Thedry Season Research Articles

Survey on the Diversity of Species Composition of Phytoplankton at Bung Binh Thien

Bung Binh Thien is considered a natural wetland conservation area in the Mekong Delta, Vietnam with adiverse flora and fauna ecosystem. The survey on phytoplankton composition here was conducted in thedry season of 2019. The results obtained 140phytoplankton species belonging to 5 algae phylums. Ofwhich, 54 species belong to Chlorophyta, 37 species ofBacillariophyta, Cyanophyta and Euglenophyta,respectively, have 27 and 20 species, and lastly, Dinophytahas 2 species.

Network complexity of rubber plantations is lower than tropical forests for soil bacteria but not for fungi

Abstract. Soil microbial communities play a crucial role in ecosystem functioning. Past research has examined the effects of forest conversion on soil microbial composition and diversity, but it remains unknown how networks within these communities respond to forest conversion, including when tropical rainforests are replaced with rubber plantations. Microbial networks are viewed as critical indicators of soil health and quality. They consist of two parts: nodes and edges. In this study, we used data from Illumina sequencing and shotgun metagenome sequencing to analyze bacterial and fungal community network structure in a large number of soil samples from tropical rainforests and rubber plantation sites on Hainan Island, China. Our results showed that only 5 %–10 % of shared network edges (i.e., links between species A and B existing in both rubber plantations and rainforests) were observed in both bacterial and fungal communities, which indicates that forest conversion altered the soil microbial network structure. The identity of keystone operational taxonomic units (OTUs) differed entirely between rubber plantation and rainforest sites, further underscoring the altered network structure. More edges and more negative correlations within the soil bacterial–fungal networks were observed at rubber plantation sites (dry season: 4284 total edges, 844 negative; rainy season: 7257 total edges, 1744 negative) than at rainforest sites (dry season: 3650 total edges, 149 negative; rainy season: 6018 total edges, 489 negative), demonstrating that soil bacterial–fungal network structure was more complex and stable in rubber plantations than in rainforests. For bacteria, a larger number of network edges were observed among bacterial networks in samples from tropical rainforest than in samples from rubber plantations, indicating that rainforest bacterial networks were more complex than those from rubber plantations. However, soil fungal networks from rubber plantations showed more links, suggesting that forest conversion increased fungal network complexity. More edges of network and more links between species and functions were observed in the rainy season than in the dry season, indicating that seasonal changes had a strong effect on network structure and function. Further analysis shows that soil pH, potassium (AK), and total nitrogen (TN) had more links with species of some phyla. In conclusion, forest conversion results in an increase in soil pH as well as a decrease in AK and TN, and these changes as well as seasonal variations had a great impact on soil microbial composition, network structure and function.

Evidence for high-elevation salar recharge and interbasin groundwater flow in the Western Cordillera of the Peruvian Andes

Abstract. Improving our understanding of hydrogeological processes on the western flank of the central Andes is critical to communities living in this arid region. Groundwater emerging as springs at low elevations provides water for drinking, agriculture, and baseflow. However, the high-elevation sources of recharge and groundwater flow paths that convey groundwater to lower elevations where the springs emerge remain poorly quantified in the volcanic mountain terrain of southern Peru. In this study, we identified recharge zones and groundwater flow paths supporting springs east of the city of Arequipa and the potential for recharge within the high-elevation closed-basin Lagunas Salinas salar. We used general chemistry and isotopic tracers (δ18O, δ2H, and 3H) in springs, surface waters (rivers and the salar), and precipitation (rain and snow) sampled from March 2019 through February 2020 to investigate these processes. We obtained monthly samples from six springs, bimonthly samples from four rivers, and various samples from high-elevation springs during the dry season. The monthly isotopic composition of spring water was invariable seasonally in this study and compared to published values from a decade prior, suggesting that the source of recharge and groundwater flow paths that support spring flow is relatively stable with time. The chemistry of springs in the low-elevations and mid-elevations (2500 to 2900 m a.s.l.) point towards a mix of recharge from the salar basin (4300 m a.s.l.) and mountain-block recharge (MBR) in or above a queñuales forest ecosystem at ∼4000 m a.s.l. on the adjacent Pichu Pichu volcano. Springs that clustered along the Río Andamayo, including those at 2900 m a.s.l., had higher chloride concentrations, indicating higher proportions of interbasin groundwater flow from the salar basin likely facilitated by a high degree of faulting along the Río Andamayo valley compared to springs further away from that fault network. A separate groundwater flow path was identified by higher sulfate concentrations (and lower Cl-/SO4-2 ratios) within the Pichu Pichu volcanic mountain range separating the city from the salar. We conclude that the salar basin is not a hydrologic dead end. Instead, it is a local topographic low where surface runoff during the wet season, groundwater from springs, and subsurface groundwater flow paths from the surrounding mountains converge in the basin, and some mixture of this water supports groundwater flow out of the salar basin via interbasin groundwater flow. In this arid location, high-elevation forests and the closed-basin salar are important sources of recharge supporting low-elevation springs. These features should be carefully managed to prevent impacts on the down-valley water quality and quantity.

