Impact of leopards on a working ranch in Laikipia,Kenya

This study of leopard predation on livestock was carried out on the Lolldaiga Hills ranch (200 km²) in the Laikipia District in Kenya between September 1989 and August 1995. The aims of the study were to find out whether leopards depend on livestock as a food resource on the ranch, and to quantify the economic impact of leopards on the livestock production systems. The density of leopards was estimated in three ways, and the biomass density of potential prey for leopards, both wild and domestic. Diet analysis of leopards revealed that leopards are not relying on livestock as an important food resource. To quantify the effects of leopards, an approach used in the economic assessment of agricultural development schemes was adopted ( Gittinger, 1982 ) and models were derived by following those criteria. It was found that leopards, not being persecuted, live at a relatively high density on the ranch but have less of an adverse impact on livestock than might be expected. Wildlife as a food resource for leopards and a buffer against the killing of livestock could be of benefit on a working ranch to reduce the economic impact of predators on the production system.     

Dietary composition of wildebeest (Connochaetes taurinus) kongoni (Alcephalus buselaphus) and cattle (Bos indicus), grazing on a common ranch in south-central Kenya

This paper gives the results of a study conducted at Game Ranching Ltd, situated at the Athi Kapiti Plains, Kenya, to determine the dietary composition of cattle (Bos indicus L), kongoni (Alcephalus buselaphus Pallas) and wildebeest (Connochaetes taurinus Burchell), through two forage growing seasons (wet and dry). The dietary preferences and overlaps between the species were also determined. The diet preference of the three herbivores was determined using a microhistological analysis technique. The three dominant grasses in the ranch: Themeda triandra Fork, Digitaria macroblephara (Hack.) Stapf and Penisetum mezianum Leeke, formed the major diets of the animals. The browse component of the diets increased during the dry season by about 100% for all the animal species, with cattle always having twice as much browse as the wild herbivores. However, the animals selected similar diets in terms of plant species during both seasons but were more selective during the wet season. Dietary overlaps were always above 75%, but more than this during the dry season. The dietary overlaps were lower between cattle and wild herbivores than between the wild herbivores. The diet preference index for the animals differed from season to season, and from plant to plant.     

Accelerometry predicts daily energy expenditure in a bird with high activity levels

Animal ecology is shaped by energy costs, yet it is difficult to measure fine-scale energy expenditure in the wild. Because metabolism is often closely correlated with mechanical work, accelerometers have the potential to provide detailed information on energy expenditure of wild animals over fine temporal scales. Nonetheless, accelerometry needs to be validated on wild animals, especially across different locomotory modes. We merged data collected on 20 thick-billed murres (Uria lomvia) from miniature accelerometers with measurements of daily energy expenditure over 24 h using doubly labelled water. Across three different locomotory modes (swimming, flying and movement on land), dynamic body acceleration was a good predictor of daily energy expenditure as measured independently by doubly labelled water (R² = 0.73). The most parsimonious model suggested that different equations were needed to predict energy expenditure from accelerometry for flying than for surface swimming or activity on land (R² = 0.81). Our results demonstrate that accelerometers can provide an accurate integrated measure of energy expenditure in wild animals using many different locomotory modes.     

Fluoride in the Bones of Foxes (Vulpes vulpes Linneaus, 1758) and Raccoon Dogs (Nyctereutes procyonoides Gray, 1834) from North-Western Poland

Assessment of exposure to fluoride (F^?) is increasingly focused on mineralized tissues, mainly bones. Their periodic growth and continuous reconstruction make them a good material for studying long-term F^? accumulation. In this study, F^?concentrations were determined in the bones of foxes and raccoon dogs from north-western Poland and relationships between bone F^? and the age categories of the animals were attempted to be identified. Bone samples were collected from femurs of 32 foxes (15 males and 17 females) and 18 raccoon dogs (10 males and 8 females) from polluted, medium-polluted, and unpolluted by F^? areas. Bone F^? was determined by potentiometric method, and results were expressed per dry weight (dw); they ranged from 176 to 3,668 mg/kg dw in foxes and from 84 to 1,190 mg/kg dw in raccoon dogs. Foxes from north-western Poland accumulated much more F^? in their bones than raccoon dogs. Our study shows that the assessment of hazards created by industrial emitters can be conducted conveniently by the measurements of fluorine content in hard tissues of wild animals. Due to availability of such type of material for studies, it seems that the analysis of fluoride content in bones can be a good tool in the development of ecotoxicology.     

