High Rainfall Years Research Articles

Scheduling irrigation events in corn using three soil water potential strategies

AbstractScheduling irrigation events is important for high corn (Zea mays L.) yield, water use efficiency, economic returns, and water conservation. The use of shallow subsurface drip irrigation (S3DI) is cost effective for small irregular shaped field areas. Currently there are no irrigation scheduling recommendations for S3DI systems for corn production. The objective was to evaluate three water potential value strategies for scheduling irrigation events and the effect on corn yield, test weight, irrigation water use efficiency (IWUE), and value water use efficiency (VWUE). Corn was grown multiple years (2012–2013; 2019–2023) at two locations (Dawson and Shellman, GA) using soil water potential sensors to schedule irrigation events. Sensors were installed at 10 and 20 inches (25 and 50 cm) soil depth. Irrigation events were scheduled when the average water potential was between 40 to 60 cbar (I1), 60 to 80 cbar (I2), 80 to 100 cbar (I3), and compared to a dryland control (I0). There was no difference in corn yield, IWUE, or VWUE between irrigation treatments, but all irrigation treatments had greater yield than I0, except in high rainfall years. At the Shellman location, total water applied for I3 was 46% less than for I1. At Dawson, I2 applied 17% more water than either I1 or I3. Across both sites, I1 and I2 applied 1.5 and 1.3 times more water than I3, respectively. Therefore, irrigation events scheduled at 80 to 100 cbar can be a viable technique for irrigating corn using S3DI without yield reductions while promoting water conservation.

No tillage and leguminous cover crop improve soil quality in a typical rainfed Mediterranean system

Soil and crop management influence soil organic carbon (SOC), chemical composition, and overall soil quality. In a Mediterranean region, a study initiated in 1994 examined the long-term effects of conventional tillage (CT) versus no-tillage (NT) practices. Initially focusing on continuous durum wheat cultivation until 2009, the experiment later introduced a 2-year rotation of durum wheat and Vicia faba L. cover crops in half of the CT and NT fields. SOC was monitored from 2008 to 2018, while microbial biomass (as dsDNA), soluble nitrogen (N), and enzyme activities (EAs) were monitored from 2011 to 2014 to evaluate the rotation’s impact. Between 2009 and 2018, CT yields were on average 15% higher than NT, especially during high rainfall years. NT significantly increased SOC content in the 0–30 cm soil layer, along with higher levels of soluble N, dsDNA, and EAs at 0–10 cm depth. NT led to a 23% and 10% increase in SOC stock and SOC stock per equivalent soil mass compared to CT. EAs increased by over 50% under NT, indicating enhanced biological activity. The SOC increase due to NT was limited to the top 10 cm, with a decrease at deeper depths (up to 50 cm). Introducing cover crops over 4 years did not yield significant impacts, suggesting the need for a longer period to observe noticeable effects. Overall, adopting NT practices resulted in higher SOC concentration, enhanced soil biological activity, and improved biogeochemical cycles, emphasizing the positive impact of NT on soil health and sustainability.

The addition of organic fertilizer can reduce the dependence of dryland yield on rainfall-based on a 32-year long-term study

Clarifying the synergistic effect between rainfall and fertilization in rainfed farming and joint effect on crop yield can provide theoretical basis for improving the sustainable productivity of farmland in dry farming. A 32-year fertilizer regulation experiment was conducted in the dry farming region of the Loess Plateau. According to the precipitation, it was divided into dry, normal and high rainfall years. The influence of long-term fertilization regulation on crop yield and farmland moisture changes under different rainfall years was analyzed, and the regulation mechanism of fertilization and precipitation coordination on crop yield under different rainfall years was explored. The results showed that effects of fertilization on crop yield and water use efficiency (WUE) were closely related to experimental years. In the early stage, the increase in treatments with higher amounts of nitrogen was more significant, while in the later stage, the increase in treatments with less organic fertilizer was more significant. The correlation of crop yield, the whole rainfall (WR), growth period rainfall (GPR), fallow period rainfall (FPR), water storage during sowing (SWS), evapotranspiration (ET), WUE and utilization efficiency of precipitation (PUE)under different rainfall years and treatments was analyzed. The results showed that the crop yield showed that the correlation with PUE showed high> dry> normal rainfall year, and the correlation with WUE showed the law of dry> high> normal rainfall year. The correlation of organic fertilizer treatments was lower than that of single chemical fertilizer. With the years extension of application organic fertilizer, application low amount of organic fertilizer can improve crop yield by improving PUE, and can achieve the effect of application high amount of organic fertilizer. No matter what the rainfall years, the long-term application of organic fertilizer can make full use of the rainfall to improve the WUE, and then ensure the sustainability of crop yield.