FIELD EVALUATION OF BIOLOGICAL CONTROL AGENTS AND CALCIUM-BASED FERTILIZERSTO CONTROL PLASMODIOPHORA BRASSICAE IN BROCCOLI (BRASSICA OLERACEA VAR.ITALICA)

ABSTRACT Broccoli plants are frequently attacked by the biotrophic pathogen Plasmodiophora brassicae, which leads to continuous significant economic losses during its cultivation. Finding environmentally friendly methods to control this aggressive pathogen is a priority. Here, broccoli plants were sown in a field that has been previously reported with a high incidence of the pathogen showing dramatic root damage and yield loss. Field evaluations were performed to evaluate lump weight, root weight, and lump diameter after soil application with Trichoderma spp., Bacillus sp., humic acids, commercial plant defense elicitor, calcium carbonate (CaCO3), and calcium nitrate (Ca(NO3)2). Treatments were applied individually and in combination during two continuous and independent production seasons (rainy and dry seasons) in the year 2018.In summary, the application of CaCO3 increased the lump weight by 25% respective to its control, but only during thedry season. Moreover, the best treatment giving a consistent increase in lump weight (20% to 50% compared to its non-treated control depending on the season) was the combination of all treatments (biological and calcium-based fertilizers) when tested during both seasons. Taking all together, it was found some alternatives that increased the production of broccoli in fields infested with Plasmodiophora brassicae. These alternatives will be validated in the future in different soil types and agricultural environments.

Ideas and perspectives: patterns of soil CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O fluxes along an altitudinal gradient – a pilot study from an Ecuadorian neotropical montane forest

Abstract. Tropical forest soils are an important source and sink of greenhouse gases (GHGs), with tropical montane forests, in particular, having been poorly studied. The understanding of this ecosystem function is of vital importance for future climate change research. In this study, we explored soil fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in four tropical forest sites located on the western flanks of the Andes in northern Ecuador. The measurements were carried out during the dry season from August to September 2018 and along an altitudinal gradient from 400 to 3010 m a.s.l. (above sea level). During this short-term campaign, our measurements showed (1) an unusual but marked increase in CO2 emissions at high altitude, possibly linked to changes in soil pH and/or root biomass, (2) a consistent atmospheric CH4 sink over all altitudes with high temporal and spatial variability, and (3) a transition from a net N2O source to sink along the altitudinal gradient. Our results provide arguments and insights for future and more detailed studies on tropical montane forests. Furthermore, they stress the relevance of using altitudinal transects as a biogeochemical open-air laboratory with a steep in situ environmental gradient over a limited spatial distance. Although short-term studies of temporal variations can improve our understanding of the mechanisms behind the production and consumption of soil GHGs, the inclusion of more rigorous sampling for forest management events, forest rotation cycles, soil type, hydrological conditions and drainage status, ground vegetation composition and cover, soil microclimate, and temporal (seasonality) and spatial (topographic positions) variability is needed in order to obtain more reliable estimates of the CO2, CH4, and N2O source/sink strength of tropical montane forests.

