Periods Of Low Rainfall Research Articles

Quantitative identification of nitrate sources in the surface runoff of three dominant forest types in subtropical China based on Bayesian model

Nitrate pollution is a global environmental issue. Forests play an important role in altering hydrological processes and purifying water pollutants in rainfall and runoff. The quantitative identification of nitrate concentration and sources in surface runoff is of great significance for watershed management and water environment improvement. In this study, water quality of surface runoff was monitored in three typical forest types in subtropical eastern China: Phyllostachys pubescens, Cunninghamia lanceolate, and Cyclobalanopsis glauca. Combined with hydrochemical analysis, we adopted the dual isotope approach (δ15N-NO3– and δ18O-NO3–) and Bayesian model (SIAR) to identify nitrate sources in forests that are subject to low anthropogenic disturbance. Results showed that the temporal variability of NO3-N concentrations was similar for all forest types, with higher values in periods of low rainfall and lower values in heavy rainfall periods. The NO3–-N concentration in runoff was much higher in C. glauca forests relative to P. pubescens and C. lanceolata. Both the Cl− concentrations and NO3–/Cl− molar ratio suggested the fertilizer inputs was the dominant source of nitrate in surface runoff. In agreement, δ15N-NO3– and δ18O-NO3– values inferred atmospheric deposition and chemical fertilizers to be the main sources of nitrate in all forest types. The Bayesian model outputs demonstrated that atmospheric deposition was the main source in the runoff in P. pubescens and C. lanceolate forests, contributing 28.83% and 35.08% to the total nitrate, respectively. In contrast, chemical fertilizers were identified as the main source in C. glauca forests, with NH4+ fertilizers and NO3– fertilizers accounting for 27.07% and 24.83%, respectively. Both chemical and isotopic analysis indicated that nitrification had little contribution to nitrate concentrations in runoff. Our results suggest that, even in forests with low anthropogenic disturbance, the application of fertilizer in surrounding agricultural regions should be effectively managed to minimize watershed nitrogen contamination.

Assessment of Spatial Variability and Temporal Dynamics of Dissolved Organic Matter (DOM) at Lower Kinabatangan River Catchment, Sabah.

The spatial and temporal variability of dissolved organic matter (DOM) characteristics and surface water quality in the Lower Kinabatangan River Catchment were determined between October 2015 and May 2016. The objectives of this study were: (i) to distinguish the DOM absorption characteristics and physicochemical quality of surface water draining from different types of land use: oil palm plantation (OP), secondary forest (SF) and semi-natural vegetation (SV); and to examine its temporal variations during dry and wet periods. The collected physicochemical parameters data was analysed and classified based on the Malaysian National Water Quality Standard (NWQS). Findings indicated all the parameters fall into Class I, except for pH, total suspended solids (TSS) and concentration dissolved oxygen (DO). Linear discriminant analysis has been applied to distinguished the physico-chemical and absorption DOM properties data into mutually-exclusive spatial and temporal groups. Interestingly, the pH, DO and total nitrogen values were exhibited as dominant parameters at SV during both low and high rainfall periods. The dominance of these parameters suggested that the spatially and temporally varied water quality were influenced by both natural processes (e.g precipitation rate) and anthropogenic factor (e.g land use change). Whereas, both absorption coefficients (a340) and spectral slope (S275-295) were more dominant at SF and OP respectively. This might be due to increasing terrestrial DOM loadings as well as significant degradation of DOM via microbial and/or photochemical reaction.

