Late Dry Season Research Articles

Seasonal Changes in the Chemical Composition of <em>Aspilia Africana</em> Plant Grown in Nigeria

The aim of the study was to evaluate the effects of season on the chemical composition of <em>Aspilia Africana</em> leaf over a 12-month period. Biomass yield, proximate and mineral compositions were analyzed. Data collected were subjected to ANOVA in a completely randomized design using SAS software package. Post hoc analysis was conducted at 5% significance using the Duncan multiple range test. Five seasons (late dry, early rainy, peak rainy, late rainy and early dry) and three stages of plant maturity (growing, blooming and aging) were identified. Results showed no effect (p>0.05) of season on the proximate composition (except for moisture and crude ash) and fibre fractions of <em>Aspilia Africana</em> leaf but mineral concentrations were influenced (p<0.05) by season. Crude protein and ash contents were higher during the rainy season but declined with the inception of the dry season while, crude fibre and its fractions were higher during the dry season. Calcium, zinc and phosphorus concentrations were highest during the peak rainy season then decline gradually as dry season progressed. Correlation result showed that an increased biomass yield led to increased (p<0.05) crude protein content with decreased crude fat, moisture and ash contents. Though biomass yield was higher between the late rainy and early dry seasons, results showed that there was no temporal variations in the nutrient composition of <em>Aspilia Africana</em> leaf during the 12-month study. Therefore, <em>Aspilia Africana</em> plant could be a valuable feed resource for all year fodder production.

Fish assemblage dynamics in an intermittent river of the northern Australian wet–dry tropics

AbstractIntermittent rivers make up a large portion of the global river network and are the dominant river type in northern Australia. Increased pressure is being placed on such systems, and a better understanding of their ecology is needed. We examined, over a 7‐year period, the fish fauna of the intermittent Fergusson River, a major tributary of the Daly River of the northern Australia. Changes in habitat structure with the onset of the dry season involved contraction of the riffle/run/pool habitat to a single refugial pool, the size of which was determined by antecedent wet season hydrology. The fishes present comprised a subset of species present within the Daly River main channel and consisted of the most widely distributed of northern Australia's freshwater fishes. The Fergusson River provides suitable spawning habitat for species during the wet season (e.g. Hephaestus fuliginosus, Leiopotherapon unicolor and Neosilurus catfishes) and during the dry season for a different set of species (e.g. Amniataba percoides, Melanotaenia australis and Glossogobius aureus). Little year‐to‐year variation in assemblage structure was observed early in the dry season, whereas interannual variation in late dry season assemblages was substantial. Dry season recruitment imparted some of the interannual variability in assemblage structure recorded between late dry season samples. Piscivorous fishes were an important, but temporally variable, component of the assemblage present in the late dry season refugial habitat, and predation was potentially another important source of variation in assemblage structure.

How do the wets burn? Fire behavior and intensity in wet grasslands in the Brazilian savanna

Although wetlands are commonly managed with fire by local communities and managers in tropical savannas, little is known about fire behavior in these ecosystems. We measured fire intensity and temperature in 13 experimental early (June) and late (September) dry season fires in wet grasslands in the Brazilian savanna, the Cerrado. We aimed to characterize Cerrado wet grasslands fire behavior and to understand how fire season (early vs. late dry season) and time since last fire affect fire behavior and intensity. We compared fire intensities in biennially burnt areas to areas unburned for 5 years. Experimental fires consumed 60–98 % of the fuel and were of low intensity (240–1083 kW m−1) compared to those in dry savanna grassland with similar fuel loads (0.4–1.3 kg m−2). Fires in areas with contrasting times since last fire (2 and 5 years) had similar intensities. Late dry season fires tended to be more intense than early dry season fires, but the difference was not significant. The low fire intensities are probably due to high soil water availability year around, a characteristic of wetlands. Maximum temperatures were low (149–442 °C, mostly at 50 cm in height) compared to fires in dry savanna ecosystems. Our results can directly contribute to plan and implementation of fire management programs in the “Cerrado”, where it is mostly still not carried out.

Effect of interaction between thermal radiation and seasonal variation on some physical properties of selected cassava cultivars(esculentacrantz) in the niger delta nigeria.

