Population dynamics and ecology of ciliates (Protozoa,Ciliophora) in an anoxic rice field soil

Wetland rice fields cover 1.46 million km² globally; the flooded soil of these fields is largely anoxic. While biogeochemistry and microbiology have been studied in detail, the microbial loop and especially the dynamics and function of ciliates are largely unknown. We used anoxic microcosms prepared with soil from an Italian rice field and recorded species composition, abundance and volume of ciliates together with numbers, volume and size distribution of bacteria. Ciliates were the dominating protists observed in the microcosms, but could be outnumbered by flagellates if the soil was amended with rice straw. The number of ciliate taxa was 23. Metopus species were dominant, but 16 of the species recorded in the anoxic soil were facultative anaerobes. Another 29 species were found in accompanying experiments that included the oxic soil surface. Total abundance in the anoxic soil was on average 110 cells g^–1 dry weight and comparable to that of other soils. The population of ciliates declined around 30 days after flooding, but recovered later. The period before the population declined was characterized by a rapid species turnover, many facultative anaerobes and large species. After recovery, the average cell size was much smaller, but even then a facultative anaerobe, Plagiacampa pentadactyla , was common. About 90% of all species were bacteriovores while the others—mainly Gymnostomatidae—were predators. Grazing ciliates may have controlled bacteria during the first 5 days after flooding, as could be shown by a negative correlation between the respective volumes and by the size spectra of the bacteria.     

Physiological and reproductive consequences of human disturbance in Humboldt penguins: The need for species-specific visitor management

Over the last decade the Humboldt penguin, Spheniscus humboldti, has become a focus for ecotourism. Current management applies visitor guidelines similar to those developed for Magellanic penguins, Spheniscus magellanicus. However, unlike these, Humboldt penguins are extremely sensitive to human presence. Breeding success was significantly reduced at frequently visited sites. Heart rate telemetry during disturbance experiments revealed that Humboldt penguins respond more strongly to human presence than do any other penguin species thus far studied. A person passing an incubating penguin at 150 m distance already provoked a significant heart rate response. Recovery times were up to half an hour after direct human approach, causing increased energy expenditure without any overt behavioural reaction. Being extraordinary sensitive to human activity with little habituation potential the Humboldt penguin proves to be a difficult focal species for ecotourism. For sustainable ecotourism visitors are required to stay out of sight of Humboldt penguin breeding and moulting areas. Management guidelines need to acknowledge that even closely related species may react very differently towards human presence.     

Experiential relationship between the farming rate of riverside land and flood concentration time factor

In order to prove a reduction function concerning flood damage according to land use, we have to compare evaluation indices, such as flood concentration times. These can be derived from the calculation of the outflows from two basins where rainfall, geology, geographical conditions, etc. are the same and only the land use is different. However, it is very difficult to obtain comparable data from large basins under the above mentioned conditions. An elaborate observation for a long period is required to obtain such data. In this paper, we aim to establish a calculation process that offers consideration factors from a viewpoint that is different from a conventional research where elaborate observation is essential. Therefore, first we use easily obtainable data of many basins, such as the information on the Internet, or data from official documents or the like, which are difficult to deal with in hydrology. Then, we obtain several evaluation indices, which are coefficients close to the flood concentration times in this paper, on each basin in which various kinds of land uses are mixed. We then perform the statistical analysis with a land use ratio. In order to use various data on several basins, we evaluate the difference in the land use ratio in the basin by using of a length of a riverside instead of an area in the basin. Moreover, since a river-mouth is at the end of the riverside and a water stage observation point is not at the river-mouth, an error arises. Although there are several problems in accuracy as mentioned above, the evaluation of the reduction function concerning the flood damage according to land use will be feasible, automatically and efficiently, if the calculation process is established.     

Bottomland hardwood forest recovery following tornado disturbance and salvage logging

Catastrophic wind events, including tornado, hurricane, and linear winds, are significant disturbances in temperate forested wetlands. Information is lacking on how post-disturbance salvage logging may impact short and long-term objectives in conservation areas where natural stands are typically managed passively. Woody regeneration and herbaceous cover were assessed for three years in a bottomland hardwood forest across a gradient of damage from an F4 tornado, with and without subsequent salvage logging. Soil disturbance intensity and recovery associated with salvage logging within wind-disturbed sites were also assessed. Woody stem density and proportion of potential overstory species (species with the potential to occupy a position in the canopy) increased as a function of wind disturbance intensity. Stem density, proportion of overstory trees, or species diversity did not differ between wind + salvage and wind-disturbed-only plots. Significant dissimilarity occurred among soil disturbance classes within salvaged sites. By the third growing season, vegetation in soil disturbance classes in wind + salvage areas was converging toward undisturbed conditions and bottomland hardwood forest recovery was underway in all vegetation disturbance types and soil disturbance classes. Post-tornado salvage logging, applied judiciously, may contribute to microsite and vegetation diversity.     

