Early Dry Season Research Articles

Demography and growth of subadult savanna trees: interactions of life history, size, fire season, and grassy understory

Tree populations in mesic (>650 mm precipitation/yr) savannas of the world have strong demographic bottlenecks to the transition of subadult trees to the canopy layer. Although such bottlenecks are a major determinant of savanna physiognomy, the factors that allow subadults to traverse the bottleneck are little studied. In a landscape‐scale field experiment in a northern Australia savanna, we determined the survival and growth of 1506 permanently marked juveniles (<150 cm tall) and saplings (150–599 cm tall) of canopy species in response to season of fire (early dry season, late dry season, wet season, and unburned), and understory type (herbaceous forbs vs. sorghum [native annual grass]) that differ in seasonal growth patterns and competitive regimes. Trees were assessed before fires and at the end of the following growing season, without repeat fires. We used Akaike‐information‐criterion‐based model selection and multi‐model inference for data analyses. Initial height was an important explanatory variable for all responses except genet mortality wherein fire season was important for juveniles and understory type for saplings. Fire season was important to height growth of large juveniles and small saplings (enhanced the year following dry‐season fires). Fire season × understory interactions were important for height growth of small juveniles and for the proportion of juveniles transitioning to saplings. Changes in stem numbers were affected by all explanatory variables. All fires topkilled most juveniles (fewer in early dry‐season fires in herbaceous understory), but genet death was rare. Late dry‐season fires topkilled most saplings; they failed to regain previous height and some died the following year. Given no further fires, persistent large juveniles can grow to sapling size within a year; whereas sapling success is severely hampered by late‐dry‐season fires, especially in grassy understory. Differences in seasonal phenological patterns of both understory vegetation and trees that vary with size and life history stage are among suggested explanatory mechanisms. Weighted averaged model coefficients for all responses to the explanatory variables are provided for use in population dynamics models. A conceptual framework links landscape‐scale variables to tree attributes and responses, with implications for population ecology and community assembly.

Seasonal diet and prey preference of the African lion in a waterhole-driven semi-arid savanna.

Large carnivores inhabiting ecosystems with heterogeneously distributed environmental resources with strong seasonal variations frequently employ opportunistic foraging strategies, often typified by seasonal switches in diet. In semi-arid ecosystems, herbivore distribution is generally more homogeneous in the wet season, when surface water is abundant, than in the dry season when only permanent sources remain. Here, we investigate the seasonal contribution of the different herbivore species, prey preference and distribution of kills (i.e. feeding locations) of African lions in Hwange National Park, Zimbabwe, a semi-arid African savanna structured by artificial waterholes. We used data from 245 kills and 74 faecal samples. Buffalo consistently emerged as the most frequently utilised prey in all seasons by both male (56%) and female (33%) lions, contributing the most to lion dietary biomass. Jacobs’ index also revealed that buffalo was the most intensively selected species throughout the year. For female lions, kudu and to a lesser extent the group “medium Bovidae” are the most important secondary prey. This study revealed seasonal patterns in secondary prey consumption by female lions partly based on prey ecology with browsers, such as giraffe and kudu, mainly consumed in the early dry season, and grazers, such as zebra and suids, contributing more to female diet in the late dry season. Further, it revealed the opportunistic hunting behaviour of lions for prey as diverse as elephants and mice, with elephants taken mostly as juveniles at the end of the dry season during droughts. Jacobs’ index finally revealed a very strong preference for kills within 2 km from a waterhole for all prey species, except small antelopes, in all seasons. This suggested that surface-water resources form passive traps and contribute to the structuring of lion foraging behaviour.