The effect of interaction between thermal radiation and seasonal variation on some physical properties of selected cassava cultivars in the Niger Delta Nigeria was studied. The study was carried out around Emuoha Local government Area of River State for a period of twelve (12) months from July to June. Three exotic cassava cultivars (coded TMS-30572; NR-8082 and NR-84292) were planted and monitored at various distances from thermal radiation source (flare site): 0-150m; 150-300m; 300-450m; 450-600m and 1000-2000m. The results showed that there were significant effects of thermal radiation on leaf area (0.561**) at 0- 600m (448.91±5.37d w/m 2 ,) but the effect was not significant (0.132) at 1000-2000m ( 428.83±0.79ew/m 2 ).Similar trends were observed with other physical parameters except for plant height and number of leaves. Results of seasonal variation showed favourable values for physical parameters at early dry and late wet seasons for all three cassava cultivars. However, NR-8082 and TMS-30572 show high degree of resistance to heat and other environmental stress while NR 84292 exhibited less resistance to radiation effect. The effect of season was significant (P<0.001). For NR-84292, early wet 117.9 ± 6.71 cm 2, late wet 192.59 ± 14.17 cm 2 , the values for early dry and late dry were 183.54 ± 10.00 cm 2 and 121.17 ± 5.05 cm 2 respectively. TMS-30572 showed high response to seasonal variations. Early dry 219.63 ± 6.93 cm 2 and late dry 153.73 ± 3.33 cm 2 .The disease index was severe (DI=3.1 ± 0.2) at late dry season with NR-8082 and less with NR-84292 and TMS-30572 (DI=0.7 ± 0.2) at late wet season the effect was significant (P<0.001).Further work that could allay the fears of the rural communities as well as guarantee cassava tolerance potential has been suggested.

Stem radial growth in response to microclimate in an Asian tropical dry karst forest

Relationships between environmental factors and stem radius variation at short temporal scales can provide useful information regarding the sensitivity of tree species' productivity to climate change. In this study, we used automatic point dendrometers to continuously record day-to-day stem radius variations of two evergreen (Alphonsea monogyna and Celtis philippensis Blanco) and two deciduous (Lagerstroemia villosa, Garuga floribunda var. gamblei) broadleaves species growing in a tropical karst forest in Xishuangbanna, Yunnan, southwest China. Daily stem radius increments were extracted from dendrometer traces, and were correlated with environmental variables recorded from nearby standard meteorological stations. The results indicated that stem radial growth of the four species initiated from late dry season (middle April), speeded in rainy season (July to August) and slowed down after October. Daily stem radius increments of the four species correlated positively with relative humidity (RH) and rainfall (Rain), while correlated negatively with daily maximum temperatures (Tmax), vapor pressure deficit (VPD) and photosynthetic active radiation (PAR). Rainfall and moisture availability during early growth season (May–June) was important for stem radius growth of the four studied species. Stem radial growth rates of two deciduous species (L. villosa, G. floribunda var. gamblei) declined significantly during short-term drought events occurred during late April and late May to early June, then recovered quickly after one or more rainfall events, which indicated a more sensitive response to climatic factors as compared with evergreen species. These results provide evidences for studying and predicting tree growths and forest productivities in the tropical karst forests under future climate change.

Are vertical migrations driven by circadian behaviour? Decoupling of activity and depth use in a large riverine elasmobranch, the freshwater sawfish (Pristis pristis)

Circadian rhythms occur widely amongst living organisms, often in response to diel changes in environmental conditions. In aquatic animals, circadian activity is often synchronised with diel changes in the depths individuals occupy and may be related to predator–prey interactions, where the circadian rhythm is determined by ambient light levels, or have a thermoregulatory purpose, where the circadian rhythm is governed by temperature. Here, these two hypotheses are examined using animal-attached accelerometers in juvenile freshwater sawfish occupying a riverine environment displaying seasonal changes in thermal stratification. Across seasons, diel patterns of depth use (shallow at night and deep in the day) tended to occur only in the late dry seasons when the water was stratified, whereas individuals were primarily shallow in the early dry season which featured no thermal stratification. Activity was elevated during crepuscular and nocturnal periods compared to daytime, regardless of the thermal environment. Our observation of resting at cooler depths is consistent with behavioural thermoregulation to reduce energy expenditure, whereas activity appears linked to ambient light levels and predator–prey interactions. This suggests that circadian rhythms in activity and vertical migrations are decoupled in this species and respond to independent environmental drivers.

