基于极坐标定位的丹顶鹤多尺度越冬生境选择研究——以江苏盐城自然保护区为例

丹顶鹤作为湿地环境的指示物种,其种群数量逐年下降引起了野生动物保护工作者的广泛关注。近年来,随着研究的深入,鸟类生境选择具有多尺度特征的观点逐渐成为研究者的共识。江苏盐城自然保护区是丹顶鹤大陆西线种群最重要的越冬栖息地,选择该区域进行多尺度越冬生境选择研究对于丹顶鹤保护具有重要的现实意义。基于遥感影像和丹顶鹤越冬分布的调查,本文用极坐标的方法在GIS软件中对丹顶鹤分布定位进行制图。借助Arc GIS 10.2和fragstats 4.2软件,从点缓冲、景观和区域3个尺度系统分析丹顶鹤越冬生境多尺度利用特征。在点缓冲尺度上,通过缓冲分析和叠置分析描述丹顶鹤生境利用的强度,发现丹顶鹤连续利用生境和经常利用生境的植被类型是碱蓬,偶尔在芦苇中活动,偏好生境区植被覆盖度在30%以下,植被高度在60 cm以下。在景观尺度上,丹顶鹤偏好程度较高的前三类生境为芦苇沼泽、碱蓬沼泽、明水,对互花米草沼泽具有负向选择。在区域尺度上,受道路和土地利用干扰影响,丹顶鹤主要分布于保护区核心区的低干扰区域;除了干扰之外还与生境面积、生境破碎程度密切相关。综合三个尺度,研究得出丹顶鹤生境选择具有明显的多尺度利用特征,丹顶鹤保护需要考虑多尺度生境保护问题。     

苏北地区丹顶鹤越冬种群数量及栖息地分布动态变化

利用资料追踪和历史时期土地利用变化数据深入研究了有资料记载以来苏北地区丹顶鹤越冬种群数量变化与栖息地分布的时空响应。结果显示,20世纪80年代之初,丹顶鹤越冬种群广泛分布于苏北地区,尤其是长江中下游的内陆湖泊、沼泽及江苏沿海滩涂湿地;20世纪90年代之后丹顶鹤分布区域逐渐向沿海滩涂湿地转移,主要分布于盐城市的射阳县境内;进入21世纪,丹顶鹤分布区域集中于盐城国家级珍禽保护区核心区。与此同时,丹顶鹤越冬种群数量也经历了十分明显的变化过程,与20世纪90年代相比,数量减少50%以上。丹顶鹤越冬种群数量及栖息地分布变化与栖息地分布点周围的土地利用方式及人为干扰有关,栖息地面积丧失和景观破碎化是丹顶鹤越冬种群数量减少的主要原因。     

丹顶鹤春迁期觅食栖息地多尺度选择——以双台河口保护区为例

双台河口保护区是世界濒危鸟类丹顶鹤大陆种群西线群体不同生活史阶段的重要栖息地。2008-2010年3-4月,采用定点观察法、二维坐标法、方差分析、因子分析等方法对保护区内春迁期丹顶鹤觅食栖息地的多尺度选择进行了监测分析。研究结果表明：(1)春迁期,该保护区丹顶鹤觅食栖息地选择包括2个尺度3个选择,即大生境尺度内觅食生境类型选择和小生境尺度内觅食区选择、觅食微生境选择;(2)觅食生境类型偏好选择芦苇沼泽(90.00%),也偶选玉米地、泥滩、草甸等生境;(3)觅食区选择通过宏生境因子和干扰因子来判定,宏生境因子包括明水面、堤坝和火烧地,距离均在30m以内;干扰因子包括居民区和油田等强干扰因子和道路等弱干扰因子,均采取远离的方式进行回避,居民区保持在1km以上,油田保持在2km以上,道路保持在300-500m;(4)觅食微生境选择通过微生境因子来判定,包括植被高度、植被密度、植被直径等,选择盖度小(<5%)且植被高度小于喙长的区域觅食。     