Pearl Millet–Groundnut Cropping Systems for the Sahel

A two-year study of pearl millet–groundnut cropping systems across two fertilizer levels was conducted in Maradi, Niger, in the Sahelian zone of West Africa. The objective of this study was to identify the best cropping system with and without fertilizer application. The experiment was conducted with ten treatment combinations of five pearl millet and groundnut cropping systems (pearl millet and groundnut sole crops, and three pearl millet—groundnut intercrops) and two fertilizer levels. Yields were approximately 300 kg ha−1 higher in the 2022 high rainfall year than in 2021, but the year did not interact with cropping systems or fertilizer application. All the intercropping systems had an LER above 1.0, and land use efficiency increased by 19 to 41%. Fertilizer application increased yields in all cropping systems by 200 to 600 kg ha−1. The government subsidy increased the value-to-cost ratio by 0.5 to 2.5 units and was required for the economic response for pearl millet sole and intercrops in 2022. The groundnut sole cropping system had the greatest economic response to fertilizer application. Based on the risky environment and multiple end uses needed by producers, the intercrop system M-G: 1:3:1 with fertilizer application is the best option to optimize pearl millet and groundnut production.

Monsoonal wet season influences the migration tendency of a catadromous fish (barramundi Lates calcarifer).

Many animals exhibit partial migration, which occurs when populations contain coexisting contingents of migratory and resident individuals. This individual-level variation in migration behaviour may drive differences in growth, age at maturity and survival. Therefore, partial migration is widely considered to play a key role in shaping population demography. Otolith chemistry and microstructural analysis were used to identify the environmental- and individual-specific factors that influence migratory behaviour in the facultatively catadromous barramundi (Lates calcarifer) at two distinct life history stages: firstly, as juveniles migrating upstream into fresh water; and secondly, as adults or sub-adults returning to the estuarine/marine spawning habitat. Monsoonal climate played an important role in determining the migration propensity of juveniles: individuals born in the driest year examined (weak monsoon) were more than twice as likely to undergo migration to freshwater than those born in the wettest (strong monsoon) year. In contrast, the ontogenetic timing of return migrations to the estuary by adults and sub-adults was highly variable and not strongly associated with the environmental parameters examined. We propose that scarce resources within saline natal habitats during lower rainfall years may provide an ecological incentive for juveniles to migrate upstream, whereas more abundant resources in higher rainfall years may promote resident life histories within estuaries. We conclude that inter-annual climatic variation, here evidenced by monsoonal strength, likely plays an important role in driving the persistence of diversified life histories within wild barramundi populations.

Root Development and Subsoil 15N-labelled N Uptake in Soybean (Glycine max (L.) Merr.)