Climate- and crop-responsive emission factors significantly alter estimates of current and future nitrous oxide emissions from fertilizer use

The current Intergovernmental Panel on Climate Change (IPCC) default methodology (tier 1) for calculating nitrous oxide (N₂O) emissions from nitrogen applied to agricultural soils takes no account of either crop type or climatic conditions. As a result, the methodology omits factors that are crucial in determining current emissions, and has no mechanism to assess the potential impact of future climate and land‐use change. Scotland is used as a case study to illustrate the development of a new methodology, which retains the simple structure of the IPCC tier 1 methodology, but incorporates crop‐ and climate‐dependent emission factors (EFs). It also includes a factor to account for the effect of soil compaction because of trampling by grazing animals. These factors are based on recent field studies in Scotland and elsewhere in the UK. Under current conditions, the new methodology produces significantly higher estimates of annual N₂O emissions than the IPCC default methodology, almost entirely because of the increased contribution of grazed pasture. Total emissions from applied fertilizer and N deposited by grazing animals are estimated at 10 662 t N₂O‐N yr^?1 using the newly derived EFs, as opposed to 6 796 t N₂O‐N yr^?1 using the IPCC default EFs. On a spatial basis, emission levels are closer to those calculated using field observations and detailed soil modelling than to estimates made using the IPCC default methodology. This can be illustrated by parts of the western Ayrshire basin, which have previously been calculated to emit 8–9 kg N₂O‐N ha^?1 yr^?1 and are estimated here as 6.25–8.75 kg N₂O‐N ha^?1 yr^?1, while the IPCC default methodology gives a maximum emission level of only 3.75 kg N₂O‐N ha^?1 yr^?1 for the whole area. The new methodology is also applied in conjunction with scenarios for future climate‐ and land‐use patterns, to assess how these emissions may change in the future. The results suggest that by 2080, Scottish N₂O emissions may increase by up to 14%, depending on the climate scenario, if fertilizer and land management practices remain unchanged. Reductions in agricultural land use, however, have the potential to mitigate these increases and, depending on the replacement land use, may even reduce emissions to below current levels.     

Aflatoxin M<Subscript>1</Subscript> levels in different marketed milk products in Nairobi,Kenya

Milk is an important source of energy and nutrients, especially for children, and in Kenya, milk consumption is higher than other countries in the region. One major concern with milk is the risks of chemical contaminants, and reports of high levels of aflatoxin M₁ (AFM₁) in milk in Kenya has been causing public health concerns. This study collected marketed milk products every month during 1 year, just as a consumer would purchase them from retailers and traders in a low-income area, and a major supermarket in a middle/high-income area. In total, 291 sampled milk products (raw, pasteurised, UHT milk, yoghurt and lala) were collected and analysed for AFM₁ using a commercial ELISA kit. More than 50% of the samples exceeded 50 ng/kg (the level allowed in the EU), but only three samples exceeded 500 ng/kg (the level allowed in the USA). Geometric mean AFM₁ level was 61.9 ng/kg in the 135 samples from the low-income area while it was 36.1 ng/kg in the 156 from the higher income area (p?<?0.001). The levels varied significantly depending on the time of year, with lowest levels of milk in January. There were also differences between manufacturers and products, with UHT milk having lower levels. There was no difference depending on the price for all dairy products, but when only including milk, higher price was associated with lower levels of AFM₁. In conclusion, this study shows that milk purchased by a consumer is likely to contain AFM₁ above 50 ng/kg, and that further research is needed to find ways to mitigate AFM₁ contamination through working with farmers and milk processors both in the formal and informal sectors.     

