Effects of spacing interval of wide bed planting on canopy characteristics and yield in winter wheat

2010-2012连续两年在大田试验条件下以多穗型品种‘百农矮抗58’为供试材料, 研究了宽幅播种(播幅8 cm)种植方式下不同带间距7 cm (KF7)、12 cm (KF12)和17 cm (KF17)对冬小麦(Triticum aestivum)冠层特征及产量的影响。结果表明: 与常规条播比较, 宽幅播种群体叶面积指数、平均叶倾角、光截获量、相对湿度、成穗数、生物量和产量较高, 而冠层开度和温度较低; 2010-2011年和2011-2012年宽幅播种成穗数和产量显著高于常规条播, 成穗数分别增加4.8%-16.4%和8.9%-21.0%, 产量分别提高2.96%-15.94%和4.09%-14.23%。宽幅播种下随带间距增大, 叶面积指数、平均叶倾角、光截获量、湿度及成穗数降低, 而冠层开度和温度升高; 穗粒数、千粒重、产量、生物量和收获指数以KF12最高, KF7最低。综合分析, 宽幅播种下12 cm带间距处理的小麦冠层结构合理, 微环境适宜, 产量最高, 可作为该种植方式的适宜带间距。     

城市林木生物量对硬化地表和种植密度的响应

以北京市典型绿化树种油松、白蜡和元宝枫为实验对象,设置不透水地表、透水地表和对照(自然地表)3种地表类型和低(株行距为2.0 m×2.0 m)、中(1.0 m×1.0 m)、高(0.5 m×0.5 m)3个种植密度,经过6年的生长,对树木的生长和生物量进行了测定。结果表明：相比于对照,不透水地表下油松、白蜡和元宝枫的树高生长受到抑制,白蜡和元宝枫的单株生物量分别降低2.1%—27.1%和33.6%—52.3%,根冠比分别增加3.4%—25.8%和15.7%—23.4%。相比于不透水地表,透水地表下白蜡和元宝枫的树高显著增加,白蜡的单株生物量增加5.3%—45.5%,根冠比下降11.4%—18.7%。随着密度的增加,3种树木的基径和单株生物量显著降低,但中低密度下的单位面积生物量无显著性差异。此外,硬化地表与种植密度对树木的基径、树高、单株生物量和根冠比均无显著的交互作用。因此,在城市绿化中,采用透水地表来替代不透水地表,有利于改善树木生境进而促进树木生长。白蜡相比元宝枫更能适应硬化地表的不利影响,是更好的城市绿化树种的选择。同时,合理的种植密度是保证城市树木生长的重要因素。     

Effects of nest size and dispersion on brood production in a North American population of wood ant Formica fusca (Hymenoptera: Formicidae)

We examined several key parameters of the population ecology of a North American population of Formica fusca (L.), including nest dispersion, colony size and brood production. Physical nest size was significantly correlated with colony size, and colony size, in turn, was significantly correlated with brood production. Sex allocation was male biased, although larger nests were more likely to produce reproductive female brood (gynes). Neither nest temperature nor moisture level was significantly correlated with brood production. Formica fusca nests in this population had a comparatively low average nearest-neighbor distance with a significantly even pattern of dispersion, which suggests relatively high intraspecific competition. However, nearest-neighbor distance was not significantly associated with either colony size or relative brood production.     

Patterns of range use,range defense,and intergroup spacing in moustached tamarin monkeys (Saguinus mystax)

In this paper we examine patterns of group spacing and habitat utilization in neighboring groups of marked free-ranging moustached tamarin monkeys (Saguinus mystax) inhabiting Padre Isla, a small island in the Amazon Basin of northeastern Peru, and describe the set of behavioral mechanisms used by tamarins to maintain the spatial isolation and social integrity of individual groups. Specifically, we address a series of questions regarding the importance of resource defense, mate defense, and territorial defense in intergroup interactions. From June through November 1990, we recorded 67 intergroup interactions involving members of our two main study groups. These interactions occurred at a rate of .14/observation hour and were of two general types. Vocal battles averaged 18 min in duration and were characterized by a series of high frequency, short syllable, long calls that were exchanged between groups separated by distances of greater than 25 m. Aggressive encounters averaged 26 min in duration and involved visual contact, alarm calls, scent marking, and sequences of chases and retreats. Intergroup confrontations did not cluster around the perimeter of a group's home range, and there was no evidence that moustached tamarins patrolled range borders. Our data indicate that 35% of aggressive encounters occurred in the vicinity of major feeding trees. Priority access to these sites is likely to have an important influence on tamarin foraging success. Mate defense and the exploration of new breeding opportunities also appear to be important functions of intergroup conflicts. Not only did the frequency of aggressive encounters increase during breeding periods, but three-fourths of all observed copulations occurred during or within 30 min of an encounter. Given the high degree of reproductive competition reported among tamarin females and the time and energy group members devote to intergroup aggression, maintaining access to a stable home range and the resources contained within that range appear to be critical functions of moustached tamarin social interactions.     

Oviposition choices by a pre-dispersal seed predator (Hylemya sp.)

