Rainfall anomalies are a significant driver of cropland expansion

Impacts of rainfall and rainfall anomalies on the population dynamics of rodents in southeast Asian rice fields

BACKGROUND

The mechanisms that regulate multi-annual population dynamics of rodent pest species of cereal crops is often unknown. Better knowledge of such aspects can aid pest management and in turn improve food security and human health. The patterns and processes of the population dynamics of Rattus argentiventer, in rice fields of Indonesia, and Rattus tanezumi, in rice fields of the Philippines were assessed in this article.

RESULTS

The meta-analysis of trapping data over 20 years in Indonesia, and 16 years in the Philippines indicated that rodent populations in rice fields did not show a regular multi-annual pattern. Rattus argentiventer populations in Indonesia responded to less rainfall from the current year. Rattus tanezumi populations in the Philippines responded positively to both rainfall and rainfall anomaly with a 1-year time lag.

CONCLUSIONS

Our study of long-term population data indicates that certain combinations of rainfall parameters could be useful to predict years when there is higher rodent abundance in rice fields. The key rodent pest species in rice fields in Indonesia (R. argentiventer) and the Philippines (R. tanezumi) differ, and the populations of each species respond differently to rainfall anomalies. Other factors such as crop cover and water availability may also be important and should be considered in future work. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Patterns of rainfall and temperature and their relationships with potential evapotranspiration rates over the period 1981-2022 in parts of central, western, southern, and southwestern Uganda

Uganda in East Africa is experiencing highly variable rainfall which is exacerbated by temperatures warming at faster rates. This study analyzed rainfall and temperature patterns in comparison with the potential evaporation transpiration rates (PETs) for parts of Central, Western, Southern, and Southwestern Uganda for varying periods from 1981 to 2022. For rainfall onset date (OD), threshold of 0.85 mm for a rainy day, rainfall of 20 mm accumulated over 5 days with at least 3 rain days, and dry spell not exceeding 9 days in the next 30 days were used. The rainfall cessation dates (RCDs) are determined when water balance (WB) falls below 5 mm in 7 days in the last month of the expected season (May and December) for the first and second season, respectively. Standardized rainfall anomaly was utilized to show seasonal and annual rainfall variability. Pearson's correlation (r) coefficient was used to show the relationship between weather variables (rainfall, temperature) and PET at five rainfall stations. Results showed highly varied onset and cessation dates for March-May (MAM) seasonal rainfall compared to those of September-December (SOND). Results showed highly variable onset and cessation of rainfall over the region and statistically significantly increasing trends in both maximum and minimum temperatures across the region, with the highest rate of increase of maximum and minimum temperature of 0.70 and 0.65 °C per decade respectively. Moreover, the maximum temperature and PET showed strong positive correlation coefficient (r) that ranged from 0.76 to 0.90 across the regions, which likely contribute to excess evaporation from the surfaces, soil moisture deficits that negatively affect plant biomass production, low crop yields and food insecurity. PET and rainfall revealed insignificant statistical negative correlation as indicated by the correlation coefficient ranging from - 0.04 to - 0.22. We recommend water management and conservation practices such as mulching, zero tillage, agroforestry, planting drought-resistant crops, and using affordable irrigation systems during period of water deficit.

Projected patterns of land uses in Africa under a warming climate

Land-use change is a direct driver of biodiversity loss, projection and future land use change often consider a topical issue in response to climate change. Yet few studies have projected land-use changes over Africa, owing to large uncertainties. We project changes in land-use and land-use transfer under future climate for three specified time periods: 2021-2040, 2041-2060, and 2081-2100, and compares the performance of various scenarios using observational land-use data for the year 2020 and projected land-use under seven Shared Socioeconomic Pathways Scenarios (SSP): SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0 and SSP5-8.5 from 2015 to 2100 in Africa. The observational land-use types for the year 2020 depict a change and show linear relationship between observational and simulated land-use with a strong correlation of 0.89 (P < 0.01) over Africa. Relative to the reference period (1995-2014), for (2021-2040), (2041-2060), (2081-2100), barren land and forest land are projected to decrease by an average of (6%, 11%, 16%), (9%, 19%, 38%) respectively, while, crop land, grassland and urban land area are projected to increase by (36%, 58%, and 105%), (4%, 7% and 11%), and (139%, 275% and 450%) respectively. Results show a substantial variations of land use transfer between scenarios with major from barren land to crop land, for the whole future period (2015-2100). Although SSP4-3.4 project the least transfer. Population and GDP show a relationship with cropland and barren land. The greatest conversion of barren land to crop land could endanger biodiversity and have negative effects on how well the African continent's ecosystem's function.