An examination of the potential efficacy of high‐intensity fires for reversing woody encroachment in savannas

Summary Frequent fires are often proposed as a way of preventing woody encroachment in savannas, yet few studies have examined whether high‐intensity fires can effectively reverse woody encroachment. We applied successive fire treatments to examine the effect of fire intensity on woody vegetation structure. The treatments included early dry season, low‐intensity fires; late dry season, higher‐intensity fires; and an unburnt control. We used pre‐ and post‐fire airborne LiDAR to compare vegetation structural changes brought about by fires of different intensity. Early dry season fires were of lower intensity (1400–2100 kW m−1) than late dry season fires (2500–4300 kW m−1). The two treatments also differed in terms of fuel consumed, scorch heights and char heights, indicating that clear differences in fire intensity and severity were achieved. After 4 years and two fire applications, relative woody cover increased by between 20 and 110% in different height categories following low‐intensity and control treatments and declined by between 3 and 70% following high‐intensity fire treatments. Declines were markedly higher following two repeated high‐intensity fires than following a high and then a moderate‐intensity fire. Because woody shrubs in lower height classes can recover rapidly, repeated high‐intensity fires would be needed to maintain lower cover. Tall trees are often assumed to be unaffected by fires. However, we found that the rate of tree loss was directly related to fire intensity, where 36% of trees were lost following repeated high‐intensity fires, compared to 22% after a high‐ and then a moderate‐intensity fire and 6% after two low‐intensity fires (3% without fire). Synthesis and applications. Using LiDAR data we show that high‐intensity fires can, at least in the short term, significantly reduce woody cover in South African savannas. The use of repeated high‐intensity fires simultaneously causes both a positive (reduction in cover of short shrubs) and a negative (loss of tall trees) outcome, and managers need to make trade‐offs when contemplating the use of fire intensity to achieve specific goals. One potential solution may be to repeatedly apply high‐intensity treatments to some areas, and not to others. This could generate a heterogeneous landscape where grasses become dominant and tall trees become scarce in some places, but in others, tall trees persist (or at least decline at slower rates), and shorter woody shrubs increase in dominance. Whether this would be acceptable, or practical, remains to be tested.

Bats (Mammalia: Chiroptera) of the southeastern Truong Son Mountains, Quang Ngai Province, Vietnam

Bat communities of mainland Southeast Asia can be highly diverse. Many are under threat. Despite this, regional faunal composition is not well documented for many areas, including regions of Vietnam. We assessed the biodiversity of bats in a watershed protection forest in the southeastern Truong Son (Annamite) Mountains, southwestern Quang Ngai Province, Vietnam in 2011–2013. Twenty species of insectivorous bats were documented including a high diversity of Murina species Tube-nosed Bats. Diversity and abundance indices were compared with that recorded previously in two nature reserves and one national park in Vietnam, and were higher or comparable in several measures despite the lack of a karst substrate for roosts. Reproduction in the insectivorous bat fauna coincided with the early rainy season. In the late dry season, pregnant females of several species were observed but volant juveniles were not present, whereas in the early wet season adult females were lactating or post-lactating and volant juveniles of nine species were detected. We recorded echolocation calls of 14 bat species; for each species, we compared features of calls with those reported previously in other Asian localities. For some species we found discrepancies in call metrics among studies, perhaps suggesting a greater hidden biodiversity of bats in Southeast Asia.

