Dry Winter Period Research Articles

Environmental Conditions for Danish Storage Buildings: A Summary of 20 Years of Air Quality Surveys

ABSTRACT Air quality in 36 Danish storage buildings was investigated, ranging from naturally ventilated historical buildings to modern purpose-built storage facilities, some with full HVAC climate control systems. Most were able to maintain a humidity level within 40–60% RH. The main deviations were for older heated buildings without humidity control, resulting in dry winter periods. Many modern stores were un-heated, which resulted in an annual average temperature about 12–13°C, and a high (>80) time-weighted preservation index (TWPI). The older buildings often struggled to maintain a moderate temperature, but experienced summer levels of 20–30°C. This lowered the TWPI considerably, typically to index 40–80. Concentration of organic acids in air was below 50 ppb for 22 sites, and only high (>100 ppb) for a few sites due to off-gassing from heritage materials. The outdoor pollutants ozone and nitrogen dioxide were mainly found in low concentrations indoors (<5 ppb) except for a few locations with forced but unfiltered air intake. Low-energy storage had the lowest energy consumption of <3 kWh/m3 annually, while repositories with traditional climate control systems were in the range of 10–30 kWh/m3. Information on energy consumption in storage buildings is sparse, and the authors call for more research. The most optimal solutions were offered by the modern low-energy buildings, where the best conservation conditions as defined by TWPI (high), pollution levels (low), and energy consumption (low) were observed, and where sustainable operation such as sharing space between several institutions was often practiced.

Methane and nitrous oxide emissions and related microbial communities from mangrove stems on Qi'ao Island, Pearl River Estuary in China

Mangrove forests, crucial carbon-rich ecosystems, are increasingly vulnerable to soil carbon loss and greenhouse gas (GHG) emissions due to human disturbance. However, the contribution of mangrove trees to GHG emissions remains poorly understood. This study monitored CO2, CH4, and N2O fluxes from the stems of two mangrove species, native Kandelia obovata (KO) and exotic Sonneratia apetala (SA), at three heights (0.7 m, 1.2 m, and 1.7 m) during the dry winter period on Qi'ao Island, Pearl River Estuary, China. Heartwood samples were analyzed to identify potential functional groups related to gas fluxes. Our study found that tree stems acted as both sinks and sources for N2O (ranging from −9.49 to 28.35 μg m−2 h−1 for KO and from −6.73 to 28.95 μg m−2 h−1 for SA) and CH4. SA exhibited significantly higher stem CH4 flux (from −26.67 to 97.33 μg m−2 h−1) compared to KO (from −44.13 to 88.0 μg m−2 h−1) (P < 0.05). When upscaled to the community level, both species were net emitters of CH4, contributing approximately 4.68 % (KO) and 0.51 % (SA) to total CH4 emissions. The decrease in stem CH4 flux with increasing height, indicates a soil source. Microbial analysis in the heartwood using the KEGG database indicated aceticlastic methanogenesis as the dominant CH4 pathway. The presence of methanogens, methanotrophs, denitrifiers, and nitrifiers suggests microbial involvement in CH4 and N2O production and consumption. Remarkably, the dominance of Cyanobacteria in the heartwood microbiome (with the relative abundance of 97.5 ± 0.6 % for KO and 99.1 ± 0.2 % for SA) implies roles in carbon and nitrogen fixation for mangroves coping with nitrogen limitation in coastal wetlands, and possibly in CH4 production. Although the present study has limitations in sampling duration and area, it highlights the significant role of tree stems in GHG emissions which is crucial for a holistic evaluation of the global carbon sequestration capability of mangrove ecosystems. Future research should broaden spatial and temporal scales to enhance the accuracy of upscaling tree stem gas fluxes to the mangrove ecosystem level.