Dry Season Browse Preference for the Black Rhinoceros (Diceros bicornis): The Case of the Midlands Black Rhino Conservancy (MBRC), Zimbabwe

Dry season browse preference for the black rhinoceros ( Diceros bicornis ) was studied at the Midlands Black Rhino Conservancy (MBRC), Zimbabwe, in 2010. Free ranging black rhinos were tracked and 8 687 individual bites were recorded at 131 feeding stations and 616 feeding points. Only 34 plant species accounted for the black rhino diet. Trees contributed much of the diet (52.9%) followed by shrubs (44.0%) and lastly herbs (7.3%), with most of the browse (68.7%) coming from the 1.0-1.5m height category. Early dry season diet was richer and more evenly distributed (34 species, H ' =3.812.) than late dry diet (27 species, H ' =3.413). Acacia nilotica, Acacia karoo, Dichrostachys cineria, Ziziphus mucronata, Lantana camara, Gardenia volkensii and Rhus tenuinervis constituted the principal diet of the rhino, contributing 69.4% and 81.6% of the browse in the early dry and late dry season respectively. In the early dry season L. camara was the most important principal species contributing 32.9% of the browse, scoring the highest proportional usage. (0.33) and was also the most available (0.26), a position that switched onto A nilotica in the late dry season. The restricted diet obtained in the study may encourage wandering of rhinos into unprotected neighbourhoods making them prone to poaching.

Prevalence of Worm Infection in Yankasa sheep and West African dwarf goats in Lafia Town and Environs, Nigeria.

The study was conducted in Lafia town, districts and wards over a 12 months period (May, 2010 – April, 2011) to investigate the prevalence of helminthosis/ eimeria infection in Yankasa sheep and West African dwarf goats. A total of 864 faecal samples comprising 432 each of Yankasa sheep and West African dwarf goats were evaluated. Worm prevalence was higher among Yankasa sheep than West African dwarf goats. Prevalence according to age groups among Yankasa sheep were, above 12 months (34.7%), 6 – 12months (28.7%) and less than 6 months (2.1%) while West African dwarf goats above 12 months had the highest prevalence of 39.4%, 6 – 12months (20.8%) and less than 6 months (2.3%). The highest prevalence of 21.29% in Yankasa sheep was obtained in the late rains followed by 15.97, 14.81and 13.43% during early rains, early and late dry seasons respectively. For West African dwarf goats the highest prevalence was 17.12%, during late rains followed by 16.73, 16.20 and 12.73% during early rains, early and late dry seasons respectively. Furthermore sheep were more burdened than goats. Female sheep and goats had higher degree of infection during the rainy season while male counterparts showed higher degree of infection during the dry season. In the study area therefore, preferential rearing of Yankasa sheep should be exploited and greater attention should be paid to West African dwarf goats, older sheep and goats and, rainy season in worm/ eimeria control.

Daily movement responses by African savanna ungulates as an indicator of seasonal and annual food stress

Context Daily movement responses could indicate food deficiencies threatening population persistence before consequences for population performance become manifested. Animals should respond to food deficiencies by spending less time in foraging areas and hence by moving more frequently between such areas between one day and the next. Aim To establish whether the day-to-day movements of a locally threatened ruminant (sable antelope) reflected anticipated seasonal and annual variation in food stress, in comparison with a non-ruminant grazer that was thriving despite being dependent on basically similar food resources (zebra). Methods Diel (24 h) displacement distances that were derived from geographic positioning systems (GPS) telemetry were used to make the following comparisons: (1) between benign and adverse seasons, (2) among years differing in rainfall, (3) between the remnant sable herd and herds of zebra in the same region, and (4) between this sable antelope herd and sable herds in a wetter region where food should be more abundant. Key results Sable herds generally moved further from day to day in the late dry season than in the wet or early dry season, especially in the years with less rainfall, and greater movement was shown by the sable herd in the drier region than for herds in the wetter region. Zebra herds generally moved further from day to day than the sable herd occupying the same region, but showed less change in their diel displacement distances during the late dry season. Key conclusions Findings were consistent with the expected effects of seasonal, annual and regional differences in food availability on the daily movement distances of sable antelope herds. Implications Daily movement distances could serve as an indicator of when and where food deficiencies are experienced by sable antelope and perhaps other large ungulates.