Surface energy exchange in a tropical montane cloud forest environment: Flux partitioning, and seasonal and land cover-related variations

Relationships between seasonal climate, land cover and surface energy exchange in tropical montane cloud forest environments are poorly understood. The goal of this study was to investigate the seasonality of flux partitioning in lower montane cloud forest (LMCF), shaded coffee (CO) and sugarcane (SU) in central Veracruz, Mexico, as well as to evaluate the changes in surface energy exchange associated with the conversion of LMCF to CO or SU. Sensible (H) and latent heat (λE) fluxes were measured during the late dry and wet seasons using eddy covariance (CO and SU) and sap flow (LMCF) methods. Other measurements included: meteorological parameters, radiation balance, soil heat flux, soil moisture and vegetation characteristics. During the wet-season month of July, average midday Bowen ratios (βs) for sunny conditions were lowest and least variable among land covers: 0.4±0.2 (SE) in LMCF, 0.5±0.1 in SU and 0.7±0.1 in CO. In contrast, during the late dry-season months of March and April, βs were higher (i.e. higher H and lower λE) and more variable. The highest values of β were observed in LMCF, reflecting effects of partial leaf-shedding by dominant deciduous species (2.4±0.8, March) and increased stomatal control (1.4±0.3, April). There was also evidence of stomatal limitation of λE in CO and SU, having βs of up to 1.0±0.1 in April and March, respectively. As compared to LMCF, the average midday available energy (Ae) for sunny conditions was very similar in CO (−3±7%) and 15±8% lower in SU. Although not all results were statistically significant, they suggest that for the wet season conversion of LMCF to shaded coffee or sugarcane led to a decrease of 15±14% or 15±17% in midday λE under sunny conditions, respectively, whereas corresponding values of H increased by 37±38% or remained about the same (−4±40%). In contrast, for the late dry season, conversion of LMCF to shaded coffee or sugarcane appears to have resulted in higher λE and lower H, with changes of, respectively, +79 (±32)%/–45 (±16)% (CO) or +39 (±32)%/–43 (±16)% (SU) for a partially leafless LMCF in March, and +17 (±16)%/–11 (±16)% (CO) for a fully-leafed LMCF in April. In order to more accurately quantify the changes in surface energy fluxes associated with LMCF conversion, future work should focus on reducing the errors in the flux estimates. Nevertheless, for sunny days during the wet season, potential changes in the moisture and heat content of the local atmosphere due to the conversion of LMCF to CO or SU seem to have been in the same direction as those induced by increased greenhouse gases (drying and warming), whereas for the late dry season the effects appear to have been opposite (moistening and cooling).

Feral swine damage to globally imperiled wetland plant communities in a significant biodiversity hotspot in Florida

We studied rooting damage during five-years of feral swine control at Avon Park Air Force Range, a significant botanical biodiversity hotspot in peninsular Florida with many globally imperiled plant species and communities. While control reduced swine abundance, remaining animals consistently rooted the 49 studied sites in both middle-dry season (MDS) and late-dry season (LDS) each year. At each study site, we measured rooting with sub-meter accuracy. Neither total nor proportional area rooted differed in either season, across study years, or among plant community types: herbaceous seepage slopes, wet pine savannas, wet grasslands. The proportion of sites with damage during MDS was at least 25 % less than pre-control baseline. During LDS, the proportion of sites with damage increased over years but remained below the initial 2 years’ MDS results. Fresh rooting frequency (rooting <1 week-old) across sites dropped precipitously from baseline and remained low for MDS. Fresh rooting frequency among sites during LDS was lower than MDS for all but year two of the study. Canopied habitat <50 m from a study site almost guaranteed rooting at the site each observation period. We propose actions for protecting wetlands, integrating swine control into other compatible land use practices, and improving swine control efficacy. While we measured damage amounts at each site very accurately, our approach of also considering frequency of rooting and frequency of fresh rooting across sites offers low-labor means to broadly assess swine damage and control efficacy at large geographic scales because in-field measurements of damage amounts are not needed.

Non-invasive quantification of immunoglobulin A in chimpanzees (Pan troglodytes schweinfurthii) at Gombe National Park, Tanzania.

