Foraging Behavior Patterns of Sheep and Horses Under a Mixed Species Grazing System

The research objective was to assess the behavior patterns of the Polish Konik horse breed and the Uhruska variety of the Polish Lowland Sheep breed under a mixed-grazing system, and their relationship with climatic factors. The observation included 4 adult horses, 27 ewes with lambs and 10 primiparous ewes. The behavior of the animals and the weather conditions were recorded at 60-min intervals. Horses and sheep displayed similarities in both species-specific behavioral patterns and timing of grazing activity, and the duration of foraging sessions was mostly influenced by time of day, lower temperature and relative humidity. In addition, the two species showed more interest in the watering place in the afternoon, and drinking frequency was mainly dependent on air temperature. The animals that pastured together gradually began to mix, but at first, they remained within their species group. Both animal species can be used for environmental protection and landscape conservation making rational use of pastures within protected areas.     

The Success of a Rotational Grazing System in Conserving the Diversity of Chalk Grassland Auchenorrhyncha

A complex rotational grazing trial on a south-facing slope of chalk grassland at the Old Winchester Hill National Nature Reserve is briefly introduced. The responses of 23 numerous species of Auchenorrhyncha, and of species richness (S) and total abundance (N), from 1981 to 1985 are described. The greatest effects were those of variation between years, between positions on the hillside (top, middle and bottom) and between grazing plots within these positions. 10 (of the total of 23) species favoured the top of the slope, where the vegetation was significantly taller than in the middle or at the bottom. S, N and the numbers of 8 species were significantly lower on plots grazed in the year of sampling compared with ungrazed plots. Early (vs. late) grazing significantly reduced S, N and the abundance of two species, but increased the numbers of Macrosteles laevis. S, N and the abundance of 13 species was significantly and positively correlated with vegetation height measured early (May–June) and late (July–October); the numbers of 4 other species were so correlated with the latter height only. The significance of the results is discussed in relation to the management of grassland nature reserves for the maintenance of high invertebrate diversity. It is concluded that rotational management is an important and valuable system, but suggested that such systems should be as simple as possible whilst remaining adequate to achieve conservation objectives.     

Spring-water Nitrate Increased with Removal of Livestock Grazing in a California Oak Savanna

We characterized spatial and temporal changes in nitrate concentrations of the leachate from annual grasslands and subsequently emergent spring-waters and tested the effect of livestock grazing removal on them. Nitrate patterns indicated that annual grassland soils are a likely N source to spring-fed wetlands, which appear to intercept and transform N along its hydrologic path from upland soils to spring-fed, headwater streams. Aboveground biomass and soil N extractions suggested that removal of livestock grazing from these wetlands impaired this function by allowing dead plant material to accumulate inhibiting plant production (hence, plant N demand), resulting in elevated stream-water nitrate (NO₃⁻) concentrations. Nitrous oxide (N₂O) fluxes indicated that grazing removal may increase the relative importance of this N-loss pathway. Microbial biomass varied with season but was not affected by grazing treatments suggesting that N₂O losses were related to differences in NO₃⁻ availability rather than grazing effects on microbial community composition or their activity. Spring-fed wetlands provide important ecosystem services such as plant uptake and denitrification at transition zones between terrestrial and aquatic ecosystems. These N-retention and transformation functions may be enhanced through biomass harvesting by livestock.     

Herding Strategies of the Datoga Pastoralists of Tanzania: Is Household Labor a Limiting Factor

Datoga herding follows a cyclical pattern depending on the availability of grazing and water. This analysis focuses on two questions: (a) Is the herding strategy followed by individual households limited by the amount of labor available to that household? and (b) does the herding strategy followed by individual households influence the dynamics of cattle herds? The results show that the availability of labor on a household level does not influence either the herding strategies used by individual households, or the dynamics of cattle herds. This suggests that once minimum labor requirements are met, livestock productivity is insensitive to additional labor inputs.     

Feeding patterns of a specialist and a generalist grasshopper: electronic monitoring on their host plants

Abstract Hypochlora alba (Dodge) is a specialist grasshopper that lives and feeds almost exclusively on Artemisia ludoviciana Nutt., a sage plant mostly avoided as food by generalist or polyphagous grasshoppers, such as Melanoplus sanguinipes (Fabr.). Adaptations to feeding on the pubescent sage foliage containing high levels of allelochemics may involve behavioural as well as physiological specialization. Using an electronic device to monitor feeding activity, we compared feeding periodicity, bout length, bout frequency, and overall time spent feeding by H.alba on sage foliage and by M.sanguinipes on seedling ryegrass ( Lolium perenne L.), the plants on which they had been reared. Although both species fed for about the same amount of time per day (c. 4–5%), they achieved this by two different feeding patterns. H. alba had feeding bouts averaging c. 10 min each, compared to c. 4–5 min for M.sanguinipes. Bout frequency was reversed, with M.sanguinipes feeding about once every hour and H.alba about half as often. Bout length for both species was unaffected by phase of the photoperiod while bout frequency, and consequently the rate of feeding in min/h, was typically reduced by two-thirds or more during the dark phase. The relationship of grasshopper feeding behaviour to host plant specialization is discussed.     