The profile of fine particulate matter (PM2.5) using Beta Attenuator Monitor (BAM) in Addis Ababa, Ethiopia

The profile of fine particulate matter (PM2.5) using Beta Attenuator Monitor (BAM) in AddisAbaba, EthiopiaAuthor List: Abera Kumie1, Alemayehu Worku1, Zelalem Tazu1, Worku Tefera1, Getu Boja1, MollaMekashaw1, Solomon Teferra2, Jonathan Patz3, Jonathan Samet4, Kiros Berhane51Addis Ababa University (Ethiopia); 2Air Quality Management District (USA), 3University of Wisconsin–Madison (USA), 4University of Colorado (USA), 5University of Southern California (USA).AbstractBackground: Ambient air pollution is currently a global agenda. The concentration of fine particulatematter (PM2.5) is one of the indicators for the air quality monitoring. The monitoring of air qualityindicators is very limited in African countries including Ethiopia.Objectives: The objective of this study is to describe the current level of air pollution in Addis Ababa anddetermine its patterns over time, days of the week and seasons.Material and Methods: MetOne® Beta Attenuator Monitor (BAM) instrument for measuring the hourlyaverage level of PM2.5 was installed at one of the referral hospital in Addis Ababa, capital city ofEthiopia. A two-year data (April 1st, 2017 to March 31st, 2019) was generated to describe the profile ofPM for this study. The raw data from the monitor was periodically downloaded and cleaned usingstandard operative procedures. R-software was used for data management and analysis.Results: The average PM2.5 concentration over the two years was found to be 43.3µg/m3. There wereunusual peaks of PM concentration that greatly exceeded the daily averages. There were differences inlevels of PM2.5 across the days of the week and week days. Sunday’s had on average low PM2.5concentration relative to other days. We also observed variations in levels of PM2.5 across the Ethiopianseasons. Generally, wet seasons exhibited high levels of PM2.5 while low levels of PM2.5 were during thedry season. These findings highlighted the need of interventions related to public transportation and urbanplanning in controlling the ambient air pollution.Keywords: Ambient air pollution, PM2.5, Status, Beta Attenuator Monitor, variation

Helminth Parasites of Anurans from Zaria, Northern Guinea Savannah Zone of Nigeria

Helminth parasitc infections were investigated in 150 Anurans collected in parts of the Northern Guinea Savannah during thedry and wet seasons of 2016. The Anurans that were investigated included Amietophrynus regularis, Kassina senegalensis,Afrixalus vittiger, Xenopus tropicalis, Xenopus fischbergi, Pyxiecephalus cf. edulis, Hoplobatrachus occipitalis, Amniranagalamensis and Ptychadena pumilio. Overall prevalence of helminth parasites was 64% (94/150). Seven species ofhelminths belonging to three taxonomic classes were recovered: Monogenea 4%, Trematoda 19.33% and Nematoda 40.67%were identified. Eupolystoma alluaudi (30%) was the only monogenean recorded from the bladder of S. regularis. Tematodesfound were Diplodischus fishthalicus (53.49%) and Haematoloechus micrurus (67.45%) from the rectum and lungs of H.occipitalis, respectively. Nematodes included Camallanus microcephalus from the oesophagus and small intestine of X.fischbergi ( 62.96%) and X. tropicalis (100 %), respectively, Camallanus dimitrovi (25.58%) from the small intestine andrectum of H. occipitalis, an unidentified nematode from the oesophagus and small intestine of X. fischbergi (1.85%) and X.tropicalis (33.33%), and an Aplectana (85.00%%) species from the small intestine and rectum of S. regularis. Except forEupolystoma alluaudi, the infestation level was generally low. Parasite prevalence was higher during the wet (39.33%) thandry (24.67%) season and the difference was not significant (p = 0.17). The prevalence and infection intensity were lower thanthose reported from anurans in southern biotopes of Nigeria. The occurrence of Camallanus macrocephalus is a new recordfor Nigeria, while X. fischbergi and X. tropicalis are new host records for C. macrocephalus.
 Keywords: Anurans, helminth, prevalence, Northern Guinea Savannah, Nigeria