Satellite soil moisture observations predict burned area in Southeast Asian peatlands

Fires that emit massive amounts of CO2 and particulate matter now burn with regularity in Southeast Asian tropical peatlands. Natural peatlands in Southeast Asia are waterlogged for most of the year and experience little or no fire, but networks of canals constructed for agriculture have drained vast areas of these peatlands, making the soil vulnerable to fire during periods of low rainfall. While soil moisture is the most direct measure of peat flammability, it has not been incorporated into fire studies due to an absence of regional observations. Here, we create the first remotely sensed soil moisture dataset for tropical peatlands in Sumatra, Borneo and Peninsular Malaysia by applying a new retrieval algorithm to satellite data from the Soil Moisture Active Passive (SMAP) mission with data spanning the 2015 El Niño burning event. Drier soil up to 30 days prior to fire correlates with larger burned area. The predictive information provided by soil moisture complements that of precipitation. Our remote sensing-derived results mirror those from a laboratory-based peat ignition study, suggesting that the dependence of fire on soil moisture exhibits scale independence within peatlands. Soil moisture measured from SMAP, a dataset spanning 2015-present, is a valuable resource for peat fire studies and warning systems.

No downregulation of immune function during breeding in two year‐round breeding bird species in an equatorial East African environment

Some equatorial environments exhibit substantial within‐location variation in environmental conditions throughout the year and yet have year‐round breeding birds. This implies that breeding in such systems are potentially unrelated to the variable environmental conditions. By breeding not being influenced by environmental conditions, we become sure that any differences in immune function between breeding and non‐breeding birds do not result from environmental variation, therefore allowing for exclusion of the confounding effect of variation in environmental conditions. This create a unique opportunity to test if immune function is down‐regulated during reproduction compared to non‐breeding periods. We compared the immune function of sympatric male and female chick‐feeding and non‐breeding red‐capped Calandrella cinerea and rufous‐naped larks Mirafra africana in equatorial East Africa. These closely‐related species occupy different niches and have different breeding strategies in the same grassland habitat. Red‐capped larks prefer areas with short grass or almost bare ground, and breed during low rainfall periods. Rufous‐naped larks prefer areas of tall grass and scattered shrubs and breed during high rainfall. We measured the following immune indices: nitric oxide, haptoglobin, agglutination and lysis, and measured total monthly rain, monthly average minimum (Tmin) and maximum (Tmax) temperatures. Contrary to our predictions, we found no down‐regulation of immune function during breeding; breeding birds had higher nitric oxide than non‐breeding ones in both species, while the other three immune indices did not differ between breeding phases. Red‐capped larks had higher nitric oxide concentrations than Rufous‐naped larks, which in turn had higher haptoglobin levels than red‐capped larks. Tmax was higher during breeding than during non‐breeding for red‐capped larks only, suggesting potential confounding effect of Tmax on the comparison of immune function between breeding and non‐breeding birds for this species. Overall, we conclude that in the two year‐round breeding equatorial larks, immune function is not down‐regulated during breeding.

Fugitive methane emissions through the cover system of a Brazilian landfill cell

This paper evaluates the fugitive emissions of methane through a compacted soil cover layer in a cell of the Metropolitan Center Sanitary Landfill, in Salvador, Bahia, Brazil. Static-flow chamber tests were carried out in cracked and non-cracked soil areas in periods of high and low rainfall. Correlation coefficients between fugitive emissions and variables such as precipitation, moisture content and distance from drains, among others, were tested, and empirical equations are proposed for the estimation of fugitive emissions in both areas. Non-linear multiple regressions were able to fit the experimental results. However, a large number of independent variables were required. The fugitive methane emissions ranged from 0 to 356 (g/m2)/d. During the rainy season, points located in cracked areas showed an increase in emissions, with cracks in the soil acting as preferential flow paths. The opposite occurred in areas with few fissures and cracks. Considering the field biogas recovery rate, fugitive methane emissions accounted for, on average, 12% of the methane produced in the area in the period of analysis.