Grazing Management, Resilience, and the Dynamics of a Fire-driven Rangeland System

We developed a stylized mathematical model to explore the effects of physical, ecological, and economic factors on the resilience of a managed fire-driven rangeland system. Depending on grazing pressure, the model exhibits one of three distinct configurations: a fire-dominated, grazing-dominated, or shrub-dominated rangeland system. Transaction costs and costs due to shrub invasion, via their effect on grazing decisions, strongly influence which stable configuration is occupied. This, in turn, determines the resilience of the rangeland system. These results are used to establish conditions under which management for profit is consistent with the maintenance of resilience. Received 2 January 2001; accepted 11 June 2001.     

Ranging Behavior of Proboscis Monkeys in a Riverine Forest with Special Reference to Ranging in Inland Forest

We observed a unimale group (BE-Group) of proboscis monkeys (Nasalis larvatus) comprising an α-male, 6 adult females, and several immatures from May 2005 to May 2006. We followed the group for 2014 h along the Menanggul River, Sabah, Malaysia (118°30′E, 5°30′N). Observations focused mainly on ranging behavior. We determined availability and seasonal changes in plant species consumed by the members of the group by vegetation surveys in a 2.15-ha area along 200–500 m trails in the riverine forest. During the observation period, the group ranged ≤800 m from the riverbank, within a total range of 138.3 ha. The daily path length of the group ranged from 220 to 1734 m (mean, 799 m), and daily path length correlates negatively with fruit availability. The monkeys were apt to remain within a small range in fruit-abundant seasons. Because the monkeys preferred to feed on fruits of dominant plant species in the study area, their daily path length may decrease on days when they feed on fruits. The core areas of the group’s home range were along the river because the monkeys typically returned to riverside trees to sleep. The group most often used areas that were nearer the riverbank and where the availability of fruits was higher. The most frequently used grids were the ones where the group often had sleeping sites and crossed the river. Avoiding predation may be the main reason for river crossing and selecting particular sleeping sites; hence not only food availability but also the risk of predation appears to influence the ranging of the BE-Group.     

一类具功能反应的食饵-捕食者两种群模型的定性分析

研究了具功能反应的食饵-捕食者两种群模型：x=xg(x)-yф(x),y=y(-d eф(x))。在g(x)和ф(x)都是非线性情形下,讨论了该系统的平衡点的性态,并证明了极限环的存在性与唯一性及其全局稳定性。     

一类食饵种群具有常数收获率的Kolmogolov系统的非线性分析

本文对一类食饵种群具有常数收获率的Ｋｏｌｍｏｇｏｌｏｖ系统进行了非线性分析,研究了 系统平衡点的性态,在较宽的条件下证明了系统不存在闭轨线;并获得了系统存在两个极限环的条件。     

一类两种群均有收获率捕食系统的细焦点与极限环

研究一类具有HollingⅡ类功能反应且两种群均为非常数收获率的捕食系统,其中食饵种群具有非线性密度制约.利用微分方程定性与稳定性理论及分支理论,得到系统平衡点的性态及极限环存在与否的充分条件,利用Hopf分支理论得到存到多个极限环的充分条件.     

具Holling-Ⅳ型功能反应函数的捕食者-食饵系统的定性分析(英文)

本文研究一类具Holling-Ⅳ型功能反应函数的捕食者-食饵模型.对模型进行定性分析得知系统正解都是有界的;因此,当平衡点不稳定,系统至少存在一稳定的极限环.本文还运用Poincare形式级数法,得到了正平衡点至多为二阶稳定细焦点的结论.并基于Hopf分支理论得知系统在一定条件下至少存在两个极限环.     

Establishment of a System with High Synchronous Frequency of Somatic Embryogenesis and Embryo Seedling Formation in Camellia sinensis var. assamica

The system of high synchronous frequency of somatic embryogenesis and somatic embryo seedling formation was established by means of embryonic cell hne 1 ( CL1 ) of Camellia sinensis var. assamica Kitamura. Modified MS was used as the basic medium. Cultures of CL1 was transferred to the aqueous induced medium (0.05 mg/L 2,4-D + 0.50 mg/L 6-BA) from the maintenance medium (0.1 mg/L 2,4-D + 0.5 mg/L 6-BA) for somatic embryos induction under dark condition. 28 days later, they were cultured in the liquid differentiation medium. Various kinds of somatic embryos were obtained after another 28 days. The frequency of somatic embryos was 81.5 %. Various mesh sizes of sieves were applied to collect the somatic embryos in different developmental stages which could develop to mature stage in the aqueous growth medium ( 1/2 MS + 1.0 mg/L GA3 + 0.5 mg/L 6-BA). ABA was effective to promote the formation of highly qualified somatic embryo. The mature somatic embryos sized 20 to 70 mesh had the conversion frequency 75 %. The development of somatic embryogenesis studied under a cell suspension culture system was similar to the zygotic embryogenesis.     