Aktivitas Harian Bekantan (Nasalis larvatus Wurmb) di Hutan Karet Kabupaten Tabalong, Kalimantan Selatan

The daily activities of the proboscis monkey (Nasalis larvatus Wurmb) living inrubber forests are poorly understood. The objectives of the research were to studyits daily movement pattern and to determine the time proportion of daily behaviors.The movement of the monkeys was followed by researchers on foot. The behaviorswere observed by scan technique in 15 second intervals for 30 minutes. In rubberforests, lowlands (baruh) were places where the monkey began and ended dailymovements and also conducted most activities. Most inter-water movements of themonkey (about 70%) were conducted twice a day. Statistically, movement distanceand rainfall were negatively and significantly correlated (ґs = -0.58; p < 0.05; n = 14).The monkey spent more time for feeding in the morning and afternoon, and restingat midday. Most behaviors of feeding, resting, playing, and grooming (84.01%) wereconducted at a tree height of less than 15 m. The monkeys moved farther during thedry season to get water and did activities in accordance with height strata to getvarious foods, avoided disturbances, and got comfortable and safe places.

IMPACT OF SALINE INTRUSION ON AGRICULTURAL PRODUCTION IN VINH THUAN DISTRICT, KIEN GIANG PROVINCE, VIETNAM

This study aimed to survey the current status of saline intrusion in Vinh Thuan district, to assess the understanding of the local people on saline intrusion, review the impact of saline intrusion on agricultural production. Salinity was measured continuously for seven months wherein 60 households and six government officials were interviewed in Vinh Binh Bac and Vinh Phong communes, Vinh Thuan district, Kien Giang province, Vietnam. The results showed that salinity was higher than 4 parts per thousand in both communes during thedry season affecting local farming models in which rice in the combined shrimp-rice model was seriously damaged resulting in household income loss by 30%. Of the 60 households interviewed, 96.7% knew aboutsaline intrusion, of which 26.7% knew about saltwater intrusion through workshops held by agrochemical sellers. At the survey site, there were three main production models, including a rice-shrimp model (58.3%), shrimp combined with other aquatic species (33.4%), and pineapple farming (8.3%). Farmers understood that saline intrusion seriously affects agricultural production (accounting for 100% of interviewed households). In terms of adaptive capacity, the interview results showed that the rice-shrimp and pineapple models are more adaptable than the shrimp and aquatic species integrated models. Based on the results, some measures are proposed to minimize the damage caused by saline intrusion as well as improve the adaptability of the farmers of Vinh Thuan district to the effects of saline intrusion.

Studying the impact of biomass burning aerosol radiative and climate effects on the Amazon rainforest productivity with an Earth system model

Abstract. Diffuse light conditions can increase the efficiency of photosynthesis and carbon uptake by vegetation canopies. The diffuse fraction of photosynthetically active radiation (PAR) can be affected by either a change in the atmospheric aerosol burden and/or a change in cloudiness. During the dry season, a hotspot of biomass burning on the edges of the Amazon rainforest emits a complex mixture of aerosols and their precursors and climate-active trace gases (e.g. CO2, CH4, NOx). This creates potential for significant interactions between chemistry, aerosol, cloud, radiation and the biosphere across the Amazon region. The combined effects of biomass burning on the terrestrial carbon cycle for the present day are potentially large, yet poorly quantified. Here, we quantify such effects using the Met Office Hadley Centre Earth system model HadGEM2-ES, which provides a fully coupled framework with interactive aerosol, radiative transfer, dynamic vegetation, atmospheric chemistry and biogenic volatile organic compound emission components. Results show that for present day, defined as year 2000 climate, the overall net impact of biomass burning aerosols is to increase net primary productivity (NPP) by +80 to +105 TgC yr−1, or 1.9 % to 2.7 %, over the central Amazon Basin on annual mean. For the first time we show that this enhancement is the net result of multiple competing effects: an increase in diffuse light which stimulates photosynthetic activity in the shaded part of the canopy (+65 to +110 TgC yr−1), a reduction in the total amount of radiation (−52 to −105 TgC yr−1) which reduces photosynthesis and feedback from climate adjustments in response to the aerosol forcing which increases the efficiency of biochemical processes (+67 to +100 TgC yr−1). These results illustrate that despite a modest direct aerosol effect (the sum of the first two counteracting mechanisms), the overall net impact of biomass burning aerosols on vegetation is sizeable when indirect climate feedbacks are considered. We demonstrate that capturing the net impact of aerosols on vegetation should be assessed considering the system-wide behaviour.