Deep Groundwater as an Alternative Source of Water in the Ogaden Jesoma Sandstone Aquifers of Somali Region, Ethiopia

Between 2015 and 2018, the Horn of Africa was affected by a series of climatic-induced events, namely El Nino, La Nina, and the Indian Ocean Dipole. These events modified the variability of rainfall patterns and resulted in extended periods of low rainfall, low recharge, and high evapotranspiration. That situation prompted humanitarian water professionals to finance the transportation of water from selected locations with high groundwater potential through water trucks to areas facing groundwater depletion and drought. To mitigate this, UNICEF identified alternative water supplies by exploring sustainable deeper groundwater sources. This paper describes a three-phase methodology of deep groundwater development of wells in the Ogaden Jesoma sandstone aquifers of the Somali region of the Horn of Africa, to a depth of 600 m below ground level. The methodology included the development of groundwater suitability maps using geological and remote sensing data, hydrogeological ground truthing of the maps, and then test drilling at the selected locations. The results concluded that the deep sandstone aquifer of Jesoma can provide fresh water with yields of 15 L/s to the local population of the Somali region. The study provided insights into deep groundwater identification and development as well as adaptive deep borehole drilling as a source for climate-resilient water supplies.

Effects of Understory Vegetation Management on Plant Communities in Oil Palm Plantations in Sumatra, Indonesia

Oil palm plantations have expanded rapidly in recent decades, and are causing substantial impacts on tropical habitats and biodiversity. However, owing to its long lifespan (25-30 years), oil palm forms a much more varied and structurally-complex habitat than many other crops. This can include abundant understory vegetation and also epiphytes on palm trunks. However, the diversity of this plantation vegetation has been poorly studied, and there has been little consideration of the impacts of common plantation vegetation management practices on plant communities. We conducted a long-term vegetation management experiment that forms part of the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme in Riau, Indonesia. We manipulated herbicide and manual cutting regimes within mature oil palm plantations to create three different understory complexity treatments (Reduced, Normal, and Enhanced vegetation) across replicated sets of plots. Plant communities were surveyed before and after experimental understory vegetation treatments began in three different microhabitats: within the middle of the plantation block (core), on the road edge (edge) and on oil palm trunks (trunk). Part of the sampling was also conducted during a drought event. We recorded 120 plant species, which comprised a mixture of native, non-native, ‘beneficial’, and ‘problem’ species. We found substantial variation in plant communities between edge, core, and trunk microhabitats, indicating high levels of heterogeneity within the plantation. There were significant effects of varying understory treatment within both core and edge microhabitats, but no spillover of impacts into the trunk microhabitat. We also observed substantial impacts of drought on plant communities, with declines in either biomass, percentage cover, or richness seen across core, edge, and trunk microhabitats during low-rainfall periods. Our findings highlight the diversity of plant communities that can be supported within oil palm plantations, and the substantial impacts that management decisions, and also drought, can have on them. Given the role that diverse plant communities can have in supporting species in other groups, this is likely to have a significant impact on the wider plantation biodiversity. We suggest that plantation management strategies give greater consideration to within-plantation understory plant communities and choose more wildlife-friendly options where possible.

Long-term responses of desert ant assemblages to climate.

Productivity is a key driver of ecosystem structure and function, so long-term studies are critical to understanding ecosystems with high temporal variation in productivity. In some deserts, productivity, driven by moisture availability, varies immensely over time (rainfall) and space (landscape factors). At high productivity, species richness is expected to be driven in opposing directions by abundance (More Individuals Hypothesis - MIH) and competition. While studies investigating the impacts of spatial variation in productivity on community structure are common, the impacts of temporal variability on productivity are poorly understood. We tested how well rainfall predicted the activity, species numbers and assemblage composition of ants and if responses were moderated by landscape position. We also asked whether the number of species (richness per sampling unit and estimated species richness) responded directly to rainfall or was moderated by ant activity or competition from dominant ants. Over a 22-year period, when annual rainfall fluctuated between 79mm and 570mm, we sampled ants using pitfall traps in paired dune and swale habitats in the Simpson Desert, Australia. We used climate records over this period to model changes in ant assemblages. Activity of dominant ants responded primarily to long-term rainfall, increasing exponentially, while subordinate ants responded to short-term weather and time. Consistent with the MIH, the number of ant species was best predicted by activity, particularly that of subordinate ants. Activity of dominant ants had a declining positive effect on numbers of species. Landscape position strongly predicted species composition, while long-term rainfall determined composition at genus level but not species level. Over time, species composition fluctuated, but several genera consistently increased in activity. Productivity moderators such as long-term rainfall and landscape position are key drivers of ant activity and composition in the study ecosystem, acting indirectly on numbers of species. Numbers of species were explained largely by ant activity, making a strong case for the MIH, but not competition. Longer periods of low rainfall may indirectly reduce species richness in desert ecosystems. However, a trend to increasing richness over time may indicate that conservation management can ameliorate this impact.