Effects of dairy farming intensification on nitrous oxide emissions

A dairy farm system trial was conducted between September 2003 and August 2005 to evaluate the effect of integration of maize silage forage on nitrous oxide (N₂O) emissions. Potentially, the integration of low-protein forage (e.g. feeding cows with maize silage) to reduce dietary-nitrogen (N) concentration can mitigate environmental N emissions and increase N use efficiency. The dairy farm systems consisted of a maize supplementation system with a stocking rate of 3.8 cows ha^?1 of grazed pasture with maize silage brought in and a control system with a stocking rate of 3.0 cows ha^?1 of grazed pasture. Direct and indirect N₂O emissions from all components of the farm systems were either measured using a closed chamber technique or calculated using the New Zealand IPCC inventory methodology. Annual average N₂O emissions were slightly lower on the maize supplementation pasture than on the control pasture. Annual total N₂O emissions from the “whole” farm systems (including direct and indict emissions from the grazed pastures, maize growing land, N fertilizer use and associated land application of farm effluent) were 7.71 and 8.00 kg N₂O–N ha^?1 of dairy farm on the control and maize supplement farm systems, respectively. The corresponding annual milk production was 13,437 and 17,925 kg ha^?1. Therefore, the N₂O emission per kg of milk production from the maize supplementation was 22% lower than that from the control system. This was due to the much greater efficiency of N use from low-protein maize silage than from pasture. The results suggest that the integration of low-protein forage can be an effective management practice to mitigate adverse environmental effects of increasing stocking rates in the New Zealand dairy farm systems, in terms of N₂O emissions per unit of milk production.     

Comparative nutritional and mycochemical contents,biological activities and LC/MS screening of tuber from new recipe cultivation technique with wild type tuber of tiger’s milk mushroom of species <Emphasis Type="Italic">Lignosus rhinocerus</Emphasis>

Tiger’s milk mushroom is known for its valuable medicinal properties, especially the tuber part. However, wild tuber is very hard to obtain as it grows underground. This study first aimed to cultivate tiger’s milk mushroom tuber through a cultivation technique, and second to compare nutritional and mycochemical contents, antioxidant and cytotoxic activities and compound screening of the cultivated tuber with the wild tuber. Results showed an increase in carbohydrate content by 45.81% and protein content by 123.68% in the cultivated tuber while fat content reduced by 13.04%. Cultivated tuber also showed an increase of up to 64.21% for total flavonoid-like compounds and 62.51% of total β-d-glucan compared to the wild tuber. The antioxidant activity of cultivated tuber and wild tuber was 760 and 840 µg mL^?1, respectively. The cytotoxic activity of boiled water extract of cultivated tuber against a human lung cancer cell line (A549) was 65.50?±?2.12 µg mL^?1 and against a human breast cancer cell line (MCF7) was 19.35?±?0.11 µg mL^?1. β-d-glucan extract from the purification of boiled water extract of cultivated tuber showed cytotoxic activity at 57.78?±?2.29 µg mL^?1 against A549 and 33.50?±?1.41 µg mL^?1 against MCF7. However, the β-glucan extract from wild tuber did not show a cytotoxic effect against either the A549 or MCF7 cell lines. Also, neither of the extracts from cultivated tuber and wild tuber showed an effect against a normal cell line (MRC5). Compound profiling through by liquid chromatography mass spectrometry (LC/MS) showed the appearance of new compounds in the cultivated tuber. In conclusion, our cultivated tuber of tiger’s milk mushroom using a new recipe cultivation technique showed improved nutrient and bioactive compound contents, and antioxidant and cytotoxic activities compared to the wild tuber. Further investigations are required to obtain a better quality of cultivated tuber.     

Carbon footprint and land requirement for dairy herd rations: impacts of feed production practices and regional climate variations