Immunoglobulin A (IgA) is the primary antibody responsible for mucosal defense in mammals and has been used as a marker for chronic stress and immune status. Therefore, this antibody may provide a more reliable indicator of an individual's immunocompetence than is currently available through other methods. Immunoglobulin A has never before been quantified in a wild population of non-human primates using non-invasive sample collection techniques. In this study, we present methodology for non-invasive IgA extraction in the field and provide quantification of mean fecal IgA concentrations in wild chimpanzees (Pan troglodytes schweinfurthii). During the study period (November 2009-October 2010), we collected fecal samples (N = 1463) from 59 individuals at Gombe National Park, Tanzania. We modified a field extraction technique for steroidal hormones to extract IgA from the fecal samples and then quantified mean IgA concentrations (ng/g) using a commercial human IgA enzyme immunoassay. Mean IgA concentration varied among individuals but not by sex or reproductive status. Mature animals tended toward higher mean IgA concentration than immature. Mean IgA concentration differed by quartile season, following a similar pattern previously observed for respiratory illness rates in this population, with the late dry season having significantly higher averages than the late wet. A circadian rhythm was also evident with mean IgA concentrations higher in samples collected in the latter half of the day. These demographic and temporal patterns of IgA concentration provide baseline values necessary to interpret future results, which may be combined with other health values to better understand the role of health and long-term stress in wild great ape populations. Am. J. Primatol. 80:e22558, 2018. © 2016 Wiley Periodicals, Inc.

The composition of mixed-species foraging flocks of birds in Kruger National Park, South Africa

Mixed-species foraging flocks (MSFFs) of birds can be defined as aggregations of more than two species that actively initiate and continue their association while foraging, without being drawn to a single resource. MSFFs have been well documented for terrestrial habitats globally, but rarely in southern Africa. This study describes the composition of MSFFs in two habitat types (Acacia and Combretum) within the southern Kruger National Park, South Africa during the late dry season. Thirty-one MSFFs were recorded in each of the two habitat types, with 1251 individuals of 74 different species being observed. We found that compared to Combretum, (mean: 10.7 ± 5.2 s.d.) Acacia had significantly more individuals per MSFFs (mean: 21.5 ± 12.6 s.d.) and more species per MSFF (Acacia mean: 8.7 ± 3.5 s.d.; Combretum mean: 5.9 ± 1.7 s.d.). The mean number of individuals per species per 31 MSFFs was 9.3 (± 4.5 s.d.) and 7.6 (± 5.6 s.d.) in the Acacia and Combretum habitat types respectively. The most frequently occurring species in both habitat types was the Fork-tailed Drongo (Dicrurus adsimilis). There was a significant association between certain species pairs in both habitats. Future studies in this area could be done to investigate the reasons behind the differences in MSFF sizes and species numbers between habitats. The season during which this study was performed excluded all summer migrants and a similar investigation in the wet season may reveal a different MSFF composition.Conservation implications: Understanding the dynamics and compositions of MSFFs, could form a valuable component of avian biodiversity monitoring both in and outside of protected areas. Within a given area, changes in the composition and behaviour of MSFFs over time could potentially be used as early indicator of threats to biodiversity.Keywords: avian; habitat; savanna

Trends of reported foodborne diseases at the Ridge Hospital, Accra, Ghana: a retrospective review of routine data from 2009-2013.

BackgroundThere are over 250 foodborne diseases and are of growing public health concern worldwide. The distribution of these diseases varies from one locality to the other. Foodborne diseases come about as a result of ingestion of food contaminated with microorganisms or chemicals. The most common clinical presentation of foodborne disease takes the form of gastrointestinal symptoms; although other systems of the body can also be affected and represents a considerable burden of disability as well as mortality. The current study was carried out with the aim of describing the trends and patterns of foodborne diseases reported at the Ridge Hospital in Accra, Ghana to serve as the first step towards understanding the profile of foodborne diseases in Accra. The study could then serve as a guide in the establishment of a sentinel site or surveillance system for foodborne diseases.MethodsA retrospective review of routine data kept on patients who visited the Ridge Hospital from January 2009 to December 2013 was conducted to describe the trends and patterns of foodborne diseases reported at the facility. All available health records were reviewed and data on foodborne diseases extracted and analysed by age group, sex, season and geographical location within the catchment area of the hospital.ResultsThe review showed significant variation in the annual reported cases of foodborne diseases [2009 = 11.5 % (118/1058); 2010 = 2.30 % (22/956); 2011 = 17.45 % (608/3485); 2012 = 7.98 % (498/6315) and 2013 = 2.56 % (345/13458)] p < 0.05. Significant seasonal variations were also observed [early dry season = 10.2 % (322/3142); late dry season = 24.4 % (909/3728); early wet season = 4.3 % (107/2494); late wet season = 6.3 % (256/4094). There were monthly variations also during the period (p < 0.001) except for the year 2010 (p = 0.428). The highest prevalence was reported during the late dry season (February–April). The most affected age group was those aged between 15 and 34 years who had significantly more infections in 2012 and 2013 than the other age groups (p < 0.001). Overall many more males than females reported of food borne diseases (p < 0.001).ConclusionThe commonly reported foodborne diseases at the Ridge Hospital were: typhoid fever, dysentery, cholera and viral hepatitis. These diseases were found to be very seasonal with peaks at the onset of the rainy season.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1472-8) contains supplementary material, which is available to authorized users.