Suspect screening and prioritization of chemicals of concern (COCs) in a forest-water reuse system watershed

Much research has assessed organic chemicals of concern (COCs) in municipal wastewater and receiving waters, but few studies have examined COCs in land treatment systems. Many prior studies have implemented targeted methods that quantify a relatively small fraction of COCs present in wastewater and receiving waters. This study used suspect screening to assess chemical features in ground- and surface waters from a watershed where secondary-treated wastewater is irrigated onto 900 ha of temperate forest, offering a more holistic view of chemicals that contribute to the exposome. Chemical features were prioritized by abundance and ToxPi scoring across seasonal sampling events to determine if the forest-water reuse system contributed to the chemical exposome of ground- and surface waters. The number of chemical features detected in wastewater was usually higher than on- and off-site ground- and surface waters; in wastewater, chemical features trended with precipitation in which greater numbers of features were detected in months with low precipitation. The number of chemical features detected in off- and on-site waters was similar. The lower overlap between chemical features found in wastewater and downstream surface waters, along with the similar numbers of features being detected in upstream and downstream surface waters, suggests that though wastewater may be a source of chemicals to ground and surface waters on-site, dissipation of wastewater-derived features (in number and peak area abundance) likely occurs with limited off-site surface water export by the forested land treatment system. Further, the numbers of features detected on site and the overlap between wastewater and surface waters did not increase during periods of low rainfall, counter to our initial expectations. The chemical features tentatively identified in this watershed appear common to features identified in other studies, warranting further examination on the potential for resulting impacts of these on humans and the environment.

Factors Affecting Thrips (Thysanoptera: Thripidae) Population Densities in Watermelon Crops

Watermelon, Citrullus lanatus (Thunb.) Matsum. & Nakai (Cucurbitales: Cucurbitaceae), is one the 5 most-consumed fresh fruits in the world. The thrips Frankliniella schultzei (Trybom) (Thysanoptera: Thripidae) is an important pest of watermelon crops in tropical regions. Among the principal factors that regulate pest populations in crops are phenological stage of the host plant, weather and climate, and natural enemies. Thus, knowledge of such factors may allow the prediction of the risk of pest damage to such crops. The objective of this study was to identify factors that drive F. schultzei population densities in watermelon crops. During 2014 and 2015, we evaluated the effect of abiotic (weather) and biotic (phenological stage of leaves, and occurrence of natural enemies) factors on F. schultzei population densities on watermelon commercial crops. Frankliniella schultzei densities were higher in dry periods with more intense winds. Insect pest density was higher on younger leaves of plants in the vegetative stage. Frankliniella schultzei preferred to attack younger leaves of the plant located at the apex of the branches. The results obtained in this work suggest that the population growth of F. schultzei in watermelon crops is higher in periods of low rainfall. The population densities of F. schultzei depend on the phenological stage of plants, weather, and populations of natural enemies. Farmers should seek to preserve the populations of Chrysoperla sp. (Neuroptera: Chrysopidae), which are an important natural enemy of F. schultzei.