Feed production is a significant source of greenhouse gas (GHG) emissions from dairy production and demands large arable and pasture acreage. This study analysed how regional conditions influence GHG emissions of dairy feed rations in a life cycle perspective, that is the carbon footprint (CF) and the land area required. Factors assessed included regional climate variations, grass/clover silage nutrient quality, feedstuff availability, crop yield and feed losses. Using the Nordic feed evaluation model NorFor, rations were optimised for different phases of lactation, dry and growing periods for older cows, first calvers and heifers by regional feed advisors and combined to annual herd rations. Feed production data at farm level were based on national statistics and studies. CF estimates followed standards for life cycle assessment and used emissions factors provided by IPCC. The functional unit was ‘feed consumption to produce 1 kg energy corrected milk (ECM) from a cow with annual milk yield of 9 900 kg ECM including replacement animals and feed losses’. Feed ration CF varied from 417 to 531 g CO₂ e/kg ECM. Grass/clover silage contributed more than 50% of total GHG emissions. Use of higher quality silage increased ration CF by up to 5% as a result of an additional cut and increased rates of synthetic N-fertiliser. Domestically produced horse bean (Vicia faba), by-products from the sugar industry and maize silage were included in the rations with the lowest CF, but horse bean significantly increased ration land requirement. Rations required between 1.4 to 2 m² cropland and 0.1 to 0.2 m²/kg semi-natural grassland per kg ECM and year. Higher yield levels reduced ration total CF. Inclusion of GHG emissions from land use change associated with Brazilian soya feed significantly increased ration CF. Ration CF and land use depended on ration composition, which was highly influenced by the regional availability and production of feedstuffs. The impact of individual feedstuffs on ration CF varies due to, for example, cultivation practices and climate conditions and feedstuffs should therefore be assessed in a ration and regional perspective before being used to decrease milk CF. Land use efficiency should be considered together with ration CF, as these can generate goal conflicts.     

Response of native ungulates to drought in semi‐arid Kenyan rangeland

The distribution and abundance of native ungulates were measured on commercially managed, semi‐arid rangeland in central Kenya over a 3‐year period that encompassed severe drought and above‐average rainfall. Native ungulate biomass density averaged 5282 kg km^?2 over the study and was dominated by elephant (Loxodonta africana), impala (Aepyceros melampus) and dik‐dik (Madoqua kirkii). Biomass density of domestic cattle (Bos taurus) averaged 2280 kg km^?2 during the study. Responses of native ungulates to severe drought were variable. Impala densities were similar to or greater than densities for similar habitat in protected areas, and varied from 12 to 16 km^?2 during and following the drought to 24–29 km^?2 following above‐average rainfall. Dik‐dik densities were also greater than densities reported for protected areas and were surprisingly stable throughout the study despite the wide annual fluctuations in rainfall. Elephant migrated out of the region during drought but were present at high densities (2.9–5.2 km^?2) during wet seasons, consistent with telemetry studies emphasizing the importance of Acacia bushland habitat on commercial rangelands for the migratory portion of the Laikipia–Samburu elephant population. Results show that substantial densities of native browsing and mixed‐feeding ungulates can occur on rangeland managed for commercial beef production and suggest that the capacity for ungulates to move over large spatial scales (>100 km²) and to shift distributions in response to locally variable thunderstorms may be important for sustaining these populations.     

Carbon exchange of grazed pasture on a drained peat soil

Land‐use changes have contributed to increased atmospheric CO₂ concentrations. Conversion from natural peatlands to agricultural land has led to widespread subsidence of the peat surface caused by soil compaction and mineralization. To study the net ecosystem exchange of carbon (C) and the contribution of respiration to peat subsidence, eddy covariance measurements were made over pasture on a well‐developed, drained peat soil from 22 May 2002 to 21 May 2003. The depth to the water table fluctuated between 0.02 m in winter 2002 to 0.75 m during late summer and early autumn 2003. Peat soil moisture content varied between 0.6 and 0.7 m³ m^?3 until the water table dropped below 0.5 m, when moisture content reached 0.38 m³ m^?3. Neither depth to water table nor soil moisture was found to have an effect on the rate of night‐time respiration (ranging from 0.4–8.0 μmol CO₂ m^?2 s^?1 in winter and summer, respectively). Most of the variance in night‐time respiration was explained by changes in the 0.1 m soil temperature (r²=0.93). The highest values for daytime net ecosystem exchange were measured in September 2002, with a maximum of ?17.2 μmol CO₂ m^?2 s^?1. Grazing events and soil moisture deficiencies during a short period in summer reduced net CO₂ exchange. To establish an annual C balance for this ecosystem, non‐linear regression was used to model missing data. Annually integrated (CO₂) C exchange for this peat–pasture ecosystem was 45±500 kg C ha^?1 yr^?1. After including other C exchanges (methane emissions from cows and production of milk), the net annual C loss was 1061±500 kg C ha^?1 yr^?1.     