Ecotoxicological Dynamics of the Coastal Soil Ecosystem of Oil Producing Regions of Ondo State, Nigeria

The industrial revolution marked the beginning of unprecedented anthropogenic growth and technological advancement that also inadvertently led to acute environmental degradation. This technological advancement was driven by the use fossil fuels such as crude oil. Crude oil extraction through drilling has resulted in widespread environmental pollution and deterioration of natural habitats. The Ondo State region in Nigeria presents one such expanse where large scale crude extraction operations have caused hazardous environmental pollution and toxic substance contamination. This study is a comprehensive and holistic study of the terrestrial soil ecosystem aimed towards elucidating the potential ecotoxicity that may have adversely affected the area. The results indicated that the terrestrial soil ecosystem was largely acidic (~pH6) and the organic matter content ranged from 6% to 12% indicating the soil was hydric. The results also indicated that the terrestrial soil environment was contaminated with toxic heavy metals including cadmium (Cd), chromium (Cr), lead (Pb) and arsenic (As). The toxic heavy metal concentration of the soil ecosystem was higher during the dry season. The Cr concentration in the soil samples was >3 ppm in most of the sampling sites, which exceeded WHO maximum permissible limit. Mean concentrations of the heavy metals in the soil samples in both seasons were of the order: Cr > Pb > Cd > As. The soil ecosystem was also characterized by a diverse and large population of microorganisms including bacteria like Enterobacter, Escherichia coli, and several species of fungi.

Study of water management on rainfed land in downstream Renggung watershed

Downstream area of Renggung Watershed is a water conservative zone which is also dominated by rainfed land with vertisol soil clay fraction dominated. Watershed downstream reaches 40% and 30% from the total area of Renggung Watershed. Rainfed farming is part of dry land farming, but the presence of rainfed land in downstream of Renggung watershed does not receive intensification treatment as water becomes a limiting factor of plant growth. About 87-90% rainfall events in downstream of Renggung watershed are happened during the rainy season from November to April with 3-4 wet months, while about 10-13% happen during the dry season from May to October. It means that water is abundant in wet months, but there is a shortage of water during the dry period. Based on zone group, 72% of potential water from rainfall occurs in downstream zone, 18.3% occurs in middle zone, and 10.4% is in upstream zone. If the number of ¾ potential water of rainfall occurred in downstream So water management on rainfed land in downstream of Renggung watershed is still not optimum which is caused by (a) dependence on supply of water downstream from HLD BR, but discharge declines in last 6 months; (b) poorly water management at farming level, because plants are not cultivated in right season; and (c) poorly institutional of management and water user group, so forum to facilitate and mediate issue in terms of management and use of irrigation water is not optimal.

Extreme Wind Characteristics of Coastal Communities in Bayelsa State: Implications for Community Planning and Development in Nigeria