An attractor domain model of seasonal and inter‐annual β diversity of stream macroinvertebrate communities

Abstract Ecological communities are dynamic systems that vary within and across years. In streams, disturbance by spates and the emergence of adult insects during the rainy summer contrast with more stable conditions in the dry winter and can potentially generate distinct and repeatable community states across years. However, demographic stochasticity and the legacies of previous spates may hamper the full attainment of characteristic community states associated with seasons. We developed an attractor domain model encapsulating these factors and hypothesised: (1) partially distinct rainy (summer) and dry (winter) communities. High benthic dynamism during the rainy period should cause higher inter‐annual variability, leading to (2) higher temporal β diversity among rainy periods than among dry periods. Historical effects (e.g., demographic stochasticity and disturbance by spates) should accumulate over the years and lead to (3) increased variation in community structures sampled further apart in time; furthermore, (4) this increase in variation should be higher among rainy than among dry communities. We used data of stream macroinvertebrates (mostly insects) in a subtropical basin in Brazil to evaluate inter‐annual variation using rank‐concordance statistics of the most common species and dissimilarity using all species. For each stream site, samples obtained in the two seasons tended to show distinct community structure using relative abundance data but were much less distinct using species composition (presence–absence). Temporal β diversity was higher among rainy than among dry seasons. The β diversity of both seasons increased with time, although this increase was 2–3 times greater during the rainy season. Our results support a model in which rainy (summer) communities are disrupted by the high dynamism caused by spates and the emergence of adult insects. The low intensity of these two factors during dry (winter) periods allows local environmental conditions to drive community structures toward a less variable, recurrent attractor state. However, the increase in β diversity with time indicates that the legacy effects of previous disturbances and demographic stochasticity preclude the full attainment of a definite stable state and that only a domain of states is approached.

Impact of Urbanization on Urban Heat Island Intensity in Major Districts of Bangladesh Using Remote Sensing and Geo-Spatial Tools

Urbanization is closely associated with land use land cover (LULC) changes that correspond to land surface temperature (LST) variation and urban heat island (UHI) intensity. Major districts of Bangladesh have a large population base and commonly lack the resources to manage fast urbanization effects, so any rise in urban temperature influences the population both directly and indirectly. However, little is known about the impact of rapid urbanization on UHI intensity variations during the winter dry period in the major districts of Bangladesh. To this end, we aim to quantify spatiotemporal associations of UHI intensity during the winter period between 2000 and 2019 using remote-sensing and geo-spatial tools. Landsat-8 and Landsat-5 imageries of these major districts during the dry winter period from 2000 to 2020 were used for this purpose, with overall precision varying from 81% to 93%. The results of LULC classification and LST estimation showed the existence of multiple UHIs in all major districts, which showed upward trends, except for the Rajshahi and Rangpur districts. A substantial increase in urban expansion was observed in Barisal &gt; 32%, Mymensingh &gt; 18%, Dhaka &gt; 17%, Chattogram &gt; 14%, and Rangpur &gt; 13%, while a significant decrease in built-up areas was noticed in Sylhet &lt; −1.45% and Rajshahi &lt; −3.72%. We found that large districts have greater UHIs than small districts. High UHI intensities were observed in Mymensingh &gt; 10 °C, Chattogram &gt; 9 °C, and Barisal &gt; 8 °C compared to other districts due to dense population and unplanned urbanization. We identified higher LST (hotspots) zones in all districts to be increased with the urban expansion and bare land. The suburbanized strategy should prioritize the restraint of the high intensity of UHIs. A heterogeneous increase in UHI intensity over all seven districts was found, which might have potential implications for regional climate change. Our study findings will enable policymakers to reduce UHI and the climate change effect in the concerned districts.

Informing Equitable Water and Food Policies through Accurate Spatial Information on Irrigated Areas in Smallholder Farming Systems.