Nitrate leaching and soil nitrous oxide emissions diminish with time in a hybrid poplar short‐rotation coppice in southern Germany

Hybrid poplar short‐rotation coppices (SRC) provide feedstocks for bioenergy production and can be established on lands that are suboptimal for food production. The environmental consequences of deploying this production system on marginal agricultural land need to be evaluated, including the investigation of common management practices i.e., fertilization and irrigation. In this work, we evaluated (1) the soil‐atmosphere exchange of carbon dioxide, methane, and nitrous oxide (N₂O); (2) the changes in soil organic carbon (SOC) stocks; (3) the gross ammonification and nitrification rates; and (4) the nitrate leaching as affected by the establishment of a hybrid poplar SRC on a marginal agricultural land in southern Germany. Our study covered one 3‐year rotation period and 2 years after the first coppicing. We combined field and laboratory experiments with modeling. The soil N₂O emissions decreased from 2.2 kg N₂O‐N ha^?1 a^?1 in the year of SRC establishment to 1.1–1.4 kg N₂O‐N ha^?1 a^?1 after 4 years. Likewise, nitrate leaching reduced from 13 to 1.5–8 kg N ha^?1 a^?1. Tree coppicing induced a brief pulse of soil N₂O flux and marginal effects on gross N turnover rates. Overall, the N losses diminished within 4 years by 80% without fertilization (irrespective of irrigation) and by 40% when 40–50 kg N ha^?1 a^?1 were applied. Enhanced N losses due to fertilization and the minor effect of fertilization and irrigation on tree growth discourage its use during the first rotation period after SRC establishment. A SOC accrual rate of 0.4 Mg C ha^?1 a^?1 (uppermost 25 cm, P = 0.2) was observed 5 years after the SRC establishment. Overall, our data suggest that SRC cultivation on marginal agricultural land in the region is a promising option for increasing the share of renewable energy sources due to its net positive environmental effects.     

Heterogeneous shedding of Brucella abortus in milk and its effect on the control of animal brucellosis

Aims: To ascertain whether in Brucella abortus‐infected water buffalo herds, the number of newly infected animals could be reduced by culling superspreaders (the animals secreting ≥10⁴ CFU per ml of milk). Methods and Results: The number of B. abortus present in the milk (CFU per ml) from 500 water buffaloes was measured by the culture. Each animal was tested three times, at one month intervals. The presence or the absence of B. abortus in each milk sample was confirmed by PCR. A majority of infected animals shed the pathogen at a low level (≤10³ CFU ml^?1). However, a few infected individuals (superspreaders) shed large numbers of B. abortus (≥10⁴ CFU ml^?1). Quantitative PCR of B. abortus positive milk samples gave comparable results to culture. Culling of the superspreaders was sufficient to arrest the spread of infection. Significance and Impact of the Study: The approach described here can reduce significantly the cost of controlling brucellosis. Culture and quantitative PCR tests identify superspreaders and, compared with the serological tests in use to detect brucellosis, provide also a more accurate estimate of the disease incidence.     

Nutrient constraints to tropical agroecosystem productivity in long‐term degrading soils