The study examined extreme wind characteristics of the coastal communities in Bayelsa State, Nigeria for possible community planning and development. To achieve this aim, data on wind speed were sourced from the Nigerian Meteorological Agency (NIMET). Personal interview and focused group discussions were done with the aid of well structured questionnaire in the various coastal communities sampled to identify impact and coping strategies from extreme winds. The Beaufort Winds Scale and regression analysis were the statistical tools used for the analysis of the data in order to achieve the objectives of the study. The results indicate that, the return period to obtain maximum 1-year wind speed value of 29.3 m/s (violent storm), 27.8 m/s (storm), 24.3 m/s (strong Gale) and 20.6 m/s (fresh Gale) will be 17 years, 5.7 years, 2.8 years and 1.4 years respectively. Fresh Gale characterized the extreme wind events in the area. Result further showed that out of 19 occurrences of wind events, 11 were extreme cases, while 2 occurred as violent storm of 29.3 m/s. Findings also showed that extreme winds occurred more (8 cases) during the early part (March-April) of the raining season when the area is under the influence of maritime moisture laden air mass than the dry season which is dried and dusty. Using a combination of return period of the magnitude of extreme wind and the log of wind speed for the 16 years a model predicting the incidence of extreme wind was done. Awareness on the dangers of wind hazard increases while early warning systems are advocated to mitigate the associated dangers with extreme wind events in the study area.

Data Exploration and Reconnaissance to Identify Ocean Phenomena: A Guide for <i>In Situ</i> Data Collection

Marine pollution is a serious geoenvironmental problem affecting the Lebanese coast. It mainly affects the coastal zone adjacent to areas of dense population. To detect the sources of pollution along this zone, as well as to identify their characteristics, remote sensing data is used. Landsat 8 Operational Land Imager (OLI) satellite images, which have medium spatial resolution, are analyzed using ENVI 5.2 and ArcGIS 10.3.1 geospatial software for the years of 2014 and 2015. Different routines are applied to reveal anomalous features with the goal being to discriminate polluted water in the marine environment. Results showed anomalies in Akkar region. This might be due to the presence of basalts rocks, and geothermal heating, or the pollution of Oustowan river that flows into the sea. The results also showed that during the dry season, there is low movement of water causing a least extension of the anomalies. In contrary, during the wet season, rivers had an intense flow into the sea which caused an intense water movement and wide extension of anomalies on the coast. Permanently polluted coastal sites are evident in Tripoli, Kalamoun, Chekka, Batroun, Amchit, Jbeil, Jounieh, Nahr Beirut and Ouzai with the most presumed polluted months being in 2014 during April and November and in 2015 in April. The least extended pollution is during July 2014 and 2015. The length and width of each anomaly at each site shows that during the year of 2015; most of the anomalies are larger than in 2014.

Calculate theDry Season fromtheRainy Season For The City Of Baghdad

Calculate theDry Season fromtheRainy Season For The City Of Baghdad

Integrating ecosystem services and climate change responses in coastal wetlands development plans for Bangladesh

This study explores the integration of ecosystem services and climate change adaptation in development plans for coastal wetlands in Bangladesh. A new response framework for adaptation is proposed, based on an empirical analysis and consultations with stakeholders, using a modified version of the DPSIR (Driver-Pressure-State-Impact- Response) framework. The framework is tested in the Narail district of Bangladesh, where temperature has increased by about 1 °C in the summer in combination with an increase in rainfall of 0.70 mm day −1 yr −1 in the last decade. Calibrated model (MAGICC/SENGEN) projections forecast, on average, a temperature increase of up to 5 °C and an increase in rainfall of 25 % by the end of this century. Water diversion in the upstream regions of the Ganges River delta contributes to increase water scarcity in the dry season. Enhanced rainfall and the immense pressure of water discharges from upstream water sources are increasing the risk of floods and river erosion in thedry season. Anincrease in thewater holding capacity of rivers, wetlandsand canals by dredging is urgently required. The empirical model ofthisstudy isintended tosupport adaptation planning and monitoring in Bangladesh and can be used in other data-poor areas which will suffer from climate change.