Inhalable Particulate Matter Burden in Selected Day-Care Centres in Ibadan, Nigeria

The indoor air quality in day-care centres may influence the occurrence of infectious diseases and increase the risk of non-communicable diseases. The World Health Organisation (WHO) and other international agencies have considered particulate matter as an indicator of impact of air pollution on human health yet information on this from childcare centres is poorly documented in developing countries. This study therefore was designed to assess the particulate matter concentration (PM₁₀) in selected day-care centres (DCCs) in Ibadan, South western Nigeria. The study was descriptive cross sectional. PM10 load was determined 3 days a week for 16 weeks spanning the late wet season and early dry season periods from 10 locations of the selected DCCs using a digital PM counter model Met one. The ratio of indoor/outdoor PM₁₀was computed. Results obtained throughout the monitoring period for all the locations were averaged and compared with WHO PM₁₀ guideline limit of 50μg/m³.Data collected were analysed using descriptive statistics and ANOVA at 5% level of significance. Mean indoor PM₁₀ readings for wet season (73.4 ± 54.4μg/m³) and dry season (296.3 ± 61.6μg/m³)significantly exceeded guideline limit (P<0.05).The indoor/outdoor PM₁₀ ratio was 1.38 ± 0.97 and being greater than 1 indicated a possible indoor source of pollution. High particulate matter concentration observed is indicative of the poor indoor air quality condition in the day care centres. Government policies on routine air quality monitoring and stringent enforcement of environmental sanitation in day care centres are advocated.

Environmental and genetic effects on the lactation curves of four genetic groups of crossbred Holstein-Zebu cows

The objective of this study was to evaluate the effects of genetic group and environmental factors, including farm of origin, season of calving and lactation number, on the individual lactation curves of 1,010 Holstein-Gyr, Guzerat-Holstein, Holstein-Nellore, and Holstein-Zebu F1 cows on the experimental farms of the Agricultural Research Company in Minas Gerais (Empresa de Pesquisa Agropecuaria de Minas Gerais, EPAMIG). Least squares analysis and the incomplete gamma function were used to investigate differences in early milk yield, peak milk yield, time from onset to the lactation peak, persistency, total milk yield and lactation duration. The highest early yields were observed for Holstein-Gyr and Holstein-Zebu, and the lowest were observed for Holstein-Nellore cows. Early yield increased with lactation number, and the lactations that began in the late rainy and early dry seasons had the highest early yield. The time between lactation onset and the lactation peak was longer for primiparous Holstein-Gyr and Holstein-Guzerat cows. The lowest yields at the lactation peak were observed for the first lactation number. The highest values of persistency were observed for the first lactation number in Holstein-Guzerat cows. Total production from Holstein-Gyr and Holstein-Zebu cows were higher by approximately 14% and 29% compared with Holstein-Guzerat and Holstein-Nellore cows, respectively. The highest total yields were observed in lactations beginning in the dry season. Total yield increased with lactation number. The shortest lactation periods were observed in lactations beginning late in the rainy season. The incomplete gamma function was used to fit the individual curves from the genetic groups evaluated. The total yield differences were linked to early yields and yields at the peak of lactation.

Future climate of the Caribbean from a super-high-resolution atmospheric general circulation model

Present-day (1979–2003) and future (2075–2099) simulations of mean and extreme rainfall and temperature are examined using data from the Meteorological Research Institute super-high-resolution atmospheric general circulation model. Analyses are performed over the 20-km model grid for (1) a main Caribbean basin, (2) sub-regional zones, and (3) specific Caribbean islands. Though the model’s topography underestimates heights over the eastern Caribbean, it captures well the present-day spatial and temporal variations of seasonal and annual climates. Temperature underestimations range from 0.1 °C to 2 °C with respect to the Japanese Reanalysis and the Climatic Research Unit datasets. The model also captures fairly well sub-regional scale variations in the rainfall climatology. End-of-century projections under the Intergovernmental Panel on Climate Change SRES A1B scenario indicate declines in rainfall amounts by 10–20 % for most of the Caribbean during the early (May–July) and late (August–October) rainy seasons relative to the 1979–2003 baselines. The early dry season (November–January) is also projected to get wetter in the far north and south Caribbean by approximately 10 %. The model also projects a warming of 2–3 °C over the Caribbean region. Analysis of future climate extremes indicate a 5–10 % decrease in the simple daily precipitation intensity but no significant change in the number of consecutive dry days for Cuba, Jamaica, southern Bahamas, and Haiti. There is also indication that the number of hot days and nights will significantly increase over the main Caribbean basin.