The aim of this study was to investigate fertiliser-derived N uptake of soybean from different depths of the soil under field conditions. In addition, soybean root growth in sandy and loess soil was evaluated to understand the impact of site and soybean variety characteristics on soybean N uptake under continental conditions in Central Europe. Root analysis to determine rooting depth and root length density (RLD) was carried out using the profile wall method at three growth stages and two soybean cultivars (Glycine max (L.) Merr. cvs. Merlin and Sultana) in three consecutive years at two locations in eastern Germany. Fertiliser-derived N uptake of soybean from the soil surface and the subsoil was determined at 0.3 and 0.6 m depths using 15N-labelled nitrate N. Root studies showed that soybean roots grew up to 1.4 m on sandy and loess soil sites. Root length densities of up to 2.4 cm cm−3 were documented in the topsoil. By means of 15N application, soybean was shown to take up 15% of the surface-applied nitrogen in the dry growing season and 67 % in high rainfall years, between 19 and 77 % of the nitrogen placed at 0.3 m soil depth, and between 2 and 64 % of the nitrogen placed at 0.6 m soil depth by flowering. The field trials showed that soybeans can absorb a high proportion of the nitrogen placed in the subsoil by flowering time. Due to a well-developed root system reaching deep into the soil, soybeans are able to cover their N demand from soil-borne sources and secure yield formation during dry periods by water uptake from the subsoil.

Analysis of social network effects on water trade in an informal water market

This paper proposes a novel agent-based model (ABM) to assess actual informal water market (IWM) trade—a highly common form of reallocating water globally, but where analysis is challenging due to data paucity. Because, typically, there is not an integrated or centralized institution coordinating transactions in IWMs, social networks and communications between farmers play a key role. This makes applications of ABMs in the informal space appealing and useful. Survey and interview data are used for the model development via a sample of farmers in Mojen Area, Iran. Also, in the final model, some critical human behaviors (e.g. adaptability and self-interest) are described in the form of parameters and formulas, with optimum values calibrated based on the Mojen sample as well as making possible a detailed assessment of the effects on water transaction and farmers’ profit margins. The result of the simulation reveals that IWM trade frees up water for use by other farmers in the Mojen area, especially when stronger social networks are in place where the average number of water transactions will be increased—about 50%. The presence of IWMs also contributes to a more stable cultivation area in dry years, where water trading helps protect perennial crops that have become an increased production system choice in recent years. Further, informal water markets help farmers to optimally use water supply in order to deal with lower rainfall years and fulfil water needs during higher rainfall years due to increasing cultivation areas.

Applying community assembly theory to restoration: overcoming dispersal and abiotic filters is key to diversifying California grassland

Ecologists have explored community assembly through the framework of ecological filters, which predicts that species must overcome a series of challenges (i.e. pass through “filters”) to successfully establish in a given community. In the context of restoration, these filters (dispersal, abiotic, and biotic) can be manipulated to alter the resulting plant community by favoring native species or disadvantaging non‐native invasive species. We conducted two studies manipulating assembly filters at two California grassland sites previously dominated by non‐native species. At Site 1, we explored how variations in sequential seeding of native grasses and forbs (to overcome dispersal and biotic filters caused by priority effects) influenced the resulting community. At Site 2, we explored how thatch removal (to overcome the abiotic filter of light limitation) and herbicide‐based weed control (to overcome the biotic filter of competition from non‐native species) influenced the addition of native forbs into a partially restored grassland. Native forbs at Site 1 did not suffer from arriving after grasses, but native grasses benefited when given 1 year priority over forbs. At Site 2, dethatching increased native forb cover in a high rainfall year. Herbicide application reduced non‐native grass cover in dethatched plots without negatively affecting native cover. Native forb and grass cover were significant predictors of non‐native grass cover. However, they accounted for only 29% of the variation observed, suggesting there are other influential factors not considered in this study. Our results suggest that forbs can be incorporated into established native grasslands more successfully after dethatching.