Distribución espacial y temporal de Elmidae (Insecta: Coleoptera) y su relación con los parámetros fisicoquímicos en el río Ocoa, Meta, Colombia

Los élmidos (Coleoptera) son organismos acuáticos de distribución mundial. Sus formas inmaduras y adultas ocupan una amplia gama de sustratos y hábitats, y son un grupo diverso. Este estudio tuvo como objetivo determinar la distribución espacial y temporal de los Elmidae, y su relación con los parámetros fisicoquímicos en el río Ocoa. Se establecieron 15 estaciones de muestreo y se revisaron 210 muestras de macroinvertebrados recolectadas en un sustrato de roca-guijarro utilizando una red Surber (250 μm) en dos periodos hidrológicos contrastantes (de baja y alta precipitación), correspondientes a octubre de 2014 y febrero de 2015. Se obtuvieron 37 organismos (larvas y adultos) de nueve géneros de Elmidae: Heterelmis, Huleechius, Macrelmis, Astrolimnius, Microcylloepus, Neoelmis, Hexacylloepus, Cylloepus, Notelmis y Phanocerus, de los cuales siete corresponden a nuevos registros para la región de la Orinoquia colombiana. En el periodo de baja precipitación hubo una mayor representatividad, con 35 registros de nueve géneros, en tanto que en el periodo de alta precipitación hubo una marcada disminución de la riqueza, con dos registros solamente, correspondientes a dos géneros. En general, la abundancia de Elmidae fue baja a lo largo del río, y en las estaciones ubicadas en el sector que atraviesa la ciudad de Villavicencio, con mayor deterioro del hábitat, se registró la menor abundancia y en algunas no se registraron élmidos. Los efectos ambientales de la urbanización, como la contaminación por materia orgánica y la proliferación de coliformes debida al vertimiento de aguas residuales, fueron los principales factores determinantes de la disminución de la riqueza y la abundancia de estos organismos. Esta es la primera exploración de Elmidae en la zona y contribuye al conocimiento ecológico de la fauna de coleópteros en cuencas urbanas de la Orinoquia colombiana. © 2019. Acad. Colomb. Cienc. Ex. Fis. Nat. Palabras clave: Bioindicador; Coleoptera; Elmidae; Cuenca urbana; Orinoco.

Precipitation variations and shifts over time: Implication on Windhoek city water supply

The scarcity of freshwater is a growing concern around the world, especially in the developing world and is increasingly threatening human survival in less affluent parts of the world. In arid and semiarid regions, freshwater resources are imperative for the survival of populations as well as development activities in urban centres. Preceding assessments for potential solutions have underestimated the scarcity of water by failing to capture main trends of precipitation and the extent of drought periods. This paper aims to investigate rainfall trends for the City of Windhoek, Namibia. A century scale is examined by reconstructing historical precipitation records, and future trends are subsequently estimated and interpolated using Ordinary Kriging in ArcGIS 10.3. Kriging responds and handles spatial correlation much better for observed data points. The results show locations that receive high rainfall and potential periods for harvesting rainwater. The findings further show that the periods of high rainfall are shorter, and after each high rainfall stretch, a long period of lower rainfall follows immediately. Each low rainfall period is anticipated to last longer than the previous one. These scenarios are highly significant for urban managers in dryland cities such as Windhoek, as they demonstrate when water would need to be extra sparingly managed. This study highlights the need for better water management strategies, if cities in dry climates are to survive the anticipated future water crises.

Effects of forestry-driven changes to groundcover and soil moisture on amphibian desiccation, dispersal, and survival.