Dry-season changes in macroinvertebrate assemblages of highly seasonal rivers: responses to low flow, no flow and antecedent hydrology

Highly seasonal rivers can experience extended low flow, and often dry, periods. Macroinvertebrate and flow data were used to explore hypotheses on the effects of antecedent hydrology and the low-flow, dry-season period on macroinvertebrate assemblages in northern Australia. Composition differed between early and late dry seasons. Taxa were more sensitive to water quality and more rheophilous in the early dry season when their habitats were lotic than when habitats later became lentic. As flow magnitudes in the antecedent dry season and on the sampling day increased, the habitats became more oxygenated and, in turn, macroinvertebrate richness increased. Higher wet-season flow magnitudes, flow variability and rates of fall were correlated with lower richness in the following dry season. Alteration of the flow-disturbance regime that increases the likelihood of flow cessation in macroinvertebrate habitats, or extends the duration of the dry season beyond that previously experienced in these highly seasonal systems, may alter the resistance and resilience of assemblages such that the seasonal decline and recovery of biodiversity may no longer be so reliable. Given the projected increase in low-flow incidence in many regions of the world, future research needs to examine the effects of reduced flow, flow cessation and stream drying as multiple, interacting stressors on stream biota.

Seasonal Variation in Body Condition of Impala at Manyeleti Game Reserve, South Africa

The physiological condition of animals connects resources in the environment to demographic responses through reproduction, survival and abundance, and it provides critical information for conservation and management of wildlife populations. We used archived data (early-wet season 1987, late-wet and early-dry season 1988) from culls of impala (Aepyceros melampus) to compare how the kidney fat index (KFI, short-term index of body condition) and carcass mass (long-term index) varied seasonally. For females, KFI increased across seasons, a pattern similar for all age classes. For males, KFI was low and relatively invariable for juveniles and yearlings. For adults, KFI varied with reproductive cycle; highest KFI occurred early in the rut for males and around the second trimester for females. Carcass mass increased over time for growing juveniles and yearlings. For adults, female carcass mass varied according to reproductive cycle and was highest when KFI was highest. Male carcass mass was highest toward the end of the rut when KFI was relatively low. Although changes in body condition can be associated with seasonal changes in forage and activity, KFI and carcass mass are most useful when comparing across years with varying conditions, but within age, sex, and season.

Influence of flushing and season of kidding on reproductive characteristics of Small East African goats (does) and growth performance of their kids in a semi arid area of Tanzania

A study was carried out to assess the effects of nutritional supplementation (flushing) and season of kidding on reproductive performance of Small East African (SEA) does and growth performance of their crossbred (Norwegian x SEA). Seasons of kidding were defined as season 1 (June- August) and 2 (September to November) which represented the early and late dry months of the year, respectively. A total of 90 grazing does were divided into three groups of 30 does each and monitored for two years. In each observational year, one group (control goats) received no concentrate supplementation while the remaining groups were subjected to 200 or 400 g of concentrate diet/doe/day for a period of 60 days (November to January) before mating. Does were then exposed to sexually active bucks from January through June in 2008 and 2009. Nutritional flushing and season of kidding had no effects (P>0.05) on fertility, prolificacy and fecundity. Nonetheless, the relative weight increase during gestation was 35.8 % in season 1 being higher (P<0.01) than 12.6% recorded in season 2. The proportion of weight loss of does kidding in season 1(6.1%) was, however, lower (P<0.05) than 8.9% in season 2. Kids born in season 1 grew at a faster rate than their counterparts born in season 2 (80 vs. 57 g/day, P<0.05). Consequently, the average weight of kids weaned per doe kidding was 2 kg in favour of season 1. It is concluded that nutritional flushing during peak-dry season may not be necessary for goats to conceive especially when raised on lightly grazed rangeland and that breeding activities of goats should preferably be restricted to January to March for kidding to take place during early dry season (June to August). Key words: Goats, nutritional flushing, seasonality, reproductive performance, growth rate.