江苏盐城国家级珍禽自然保护区丹顶鹤的承载力

江苏盐城沿海滩涂地区是世界上最大的丹顶鹤(G rus jap onensis)越冬地。如今全球的丹顶鹤仅约2700只,而每年在此越冬的丹顶鹤接近世界野生个体总数的一半。因此,盐城滩涂的环境状况对于保护该物种的意义不言而喻。该地区能够容纳承养多少丹顶鹤?这是一个关键性的问题。此前尚无人就盐城滩涂对丹顶鹤的承载力作过详细分析。处于保护下的野生动物应按照“生态承载力”来分析其容纳量。由于滩涂上水源较充足,食物和隐蔽物就是丹顶鹤对生境的主要两方面需求,也即限制因子。根据2004~2005年越冬期统计的鹤数及其分布,运用N eu方法分析丹顶鹤对盐城8种不同栖息地的选择性,结果显示它们最偏爱的生境是稻田和草滩,可以栖息在芦苇(P hragm ites comm un is)地、淡水养殖塘或大米草滩,而回避的生境是泥滩、盐田、盐地碱蓬(Suaed a sa lsa)滩。之后,作者用“热量法”计算了射阳基地圈养丹顶鹤的饲料成分,基本符合营养定额标准;而人工投放的玉米饲料难以保障野生鹤的生存。又按“重量法”,以丹顶鹤对各生境的利用程度为权重,估算得盐城保护区可利用的食物总量远远大于鹤群一个越冬期所需量,表明食物并非生境的决定性因子。此外,作者分析了丹顶鹤对各种主要食物的选择性,发现植物在食物总量中占比例极小,但其喜爱的食物却是植物性的稻谷和人工的玉米饲料。总而言之,其种群喜爱居留在淤长型海岸带及食物量大、距道路(人类活动)远、盐度小的栖息地。核心生境丹顶鹤的分布密度约0.8~2.5只/km2,则1000km2最适宜生境的容纳量为800~2500只;实际上,近10a来80%~90%的鹤群分布收缩在核心区与缓冲区(面积共641km2),则整个保护区容纳量为570~2004只。结合这两方面考虑,作者预测盐城保护区的丹顶鹤承载力为2000~2500只,目前其数量未达饱和,种群还将增长。     

黄河三角洲丹顶鹤秋冬季生境选择机制

影响水禽生境选择要素可分为水、食物、隐蔽物和干扰4类,对其划分等级标准,确定采样点的生境类型。在研究区内分秋冬两季调查丹顶鹤(迁徙期和越冬期)生境选择机制的差异;在不同时期按区域的特点和丹顶鹤的生活习性分别选择样点;经过实地野外调查后再利用方差分析和频数对丹顶鹤生境选择机制进行研究。结果表明,迁徙期影响丹顶鹤生境选择的主要因子是干扰,最适生境为远离人类干扰、有浅水域分布的、植被覆盖率较低的地区;越冬期影响丹顶鹤生境选择的主要因子是食物,最喜欢选择人类干扰相对较小的、有水域分布的、动物性食物占主导地位的植被覆盖率较低的地区栖息。     

2000-2015年丹顶鹤重要繁殖地景观格局变化研究

以18个自然保护区为研究对象,全面系统地研究了我国丹顶鹤大陆种群重要繁殖地景观格局变化,结果表明：2000-2015年丹顶鹤重要繁殖地土地利用变化明显,突出表现为沼泽湿地面积急剧减少了1400.5 km²,主要转化为耕地、水体和草地,耕地面积大幅增加了1085.4 km²,主要由沼泽湿地、草地和林地转化而来;丹顶鹤重要繁殖地2000-2015年景观连通性保持稳定,但吉林莫莫格、黑龙江七星河、挠力河等自然保护区景观破碎化程度明显增加;东部种群重要繁殖地沼泽湿地缩减面积和不适宜生境增加面积均大于西部种群,表明东部种群繁殖地的恶化程度更为严重,需引起高度关注。首次基于长时间序列对丹顶鹤大陆种群繁殖地的变化开展了较为全面的研究,为有针对性地开展栖息地保护管理工作、促进丹顶鹤野生种群健康可持续发展提供了依据。     

扎龙湿地丹顶鹤繁殖生境质量变化

基于1996和2004年扎龙湿地丹顶鹤生境因子专题图,通过建立生境适宜性模型和种群格局最邻近体模型,定量分析了扎龙湿地丹顶鹤繁殖生境质量的变化.结果表明:研究期间,扎龙湿地丹顶鹤繁殖适宜生境经历了面积丧失和功能丧失过程;2004年,研究区内丹顶鹤繁殖适宜性生境已大量丧失,核心区繁殖适宜生境已经严重斑块化.丹顶鹤繁殖生境选择行为对生境质量变化的响应表现为两个过程:一是丹顶鹤巢址不断向核心区集中的过程,二是在核心区的分布格局经历了从均匀分布到成群分布的生态过程.     