半圈养环境下东方白鹳的行为适应性研究(英文)

环境因素会影响到动物行为的表达。圈养环境和野生环境相比,活动空间小、种群密度高,且人为干扰强度大。动物在圈养环境下往往表现出较多的刚性行为而丧失许多弹性的行为,并出现一些刻板行为,这可能导致动物在圈养条件下繁殖失败或存活率较低,还会影响到以后将其再引入到野外环境下的成功率。为了了解东方白鹳(Ciconia boyciana)在圈养环境下的现状,以及影响圈养个体的受胁因素,我们于2005年10月至2006年9月,在合肥野生动物园,对环境因子、人为干扰和自身繁殖周期等因素与行为之间的相关性进行了研究,通过瞬间扫描取样法采集行为数据。结果表明:繁殖多代组(组 1),繁殖一代组(组 2)和非繁殖组(组 3)相比,维持行为(觅食和运动)的比例没有变化,但是弹性行为(防御、理羽及繁殖)的比例在 3 组之间存在差异。相对于繁殖组,非繁殖组呈现出较少的弹性行为。同时,由于不同季节环境温度、人为干扰、日照时间的变化,使得不同行为的时间分配也随之发生变化。通过对东方白鹳在半圈养条件下行为时间分配和环境因子的相关性研究,希望能为这一濒危物种未来的保护提供基础数据。     

Multi-scale factors and long-term responses of Chihuahuan Desert grasses to drought

Factors with variation at broad (e.g., climate) and fine scales (e.g., soil texture) that influence local processes at the plant scale (e.g., competition) have often been used to infer controls on spatial patterns and temporal trends in vegetation. However, these factors can be insufficient to explain spatial and temporal variation in grass cover for arid and semiarid grasslands during an extreme drought that promotes woody plant encroachment. Transport of materials among patches may also be important to this variation. We used long-term cover data (1915–2001) combined with recently collected field data and spatial databases from a site in the northern Chihuahuan Desert to assess temporal trends in cover and the relative importance of factors at three scales (plant, patch, landscape unit) in explaining spatial variation in grass cover. We examined cover of five important grass species from two topographic positions before, during, and after the extreme drought of the 1950s. Our results show that dynamics before, during, and after the drought varied by species rather than by topographic position. Different factors were related to cover of each species in each time period. Factors at the landscape unit scale (rainfall, stocking rate) were related to grass cover in the pre- and post-drought periods whereas only the plant-scale factor of soil texture was significantly related to cover of two upland species during the drought. Patch-scale factors associated with the redistribution of water (microtopography) were important for different species in the pre- and post-drought period. Another patch-scale factor, distance from historic shrub populations, was important to the persistence of the dominant grass in uplands (Bouteloua eriopoda) through time. Our results suggest the importance of local processes during the drought, and transport processes before and after the drought with different relationships for different species. Disentangling the relative importance of factors at different spatial scales to spatial patterns and long-term trends in grass cover can provide new insights into the key processes driving these historic patterns, and can be used to improve forecasts of vegetation change in arid and semiarid areas.     

大熊猫栖息地干扰因素研究进展

人类活动加剧了大熊猫栖息地的破坏。通过检索和分析近40年关于大熊猫栖息地干扰因素的文献,发现大熊猫栖息地主要干扰因素为自然灾害、气候变化、竹子开花、竹子病虫害、放牧、旅游开发、道路建设、采伐、采矿等。通过文献梳理,指出现有研究区域集中,未来应拓宽研究范围,加强从人地关系视角研究大熊猫栖息地人类活动与自然环境之间相互作用机制;指出现有研究中,人类活动对大熊猫栖息地干扰因素以定性研究为主,未来应结合人地关系理论,探索大熊猫栖息地人与自然相互作用的演化机制和规律,建立影响因子评价模型,定量分析干扰因子。     

景观生态学中的干扰问题小议

干扰是景观生态学中的重要概念,本文探讨了干扰的定义,认为:干扰是在目标尺度内,改变景观生态过程和生态现象的不连续事件。或者说在目标尺度内,造成生态不整合的不连续事件。同时探讨了干扰的一些基本性质和理论,如干扰-尺度原理、干扰-异质性原理、干扰-稳定性原理和干扰-层系原理等。最后,就尚未成熟的干扰的模型提出一些见解,这可能会成为研究干扰的一种途径。     

极端干旱干扰下松嫩草原土壤含水量与植物的反映

自然干旱是一种干扰。本文研究了极端干旱干扰松嫩草原土壤含水量和植物的反映。结果表明 :极端自然干旱下 ,羊草地上生物量、株高与植物根系集中分布土层的含水量呈显著线性相关 ,相关系数分别为 0 .98和 0 .94;不同生境羊草群落、不同植物群落间土壤含水量和干旱深度差异明显。最后 ,提出了评价自然干旱干扰强度的指标 :当地优势植物群落在典型生境下的地上生物量和根系集分布土层的含水量     

基于Landsat时间序列的香格里拉市土地覆盖变化检测

基于Google Earth Engine平台,使用Landsat Level遥感影像,利用归一化燃烧指数作为LandTrendr时间分割算法的光谱数值,对香格里拉市进行土地覆盖变化检测。结果表明：1986—2016年,林地、未利用地、永久性冰川雪地面积持续减少,草地、水体和建设用地面积持续增加;林地为香格里拉最主要的土地覆盖类型,总占比超过80%。香格里拉土地覆盖的变化动态度总体较低,土地覆盖变化过程较为平缓;大部分林地未发生变化,在31 a内以中度干扰和轻微恢复为主。但香格里拉林地总面积多年来持续减少,按干扰和恢复的持续时间来看,1986—2016年林地发生变化的主要类型为持续1～5 a的干扰和持续21～31 a的恢复。自然灾害与人为采伐的消耗速度远大于林分的自然增长速度,如果不健全林地保护的措施,林地资源将日益稀少。