Epidemiology of malaria in the Papua New Guinean highlands

To conduct an in-depth investigation of the epidemiology of malaria in the Papua New Guinea (PNG) highlands and provide a basis for evidence-based planning and monitoring of intensified malaria control activities. Between December 2000 and July 2005, 153 household-based, rapid malaria population surveys were conducted in 112 villages throughout the central PNG highlands. The presence of malaria infections was determined by light microscopy and risk factors assessed using a structured questionnaire.The combined dataset from all individually published surveys was reanalysed. The prevalence of malaria infections in the different surveys ranged from 0.0% to 41.8%(median 4.3%) in non-epidemic surveys and 6.6% to 63.2% (median 21.2%, P < 0.001) during epidemics. Plasmodium falciparum was the predominant infection below 1400 m and during epidemics, Plasmodium vivax at altitudes >1600 m. Outside epidemics, prevalence decreased significantly with altitude, was reduced in people using bed nets [odds ratio (OR) = 0.8, P < 0.001] but increased in those sleeping in garden houses (OR = 1.34, P < 0.001) and travelling to highly endemic lowlands (OR = 1.80, P < 0.001). Below 1400 m, malaria was a significant source of febrile illness. At higher altitudes, malaria was only a significant source of febrile illness during epidemic outbreaks, but asymptomatic malaria infections were common in non-epidemic times. Malaria is once again endemic throughout the PNG highlands in areas below 1400–1500 m of altitude with a significant risk of seasonal malaria outbreaks in most area between 1400–1650 m. Ongoing control efforts are likely to result in a substantial reduction in malaria transmission and may even result in local elimination of malaria in higher lying areas.

Does long‐term fire exclusion in an Australian tropical savanna result in a biome shift? A test using the reintroduction of fire

AbstractThe structure of tropical savanna ecosystems is influenced by fire frequency and intensity. There is particular interest in the extent to which long‐term fire exclusion can result in a shift from savanna to forest vegetation that is not easily reversed by the reintroduction of fire. This study examined changes in the structure and composition of a long‐unburnt site within the northern Australian savannas following an extended period of active fire exclusion (&gt;20 years), and the effect of the reintroducing fire through experimental fire regimes, including fires in the early and late dry season at a range of frequencies. After the long period of fire exclusion, the vegetation community was characterized by a well‐developed midstorey and canopy layer, low grass cover, substantially higher densities of woody sprouts and saplings than frequently burnt savanna. The community composition included a high proportion of rainforest‐affiliated species. Three years of experimental fires had no detectable effect on the overall composition of grass layer and woody plants but had an effect on woody vegetation structure. Continued fire exclusion further increased the density of woody stems, particularly in the midstorey (2.0–4.99 m), whereas moderate‐intensity fires (&gt;800 kW m−1) significantly reduced the density of midstorey stems. The reintroduction of higher moderate intensity fire events resulted in the vegetation in some compartments reverting to the open savanna structure typical of frequently burnt sites. Such rapid reversibility suggests that in general, the woody thickening resulting from long‐term fire exclusion did not represent a biome shift to a non‐savanna state. However, there was a small proportion of the site that could not sustain the fires applied to them because grass cover was very low and patchy and therefore appeared to have crossed an ecological threshold towards closed forest.

Influence of Climatic Variables on the Abundance of a Brazilian Salamander (Bolitoglossa paraensis) in Santa Bárbara Do Pará, Brazil

ABSTRACT. Very little is known on the ecological attributes of Neotropical salamanders. The aim of this study was to evaluate the effect of two abiotic factors on the temporal and spatial abundance of B. paraensis. Data were collected during four periods, in 23 plots of 250 m2 distributed randomly in Gunma Ecological Park, in the Brazilian state of Para. In each plot, temperature and relative humidity of the air were measured during searches, and abundance of salamanders was determined by active nocturnal searches. The abundance of salamanders varied significantly during the course of the year. The highest abundance (0–18) was recorded in the mid wet season, followed by the late wet season (0–7), early dry season (0–9), and late dry season (0–6). Spatial abundance of salamanders was influenced by climatic conditions only in the late dry season. Temporal and spatial variation in the abundance of the salamanders is associated with relative humidity, which was highest in the mid wet season, and lowest in the...