Spatiotemporal Rainfall Variability and Trends over the Mahi Basin, India

Climate change can have an influence on rainfall that significantly affects the magnitude frequency of floods and droughts. Therefore, the analysis of the spatiotemporal distribution, variability, and trends of rainfall over the Mahi Basin in India is an important objective of the present work. Accordingly, a serial autocorrelation, coefficient of variation, Mann–Kendall (MK) and Sen’s slope test, innovative trend analysis (ITA), and Pettitt’s test were used in the rainfall analysis. The outcomes were derived from the monthly precipitation data (1901–2012) of 14 meteorology stations in the Mahi Basin. The serial autocorrelation results showed that there is no autocorrelation in the data series. The rainfall statistics denoted that the Mahi Basin receives 94.8% of its rainfall (821 mm) in the monsoon period (June–September). The normalized accumulated departure from the mean reveals that the annual and monsoon rainfall of the Mahi Basin were below average from 1901 to 1930 and above average from 1930 to 1990, followed by a period of fluctuating conditions. Annual and monsoon rainfall variations increase in the lower catchment of the basin. The annual and monsoon rainfall trend analysis specified a significant declining tendency for four stations and an increasing tendency for 3 stations, respectively. A significant declining trend in winter rainfall was observed for 9 stations under review. Likewise, out of 14 stations, 9 stations denote a significant decrease in pre-monsoon rainfall. Nevertheless, there is no significant increasing or decreasing tendency in annual, monsoon, and post-monsoon rainfall in the Mahi Basin. The Mann–Kendall test and innovative trend analysis indicate identical tendencies of annual and seasonal rainfall on the basin scale. The annual and monsoon rainfall of the basin showed a positive shift in rainfall after 1926. The rainfall analysis confirms that despite spatiotemporal variations in rainfall, there are no significant positive or negative trends of annual and monsoon rainfall on the basin scale. It suggests that the Mahi Basin received average rainfall (867 mm) annually and in the monsoon season (821 mm) from 1901 to 2012, except for a few years of high and low rainfall. Therefore, this study is important for flood and drought management, agriculture, and water management in the Mahi Basin.

Statistical study and analysis of annual rainfall in the Naama region (Algeria)

Knowing the recent evolution and variability of the climate in arid and semi-arid regions is a necessity to anticipate what the consequences on the environments and societies of these regions could be, and thus define sustainable adaptation policies. In this modest work we studied the evolution of rainfall in an arid region. Thus, a good knowledge of the rainfall distribution both in time and in space, is essential to identify on the one hand the critical periods of drought to which the crops are exposed and on the other hand the favorable zones and the zones unfavorable. In this perspective, we have contributed to study the essential element of the balance which is the precipitations by using the statistical treatment and the analysis of the indices of dryness, also we adopted a methodology which is characterized by the Collection of the pluviometric data and creation from a computer database.
 The calculation of the indices for the different stations reveals the existence of two distinct wet and dry periods. Drought years are more notable as they can set in for 4 years. There is a decrease in rainfall during this study period but it is also interrupted by other years of high rainfall in certain regions such as El Kheiter and Mecheria. It is as if the further south you go, the more the drought impact is present.

Functional traits' annual variation exceeds nitrogen-driven variation in grassland plant species.

Effective application of functional trait approaches to ecological questions requires understanding the patterns of trait variation within species as well as between them. However, few studies address the potential for intraspecific variation to occur on a temporal basis and, thus, for trait-based findings to be contingent upon sampling year. To quantify annual variation in the functional traits of grassland plant species, we measured specific leaf area, leaf dry matter content, plant height, and chlorophyll content in 12 shortgrass prairie plant species. We repeated these measurements across 4years, both in long-term nitrogen addition plots and in corresponding control plots. Three of the four traits showed significant year-to-year variation in a linear mixed model analysis, generally following a pattern of more acquisitive leaf economics spectrum traits in higher rainfall years. Furthermore, two of the measured traits responded interactively to nitrogen addition and sampling year, although only one, leaf dry matter content, showed the expected pattern of stronger nitrogen responses in high rainfall years. For leaf dry matter content and specific leaf area, trait responses to sampling year were larger than responses to the nitrogen addition treatment. These findings illustrate that species' functional traits can respond strongly to environmental changes across years, and thus that trait variation in a species or community is likely to extend beyond the values and patterns observed in any single year.