Chlorophyll Fluorescence Quenching During Photosynthetic Induction in Leaves of Abutilon striatum Dicks. Infected with Abutilon Mosaic Virus,Observed with a Field-Portable Imaging System

A portable Chi fluorescence imaging system was used to characterise nonuniform Chi fluorescence quenching in Abutilon striatum leaves infected with phloem-localised abutilon mosaic virus. The instrument was used to observe fluorescence emission at intervals during induction transients, and to map nonphotochemical quenching during saturating pulses applied in the course of these transients. Two symptom types were distinguished: yellow vein-associated motifs that showed lower maximum Chi fluorescence than nearby green tissues, but virtually zero nonphotochemical quenching, and vein-defined mosaics (pale green) that initially showed normal maximum Chi fluorescence but strongly impaired nonphotochemical quenching. Mature vein-defined mosaics (yellow to white areas) resembled vein-associated symptoms with zero nonphotochemical quenching. Islands of apparently healthy green tissue enclosed by mosaic symptoms showed slower nonphotochemical quenching than controls. Possible effects of localised carbohydrate accumulation, thought to follow from infection by the phloem-limited virus, on photosynthetic processes as well as the synthesis and stability of chloroplast protein complexes, are discussed in the context of symptom development.     

一类稀疏效应下的捕食系统存在唯一极限环的充要条件

给出了如下一类稀疏效应下的捕食系统：x=bx^2k-x)-bxy,y=-cy (βx-γy)y存在唯一极限环的充要条件。     

基于超高速摄影显微成像和超声散射的纳米包膜造影微泡包膜厚度估计

纳米包膜微泡和携带药物的生物微系统在超声成像和药物传递与释放等方面具有重要的应用价值。通过使用时间分辨率最小可达10ns的新型超高速显微成像装置,得到微泡在医用频率超声场中的半径振动曲线,对参数做灵敏度分析后,与理论预测结果做最小均方误差对比,经反向参数估计,获得包膜厚度估计值。结果表明,该技术在不破坏样品的务件下,能得到较为准确的包膜参数。     

Chlorophyll-Protein Complexes of Blue-Green Algae Isolated by a New Gel Electrophoresis System with High Resolving Power

At least 13 chlorophyll bands from the thylakoid membranes of blue-green algae could be clearly resolved by SDS-PAGE employing a new improved procedure. They were designated as CPIa, CPIb, CPIc, CPId, CPIe, CPIf, CPIg, CHIh, CPal, CPa2, CPa3, CPa4 and FC. 8 chlorophyll-protein complexes, CPIa-CPIh, had the same absorption spectrum at 676 nm in the red and 436 nm in the blue region. They belonged to the chlorophyll-protein complexes of PS Ⅰ. 4 chlorophyll-protein complexes, CPal-CPa4, had a red absorption peak at 670­672 nm and a blue one at 436 nm. Their fluorescence emission peak at 77K was at 685 nm. They were chlorophyll-protein complexes of PS Ⅱ.     

Paternal care as a conditional strategy: distinct reproductive tactics associated with elaboration of plumage ornamentation in the house finch

When individuals in a population differ in physiological conditionand residual reproductive value, selection should favor phenotypicplasticity in reproductive investment such that individualsare able to adopt the reproductive tactic that results in thehighest fitness under given conditions. Here we examined reproductivetactics in relation to the elaboration of condition-dependentsexual ornamentation (carotenoid breast coloration) in a Montanapopulation of the house finches (Carpodacus mexicanus). Malesused distinct reproductive tactics depending on elaborationof their sexual ornamentation. Males with red pigmentation (maximum ornament elaboration) paired with females that nestedearlier, but these males did little provisioning of incubatingfemales and nestlings. In contrast, males with yellow colorationpaired with females that nested later, but these males fedfemale and nestlings more. Consequently, for red males offspringrecruitment was primarily affected by earlier nest initiation, whereas in yellow males it was affected most by male provisioning.In males with intermediate plumage coloration, all measuredcomponents, nest initiation, provisioning of incubating female,and nestling feeding, strongly contributed to offspring recruitment.The fitness consequences of alternative reproductive tacticsof males were influenced by breeding experience and fidelityof their mates. Among first-time breeders, red males achievedthe highest fecundity because of the advantage gained throughearly nesting and pairing with more experienced females andbecause of compensation by their mates for low male provisioningof nestlings. Among experienced breeders, males with intermediateplumage coloration achieved the highest fecundity because ofthe combined benefits of relatively early pairing and high parental care. High variation in sexual ornamentation in a Montana populationof house finches may favor distinct associations of sexualdisplays with a particular set of reproductive behaviors.