Seasonality of isoprenoid emissions from a primary rainforest in central Amazonia

Abstract. Tropical rainforests are an important source of isoprenoid and other volatile organic compound (VOC) emissions to the atmosphere. The seasonal variation of these compounds is however still poorly understood. In this study, vertical profiles of mixing ratios of isoprene, total monoterpenes and total sesquiterpenes, were measured within and above the canopy, in a primary rainforest in central Amazonia, using a proton transfer reaction – mass spectrometer (PTR-MS). Fluxes of these compounds from the canopy into the atmosphere were estimated from PTR-MS measurements by using an inverse Lagrangian transport model. Measurements were carried out continuously from September 2010 to January 2011, encompassing the dry and wet seasons. Mixing ratios were higher during the dry (isoprene – 2.68 ± 0.9 ppbv, total monoterpenes – 0.67 ± 0.3 ppbv; total sesquiterpenes – 0.09 ± 0.07 ppbv) than the wet season (isoprene – 1.66 ± 0.9 ppbv, total monoterpenes – 0.47 ± 0.2 ppbv; total sesquiterpenes – 0.03 ± 0.02 ppbv) for all compounds. Ambient air temperature and photosynthetically active radiation (PAR) behaved similarly. Daytime isoprene and total monoterpene mixing ratios were highest within the canopy, rather than near the ground or above the canopy. By comparison, daytime total sesquiterpene mixing ratios were highest near the ground. Daytime fluxes varied significantly between seasons for all compounds. The maximums for isoprene (2.53 ± 0.5 µmol m−2 h−1) and total monoterpenes (1.77 ± 0.05 µmol m−2 h−1) were observed in the late dry season, whereas the maximum for total sesquiterpenes was found during the dry-to-wet transition season (0.77 ± 0.1 µmol m−2 h−1). These flux estimates suggest that the canopy is the main source of isoprenoids emitted into the atmosphere for all seasons. However, uncertainties in turbulence parameterization near the ground could affect estimates of fluxes that come from the ground. Leaf phenology seemed to be an important driver of seasonal variation of isoprenoid emissions. Although remote sensing observations of changes in leaf area index were used to estimate leaf phenology, MEGAN 2.1 did not fully capture the behavior of seasonal emissions observed in this study. This could be a result of very local effects on the observed emissions, but also suggest that other parameters need to be better determined in biogenic volatile organic compound (BVOC) models. Our results support established findings that seasonality of isoprenoids are driven by seasonal changes in light, temperature and leaf phenology. However, they suggest that leaf phenology and its role on isoprenoid production and emission from tropical plant species needs to be better understood in order to develop mechanistic explanations for seasonal variation in emissions. This also may reduce the uncertainties of model estimates associated with the responses to environmental factors. Therefore, this study strongly encourages long-term measurements of isoprenoid emissions, environmental factors and leaf phenology from leaf to ecosystem scale, with the purpose of improving BVOC model approaches that can characterize seasonality of isoprenoid emissions from tropical rainforests.