Impact of high-density managed aquifer recharge implementation on groundwater storage, food production and resilience: A case from Gujarat, India

Study regionThe study region is the Kamadhiya catchment (1150 km2), located in the Saurashtra region of the western state of Gujarat, India. The region has seen intensive development of check dams (CDs) for groundwater recharge with an estimated 27,000 CDs constructed up until 2018. Study focusThe impact of CDs on groundwater storage, food production and resilience are assessed for Kamadhiya catchment by estimating and comparing changes, across periods of low and high CD development, in potential recharge from CDs, rainfall trends, and irrigation demand. The analysis is carried out for the period from 1983 to 2015. New hydrological insights for the regionGroundwater storage gains observed following CD development can partly be attributed to an increase in high rainfall years after several drought years. Groundwater demand for irrigation has increased substantially, outweighing increase in groundwater recharge from CDs. This deficit in supply relative to demand is greatest in dry years, and when considered together with the low inter-annual carry-over storage of the region’s hardrock aquifers, means that CDs capacity to enhance groundwater storage and mitigate the negative impacts of drought remains limited. Findings suggest that a standalone focus on MAR, unless complemented by greater emphasis on management of water demand and groundwater resources more broadly, may not be sufficient to achieve the long-term goals of sustainable groundwater and concurrently expanding agricultural crop production.

Personalities are not associated with different reproductive tactics in male Cape ground squirrels, Xerus inauris

Personality may influence social living and the maintenance of alternative reproductive tactics (ARTs). In some species, suppressing aggression may be important for facilitating social living, and different personalities may be linked with different types of social associations. Yet, few studies have examined personality in species with low levels of aggression. In Cape ground squirrels, males have two discrete ARTs. Males either live in family groups (‘natal’) or all-male groups (‘band’) and lack physical aggression and territoriality. We measured docility (during trapping and handling in 2014–2019, N males = 275) and activity and exploration (during an open field test in 2015, N males = 34) in adult males to determine whether personality contributes to the maintenance of ARTs. We found repeatability in docility (adjusted repeatability = 0.25–0.26) but not in activity or exploration, and docility was not associated with different ARTs. However, docility and ARTs were influenced by abiotic and biotic factors. Males were more docile after their first capture, and older males (longer on-site tenure) tended to be less docile. In years of higher rainfall, there were more band males, suggesting that ARTs may depend on ecological conditions. • Cape ground squirrels are a highly social species with low rates of aggression. • Males have two discrete reproductive tactics; ‘natal’ and all-male ‘band’ groups. • Males have docile personalities. • Personalities are not associated with different reproductive tactics. • Males became less docile with longer on-site tenure (years captured).

Economic penalties associated with irrigation during high rainfall years in the southeastern United States

Although cotton is a drought-tolerant crop, irrigation is still needed to ensure productivity, even in the humid Southeastern United States. Irrigation must be carefully managed to limit unnecessary water use while ensuring maximum economic productivity. To better understand the costs and net returns of irrigation and cultivar selection, field experiments were conducted in 2016 and 2017 to compare cotton lint yield and fiber quality in dryland plots and plots irrigated using the University of Georgia checkbook method (UGA Checkbook) at a field site near Camilla, Georgia. Results showed cultivar differences in fiber quality parameters of micronaire and uniformity in 2016, but there was no cultivar difference in fiber quality in 2017. Cultivar differences were not observed in yield or net returns for both years. However, stoplight chart analysis of net returns indicated differences in cultivar selection for irrigated or dryland production. ST 6182 GLB2 would be a better option for a producer to minimize downside risk under dryland conditions, and PHY 333 WRF would be a better option under irrigated production. Results also indicated that broadly applying simplistic water balance approaches could decrease yield, water productivity, and net returns, especially in environments where rainfall is sufficient yet unpredictable. Overirrigation affected some fiber quality parameters but did not impact the overall market price for cotton. In 2016, irrigating according to the UGA Checkbook method negatively impacted yield and net returns. In 2017, irrigation did not affect yield but negatively impacted net returns. Average losses in net returns associated with excessive irrigation in these two wet years were $336 per hectare for net return over irrigation variable costs, and $645 per hectare for net return over irrigation total costs. Implementing robust, efficient irrigation strategies is necessary to achieve high cotton yields, reduce water usage, and improve economic returns.