Accurate information on irrigated areas' spatial distribution and extent are crucial in enhancing agricultural water productivity, water resources management, and formulating strategic policies that enhance water and food security and ecologically sustainable development. However, data are typically limited for smallholder irrigated areas, which is key to achieving social equity and equal distribution of financial resources. This study addressed this gap by delineating disaggregated smallholder and commercial irrigated areas through the random forest algorithm, a non-parametric machine learning classifier. Location within or outside former apartheid "homelands" was taken as a proxy for smallholder, and commercial irrigation. Being in a medium rainfall area, the huge irrigation potential of the Inkomati-Usuthu Water Management Area (UWMA) is already well developed for commercial crop production outside former homelands. However, information about the spatial distribution and extent of irrigated areas within former homelands, which is largely informal, was missing. Therefore, we first classified cultivated lands in 2019 and 2020 as a baseline, from where the Normalised Difference Vegetation Index (NDVI) was used to distinguish irrigated from rainfed, focusing on the dry winter period when crops are predominately irrigated. The mapping accuracy of 84.9% improved the efficacy in defining the actual spatial extent of current irrigated areas at both smallholder and commercial spatial scales. The proportion of irrigated areas was high for both commercial (92.5%) and smallholder (96.2%) irrigation. Moreover, smallholder irrigation increased by over 19% between 2019 and 2020, compared to slightly over 7% in the commercial sector. Such information is critical for policy formulation regarding equitable and inclusive water allocation, irrigation expansion, land reform, and food and water security in smallholder farming systems.

Dry Post Wintertime Mass Surveillance Unearths a Huge Burden of P. vivax, and Mixed Infection with P. vivaxP. falciparum, a Threat to Malaria Elimination, in Dhalai, Tripura, India.

With India aiming to achieve malaria elimination by 2030, several strategies have been put in place. With that aim, mass surveillance is now being conducted in some malaria-endemic pockets. As dry season mass surveillance has been shown to have its importance in targeting the reservoir, a study was undertaken to assess the parasite load by a sensitive molecular method during one of the mass surveys conducted in the dry winter period. It was executed in two malaria-endemic villages of Dhalai District, Tripura, in northeast India, also reported as P. falciparum predominated area. The present study found an enormous burden of Rapid Diagnostic Test negative malaria cases with P. vivax along with P. vivax and P. falciparum mixed infections during the mass surveillance from febrile and afebrile cases in dry winter months (February 2021–March 2021). Of the total 150 samples tested, 72 (48%) were positive and 78 (52%) negative for malaria by PCR. Out of the 72 positives, 6 (8.33%) were P. falciparum, 40 (55.55%) P. vivax, and 26 (36.11%) mixed infections. Out of 78 malaria negative samples, 6 (7.7%) were with symptoms, while among the total malaria positive, 72 cases 7 (9.8%) were with symptoms, and 65 (90.2%) were asymptomatic. Out of 114 samples tested by both microscopy and PCR, 42 samples turned out to be submicroscopic with 4 P. falciparum, 23 P. vivax, and 15 mixed infections. Although all P. vivax submicroscopic infections were asymptomatic, three P. falciparum cases were found to be febrile. Evidence of malaria transmission was also found in the vectors in the winter month. The study ascertained the use of molecular diagnostic techniques in detecting the actual burden of malaria, especially of P. vivax, in mass surveys. As Jhum cultivators in Tripura are at high risk, screening for the malarial reservoirs in pre-Jhum months can help with malaria control and elimination.

Particulate matter removal by forest cover in Delhi

ABSTRACT Increasing levels of particulate matter (PM) in the atmosphere of megacities is a serious concern due to implications for human exposure and overall environmental quality. Delhi experiences extremely high levels of particulate pollution. The present study sheds light on the seasonal differences in PM removal from the atmosphere by the available forest cover and quantifies this for Delhi. Particulate matter data from 40 stations across Delhi along with leaf area index (LAI) derived from remotely sensed satellite images were used. PM removed in the wet summer period was found to be lower than for the dry winter period in a year. The results highlight an unusual schedule for foliage fall in Delhi, as substantiated by the calculated LAI during the wet summer season and dry winter season. Overall, the study quantitatively evaluates the PM removal potential of forest cover in Delhi and suggests a need for the careful selection of trees in afforestation programmes.