Seasonal patterns of soil carbon dioxide efflux from a wet-dry tropical savanna of northern Australia

Soil CO2 efflux rates were measured in a eucalypt open forest in a tropical savanna of northern Australia, with a portable closed chamber and CO2 gas analyser. Both abiotic (soil temperature and water content) and biotic (litterfall and fine-root growth) factors that may influence soil CO2 efflux were examined. Daytime rates of soil CO2 efflux rate were consistently higher than nocturnal values. Maximal rates occurred during late afternoons when soil temperatures were also maximal and minimum values were recorded during the early morning (0400–0800 hours). Average soil CO2 efflux was 5.37 mol m–2 s–1 (range 3.5–6.7 mol m–2 s–1 during the wet season and declined to 2.20 mol m–2 s–1 (range 1.2–3.6 mol m–2 s–1) during the dry season. The amount of carbon released from soil was 14.3 t ha–1 year–1, with approximately 70% released during the wet season and 30% during the dry season. The rate of efflux was correlated with soil moisture content and soil temperature only during the wet season, when root growth and respiration were high. During the dry season there was no correlation with soil temperature. These results are discussed in relation to the carbon balance of tropical savannas.

Corrigendum to: Seasonal patterns of soil carbon dioxide efflux from a wet¿dry tropical savanna of northern Australia

Soil CO2 efflux rates were measured in a eucalypt open forest in a tropical savanna of northern Australia, with a portable closed chamber and CO2 gas analyser. Both abiotic (soil temperature and water content) and biotic (litterfall and fine-root growth) factors that may influence soil CO2 efflux were examined. Daytime rates of soil CO2 efflux rate were consistently higher than nocturnal values. Maximal rates occurred during late afternoons when soil temperatures were also maximal and minimum values were recorded during the early morning (0400–0800 hours). Average soil CO2 efflux was 5.37 mol m–2 s–1 (range 3.5–6.7 mol m–2 s–1 during the wet season and declined to 2.20 mol m–2 s–1 (range 1.2–3.6 mol m–2 s–1) during the dry season. The amount of carbon released from soil was 14.3 t ha–1 year–1, with approximately 70% released during the wet season and 30% during the dry season. The rate of efflux was correlated with soil moisture content and soil temperature only during the wet season, when root growth and respiration were high. During the dry season there was no correlation with soil temperature. These results are discussed in relation to the carbon balance of tropical savannas.

Mollusc fauna of the mangrove root-fouling community at the Colombian Archipelago of San Andrés and Old Providence.

This paper advances a qualitative and quantitative preliminarycharacterization of the mollusc fauna associated with the submerged rootsof Rhizophora mangle L. in three mangrove areas with differentdegrees of anthropogenic impact in the San Andres (Hooker and HondaBays) and Providence (Old Providence McBean Lagoon National Park)archipelago in the Western Caribbean. The study was carried out during thedry and rainy seasons (July and November, respectively) back in 1998.Samples were taken from 34 submerged roots which were not fixed to thesubstrate. Several physico-chemical parameters were also measured insitu. All molluscs were identified and counted and indexes of speciesrichness, diversity, uniformity, similarity, dominance of species and densityof individuals were calculated. All in all 5,771 individuals belonging to 21species of 17 families were counted. Most of the species were epibenthic,herbivorous and with undifferentiated planctonic larvae, but most of theindividuals were epifaunal and attached as well as filter-feeders withplanctonic larvae. Most individuals were found in juvenile stages. The threesites, under different degrees of anthropogenic impacts, showed relatedvalues of species richness, diversity and abundance, as well as densities ofmollusc taxa in oceanic communities associated with mangrove roots.Further research should be done to find similar responses in accompanyingsignificant groups, such as Crustacea and Polychaeta.

Chemical composition and physical characteristics of cowpea haulms as forage for ruminants

Extracted from text ... Chemical composition and physical characteristics of cowpea haulms as forage forruminantsH.K. Mokoboki, K.K. Ayisi and L.R. Ndlovu #Dept of Animal Production, University Of The North, P Bag X 1106, Sovenga, 0727# e-mail:NdlovuL@unin.unorth.ac.za.IntroductionCowpea ( Vigna unguiculata) is a major grain legume grown by small- scale farmers in the NorthernProvince of South Africa. The crop is indigenous to Africa and is used extensively in many cropping systemsthroughout Africa (Eaglesham et al., 1981). Cowpea straws are potential supplementary feed for ruminants in thedry season. Cowpea straws are likely to have higher crude protein than cereal straws and may thus improvedigestibility of cereal straws ..