Fire regime and climate determine spatial variation in level of serotiny and population structure in a fire-killed conifer

Fire-killed serotinous trees are often dominant species in fire-prone regions with contrasting wet and dry seasons. We studied a serotinous fire-killed conifer (Callitris preissii, Cupressaceae) to identify the influence of fire regime and climate on geographic variation in level of serotiny, recruitment and population structure. We measured population size distributions, seedling recruitment and level of serotiny for sample stands across a climatic gradient from mesic coastal (including two islands) to semi-arid inland sites in SW Australia. Trees on islands were mostly non-serotinous and were only weakly serotinous on the adjacent mainland in the higher rainfall West coast region. In the semi-arid Goldfields and South inland, and the higher rainfall South coast region, trees were more strongly serotinous with up to six cohorts of closed cones retained on trees. Level of serotiny was stronger at the drier end of the climatic gradient where severe to extreme fire danger weather occurs most frequently, and where vegetation type (e.g., shrublands) supports frequent crown-type, stand-replacing fires. Recruitment was most abundant post-fire in all regions, but seedlings also established inter-fire where there was regular seed fall due to low level of serotiny or spontaneous release of seeds from old cones on trees with a high cone load. Population structures for mainland stands shifted from approximately reverse-J (indicating continuous recruitment) in mesic regions to mainly unimodal (establishment mostly after fire) in drier, inland regions, although some long-unburned inland stands showed occasional inter-fire recruitment, likely linked to high rainfall years. Unimodal population structures characterized islands, where previous studies have identified herbivory on seedlings by refugial populations of native macropods as a limiting factor on inter-fire establishment. Understanding landscape context, response to disturbance, biotic interactions and reproductive traits of dominant species is essential in conservation planning in a rapidly changing global environment.

Cotton Crop Yield Prediction using Data Mining Technique

Cotton is a very important crop, as India leads it in terms of production in the world; and also that a vast number of manpower is engaged in farming as well as post-harvest processing and management of different derivatives of it. Weather is crucial for the productivity of the crop. The challenges of climate change; availability of limited land and water for farming; lake of knowledge for good cultivation practices and judicious use of agricultural inputs with farmers are critical hindrances for improving productivity. This requires thorough research on land preparation and use, how to improve fertility of soil, good agronomic practices in lieu of variable climatic conditions, etc. All the talukas of the three districts of North Gujarat where cotton is cultivated have been selected purposively for this study. The effect of soil type, soil pH, soil organic carbon, phosphorous, potassium, precipitation and temperature were selected as independent factors. The yield of cotton crop has positive correlation with the selected parameters. The data sets were applied for analytical process to WEKA. The difference between average of predicted and actual yields of all talukas for high rainfall year 2013 was only 1.55 per cent. The difference between actual and predicted yield for the low temperature year (2015) in different talukas of all talukas was only 0.44 per cent.

Seroprevalence of

Toxoplasma gondii is a ubiquitous protozoan transmitted by felids and infection, morbidity, and mortality occur in numerous marsupial species. This study explores the relationship between cat exposure and Toxoplasma in burrowing bettongs (Bettongia lesueur) in the Arid Recovery Reserve (ARR), South Australia. We estimated seroprevalence, using a modified agglutination test for T. gondii-specific immunoglobulins, in cat-free and cat-exposed bettong populations. Tissue samples collected opportunistically from bettong carcasses and from cats within and around the reserve were screened for T. gondii DNA using multiplex real-time polymerase chain reaction (M-qPCR). Two cats trapped inside the ARR tested positive (50.0%; 95% CI: 15.0–85.0%). All bettongs tested from the cat-free (n = 48) and cat-exposed (n = 19) exclosures were seronegative (95% CI: 0–7.41% and 0–16.82% respectively). We found no evidence of fatal toxoplasmosis, with all bettong carcasses negative on M-qPCR (n = 11). We propose that T. gondii was not detected in bettongs coexisting with cats primarily due to low exposure of bettongs at the time of sampling, possibly due to poor oocyst viability in arid conditions or low shedding by cats. Ongoing screening throughout high and low rainfall years should be conducted to better establish the risk of Toxoplasma to bettongs in the ARR.