Edaphic and climatic factors and the nutrient dynamics in Uapaca kirkiana dominated miombo woodland agroforestry ecosystems

Soil and foliar analysis were used to investigate influence of edaphic and climatic factors on the soil–plant nutrient dynamics in Uapaca kirkiana dominated woodland ecosystem in Zimbabwe. Examination of the relationship between soil factors and foliar nutrient concentrations as analysed by multiple regression analysis showed that between 60 and 97% of the variations in foliar nutrient concentrations during the wet period, with the exception of nitrogen, could be explained by soil factors: soil nutrient content, texture and pH. In the dry winter period, influence of these soil factors on foliar nutrient content was in the range between 48 and 97%. Factors that had significant influence (P < 0.05) were particularly exhibited during the wet period and these were those influencing foliar P, Fe, Mn and Zn. Multiple regression analysis between climatic factors and foliar nutrients showed temperature had a statistically significant negative relationship with Fe whilst precipitation had a highly significant positive relationship with Fe during the dry winter period. Correlation between foliar Fe and rainfall was negatively statistically significant during the rainy period (P < 0.05) and became positively statistically highly significant during the dry period (P < 0.01). There was also a highly statistically significant negative relationship between the total annual rainfall and foliar nitrogen during the dry winter period. Findings of the study highlight importance of both soil and climatic factors on soil–plant nutrient dynamics in the miombo ecosystem, and should therefore be taken into consideration when establishing U. kirkiana in an agroforestry system.

Spatial and seasonal variability of forested headwater stream temperatures in western Oregon, USA

Thermal regimes of forested headwater streams control the growth and distribution of various aquatic organisms. In a western Oregon, USA, case study we examined: (1) forested headwater stream temperature variability in space and time; (2) relationships between stream temperature patterns and weather, above-stream canopy cover, and geomorphic attributes; and (3) the predictive ability of a regional stream temperature model to account for headwater stream temperature heterogeneity. Stream temperature observations were collected at 48 sites within a 128-ha managed forest in western Oregon during 2012 and 2013. Headwater stream temperatures showed the greatest spatial variability during summer (range up to 10 $$^\circ$$ C) and during cold and dry winter periods (range up to 7.5 $$^\circ$$ C), but showed less spatial variability during spring, fall and wet winter periods (range between 2 and 5 $$^\circ$$ C). Distinct thermal regimes among sites were identified; however, geomorphic attributes typically used in regional stream temperature models were not good predictors of thermal variability at headwater scales. A regional stream temperature model captured the mode of mean August temperatures observed across the study area, but overpredicted temperatures for a quarter of the sites by up to 2.8 $$^\circ$$ C. This study indicates considerable spatial thermal variability may occur at scales not resolved by regional stream temperature models. Recognizing this sub-landscape variability may be important when predicting distributions of aquatic organisms and their habitat under climate and environment change scenarios.

Rainwater harvesting potential for farming system development in a hilly watershed of Bangladesh

Water resources management is an important part in farming system development. Agriculture in Chittagong Hill Tracts of Bangladesh is predominantly rainfed with an average 2210 mm monsoonal rain, but rainfall during dry winter period (December–February) is inadequate for winter crop production. The natural soil water content (as low as 7 %) of hillslope and hilltop during the dry season is not suitable for shallow-rooted crop cultivation. A study was conducted to investigate the potential of monsoonal rainwater harvesting and its impact on local cropping system development. Irrigation facilities provided by the managed rainwater harvesting reservoir increased research site’s cropping intensity from 155 to 300 %. Both gravity flow irrigation of valley land and low lift pumping to hillslope and hilltop from rainwater harvesting reservoir were much more economical compared to forced mode pumping of groundwater because of the installation and annual operating cost of groundwater pumping. To abstract 7548 m3 of water, equivalent to the storage capacity of the studied reservoirs, from aquifer required 2174 kWh energy. The improved water supply system enabled triple cropping system for valley land and permanent horticultural intervention at hilltop and hillslope. The perennial vegetation in hilltop and hillslope would also conserve soil moisture. Water productivity and benefit–cost ratio analysis show that vegetables and fruit production were more profitable than rice cultivation under irrigation with harvested rainwater. Moreover, the reservoir showed potentiality of integrated farming in such adverse area by facilitating fish production. The study provides water resource managers and government officials working with similar problems with valuable information for formulation of plan, policy, and strategy.