Soil degradation is one of the most serious threats to sustainable crop production in many tropical agroecosystems where extensification rather than intensification of agriculture has occurred. In the highlands of western Kenya, we investigated soil nitrogen (N) and phosphorus (P) constraints to maize productivity across a cultivation chronosequence in which land‐use history ranged from recent conversion from primary forest to 100 years in continuous cropping. Nutrient treatments included a range of N and P fertilizer rates applied separately and in combination. Maize productivity without fertilizer was used as a proxy measure for indigenous soil fertility (ISF). Soil pools of mineral nitrogen, strongly bound P and plant‐available P decreased by 82%, 31% and 36%, and P adsorption capacity increased by 51% after 100 years of continuous cultivation. For the long rainy season (LR), grain yield without fertilizer declined rapidly as cultivation age increased from 0 to 25 years and then gradually declined to a yield of 1.6 Mg ha^?1, which was maintained as time under cultivation increased from 60 to 100 years. LR grain yield in the old conversions was only 24% of the average young conversion grain yield (6.4 Mg ha^?1). Application of either N or P alone significantly increased grain yield in both the LR and short rainy (SR) seasons, but only application of 120 kg N ha^?1 on the old conversion increased yield by >1 Mg ha^?1. In both SR and LR, there was a greater average yield increment response to N and P when applied together (ranging from 1 to 3.8 Mg ha^?1 for the LR), with the greatest responses on the old conversions. The benefit–cost ratio (BCR) for applying 120 kg N ha^?1 alone was <1 except on the old conversions, while BCRs were>1 for applying 25 kg P ha^?1 alone at all levels of conversion for both seasons. Application of both N (120 kg N ha^?1) and P (25 kg P ha^?1) on the old conversions resulted in the greatest BCRs. This study clearly indicates that maize productivity responses to N and P fertilizer are significantly affected by the age of cultivation and its influence on ISF, but that loss of productivity can be restored rapidly when these limiting nutrients are applied. Management strategies should consider ISF and economic factors to determine optimal N and P input requirements for achieving and sustaining profitable crop production on degraded soils.     

Expansion of human settlement in Kenya's Maasai Mara: what future for pastoralism and wildlife?

Aim Wildlife and pastoral peoples have lived side‐by‐side in the Mara ecosystem of south‐western Kenya for at least 2000 years. Recent changes in human population and landuse are jeopardizing this co‐existence. The aim of the study is to determine the viability of pastoralism and wildlife conservation in Maasai ranches around the Maasai Mara National Reserve (MMNR). Location A study area of 2250 km² was selected in the northern part of the Serengeti‐Mara ecosystem, encompassing group ranches adjoining the MMNR. Emphasis is placed on Koyake Group Ranch, a rangeland area owned by Maasai pastoralists, and one of Kenya's major wildlife tourism areas. Methods Maasai settlement patterns, vegetation, livestock numbers and wildlife numbers were analysed over a 50‐year period. Settlement distributions and vegetation changes were determined from aerial photography and aerial surveys of 1950, 1961, 1967, 1974, 1983 and 1999. Livestock and wildlife numbers were determined from re‐analysis of systematic reconnaissance flights conducted by the Kenya Government from 1977 to 2000, and from ground counts in 2002. Corroborating data on livestock numbers were obtained from aerial photography of Maasai settlements in 2001. Trends in livestock were related to rainfall, and to vegetation production as indicated by the seasonal Normalized Difference Vegetation Index. With these data sets, per capita livestock holdings were determined for the period 1980–2000, a period of fluctuating rainfall and primary production. Results For the first half of the twentieth century, the Mara was infested with tsetse‐flies, and the Maasai were confined to the Lemek Valley area to the north of the MMNR. During the early 1960s, active tsetse‐control measures by both government and the Maasai led to the destruction of woodlands across the Mara and the retreat of tsetse flies. The Maasai were then able to expand their settlement area south towards MMNR. Meanwhile, wildebeest (Connochaetes taurinus) from the increasing Serengeti population began to spill into the Mara rangelands each dry season, leading to direct competition between livestock and wildlife. Group ranches were established in the area in 1970 to formalize land tenure for the Maasai. By the late 1980s, with rapid population growth, new settlement areas had been established at Talek and other parts adjacent to the MMNR. Over the period 1983–99, the number of Maasai bomas in Koyake has increased at 6.4% per annum (pa), and the human population at 4.4% pa. Over the same period, cattle numbers on Koyake varied from 20,000 to 45,000 (average 25,000), in relation to total rainfall received over the previous 2 years. The rangelands of the Mara cannot support a greater cattle population under current pastoral practices. Conclusions With the rapid increase in human settlement in the Mara, and with imminent land privatization, it is probable that wildlife populations on Koyake will decline significantly in the next 3–5 years. Per capita livestock holdings on the ranch have now fallen to three livestock units/reference adult, well below minimum pastoral subsistence requirements. During the 1980s and 90s the Maasai diversified their livelihoods to generate revenues from tourism, small‐scale agriculture and land‐leases for mechanized cultivation. However, there is a massive imbalance in tourism incomes in favour of a small elite. In 1999 the membership of Koyake voted to subdivide the ranch into individual holdings. In 2003 the subdivision survey allocated plots of 60 ha average size to 1020 ranch members. This land privatization may result in increased cultivation and fencing, the exclusion of wildlife, and the decline of tourism as a revenue generator. This unique pastoral/wildlife system will shortly be lost unless land holdings can be managed to maintain the free movement of livestock and wildlife.     