Seasonal activity of Dinoponera quadriceps Santschi (Formicidae, Ponerinae) in the semi-arid Caatinga of northeastern Brazil

Seasonal activity of Dinoponera quadriceps Santschi (Formicidae, Ponerinae) in the semi-arid Caatinga of northeastern Brazil. We studied seasonal foraging patterns of the queenless ant D. quadriceps (Formicidae, Ponerinae) for 24 months in a Caatinga area of northeastern Brazil, an ecosystem characterized by strong climatic changes throughout the year, in order to determine if regulation of worker activity is based on environmental conditions (air temperature, relative humidity, precipitation) and/or food resources (potential prey: Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Orthoptera, Araneae, Chilopoda and Diplopoda). Foraging activity of D. quadriceps varied over the course of both years, with the highest frequency occurring from May to August, corresponding to the late rainy season and early dry season. This foraging activity was negatively correlated with temperature and positively correlated with the availability of potential prey, but not with total abundance of soil arthropods or with rainfall and relative humidity. Diet composition, in relation to the main taxonomic prey groups, seems to be common to the species, regardless of habitat. Our results suggest that D. quadriceps workers adjust foraging activity to the most suitable period of the year, to avoid thermal stress and increase efficiency. Thus, they present an appropriate behavioral response to seasonal fluctuations in the Caatinga.

A spatio-temporal analysis of fire recurrence and extent for semi-arid savanna ecosystems in southern Africa using moderate-resolution satellite imagery

Savanna ecosystems are semi-arid and fire-prone. Increasing temperatures and decreasing precipitation in Southern Africa will probably have a series of strong impacts on the various components of fire regimes in these ecosystems that will, in turn, affect their ecology, structure, and function. This paper presents a geospatial analysis to quantify changes in fire frequency, seasonality and spatial distribution during the last decade and creates a fire return interval map for the core area of the Kavango-Zambezi Transfrontier Conservation Area, which spans five Southern African countries and is the largest cooperative multistate conservation region in the world. To disentangle the relative contribution of environmental variability from country-specific land management decisions in driving changes in fire regimes, we use two different products from the MODIS Terra platform (Active Fire and Burned Area products), TRMM precipitation data and the Multivariate ENSO Index data to analyze change in fire regimes among the five countries, differentiating between different land uses such as protected areas, forest reserves, and communal lands and accounting for specific changes in fire management policies. There are significant differences in fire frequencies between countries with more effective fire management (Botswana and Zimbabwe) and countries where anthropogenic, mainly early-dry season, burning is largely uncontrolled (Namibia, Angola, and Zambia), both within and outside protected areas, while all countries and land-use units show an overall increasing trend in fire occurrences. Large fire occurrences increased up to 200% in the period before the beginning of the natural fire season in Namibia, where a new prescribed burn policy was introduced in 2006, while the other countries show a slightly different shift in seasonality of increasing fire occurrences mainly during the dry season. The mean size of fires also increases significantly across all land uses despite increasing fire prevention efforts in most protected areas in the five countries. These findings can contribute to more effective transboundary natural resource and wildlife habitat management by providing a baseline assessment of fire return intervals across five countries with different fire management policies and have implications in the climate change arena.

Water harvesting and better cropping systems for the benefit of small farmers in watersheds of the East India Plateau

This paper discusses an integrated approach for water resource management to improve rural livelihoods in the East India Plateau. This has involved linking hydrological, agronomic and social aspects to increase access to water, improve water use efficiency and develop capacity within the villages for better decision making regarding use of the available resources. To this end, the research adopted a participatory, action-learning approach, with villagers joining in developing research questions, executing experiments, collecting data and sharing in their interpretation, as well as planning intervention work designed to improve access to water, particularly in the early dry season. The focus of this paper is on the integration of the different aspects of water resource management, with particular emphasis on the social issues. This included working with women's self-help groups and village watershed committees, and specific efforts to engage women in research and related development activities. The result has been an improved capacity within the village for managing water resources, including improved self-perceptions as farmers (especially women), better understanding of the potential resources and any constraints (e.g. soil fertility) and knowledge of how to manage the constraints (e.g. fertilisers), as well as a better understanding of the social capacities within the village.