PHYSIOLOGICAL AND YIELD RESPONSE OF SOME UPLAND RICE VARIETIES TO RE-WATERING AFTER IMPOSED SOIL MOISTURE STRESS

A pot experiment was conducted in the Screen house of Federal University of Agriculture, Abeokuta, October, 2011 (late dry season) to study drought recovery ability of 13 upland rice varieties exposed to soil moisture stress (20 days) at three growth stages (vegetative, reproductive and grain filling stage). The experiment was in completely randomized design, with three replicates. Under moisture stress significantly higher growth recovery, more erect canopy and flatter leaf surface were obtained in all the rice varieties at vegetative growth stage than other growth stages with increasing duration of re-watering. Under stress condition NERICA 4 maintained a significantly higher leaf area (27.50 cm2 and 40.18 cm2), plant height (53.45 cm and 67.62 cm) and number of tillers (1.67 and 1.67), but with a depressed number of leaf, slanted leaf posture and curved leaf especially during the later stage of its growth (Reproductive and grain filling stage respectively). It could be concluded that NERICA 4 had higher recovery ability than other rice varieties in drought prone upland ecology.

Community-based tsetse fly control significantly reduces fly density and trypanosomosis prevalence in Metekel Zone, Northwest, Ethiopia.

African animal trypanosomosis is a great obstacle to livestock production where tsetse flies play a major role. Metekel zone is among the tsetse-infested areas. Community-based tsetse fly and trypanosomosis control using targets was conducted from June 2011 to May 2012 in Metekel zone, Ethiopia, to decrease trypanosomosis and tsetse fly. Cloth screen targets were developed, impregnated with 0.1% deltamethrin, and deployed alongside rivers by the research team together with the community animal health workers. Monthly parasitological and entomological data were collected, processed, and compared with similar data collected before control. Overall average tsetse fly (Glossina tachinoides) density decreased from 1.13 to 0.18fly/trap/day after control. The density was decreased in all sites with no significant difference among the sites. However, higher decrements were observed in the dry and late dry seasons by more than 12 and 6 times, respectively. The reduction in overall apparent prevalence of trypanosomosis caused by Trypanosoma congolense, Trypanosoma brucei, and Trypanosoma vivax from 12.14% before to 3.61% after control coincides with the tsetse fly reduction. In all the study sites, significant reduction was observed before and after control. The highest decrement was observed in the late dry season when the apparent prevalence was reduced from 7.89 to 1.17% before and after control, respectively. As this approach is simple, cost-effective, and appropriate for riverine tsetse species, we recommend to be scaled up to other similar places.

Seasonal and spatial ontogenetic movements of Gerreidae in a Brazilian tropical estuarine ecocline and its application for nursery habitat conservation.

The density and biomass of different ontogenetic phases (juvenile, sub-adult and adult) of the two most important sympatric Gerreidae species in the Goiana Estuary, north-east Brazil, are described in order to determine the patterns of estuarine habitat use and to identify nursery grounds. Eugerres brasilianus and Eucinostomus melanopterus were the most abundant gerreids in the main channel and adjacent estuarine beach habitats. Eugerres brasilianus is abundant in the main channel, whereas E. melanopterus is most common in the beach habitats. Significant interaction in density and biomass of juvenile and sub-adult size classes of E. brasilianus was found between season and area. In addition, E. brasilianus adults and E. melanopterus sub-adults differed significantly in density and biomass between areas of the estuary. Both the upper estuary, during the late dry season, and the middle estuary, during the early rainy season, functioned as nursery habitats for E. brasilianus. During the early rainy season and dry season, the beaches were a nursery for the E. melanopterus. The concentration of these ontogenetic phases was mainly related to the dissolved oxygen and salinity gradients of the estuary, which drive not only gerreid movement between estuarine habitats but also moves the habitats. This study reinforces the importance of conserving the habitats of the Goiana Estuary so that species such as gerreids can complete their life cycle in the face of pressure from anthropogenic activities, such as mangrove forest deforestation, overfishing, fish contamination by plastic ingestion and domestic effluent disposal.