Comparison of startup and anaerobic wastewater treatment in UASB, hybrid and baffled reactor

An experimental study was carried out to compare the performance of selected anaerobic high rate reactors operated simultaneously at 37?°C. The three reactors, namely upflow anaerobic sludge bed reactor (UASB), hybrid of UASB reactor and anaerobic filter (anaerobic hybrid reactor – AHR) and anaerobic baffled reactor (ABR), were inoculated with the anaerobic digested sludge from municipal wastewater treatment plant and tested with synthetic wastewater. This wastewater contained sodium acetate and glucose with balanced nutrients and trace elements (COD 6000?mg?·?l^?1). Organic loading rate (B _v ) was increased gradually from an initial 0.5?kg?·?m^?3?·?d^?1 to 15?kg?·?m^?3?·?d^?1 in all the reactors. From the comparison of the reactors' performance, the lowest biomass wash-out resulted from ABR. In the UASB, significant biomass wash-out was observed at the B _v 6?kg?·?m^?3?·?d^?1, and in the AHR at the B _v 12?kg?·?m^?3?·?d^?1. The demand of sodium bicarbonate for pH maintenance in ABR was two times higher as for UASB and AHR. The efficiency of COD removal was comparable for all three reactors – 80–90%. A faster biomass granulation was observed in the ABR than in the other two reactors. This fact is explained by the kinetic selection of filamentous bacteria of the Methanotrix sp. under a high (over 1.5?g?·?l^?1) acetate concentration.     

Ecosystem Linkages Between Lakes and the Surrounding Terrestrial Landscape in Northeast Iceland

Despite a recent emphasis on understanding cross-habitat interactions, few studies have examined the ecological linkages between lakes and surrounding terrestrial habitats. The current paradigm of land–lake interactions is typically unidirectional: the view is that nutrients and matter are transported downslope from the surrounding watershed to their ultimate lacustrine destination. Emergent aquatic insects, which spend their larval stages in lake sediments and emerge as adults to mate over land, can act as vectors of material, energy and nutrients from aquatic to terrestrial habitats. In this study, we document a gradient of midge (Diptera: Chironomidae) infall rates into terrestrial habitats (measured as g dw midges m^?2 d^?1) surrounding eight lakes in Northern Iceland (≈66°N latitude). Lakes ranged from having virtually no midge infall (for example, Helluvaðstjörn, 0.03 g m^?2 d^?1) to extreme levels (for example, Mývatn, 19 g m^?2 d^?1) with abundances of midges decreasing logarithmically with distance from shore. Annual midge input rates are estimated as high as 1200–2500 kg midges ha^?1 y^?1. As midges are approximately 9.2% total N, this can result in a significant fertilization effect of terrestrial habitats with consequences for plant quality and community structure. In addition, we used naturally-occurring δ¹³C and δ¹⁵N isotopes to examine food web structure and diet sources of terrestrial arthropod consumers surrounding lakes with differing amounts of midge input. Terrestrial arthropods showed increased utilization of aquatic-derived (that is, midge) C relative to terrestrial sources as midge infall increased. This pattern was particularly pronounced for predators, such as spiders and opiliones, and some detritivores (Collembola). These findings suggest that, despite being largely ignored, aquatic-to-terrestrial linkages can be large and midges can fuel terrestrial communities by directly serving as resources for predators and decomposers.     