丹顶鹤(Grus japonensis)东、西种群巢址选择的分异

丹顶鹤(Grus japonensis) 大陆种群以布列亚山-小兴安岭-张广才岭为界分为东、西两部分.2004～2005年,通过实地测量丹顶鹤东、西种群主要繁殖地的31处巢址的生境因子并进行统计学分析发现:丹顶鹤东、西种群巢址的芦苇密度、苇丛面积及巢距干扰源距离的差异显著(P﹤0.05);采用系统聚类分析的方法可将位于5 个保护区的丹顶鹤巢分成两类,且两类鹤巢分属东、西种群;丹顶鹤东、西种群巢址选择的分异不仅表现在单个生境因子的数量差别,还表现为群体采取不同的隐蔽对策;丹顶鹤东、西种群营巢对水深和芦苇高度的选择稳定一致.生境丧失作为外因通过丹顶鹤的"K生活史"特征起作用,导致丹顶鹤东、西种群的巢址选择具有群体特征.     

耦合种群动态的生境格局变化分析粒度与景观因子选择——以盐城越冬丹顶鹤及其生境的变化为例

选择盐城珍禽国家级自然保护区,以丹顶鹤越冬生境景观与种群动态这一格局-过程关系为切入点,尝试从丹顶鹤最小存活面积特征与种群动态视角探讨一下最佳粒度、景观格局变化分析的指数遴选方法。结果发现:根据丹顶鹤最小生存面积确定200m为最大转换粒度,综合景观指数随空间粒度变化的规律和粒度转换精度损失评价的结果,确定最佳分析粒度为70m。在众多景观因子中,运用Spearman秩相关分析,再利用逐步回归分析建立起景观与丹顶鹤数量指标间的联系,最终筛选出反映景观面积(CA)和空间格局(IJI,ENN_MN)的3种影响显著景观因子,其解释贡献率(累计R2)达到70.5%,且其所代表的生境景观的组成和结构信息较为客观地反映出研究区丹顶鹤种群动态分布的显示状态。与纯粹的景观指数分析相比,这种方法更能反应景观格局演变特征的特定生态学意义。     

栖息地特征对褐马鸡种群密度和集群行为的影响

1998-2000年冬季在山西芦芽山自然保护区选择车道沟和梅洞 2个研究地,就栖息地特征对褐马鸡 (Cros soptilonmantchuricum)越冬种群密度和集群大小的影响进行了研究。经χ2 检验,针叶林是褐马鸡冬季经常利用的栖息地类型。对 2个研究地的栖息地结构比较发现,车道沟适宜栖息地的面积较梅洞大,连接性也较好,褐马鸡种群有更为广阔的取食空间和更多的隐蔽场所,而且活动的阻碍也较小;而梅洞栖息地的取食空间较小,隐蔽场所较少,其活动时受到的阻碍也较大。从 2个研究地微生境结构特征的差异,并结合褐马鸡越冬期栖息地选择来看,树高和高层盖度对褐马鸡在 2个栖息地的选择上起重要作用。车道沟乔木较粗大,不但有丰富的食物,而且可提供较好的夜宿条件;高层盖度越大,栖息地的隐蔽条件越好,能吸引更多的褐马鸡个体取食和越冬。研究结果表明,栖息地结构连接性、微生境结构特征的差异以及人为干扰是褐马鸡种群密度和集群行为差异的主要影响因素。     

Effects of cycloheximide on thymidine metabolism and on DNA strand elongation in Physarum polycephalum

Treatment of Physarum polycephalum with cycloheximide during the DNA synthesis period resulted in a reduction in the incorporation of [³H]thymidine into DNA. This effect was caused by both a reduction in the specific activity of TTP and by an inhibition of progeny strand elongation within replication units. No effect of the drug on the initiation of synthesis of replication units or on the ligation of DNA fragments was detected.     

Components of Partial Disease Resistance in Wheat Detected in a Detached Leaf Assay Inoculated with Microdochium majus using First, Second and Third Expanding Seedling Leaves

The use of first, second and third expanding seedling leaves of wheat (L1, L2 and L3 respectively), inoculated with conidial suspensions of Microdochium majus (syn. Microdochium nivale var. majus) in a detached leaf assay, for detecting components of partial disease resistance (PDR) was investigated across a range of wheat cultivars. Incubation periods (period from inoculation to first appearance of symptoms; a dull grey–green water‐soaked lesion) and latent periods (period from inoculation to the first appearance of sporodochia) were longest and lesions smallest on L3. The expression of PDR components on L2 was intermediate to those on L1 and L3. The longer latent periods on L3 typically occurred after leaf senescence contrasting with latent periods on L1 and L2 where sporulation most frequently occurred on relatively green leaf tissue. Cultivar differences in the first appearance of symptoms, incubation period, which occurred before any leaf senescence was observed, correlated significantly across all leaf positions. Similarly cultivar differences in latent period were correlated for L1 and L2. However, latent periods on L3, which were the least consistent between cultivars across experiments, were not correlated with those of L1 or L2 in any experiment. The results indicate that due to the delay in sporulation until after leaf senescence, observations on latent period in L3 are less representative of what occurs in the whole plant where infection of living tissue is of greatest interest. This work indicates that the selection of the first or second expanding leaf of wheat is optimal for the use in the detached leaf assay using M. majus for studying components of PDR.     