Over 80% of amphibian species that are declining are forest dependent. Forestry practices are a major cause of forest alterations globally, and it is well documented that clearcutting can contribute to amphibian declines. However, there might be adverse effects of forestry practices other than clearcutting. For example, planting overstory trees in rows (plantations) can change groundcover microhabitats and soil moisture levels, but the effects of this common practice on amphibian populations are not well studied. We compared the impacts of common intensive pine plantation operations to naturally regenerated pine forests on the desiccation, movement rates, behavior, and survival of >900 juvenile southern toads (Anaxyrus terrestris). Pine plantations had significantly more accumulation of conifer needles and less exposed soil, herbaceous groundcover, broadleaf litter, and soil moisture than natural pine forests despite the greater canopy cover at plantations. Litter cover explained 85% of groundcover microhabitat variance among forest types and predicted minimum soil moisture levels. When toads were held in small outdoor enclosures that constrained microhabitat selection, 24-h desiccation rates and 72-h mortality were significantly greater in pine plantation than in naturally regenerated pine forest because of lower soil moisture, especially during low rainfall periods. In large outdoor pens where juvenile amphibians could select microhabitats, movement was strongly directed down slope and increased with precipitation. However, initial speeds were positively associated with pine density, likely because toads were trying to evacuate from the drier high-pine-density areas. High-intensity silviculture practices that eliminate herbaceous or vegetative groundcover, such as roller chopping and scalping, increase amphibian desiccation because planted conifers dry the upper soil layer. Our study highlights the importance of prioritizing lower intensity silviculture practices or lower pine densities to retain groundcover microhabitat that serves as amphibian refugia from dry conditions that are predicted to increase in frequency with climate change.

DIVERSIDAD FÚNGICA EN LA ATMÓSFERA DE LA HABANA (CUBA) DURANTE TRES PERÍODOS POCO LLUVIOSOS

The climate of Havana favors a high representation of fungi in the air during the year, mainly in the day-time. In the periods of low rainfall (November to April), the greatest climatic variations are evident, which can affect the appearance of allergic and respiratory diseases. The objective of this work was to characterize the atmospheric diurnal mycobiota of Havana during three consecutive dry periods. Forty-eight viable volumetric samples were obtained using a slit biocolector (chirana aeroscope) during three periods of low rainfall (November/2012-April/2013, November/2013-April/2014 and November/2014-April/2015). The collected fungi were isolated and identified. Simultaneously, visual identification of spores was conducted on the preparations from a Hirst type sampler (Lanzoni VPPS 2000), on the same day and time as the viable samplings. Subsequently, the concentration, relative density and relative frequency of fungal propagules identified by both methods were calculated. The three evaluated periods were quantitatively and qualitatively similar. Thirtyt two genera were identified, three genera only by viable methodology, 17 by non-viable and 11 by both methodologies. Spores of the order Uredinales and of the family Xylariaceae were also identified by the non-viable method. The genera Cladosporium, Aspergillus, Penicillium, Fusarium and Curvularia highlighted by their abundance and relative frequency. The mycobiota detected in both periods was similar in diversity and concentration of genera. Mean temperature and mean relative humidity were correlated with atmospheric concentrations of fungal propagules. The data provided are useful for the prevention of allergies and respiratory diseases, with a high incidence in the Cuban population during winter and dry periods.

Variación poblacional de Rhodnius prolixus (Reduviidae: Triatominae) en Attalea butyracea (Arecaceae) en la Orinoquia colombiana

El objetivo de esta investigación fue determinar la densidad poblacional de Rhodnius prolixus y de sus estadios de desarrollo, en bosques naturales de Attalea butyracea a lo largo de un periodo hidrológico, en ecosistemas de sabana inundable de la Orinoquia colombiana. Se muestrearon 120 palmas durante un año, usando trampas cebo vivo para Triatominae. Se halló que R. prolixus presenta alta densidad poblacional durante todo el año; que aumenta en época de bajas lluvias y disminuye en los meses de mayor precipitación. También se encontró que todos los estadios de desarrollo están presentes durante todo el año, aunque con diferencias en su representatividad, mostrando una disminución de la densidad a medida que aumenta la etapa de desarrollo. Por otra parte, se observaron altos índices de infestación, colonización y agrupamiento. Lo anterior sugiere que la especie presenta estabilidad de sus poblaciones en bosques de A. butyracea a pesar de la época climática, además de éxito reproductivo y, por ende, con individuos en capacidad de dispersión y colonización de otros micro hábitats en cualquier momento sin importar la condición climática.