Forest and agricultural land-use-dependent CO2 exchange in Thuringia, Germany

Eddy covariance was used to measure the net CO₂ exchange (NEE) over ecosystems differing in land use (forest and agriculture) in Thuringia, Germany. Measurements were carried out at a managed, even‐aged European beech stand (Fagus sylvatica, 70–150 years old), an unmanaged, uneven‐aged mixed beech stand in a late stage of development (F. sylvatica, Fraxinus excelsior, Acer pseudoplantanus, and other hardwood trees, 0–250 years old), a managed young Norway spruce stand (Picea abies, 50 years old), and an agricultural field growing winter wheat in 2001, and potato in 2002. Large contrasts were found in NEE rates between the land uses of the ecosystems. The managed and unmanaged beech sites had very similar net CO₂ uptake rates (～?480 to ?500 g C m^?2 yr^?1). Main differences in seasonal NEE patterns between the beech sites were because of a later leaf emergence and higher maximum leaf area index at the unmanaged beech site, probably as a result of the species mix at the site. In contrast, the spruce stand had a higher CO₂ uptake in spring but substantially lower net CO₂ uptake in summer than the beech stands. This resulted in a near neutral annual NEE (?4 g C m^?2 yr^?1), mainly attributable to an ecosystem respiration rate almost twice as high as that of the beech stands, despite slightly lower temperatures, because of the higher elevation. Crops in the agricultural field had high CO₂ uptake rates, but growing season length was short compared with the forest ecosystems. Therefore, the agricultural land had low‐to‐moderate annual net CO₂ uptake (?34 to ?193 g C m^?2), but with annual harvest taken into account it will be a source of CO₂ (+97 to +386 g C m^?2). The annually changing patchwork of crops will have strong consequences on the regions' seasonal and annual carbon exchange. Thus, not only land use, but also land‐use history and site‐specific management decisions affect the large‐scale carbon balance.     

Environmental Effects over the First 2½ Rotation Periods of a Fertilised Poplar Short Rotation Coppice

A short rotation coppice (SRC) with poplar was established in a randomised fertilisation experiment on sandy loam soil in Potsdam (Northeast Germany). The main objective of this study was to assess if negative environmental effects as nitrogen leaching and greenhouse gas emissions are enhanced by mineral nitrogen (N) fertiliser applied to poplar at rates of 0, 50 and 75 kg N ha^?1 year^?1 and how these effects are influenced by tree age with increasing number of rotation periods and cycles of organic matter decomposition and tree growth after each harvesting event. Between 2008 and 2012, the leaching of nitrate (NO₃ ^?) was monitored with self-integrating accumulators over 6-month periods and the emissions of the greenhouse gases (GHG) nitrous oxide (N₂O) and carbon dioxide (CO₂) were determined in closed gas chambers. During the first 4 years of the poplar SRC, most nitrogen was lost through NO₃ ^? leaching from the main root zone; however, there was no significant relationship to the rate of N fertilisation. On average, 5.8 kg N ha^?1 year^?1 (13.0 kg CO_2equ) was leached from the root zone. Nitrogen leaching rates decreased in the course of the 4-year study parallel to an increase of the fine root biomass and the degree of mycorrhization. In contrast to N leaching, the loss of nitrogen by N₂O emissions from the soil was very low with an average of 0.61 kg N ha^?1 year^?1 (182 kg CO_2equ) and were also not affected by N fertilisation over the whole study period. Real CO₂ emissions from the poplar soil were two orders of magnitude higher ranging between 15,122 and 19,091 kg CO₂ ha^?1 year^?1 and followed the rotation period with enhanced emission rates in the years of harvest. As key-factors for NO₃ ^? leaching and N₂O emissions, the time after planting and after harvest and the rotation period have been identified by a mixed effects model.     

Physiological and production response of dairy goats bred in a tropical climate

The aim of this work was to determine the adaptability of Saanen and ½Saanen?×?½Anglo-Nubian (½S½AN) goats bred in tropical climates. The study included 30 goats, 15 Saanen and 15 ½S½AN. The data was collected during the rainy and dry seasons. During the whole experimental period, the environment variables were recorded, as well as rectal temperature (RT), superficial temperature (ST), respiratory rate (RR) and heart rate (HR) and milk production (MP). The adaptability coefficient (AC) was calculated for both genotypes. The averages were evaluated by ANOVA at 5 % probability. There was a genotype and period of year effect, as well as the interaction genotype?×?period of year. Pearson's simple correlation analysis was then carried out between milk production and physiological and environment variables. There was a statistical difference (p?p?p?相似文献