北京地区夏大豆田间杂草的生态经济杀除阈期研究

 本文提出了杂草生态经济杀除阈期的概念,并在北京地区田间试验的基础上,建立了苗后放任和免除夏大豆田间杂草生长的相对时间与大豆相对产量间的函数关系,并在此基础上确立了夏大豆田间杂草群落的生态经济杀除阈期的计算模型。结果表明,夏大豆田间杂草的相对生态经济杀除阈期约处在大豆出苗至成熟期总天数的12.4%—31.0%的天数之前。在此期间进行除草,既能确保大豆不会因杂草生长而显著减产,又可节约阈期之前和之后盲目除草所消耗的费用,并在一定程度上可利用杂草的固土保肥、增加土壤有机质等作用。     

A study of the macro-environment at BenCat in southern Vietnam

Based on the meteorological data over a period of 4 years (1980–3), the macro-environment of BenCat Farm situated in the southern part of Vietnam (27 m above mean sea-level, 11° N and 106° E) was categorized as a “monsoon tropical climate”, due to heavy rainfall (annual mean 2028.96 mm) and about 32% wet days (annual mean 116.52 days) together with high air temperature (annual mean daily temperature 28.58, max. 32.33 and min 24.85° C). April was the hottest (monthly mean >35°C) and January the coldest month (monthly mean <22° C) of the year. The maximum number of wet days were during September and October (mean 18 days.month), whereas the minimum number of wet days were during January and February (mean <1 day/month). The months of December and January at Ben-Cat buffalo farm were categorized as the “comfortable (moderate-Dry) period” as the mean daily temperature was <27° C, while the remaining 10 months of the Calender year (February–November) were categorized as the “hot period” (mean daily temperature >27° C). On the basis of rainfall and the number of wet days, the hot period was further subdivided into a “hot-dry period” (February–April, mean of 1.67 wet days/month and mean rainfall 19.43 mm/month) and a “hot-humid period” (May–November, mean of 15.57 wet days/month and mean rainfall 276.28 mm/month).     

The Effects of Temperature on the Incubation and Latent Periods of Powdery Mildew (Erysiphe polygoni) on Clematis

The effects of temperature on the length of the incubation and latent periods of clematis powdery mildew, caused by Erysiphe polygoni , were studied. At constant temperatures over the range of 10–29°C, the length of the incubation period ranged from 4 to 11 days, and the length of the latent period ranged from 4 to 13 days; no visible colonies developed at 30°C after 19 days. The relationship between temperature and the rates of fungal development within the incubation and latent periods (expressed as the reciprocal of the lengths of the incubation and latent periods) under constant temperature were described well by a non-linear model. The resulting curves were not the usual form of an asymmetrically bell-shaped type; instead, they were of exponential type with the development rate increasing with increasing temperatures. The relationship between temperature and the development rate during the post-incubation (before sporulation) period was non-linear with an optimum temperature of approximately 20°C.     

夏大豆田稗草的生态经济防治阈期研究

本文提出了杂草生态经济防治阈期的概念。并在北京地区１９８４和１９８５年田间试验的基础上,建立了苗后放任的免除夏大豆田稗草生长的相对天数与大豆相对产量的函数关系及其生态经济防治阈期的计算模型。利用此模型计算的结果表明,夏大豆田稗草的生态经济防治阈期处在大豆苗后生育期总天数的１６．８％－２６．０％之间,即按绝对天数计算,北京地区夏大豆田该杂草的生态经济防治阈期约处在大豆苗后１５－２３ｄ之间,此期保持无     

一类传染病动力学时滞模型的分析

研究了一类传染病动力学模型,用摄动理论讨论了相应的非线性时滞问题,得到了被传染病感染的人群数与健康人群数比例的变化规律的渐近表达式,从而揭示了传染病的潜伏期和传染期对疾病传播的影响和作用.本文的研究为解决这一类非线性时滞模型提供了一种有效的方法.     

