures. Otters tended to be rare at higher elevations and in areas with less annual precipitation, probably as a result of trophic resource limitations and large water flow fluctuations, respectively. A combination of natural and anthropogenic factors, both at drainage area and local scales, was needed to understand the current occurrence of the species. Our study highlights a need for urgent action to conserve the Eurasian otter in northern Africa, where freshwater ecosystems and their associated biodiversity are threatened by rapid human development in areas of marginal climatic conditions.

Piping formation and distribution in the semi-arid Northern Negev environment: A new conceptual model

Soil piping is a complex erosion process caused by subsurface water flow. We studied the effects of soil cracks and hillslope aspects on piping development and spatial distribution, and introduce a conceptual model of piping development in semi-arid environments. The model addresses factors that substantially influence piping formation: rainfall regime, solar radiation, soil properties, and geospatial characteristics extracted from unmanned aerial vehicle scans. To provide evidence for the ideas presented in the conceptual model, 322 pipes were sampled and measured in the field. Soil texture, sodium, calcium magnesium and organic matter contents, and sodium adsorption ratio (SAR) were analyzed using standard laboratory methods. Our results demonstrate the profound effects of subsurface soil properties on piping-formation processes but do not fully explain substantial differences in spatial distribution between north- and south-facing slopes. However, the synergy of soil properties, rainfall data, and simulated differences in heat flux between aspects led to the development of a landscape with considerably more pipes in the south-facing slopes.