Seasonal changes in optical properties of two contrasting tropical freshwater systems

&lt;p&gt;We investigated how allochthonous and autochthonous sources of dissolved organic matter (DOM) affected the optical conditions and chemical characteristics of two contrasting tropical freshwater systems (Dom Helvécio-DH and Pampulha reservoir) in a dry and rainy period in 2013. We analyzed PAR (photosynthetically active radiation) and UV (ultraviolet) attenuation coefficients, nutrients, chlorophyll-a (Chl-a), dissolved organic matter (DOC) and spectral characteristics of CDOM (colored dissolved organic matter). Significant differences in CDOM sources and quantity were observed, with a dominantly terrestrial input in DH during the rainy period with approximately 50% higher DOC and Chl-a levels, and a doubling in total nitrogen (TN) and total phosphorus (TP) compared to the dry winter period. The eutrophic Pampulha had several fold higher levels of DOC, Chl-a, TN and TP, with organic matter of mostly originating from phytoplankton in both seasons. Differences in source and quantity had strong implications on water transparency, DOC concentrations, CDOM quality and its susceptibility to photo- and biodegradation. DH was several fold clearer in both the UV and PAR spectrum. In DH transparency to both UV and PAR radiation was highest during the summer, suggesting elevated photo- and biodegradation during stratification. Pampulha was most transparent in the dry period even during period of algal bloom. In both systems we observed seasonal variations in concentrations of nutrients and Chl-a, and in DH differences were also found in DOC concentrations as well as the specific UV absorbance (SUVA&lt;sub&gt;254&lt;/sub&gt;) and molecular size (M). Our results documents that different sources of DOM and seasonal inputs reflect in the seasonality of apparent and inherent optical properties and nutrients availability with implications for water quality and aquatic community. &lt;/p&gt;

The density-driven circulation of the coastal hypersaline system of the Great Barrier Reef, Australia

The coastal hypersaline system of the Great Barrier Reef (GBR) in the dry season, was investigated for the first time using a 3D baroclinic model. In the shallow coastal embayments, salinity increases to c.a. 1‰ above typical offshore salinity (~35.4‰). This salinity increase is due to high evaporation rates and negligible freshwater input. The hypersalinity drifts longshore north-westward due to south-easterly trade winds and may eventually pass capes or headlands, e.g. Cape Cleveland, where the water is considerably deeper (c.a. 15m). Here, a pronounced thermohaline circulation is predicted to occur which flushes the hypersalinity offshore at velocities of up to 0.08m/s. Flushing time of the coastal embayments is around 2–3weeks. During the dry season early summer, the thermohaline circulation reduces and therefore, flushing times are predicted to be slight longer due to the reduced onshore-offshore density gradient compared to that in the dry season winter period.

Short day-triggered quiescence promotes water conservation in the American dog tick, Dermacentor variabilis.

A short day-long day exposure comparison of water balance characteristics throughout the life history of the American dog tick, Dermacentor variabilis, was conducted to examine how this tick survives winter-associated dryness. Larvae, nymphs, and adults under potential diapause-inducing conditions (short day, 20 °C) have low water loss rates compared to long day exposed ticks. Above the critical equilibrium activity, these nonfed ticks show greater water gain from lower water vapor activities. In contrast to nonfed stages, eggs and blood-engorged stages (fed larva, fed nymph) were enhanced for water conservation independent of short day exposure and did not display reduced water loss rates under short day conditions. This short day-prompted response in nonfed ticks was distinguished from a genetically programmed diapause as noted in other arthropods by: (1) reduction in water loss was temporary and could be reversed quickly by transferring to long day for only a single day, then re-triggered by returning to short day conditions; (2) switch between low and high water loss rates could be induced multiple times and for multiple different stages; and (3) response by ticks was to the photoperiod they were under, not the condition that was experienced by previous fed stages or in the mother in the case of eggs. Furthermore, short day had no impact on altering body water content, dehydration tolerance limit, instar yields, or developmental stadia. We conclude that a short day-triggered quiescence reduces desiccation stress associated with overwintering in nonfed ticks. This effect on water conservation due to short day exposure is more pronounced for subadults and is likely due to their increased sensitivity to water loss as a result of their smaller size, which is critical to prevent dehydration during the dry winter periods.