Stormwater influences phytoplankton assemblages within the diverse, but impacted Sydney Harbour estuary.

Sydney Harbour is subjected to persistent stress associated with anthropogenic activity and global climate change, but is particularly subjected to pulse stress events associated with stormwater input during episodic periods of high rainfall. Photosynthetic microbes underpin metazoan diversity within estuarine systems and are therefore important bioindicators of ecosystem health; yet how stormwater input affects their occurrence and distribution in Sydney Harbour remains poorly understood. We utilised molecular tools (16S/18S rRNA and petB genes) to examine how the phytoplankton community structure (both prokaryotes and eukaryotes) within Sydney Harbour varies between high and low rainfall periods. The relative proportion of phytoplankton sequences was more abundant during the high rainfall period, comprising mainly of diatoms, an important functional group supporting increased productivity within estuarine systems, together with cyanobacteria. Increased spatial variability in the phytoplankton community composition was observed, potentially driven by the steepened physico-chemical gradients associated with stormwater inflow. Conversely, during a low rainfall period, the proportion of planktonic photosynthetic microbes was significantly lower and the persistent phytoplankton were predominantly represented by chlorophyte and dinoflagellate sequences, with lower overall diversity. Differences in phytoplankton composition between the high and low rainfall periods were correlated with temperature, salinity, total nitrogen and silicate. These results suggest that increased frequency of high-rainfall events may change the composition, productivity and health of the estuary. Our study begins to populate the knowledge gap in the phytoplankton community structure and substantial changes associated with transient environmental perturbations, an essential step towards unravelling the dynamics of primary production in a highly urbanised estuarine ecosystem in response to climate change and other anthropogenic stressors.

Modelling surface runoff using the soil conservation service-curve number method in a drought prone agro-ecological zone in Rwanda

Runoff farming is reported to improve land productivity and crop yields in hot and dry climates. This study was conducted to assess the available rainwater that can be harvested in a conserved catchment in a drought prone agro-ecological zone. The study was carried out in the Cyili sub-catchment, southern province of Rwanda, which has an irregular rainfall pattern and unexploited runoff water. Soil Conservation Service-Curve Number method (SCS-CN), CROPWAT model version 8 and Hazen model with an average daily rainfall data recorded from 1971 to 2016 were applied to estimate the runoff and water requirements in the study area. Findings of the study revealed that more than half rainfall water received in the catchment was lost through runoff (229.8 mm) and effective rainfall was lower (246.9 mm) than the actual crop water requirement for maize (330 mm). The expected seasonal surface runoff volume to be harvested by the farmers was 3008 m3 ha−1 per season and 1.29 × 106 m3 per season for the entire whole sub-catchment (430 ha). Based on Hazen model, the return period of low rainfall (dry spell) event would be expected every 2 years with a 98% probability of occurrence. Cyili sub-catchment has higher potential runoff volume to stabilize the deficit of water demand in the period of short rainy season. This suggests that rainwater harvesting through supplementary irrigation is an option to improve the crop yield in the dry period as well as in the annual dry season.

Spatial and Temporal Variation of the Blowflies Community (Diptera: Calliphoridae) From an Urban Area in Northern South America.