Rainfall-induced changes in aquatic microbial communities and stability of dissolved organic matter: Insight from a Fen river analysis

Microbial communities are pivotal in aquatic ecosystems, as they affect water quality, energy dynamics, nutrient cycling, and hydrological stability. This study explored the effects of rainfall on hydrological and photosynthetic parameters, microbial composition, and functional gene profiles in the Fen River. Our results demonstrated that rainfall-induced decreases in stream temperature, dissolved oxygen, pH, total phosphorus, chemical oxygen demand, and dissolved organic carbon concentrations. In contrast, rainfall increased total dissolved solids, salinity, and ammonia-nitrogen concentrations. A detailed microbial community structure analysis revealed that Cyanobacteria was the dominant microbial taxon in the Fen River, accounting for approximately 75% and 25% of the microalgal and bacterial communities, respectively. The abundance of Chlorophyta and Bacillariophyta increased by 47.66% and 29.92%, respectively, whereas the relative abundance of Bacteroidetes decreased by 37.55% under rainfall conditions. Stochastic processes predominantly affected the assembly of the bacterial community on rainy days. Functional gene analysis revealed variations in bacterial functions between sunny (Sun) and rainy (Rain) conditions, particularly in genes associated with the carbon cycle. The 3-oxoacyl-[acyl-carrier-protein] reductase gene was more abundant in the Fen River bacterial community. Particular genes involved in metabolism and environmental information processing, including the acetyl-CoA C-acetyltransferase (atoB), enoyl-CoA hydratase (paaF), and branched-chain amino acid transport system gene (livK), which are integral to environmental information processing, were more abundant in Sun than the Rain conditions. In contrast, the phosphate transport system gene, the galactose metabolic gene, and the pyruvate metabolic gene were more abundant in Rain. The excitation-emission matrix analysis with parallel factor analysis identified four fluorescence components (C1-C4) in the river, which were predominantly protein- (C1) and humic-like (C2-C4) substances. Rainfall affected organic matter production and transport, leading to changes in the degradation and stability of dissolved organic matter. Overall, this study offers insight into how rainfall affects aquatic ecosystems.

Climate-driven changes in the predictability of seasonal precipitation

Climate-driven changes in precipitation amounts and their seasonal variability are expected in many continental-scale regions during the remainder of the 21st century. However, much less is known about future changes in the predictability of seasonal precipitation, an important earth system property relevant for climate adaptation. Here, on the basis of CMIP6 models that capture the present-day teleconnections between seasonal precipitation and previous-season sea surface temperature (SST), we show that climate change is expected to alter the SST-precipitation relationships and thus our ability to predict seasonal precipitation by 2100. Specifically, in the tropics, seasonal precipitation predictability from SSTs is projected to increase throughout the year, except the northern Amazonia during boreal winter. Concurrently, in the extra-tropics predictability is likely to increase in central Asia during boreal spring and winter. The altered predictability, together with enhanced interannual variability of seasonal precipitation, poses new opportunities and challenges for regional water management.

Climate change unequally affects nitrogen use and losses in global croplands

Maintaining food production while reducing agricultural nitrogen pollution is a grand challenge under global climate change. Yet, the response of global agricultural nitrogen uses and losses to climate change on the temporal and spatial scales has not been fully characterized. Here, using historical data for 1961-2018 from over 150 countries, we show that global warming leads to small temporal but substantial spatial impacts on cropland nitrogen use and losses. Yield and nitrogen use efficiency increase in 29% and 56% of countries, respectively, whereas they reduce in the remaining countries compared with the situation without global warming in 2018. Precipitation and farm size changes would further intensify the spatial variations of nitrogen use and losses globally, but managing farm size could increase the global cropland nitrogen use efficiency to over 70% by 2100. Our results reveal the importance of reducing global inequalities of agricultural nitrogen use and losses to sustain global agriculture production and reduce agricultural pollution.