Apportioned contributions of PM2.5 fine aerosol particles over the Maldives (northern Indian Ocean) from local sources vs long-range transport

Urban-like plumes of gases and particulate matter originating from the South Asian region are frequently observed over the Indian Ocean, especially during the dry winter period. However, in addition to the strong sources on mainland South Asia, there are also local Maldivian emissions. The local contributions to the load of fine particulate matter (PM2.5) in the Maldivian capital Malé was assessed using the well-established Maldives Climate Observatory at Hanimaadhoo (MCOH) to represent local background, recording the long-range transported component for a full-year synoptic campaign at both sites in 2013. The year-round levels in both Malé and MCOH are strongly influenced by the seasonality of the monsoon cycle, including precipitation patterns and air-mass transport pathways, with lower levels during the wet summer season. The annual-average PM2.5 levels in Malé are higher (avg. 19μg/m3) than at MCOH (avg. 13μg/m3) with the difference being the largest during the summer, when local emissions play a larger role. The 24-h World Health Organization (WHO) PM2.5 health guideline was surpassed for the weeklong collections in 71% of the cases in Malé and in 74% of the cases for Hanimaadhoo. This study shows that in the dry/winter season 90±11% of PM2.5 levels in Malé could be from long-range transport with only 8±11% from local emissions while in the wet/monsoon season the relative contributions are about equal. The concentrations of organic carbon (OC) and elemental carbon (EC) showed similar seasonal patterns as bulk mass PM2.5. The relative contribution of total carbonaceous matter to bulk mass PM2.5 was 17% in Malé and 13% at MCOH, suggesting larger contributions from incomplete combustion practices in the Malé local region.

A 500-year seasonally resolved δ&amp;lt;sup&amp;gt;18&amp;lt;/sup&amp;gt;O and δ&amp;lt;sup&amp;gt;13&amp;lt;/sup&amp;gt;C, layer thickness and calcite aspect record from a speleothem deposited in the Han-sur-Lesse cave, Belgium

Abstract. Speleothem δ18O and δ13C signals enable climate reconstructions at high resolution. However, scarce decadal and seasonally resolved speleothem records are often difficult to interpret in terms of climate due to the multitude of factors that affect the proxy signals. In this paper, a fast-growing (up to 2 mm yr−1) seasonally laminated speleothem from the Han-sur-Lesse cave (Belgium) is analyzed for its δ18O and δ13C values, layer thickness and changes in calcite aspect. The studied record covers the period between AD 2001 and 1479 as indicated by layer counting and confirmed by 20 U / Th ages. The Proserpine proxies are seasonally biased and document drier (and colder) winters on multidecadal scales. Higher δ13C signals reflect increased prior calcite precipitation (PCP) and lower soil activity during drier (and colder) winters. Thinner layers and darker calcite relate to slower growth and exist during drier (and colder) winter periods. Exceptionally dry (and cold) winter periods occur from 1565 to 1610, at 1730, from 1770 to 1800, from 1810 to 1860, and from 1880 to 1895 and correspond to exceptionally cold periods in historical and instrumental records as well as European winter temperature reconstructions. More relative climate variations, during which the four measured proxies vary independently and display lower amplitude variations, occur between 1479 and 1565, between 1610 and 1730, and between 1730 and 1770. The winters during the first and last periods are interpreted as relatively wetter (and warmer) and correspond to warmer periods in historical data and in winter temperature reconstructions in Europe. The winters in the period between 1610 and 1730 are interpreted as relatively drier (and cooler) and correspond to generally colder conditions in Europe. Interpretation of the seasonal variations in δ18O and δ13C signals differs from that on a decadal and multidecadal scale. Seasonal δ18O variations reflect cave air temperature variations and suggest a 2.5 °C seasonality in cave air temperature during the two relatively wetter (and warmer) winter periods (1479–1565 and 1730–1770), which corresponds to the cave air temperature seasonality observed today. Between 1610 and 1730, the δ18O values suggest a 1.5 °C seasonality in cave air temperature, indicating colder summer temperatures during this drier (and cooler) interval. The δ13C seasonality is driven by PCP and suggests generally lower PCP seasonal effects between 1479 and 1810 compared to today. A short interval of increased PCP seasonality occurs between 1600 and 1660, and reflects increased PCP in summer due to decreased winter recharge.