Blowflies (Diptera: Calliphoridae) are necrophagous flies with ecological, medical, veterinary, and forensic importance. These flies carry pathogens that they spread to animals and humans, and produce myiasis. Furthermore, they are useful tools in forensic science as indicators of postmortem intervals, and in biomedicine they are successfully used in larval therapy. This study aimed to assess the spatiotemporal variation of the blowflies community from the urban area of Sincelejo City, located in the Colombian Caribbean region. Samplings were conducted from May 2012 to April 2013, using Van Someren Rydon-traps baited with bovine meat, fish, and chicken that decomposed for 48 h. Six species were registered, Cochliomyia macellaria (Fabricius, 1775) was the most abundant, followed by Lucilia eximia (Wiedemann, 1819) and Chrysomya albiceps (Wiedemann, 1819), while Chloroprocta idioidea (Robineau-Desvoidy, 1830), Chrysomya megacephala (Fabricius, 1794), and Lucilia cuprina (Wiedemann, 1830) presented the least individuals. The blowflies community did not change significantly throughout the sampling months or between the periods of low or high rainfall, nor was it influenced by weather variables. Although the species composition was the same in all sampled localities, species abundances presented significant differences. The possible causes of this pattern are discussed herein. Sex ratios were female biased for all the recorded species, except C. idioidea. Our findings provide the first assessment of the blowflies community from the urban area of Sincelejo City.

Association of carbon isotope discrimination with leaf gas exchange and water use efficiency in maize following soil amendment with superabsorbent hydrogel

The correlation of carbon isotope discrimination (△<sup>13</sup>C) with photosynthetic gas exchange and water use efficiency (WUE) in maize was investigated under low rainfall conditions with or without superabsorbent polymer (SAP). SAP (45 kg/ha) was mixed into the top 10 cm soil layer at sowing in lysimeters. Compared with the control plants not treated with SAP, the application of SAP increased net photosynthesis rate; stomatal conductance (g<sub>s</sub>); transpiration rate; chlorophyll content (Chl) and intrinsic water use efficiency at leaf level (WUE<sub>i</sub>), but decreased intercellular CO<sub>2</sub> concentration (C<sub>i</sub>) and leaf △<sup>13</sup>C. In plants supplied with SAP, leaf △<sup>13</sup>C was positively correlated with C<sub>i</sub> (r = 0.864, P < 0.01) and negatively correlated with g<sub>s</sub> and WUE<sub>i</sub> (r = –0.860 and –0.626, P < 0.01, respectively). Leaf △<sup>13</sup>C was not correlated with Chl with or without SAP. Grain △<sup>13</sup>C significantly decreased by 12.4% and showed a significant negative correlation with grain WUE under SAP treatments (r = –0.670, P < 0.05). These results suggest that in the presence of SAP, maize leaf and grain △<sup>13</sup>C could be good indicators for evaluating maize WUE during periods of low rainfall.

Catastrophic storm impact and gradual recovery on the Mississippi-Alabama barrier islands, 2005–2010: Changes in vegetated and total land area, and relationships of post-storm ecological communities with surface elevation

One of the most destructive tropical cyclones ever to strike the U.S., Hurricane Katrina made landfall along the Mississippi coast on 29th August 2005. The Mississippi-Alabama (MS-AL) barrier islands were subjected to storm breaching, area reduction, and vegetation loss caused by a number of parameters including salt spray, saltwater flooding, mechanical damage (e.g., ablation of bark from tree trunks), removal of plants and their soil substrate by scouring, burial under sand, and a 10-month, post-storm period of low rainfall. Repeated acquisitions of remotely-sensed data served as an essential tool in quantifying vegetated and total land area before and after the storm, and post-storm ecological community type and topographic elevation. Vegetated land area continued to decline on some islands in the first year following the storm. However, by November 2007, only 2.2 years after the storm, total vegetated land area had recovered to 72, 96, 77, 93, and 82%, and total subaerial land area to 97, 94, 33, 100, and 104%, of pre-Katrina values on Cat, W. Ship, E. Ship, Horn, and Petit Bois islands by natural re-growth and sediment accretion, respectively. Comparing ecological community-type maps that were developed from field and remotely-sensed data with LiDAR-derived digital elevation models determined that year 2010 ecological community type changed distinctively at the decimeter scale as mean surface elevation ranged from 0.1 m to 1.2 m. Storm-related changes in ecological community type included subtidal to supratidal sand flat, low marsh to wet or dry herbland, and woodland to wet herbland/shrubland.