Relationship between latex yield of Hevea brasiliensis and antecedent environmental parameters

A study on the relationship between latex yield and antecedent environmental data was undertaken for five clones (RRII203, RRII118, RRIM600, RRII105 and GT1) of Hevea brasiliensis (rubber) in Agartala, northeast India, a region in which rubber is not traditionally cultivated. The explained variance for the regression equations based on parameters determined on the day of tapping and up to 3 days prior to it, varied from 72% to 37% during the NWT period and 94-83% during the WT period. Soil moisture storage, 1 and 3 days prior to tapping, was found to be the primary parameter affecting yield for the NWT and WT periods, respectively. It was observed that the clone RRII105, with a comparatively lower yield to that of RRIM600, was more susceptible to daily WD conditions during the non-winter season. RRIM600 and RRII105 being high-yielding clones were also found to be fairly dependent on the AT of the day prior to tapping. The mean lag period correlation of this parameter with yield was also found to be higher during the WT period than during the NWT period. As a whole, the mean lag period based on prior measurements of environmental variables showed optimum correlation with yield at 15-20 days prior to the day of tapping. The study also confirms that varied responses of yield with environmental factors in this non-traditional region of rubber cultivation depend on clonal character.     

泽雅水库混合深度的年内变化及其对藻类生消影响

就水库藻类水华的发生机制而言,近年来值得关注的研究动向是,一些研究者开始认识到光照和混合的交互作用可能对藻类水华生消过程起到了关键作用,即认为水体混合深度的变化直接影响着可获得光强,从而决定着藻类生物量的时空分布。在这些研究中,混合层深度的确定是探讨藻类生消过程影响的前提。然而已有的研究大都只进行粗略的估计。本文提出采取系统聚类分析的方法确定泽雅水库不同时期的混合深度。在具体分析过程中,将测得的某一天某一深度处的 pH,DO,温度,电导率,氧化还原电位等 5 个参数结果看成一类,采用类间平均连接法,间隔尺度变量为欧氏距离的平方进行聚类。对采用系统聚类分析法和已有的"1?C"法计算得的全年的混合深度的变化趋势进行比较,认为系统聚类分析法可以更为准确地反应水体混合的实际情况。依据混合深度的不同特征,在年内水库水体可划分为热成层时期,全混时期和两者之间的过渡期,藻类生物量与混合深度呈负相关。在热成层期间,藻类生物量都超过了 13mm3L-1。而到了 9 月份,当混合层深度扩展到 15m 以上时,藻类生物量明显下降,此后水体处于全混时期,藻类生物量较低,在 9-20mm3/L-1波动。基于稳态假设的前提下,发现随着混合深度增加,稳态藻类生物量呈单峰变化,在混合深度 2m 处达到最大值,即在混合深度为 0-2m 之间时,藻类沉降作用是藻类生物量的主要影响因素,随着深度增加,沉降作用下降,因此藻类生物量增加;当混合深度超过 2m 之后,光限制作用占主导因素,藻类生物量随混合深度增加而下降。这一结果为 Diehl 的假说提供了水库现场的实证。     

Agriculture and food from the Roman to the Islamic Period in the North-East of the Iberian peninsula: archaeobotanical studies in the city of Lleida (Catalonia, Spain)

The urban archaeological excavations carried out in the city of Lleida (Catalonia, Spain) have opened the way for an interdisciplinary project on the ancient landscape, agriculture and food. Here we present the results of the archaeobotanical study of seeds and fruits from this project, centred on the Roman and Islamic periods of the city, between the 2nd century B.C. and the 11th century A.D. During the whole of this period the cultivation and consumption of cereals was found. The most important cereals were hulled barley and naked wheat. This was already known from the later prehistoric era in the area and is similar to findings at other sites from the same period in the western Mediterranean. These cereals are accompanied by some leguminous crops and the presence of grapes and figs is very significant. The expansion of vine cultivation, together with a certain amount of tree growing was one of the basic contributions of the Roman world to proto-historical (Bronze- and Iron Age) agriculture in western Catalonia, as in other parts of Europe. In the Islamic period, there seems to have been an increase in the number of fruit tree species; however for taphonomical reasons this has to be confirmed by future investigations. Flax, already known in prehistoric times, and Gold-of-pleasure must be added to the finds. Also since the Roman period some other taxa, such as celery or fennel, might have been grown. During the time period considered in this paper, there was a wide range of plants grown and consumed. This clearly contrasts with everything known about earlier periods in western Catalonia, during which the only cultivated plants were cereals and flax.