Summary Although the importance of pollinators has most often been examined in the evolution of floral characters, seed predators may also play a role in shaping floral evolution. In this study, I examined the role of interplant distance, plant size, and flower morphology on Ipomopsis aggregatás (Polemoniaceae) attractiveness to a pre-dispersal seed predator, Hylemya sp. (Anthomyiidae) and to hummingbird pollinators. The attractiveness of I. aggregata individuals to Hylemya was nonlinearly related to interplant distance in experimental arrays. Clumped and highly dispersed plants were preyed upon more frequently than those at intermediate distances. I found no relationship between interplant distance and visitation rates by hummingbird pollinators in these experimental arrays. However, in natural populations studied, clumped plants were more frequently approached by hummingbirds than those growing more widely dispersed. Display size was unrelated to visitation by Hylemya on inflorescences I clipped and maintained as large, small and control. Display size was also unrelated to the total number of visits by hummingbird pollinators to each of these experimental plants, however large display plants were more likely to be visited first in any given visitation sequence. Of various morphological measurements, corolla length showed the strongest positive correlation with Hylemya egg presence. To the extent that plant spacing and morphology is correlated with pollinator visits and ultimate seed set, Hylemya could be choosing flowers optimally, and playing a role in the evolution of floral traits.     

Effects of Fruit Patch Availability on Feeding Subgroup Size and Spacing Patterns in Four Primate Species at Tinigua National Park, Colombia

We examined the effects of fruit patch size, density, and distribution on feeding subgroup size and feeding bout duration in four Neotropical primates—Lagothrix lagotricha, Ateles belzebuth, Cebus apella, and Alouatta seniculus—based on 2494 hr of focal animal sampling in Tinigua National Park, Colombia. All four species show positive correlations between patch size (tree diameter at breast height; DBH) and subgroup size (maximum number of individuals from the focal group feeding at the same time), but the determination coefficients are very low and this relationship does not seem to influence strongly the actual size of the groups. Ateles showed the weakest correlation between patch size and feeding party size, and their fission–fusion sociality is best explained as a mechanism to reduce intragroup competition rather than to adjust the subgroup size to the availability of patches. Feeding associations as well as proximal spacing patterns, in general, are more alike in species with similar ecological requirements.     

Spatial selection in captive adult female chimpanzees

Spatial selection refers to an animal's frequent use of certain areas of its enclosure or range. Through differential use of habitat, an individual can limit the amount of time spent in close proximity to other group members. The four adult female chimpanzees at the Tulsa Zoo were studied to determine if they used their enclosure differently from one another, if each had selected areas it occupied most frequently, and if an individual's preferred area was used by other female group members. Pairwise comparisons showed that the females used their island habitat differently from one another with the exception of one pair. Although these two females overlapped in their use of the enclosure, they separated their use temporally, thereby reducing the amount of time spent in close proximity to one another. Each female had a selected site that she occupied more frequently than did the other females. However, there was variation in the extent to which the females occupied each other's selected sites. Time of day and temperature had no effect on use of the habitat, however, one female showed a seasonal variation in her use of the enclosure. The spatial selection exhibited by these females may be comparable to the use of core areas by wild female chimpanzees. © 1994 Wiley-Liss, Inc.     

Molybdenum Disulfide/Nitrogen‐Doped Reduced Graphene Oxide Nanocomposite with Enlarged Interlayer Spacing for Electrocatalytic Hydrogen Evolution

Facile design of low‐cost and highly active catalysts from earth‐abundant elements is favorable for the industrial application of water splitting. Here, a simple strategy to synthesize an ultrathin molybdenum disulfide/nitrogen‐doped reduced graphene oxide (MoS₂/N‐RGO‐180) nanocomposite with the enlarged interlayer spacing of 9.5 Å by a one‐step hydrothermal method is reported. The synergistic effects between the layered MoS₂ nanosheets and N‐doped RGO films contribute to the high activity for hydrogen evolution reaction (HER). MoS₂/N‐RGO‐180 exhibits the excellent catalytic activity with a low onset potential of ?5 mV versus reversible hydrogen elelctrode (RHE), a small Tafel slope of 41.3 mV dec^?1, a high exchange current density of 7.4 × 10^?4 A cm^?2, and good stability over 5 000 cycles under acidic conditions. The HER performance of MoS₂/N‐RGO‐180 nanocomposite is superior to the most reported MoS₂‐based catalysts, especially its onset potential and exchange current density. In this work, a novel and simple method to the preparation of low‐cost MoS₂‐based electrocatalysts with the extraordinary HER performance is presented.     

A shift in female social organization independent of relatedness: an experimental study on the field vole (Microtus agrestis)

Home range size, overlap between home ranges, movement patternsand social behavior in two generations of female field voleswere examined by radio tracking unrelated individuals in enclosedareas. In addition, potential effects of increased relatednesswere examined by comparing setups with groups of sisters andunrelated females. Overwintered females showed less overlapbetween ranges and moved shorter and more irregular distancescompared with females of the year. Based on responses to introduced,unfamiliar conspecifics it was concluded that the overdisperseddistribution of overwintered females was maintained primarilyby avoidance behavior and that infanticidal behavior was equallyfrequent in the two generations. Observed differences betweengenerations could not be ascribed to differences in relatedness,and experimental increase of the degree of relatedness had negligibleeffects. The overdispersion and restricted movements shown byoverwintered females are instead suggested to be caused by acombination of low food availability and exposure to intensepredation in spring/early summer, whereas spacing and movementpatterns of females of the year are less influenced by thesefactors. As aggressive interactions are rare and populationdensity is usually low in spring, it is unlikely that breedingdensity and population growth is restrained by the social behaviorof overwintered females.