English

Evaluation of existing and potential feed resources was conducted in Orodora district in the Southern region of Burkina Faso using Feed Assessment Tool (FEAST). The assessment was carried out through focus group discussions and individual interviews in Mahon and Sayaga communities in Orodara district. The study sites were characterized by mixed crop-livestock production systems. Seventy-percent of cropping activities were focused on fruit tree cultivation while food crop production accounted for the rest. Livestock species (predominantly local breeds) in the area included cattle sheep, goat, pig, poultry and donkey which are kept for different purposes. The main source of household income is crop production while livestock production contributed 35 and 45% to the household income in Mahon and Sayaga, respectively. In both study sites, natural grazing contributes highest (49 and 64% respectively) to the dry matter (DM) content of the total diet. Cultivated fodder contributed 1% of dry matter (DM), metabolizable energy and crude protein to the total diet of the existing feed resource in Mahon, while farmers in Sayaga depended more on purchased feed than in Mahon. Constraints to livestock production in the study sites included shortage of water in the dry season, insufficient quantity and quality of feed in the late dry season of the year and high cost of veterinary drugs and services. To mitigate these constraints farmers suggested an integrated approach to improve livestock production through: construction of small reservoir to provide water for human and animal consumption; training on the integration of forage legume into both tree and arable cropping, and efficient utilization of available feed resources; establishment of a veterinary service and drug centre in the village; better management of the existing water resources. Key words: Animal nutrition, livestock productivity, feed resources, feed scarcity.

Evapotranspiration of rubber (Hevea brasiliensis) cultivated at two plantation sites in Southeast Asia

AbstractTo investigate the effects of expanding rubber (Hevea brasiliensis) cultivation on water cycling in Mainland Southeast Asia (MSEA), evapotranspiration (ET) was measured within rubber plantations at Bueng Kan, Thailand, and Kampong Cham, Cambodia. After energy closure adjustment, mean annual rubber ET was 1211 and 1459 mm yr−1 at the Thailand and Cambodia sites, respectively, higher than that of other tree‐dominated land covers in the region, including tropical seasonal forest (812–1140 mm yr−1), and savanna (538–1060 mm yr−1). The mean proportion of net radiation used for ET by rubber (0.725) is similar to that of tropical rainforest (0.729) and much higher than that of tropical seasonal forest (0.595) and savanna (0.548). Plant area index (varies with leaf area changes), explains 88.2% and 73.1% of the variance in the ratio of latent energy flux (energy equivalent of ET) to potential latent energy flux (LE/LEpot) for midday rain‐free periods at the Thailand and Cambodia sites, respectively. High annual rubber ET results from high late dry season water use, associated with rapid refoliation by this brevideciduous species, facilitated by tapping of deep soil water, and by very high wet season ET, a characteristic of deciduous trees. Spatially, mean annual rubber ET increases strongly with increasing net radiation (Rn) across the three available rubber plantation observation sites, unlike nonrubber tropical ecosystems, which reduce canopy conductance at high Rn sites. High water use by rubber raises concerns about potential effects of continued expansion of tree plantations on water and food security in MSEA.

Modelling Seasonal and Inter-annual Variations in Carbon and Water Fluxes in an Arid-Zone Acacia Savanna Woodland, 1981–2012

Changes in climatic characteristics such as seasonal and inter-annual variability may affect ecosystem structure and function, hence alter carbon and water budgets of ecosystems. Studies of modelling combined with field experiments can provide essential information to investigate interactions between carbon and water cycles and climate. Here we present a first attempt to investigate the long-term climate controls on seasonal patterns and inter-annual variations in water and carbon exchanges in an arid-zone savanna-woodland ecosystem using a detailed mechanistic soil–plant–atmosphere model (SPA), driven by leaf area index (LAI) simulated by an ecohydrological model (WAVES) and observed climate data during 1981–2012. The SPA was tested against almost 3 years of eddy covariance flux measurements in terms of gross primary productivity (GPP) and evapotranspiration (ET). The model was able to explain 80 and 71% of the variability of observed daily GPP and ET, respectively. Long-term simulations showed that carbon accumulation rates and ET ranged from 20.6 g C m−2 mon−1 in the late dry season to 45.8 g C m−2 mon−1 in the late wet season, respectively, primarily driven by seasonal variations in LAI and soil moisture. Large climate variations resulted in large seasonal variation in ecosystem water-use efficiency (eWUE). Simulated annual GPP varied between 146.4 and 604.7 g C m−2 y−1. Variations in annual ET coincided with that of GPP, ranging from 110.2 to 625.8 mm y−1. Annual variations in GPP and ET were driven by the annual variations in precipitation and vapour pressure deficit (VPD) but not temperature. The linear coupling of simulated annual GPP and ET resulted in eWUE having relatively small year-to-year variation.