Seasonal precipitation forecasts over China using monthly large-scale oceanic-atmospheric indices

Summary Forecasting precipitation at the seasonal time scale remains a formidable challenge. In this study, we evaluate a statistical method for forecasting seasonal precipitation across China for 12 overlapping seasons. We use the Bayesian joint probability modelling approach to establish multiple probabilistic forecast models using eight large-scale oceanic-atmospheric indices at lag times of 1–3 months as predictors. We then merge forecasts from the multiple models with Bayesian model averaging to combine the strengths of the individual models. Forecast skill and reliability are assessed through leave-one-year-out cross validation. The merged forecasts exhibit considerable seasonal and spatial variability in forecast skill. The merged forecasts are most skillful over west China in spring periods and over central-south China in autumn periods. In contrast, forecast skill in most wet summer and dry winter periods is generally low. Positive forecast skill is mostly retained when forecast lead time is increased from 0 to 2 months. Forecast distributions are found to reliably represent forecast uncertainty. Climate indices derived from sea surface temperature in the western Pacific and Indian Ocean tend to contribute more to forecast skill than indices of the El Nino-Southern Oscillation. Large-scale atmospheric circulation patterns, represented by the Arctic Oscillation and North Atlantic Oscillation, appear to contribute little to forecast skill.

Plant drought tolerance assessment for re-vegetation in heterogeneous karst landscapes of southwestern China

A better understanding of plant water relations is needed for evaluating the suitability of plant species to site-specific reforestation programs in the heterogeneous karst landscapes in southwestern China that are characterized by temporary water deficit. During both wet and dry periods, leaf water potentials of 65 plant species from five different growth forms were studied at three representative sites (forest, shrubland and grassland), to compare their adaptive strategies against water stress and assess their suitability for reforestation programs. Herbs showed the highest predawn and midday water potentials and smallest diurnal ranges of water potential values at all the three sites, indicating that they follow water stress avoidance strategies. During the dry period, evergreen shrubs showed low water potentials, the largest diurnal ranges and highest soluble sugar contents. This indicates that they have a tolerance strategy responding to water stress. Deciduous shrubs and trees still showed relatively large diurnal ranges of water potential values and high soluble sugar contents, and did not shed leaves when experiencing the lowest midday water potentials during the dry period. They shed leaves only later in the dry winter period when even more serious drought was experienced. Their strategies seem to include both tolerance and avoidance mechanisms. Evergreen trees revealed relatively low water potentials with smallest diurnal range water potentials at the shrubland site, especially during the dry period, which indicated their weak ability to tolerate severe water stress. Increasing degradation of the vegetation clearly impacts negatively plant water relations. Using the ranges of leaf water potentials, the relative suitability of the plants for reforestation could be evaluated.