Droughts and deforestation: Does seasonality matter?

Extreme weather events, particularly droughts, have strong impacts on the livelihoods of populations in rural areas. In a context of low access to insurance and credit markets, households respond to such shocks by implementing different risk-management strategies, which in turn are likely to have an impact on the environment, in particular through land-use changes and deforestation. This paper contributes to the emerging literature on the links between droughts and deforestation: (1) distinguishing responses to previously experienced droughts versus current droughts, and (2) disentangling the time of the agricultural season at which droughts occur. We show that deforestation declines whenever a drought occurs during the growing season, while it increases whenever a drought occurs during the harvesting season. These impacts are mitigated within protected areas and are exacerbated in more accessible locations, i.e., areas within 4 hours of travel time of main/major cities. By contrast, deforestation outcomes following droughts that occur during the planting season depend on whether the crop considered is maize or cassava.

Climate change and the nonlinear impact of precipitation anomalies on income inequality

Climate anomalies, such as floods and droughts, as well as gradual temperature changes have been shown to adversely affect economies and societies. Although studies find that climate change might increase global inequality by widening disparities across countries, its effects on within-country income distribution have been little investigated, as has the role of rainfall anomalies. Here, we show that extreme levels of precipitation exacerbate within-country income inequality. The strength and direction of the effect depends on the agricultural intensity of an economy. In high-agricultural-intensity countries, climate anomalies that negatively impact the agricultural sector lower incomes at the bottom end of the distribution and generate greater income inequality. Our results indicate that a 1.5-SD increase in precipitation from average values has a 35-times-stronger impact on the bottom income shares for countries with high employment in agriculture compared to countries with low employment in the agricultural sector. Projections with modeled future precipitation and temperature reveal highly heterogeneous patterns on a global scale, with income inequality worsening in high-agricultural-intensity economies, particularly in Africa. Our findings suggest that rainfall anomalies and the degree of dependence on agriculture are crucial factors in assessing the negative impacts of climate change on the bottom of the income distribution.

Rainfall Variability and Rice Sustainability: An Evaluation Study of Two Distinct Rice-Growing Ecosystems

The inconsistency of the Indian monsoon has constantly threatened the country’s food production, especially key food crops such as rice. Crop planning measures based on rainfall patterns during the rice-growing season can significantly improve the sustainable water usage for water-intensive crops such as rice. This study examines the variability of Indian monsoonal rainfall in rainfed and irrigated rice-cultivating regions to improve rainfall utilization and irrigation water-saving practices. Two distinct rice-growing conditions in southern peninsular India are chosen for this study. The preliminary seasonal rainfall analysis (1951–2015) showed anomalies in the Sadivayal (rainfed rice) region compared to the Karaikal (irrigated rice). The dry-spell analysis and weekly rainfall classification suggested shifting the sowing date to earlier weeks for the Thaladi season (September–February) and Kar season (May–September) to avoid exposure to water stress in Sadivayal. Harvesting of excess rainwater during the wet weeks is proposed as a mitigation strategy for Karaikal during the vegetative stage of the Kuruvai season (June–October) and Late Thaladi season (October–February), where deficit rainfall is expected. Results showed that an adaptation strategy of early sowing is the most sustainable measure for rainfed rice cultivation. However, harvesting the excess rainwater is an ideal strategy to prevent water stress during deficient rainfall periods in irrigated rice farming. This comparative study proposes a comprehensive rainfall analysis framework to develop sustainable water-efficient rice cultivation practices for the changing rainfall patterns.