English

Rainwater harvesting is a water conservation measures. Water is harvested in addition to reducing runoff, and erosion control can be used as a supplemental source of irrigation for crops on marginal land. A study was conducted to test the effectiveness of a small pool of rainwater harvesting usually termed as a small farm reservoir (SFRs) as a complementary source of irrigation water in improving the productivity of farming on marginal land. The experiment was conducted from December 2005 to August 2007 in Buanasakti, East Lampung, Indonesia. Three SFRs with a volume of 7 x 3 x 2.5 m (50 m 3 were made ​​on upland at sloping area (8-15%) of ​​1.5 ha. Further rain was deposited to be used by farmers for crop watering, especially in the early dry season. Extensive planting of crops that can be irrigated with SFRs, based on consideration of the farmers themselves. Observation result indicated that the SFRs were used by the farmers to water the vegetables and tobacco plants with different extents. However, on average, the presence of SFRs increased the planting area of vegetables such as beans and cucumbers in the dry season to 650%. Increased intensity of cultivation of vegetables and tobacco cultivation also increase farmers' income of 1.5 ha of marginal land as much as 37.49%. &nbsp; Keywords: small farm reservoir, supplemental irrigation, vegetables, marginal land

SMALL FARM RESERVOIR AS A SUPPLEMENTAL IRRIGATION SOURCE FOR CROPS PLANTED ON MARGINAL LAND

Rainwater harvesting is a water conservation measures. Water is harvested in addition to reducing runoff, and erosion control can be used as a supplemental source of irrigation for crops on marginal land. A study was conducted to test the effectiveness of a small pool of rainwater harvesting usually termed as a small farm reservoir (SFRs) as a complementary source of irrigation water in improving the productivity of farming on marginal land. The experiment was conducted from December 2005 to August 2007 in Buanasakti, East Lampung, Indonesia. Three SFRs with a volume of 7 x 3 x 2.5 m (50 m 3 were made ​​on upland at sloping area (8-15%) of ​​1.5 ha. Further rain was deposited to be used by farmers for crop watering, especially in the early dry season. Extensive planting of crops that can be irrigated with SFRs, based on consideration of the farmers themselves. Observation result indicated that the SFRs were used by the farmers to water the vegetables and tobacco plants with different extents. However, on average, the presence of SFRs increased the planting area of vegetables such as beans and cucumbers in the dry season to 650%. Increased intensity of cultivation of vegetables and tobacco cultivation also increase farmers' income of 1.5 ha of marginal land as much as 37.49%. &nbsp; Keywords: small farm reservoir, supplemental irrigation, vegetables, marginal land

GIS analysis of conjunctive water resource use in Nganjuk district, east Java, Indonesia

Water shortages during the dry season threaten sustainable agricultural production in Nganjuk District, East Java, Indonesia. To mitigate this problem, farmers adopted conjunctive use of surface water and groundwater, but the sustainability of this practice has not been investigated. This study temporally and spatially assessed water allocation in Nganjuk District when conjunctive irrigation was used. In particular, the land cover, water balance, and irrigation well density (IWD) were analyzed using time series GIS and remote sensing data to obtain their temporal and spatial distributions. First, the land cover was analyzed to determine cropping intensity, and the water balance was analyzed temporally and spatially. IWD was introduced to facilitate the water balance analysis. Second, the land cover, water balance, and IWD results were overlaid. Third, the effectiveness of the IWD method, the magnitude of water shortages, and the sustainability of groundwater resources were considered. Temporal and spatial water shortages in irrigation blocks were observed during the dry season. The change of storage showed a surplus during the wet and early dry seasons and a shortage during the late dry season. The annual water balances indicated that the southern part had a surplus, and the northern part experienced water shortages, especially downstream of the Widas River. Conjunctive use during the late dry season was predominant and concentrated in the southern part (83% of southern blocks). IWD was appropriate for examining groundwater use trends and was effective for expressing average withdrawal data (R 2 = 0.87).