The effects of high temperature and wallow on physiological responses of swamp buffaloes ( Bubalus bubalis) during winter season in Thailand

The objective was to measure the effects of wallowing on the performance and physiology of 12 female buffaloes with similar live weight of 250 kg. The study took place at Chainat Agriculture and Technology College, Chainat Province, Thailand. The animals were divided randomly into two groups, each group comprising of 6 buffaloes. The two groups were used to evaluate the effects of wallowing on the animals' thermal status under hot humid conditions. Results (no wallow vs. wallow) indicated that wallowing was sufficient to result in the buffaloes having a significantly lower mean rectal temperature (39.86±0.85 vs. 39.21±0.62 °C; P<0.01), water intake (28.02±4.96 vs. 27.47±4.94 l/hd/d; P<0.05), Free triiodothyronine (4.12±1.17 vs. 3.4±0.74 ng/ml; P<0.05) and cortisol (3.55±1.53 vs. 2.33±1.39 ng/ml; P<0.05 ). It was concluded that wallowing enabled the buffaloes to cool themselves down by cutaneous evaporation. The use of wallowing proved to be an effective method of alleviating thermal stress in buffaloes and is recommended for use during dry winter periods in monsoonal areas.

Personal Perspectives on Commercial versus Communal African Fire Paradigms when Using Fire to Manage Rangelands for Domestic Livestock and Wildlife in Southern and East African Ecosystems

Africa is often referred to as the Fire Continent, and fire is recognised as a natural factor of the environment due to the prevalence of lightning storms and an ideal fire climate in the less arid regions with seasonal drought. On a global scale, the most extensive areas of tropical savanna, characterized by grassy under stories that become extremely flammable during the dry season, occur in Africa. The use of fire in Africa to manage vegetation for domestic livestock and indigenous wildlife is widely recognized by both commercial and communal land users. Research on the effects of fire has been conducted throughout the grassland and savanna areas since the early twentieth century, resulting in the development of effective and practical guidelines for prescribed burning for domestic livestock and wildlife management systems. Generally, the reasons for prescribed burning in Africa are similar for both commercial and communal land users, namely, to remove moribund and or unacceptable plant material and to control the encroachment of undesirable plants negatively affecting domestic livestock and wildlife. In addition, commercial operators use fire to manage wildlife conservation areas. Prescribed burning to control ticks is also widely used in communal communities but is generally not recognised in commercial livestock enterprises. However, research has shown that tick populations can be reduced using fire to alter the micro-habitat for these organisms. Until recently, commercial and communal land users held differing views on the appropriate season for prescribed burning, with the former igniting fires shortly after the first spring rains and the latter burning throughout the dry winter period. Subsequent research has shown that both seasons of burn have similar effects; the key requirement being that the grass sward is dormant at the time of burning to minimise the negative effects on the vegetation. A valuable tentative comparison has been made between fire management practices applied by commercial land users and communal land users, and provides an exciting opportunity for further and essential research to be conducted to gain greater insight into how communal African communities use fire. Based on extensive experience, my aim is to provide a personal perspective on the use of fire by commercial and communal land users for managing rangelands in southern and east African regions of the continent.

Sustainability of maize-based cropping systems in rural areas of Zimbabwe: an assessment of the residual soil fertility effects of grain legumes on maize (&lt;I&gt;Zea mays&lt;/I&gt; [L.]) under field conditions

The residual soil fertility benefits of the preceding legumes to the following maize crop were demonstrated in the study. Incorporating stover of Bambara nut, cowpea, groundnut dry bean and soyabean gave higher maize yields compared to plots where the stover was removed. Total maize dry matter yield increases of 1.30 tha-¹ to 5.19 ha-¹ were recordedfollowing legume stover incorporation compared to stover removal. Even removal of stover of these same legumes gave significant maize yield increases compared to those from the maize after maize or after fallow plots. The total maize dry matter yield was greater after legumes with stover removed (ranging from 4.41 to 9.91 tha-¹) than after maize (2.16 to 2.26 tha-¹) or one season fallow (1.57 to 1.84 tha-¹). So farmers who keep livestock can still remove legume residues as fodder to supplement grazing in the dry winter period and still benefit from improved maize yields. International Journal of Engineering, Science and Technology, Vol. 2, No. 7, 2010, pp. 141-148