Understanding impacts of cropland pattern dynamics on grain production in China: A integrated analysis by fusing statistical data and satellite-observed data

Detailed information on spatial distribution of croplands and grain yields is crucial for agricultural management and food security, but is often limited by a lack of geospatial data. By integrating satellite observation and statistical data, this study produced new geospatial data of cropland areas and grain yields in China during 2000-2020. We found that the decrease of relatively high-yielding croplands in southern China mainly caused by the expansion of constructed land. Yet, the increase of croplands largely occurred in temperature/water-limited regions of Northern Arid and Semiarid Region (NASR) and Northeast China Plain (NCP). Croplands' decrease in southern China and expansion in NCP and NASR jointly led to the continuous northward shift of the centre of gravity of croplands and grain yields. This spatial transfer of croplands resulted in relatively lower-than- average grain yield per unit area (AGYA) croplands decreasing from 38.96% (2000) to 35.75% (2020), but also relatively higher-than-AGYA croplands decreasing from 38.41% (2000) to 35.01% (2020), implying spatial challenges of grain production. Generally, every 1 km² of cropland loss in traditional high-yield zones required nearly 1-3 times expansion in area in NASR and NCP to balance grain yield losses. The new geospatial data and these findings from this study could provide valuable information for regional agriculture development and policy marking.

Upscaling tropical restoration to deliver environmental benefits and socially equitable outcomes

The UN Decade on Ecosystem Restoration offers immense potential to return hundreds of millions of hectares of degraded tropical landscapes to functioning ecosystems. Well-designed restoration can tackle multiple Sustainable Development Goals, driving synergistic benefits for biodiversity, ecosystem services, agricultural and timber production, and local livelihoods at large spatial scales. To deliver on this potential, restoration efforts must recognise and reduce trade-offs among objectives, and minimize competition with food production and conservation of native ecosystems. Restoration initiatives also need to confront core environmental challenges of climate change and inappropriate planting in savanna biomes, be robustly funded over the long term, and address issues of poor governance, inadequate land tenure, and socio-cultural disparities in benefits and costs. Tackling these issues using the landscape approach is vital to realising the potential for restoration to break the cycle of land degradation and poverty, and deliver on its core environmental and social promises.

Physiological and Molecular Characterization of the Differential Response of Broccoli (Brassica oleracea var. Italica) Cultivars Reveals Limiting Factors for Broccoli Tolerance to Drought Stress

Broccoli is a cruciferous crop rich in health-promoting metabolites. Due to several factors, including anthropogenic global warming, aridity is increasing in many cultivation areas. There is a great demand to characterize the drought response of broccoli and use this knowledge to develop new cultivars able to maintain yield under water constraints. The aim of this study is to characterize the drought response at the physiological and molecular level of different broccoli (Brassica oleracea L. var. Italica Plenck) cultivars, previously characterized as drought-sensitive or drought-tolerant. This approach aims to identify different traits, which can constitute limiting factors for drought stress tolerance in broccoli. For this purpose, we have compared several physiological parameters and the complete profiles of amino acids, primary metabolites, hormones, and ions of drought-tolerant and drought-sensitive cultivars under stress and control conditions. We have found that drought-tolerant cultivars presented higher levels of methionine and abscisic acid and lower amounts of urea, quinic acid, and the gluconic acid lactone. Interestingly, we have also found that a drought treatment increases the levels of most essential amino acids in leaves and in florets. Our results have established physiological and molecular traits useful as distinctive markers to predict drought tolerance in broccoli or which could be reliably used for breeding new cultivars adapted to water scarcity. We have also found that a drought treatment increases the content of essential amino acids in broccoli.

Impact of Climate Change on Agriculture and Its Mitigation Strategies: A Review

Climate change is a global threat to the food and nutritional security of the world. As greenhouse-gas emissions in the atmosphere are increasing, the temperature is also rising due to the greenhouse effect. The average global temperature is increasing continuously and is predicted to rise by 2 °C until 2100, which would cause substantial economic losses at the global level. The concentration of CO2, which accounts for a major proportion of greenhouse gases, is increasing at an alarming rate, and has led to higher growth and plant productivity due to increased photosynthesis, but increased temperature offsets this effect as it leads to increased crop respiration rate and evapotranspiration, higher pest infestation, a shift in weed flora, and reduced crop duration. Climate change also affects the microbial population and their enzymatic activities in soil. This paper reviews the information collected through the literature regarding the issue of climate change, its possible causes, its projection in the near future, its impact on the agriculture sector as an influence on physiological and metabolic activities of plants, and its potential and reported implications for growth and plant productivity, pest infestation, and mitigation strategies and their economic impact.