Evaluation of saline water irrigation on cotton growth and yield using the AquaCrop crop simulation model

It is imperative to evaluate the practicality of brackish water irrigation for alleviating the conflict between freshwater resources shortages and food production. Four years experiments were carried out on cotton from 2012 to 2015 seasons with four salinity levels in irrigation water, including 1.3 dS m-1 (CK), 5.4 dS m-1 (S1), 8.8 dS m-1 (S2), and 12.4 dS m-1 (S3) in lowland plain of Hebei in the North China Plain (NCP). Parameters of the FAO AquaCrop model were calibrated with a dataset collected in the 2012 season, and the model was validated with independent data from the next three seasons. Under the condition of saline water irrigation, the simulation of canopy cover, soil water content, soil electric conductivity, biomass, and yield was accurate (the coefficient of determination (R2) > 0.65, the index of agreement (d) > 0.89). The scenario simulations with different salinity levels in irrigation water were run in growing degree days mode in AquaCrop with climatic data from 1958 to 2010. In the high (483 mm) and normal (430 mm) rainfall years, salt was drained out of the soil profile. Whereas, salt was accumulated in the soil profile under the scenario of S2 and S3, while was leaving out the root zone in the scenario of CK and S1 in the low (324 mm) rainfall years. With the salinity of 4.5 dS m-1, the difference between salt inside and outside of the soil profile tends to be zero. Based on the scenario simulations, the relationships between crop evapotranspiration (ETa) and cotton yield and between ETa and water productivity were fitted with a quadratic curve. It is concluded from the scenario simulations that there are real risks in soil salinization for cotton production in the lowland plain of Hebei in the NCP due to saline water irrigation.

Spatial Appraisal of the Impacts of Drought on Agricultural Patterns in Karachi

This paper is aimed at studying the spatial changes in agricultural patterns practiced in the suburbs of Karachi, which is the most densely populated city of Pakistan with high food demands of the inhabitants. This study deals mainly with Physical factors primarily climatic indicators to observe and analyze the changes in the pattern of agricultural production and the types of crops in last 20-30 years. Variability of climate when coupled with anthropogenic factors play important role in the acceleration of problems for farmers. Trends of associated agricultural output observed in different years of high and low rainfall. This study has successfully demonstrated inquisitive approach by using published secondary data from governmental sources and ground verification in recent times. Temporal variation in biomass, was found dependent upon pattern of rainfall and temperature etc. Study reveals that there are clear signs of desertification and drought in the study area.

Vulnerability of an arid zone coastal wetland landscape to sea level rise and intense storms

AbstractArid zone coastal wetlands provide disproportionally important ecosystem services due to their relatively high levels of productivity relative to adjacent terrestrial systems. However, these wetlands are vulnerable to sea level rise as sediments needed for vertical accretion are limited. In order to assess the processes important for vertical accretion in arid zone coastal wetlands, we assessed vertical accretion across an arid zone wetland landscape in Western Australia. We found that overall coastal wetlands were declining in elevation at −0.18 mm yr−1 (± standard error 0.12 mm yr−1). Vertical accretion in mangroves was evident in years of high mean sea level, but this was insufficient to counteract shallow subsidence. The high intertidal cyanobacterial mat and salt flat zones were eroding, particularly in years of high rainfall. We observed retreat of the seaward mangrove fringe associated with tree mortality caused by cyclones, but we also observed recruitment of mangroves onto the high intertidal cyanobacterial mat zone, attributed to higher sea levels. Our study found complexity in the factors causing landscape change across the intertidal zone, where variation in sea level, intense storms, and other climatic and biotic factors interact.