栖息地荒漠化对草原沙蜥食性的影响

栖息地退化会使环境中蜥蜴的可利用食物资源发生改变。采用剖胃法对内蒙古自治区鄂尔多斯市准格尔旗和达拉特旗地区采集的草原沙蜥样本进行了食性分析。对固定沙丘、半固定沙丘和流动沙丘三类样地中77个实胃样本的652只(套)食物进行鉴定和分析的结果表明,这些食物主要为节肢动物,分为35类,隶属3纲11目32科;也在少部分个体(4.69%)的胃容物中发现少量(1.95%)植物碎片。上述三类栖息地中,草原沙蜥对蚁科、蚜科、瓢虫科、叶蝉科和茧蜂科昆虫均有较大的捕食比例;但相比固定沙区栖息地,草原沙蜥在半固定及流动沙丘中增减的食物种类均比较多,导致草原沙蜥在流动沙区与其他两类样地之间有较大的食物相异性。从固定沙丘、半固定沙丘到流动沙丘,随栖息地荒漠化程度的增加,草原沙蜥捕食食物类群的丰富度逐步减少,辛普森优势度指数相应地下降,但营养生态位宽度、香农威纳多样性指数和皮洛均匀性指数却在流动沙丘栖息地上明显增大。这表明鄂尔多斯地区的草原沙蜥是以捕食昆虫等节肢动物为主、兼食极少量植物的杂食性动物。栖息地荒漠化所致的环境变化显著地影响草原沙蜥的食物组成,使其觅食的食物种类逐步减少。     

气候变化对黄腹角雉潜在栖息地的影响

气候变化直接影响物种赖以生存的栖息地环境条件,进而影响物种的分布、数量和存活率。基于优化后最大熵(MaxEnt)模型预测气候变化下黄腹角雉(Tragopan caboti)过去、当前、未来时期的潜在栖息地格局。结果表明,降水量、温度、海拔是栖息地的主要影响因子。当前时期适宜栖息地面积较过去时期下降24.69%;未来2041—2060年间,共享社会经济路径(SSP)3-7.0与SSP5-8.5情景下黄腹角雉适宜栖息地面积较当前时期分别下降55.19%、58.10%。浙江、江西和福建是当前以及未来黄腹角雉核心适宜栖息地,适宜栖息地面积呈现下降的趋势,并往高纬度区域移动。     

生境异质性及源株密度对互花米草入侵力的影响

外来物种互花米草(Spartina alterniflora)被引种到我国海岸带后,已带来一系列生态危害,严重影响了入侵地生态系统结构和功能,深入了解其入侵机制是实施有效控制的基础和理论依据。长江口的滩涂湿地是我国典型的异质潮滩,拥有多种生境。为了探究异质潮滩环境中互花米草初始源株对其入侵力的影响,研究通过野外移栽实验,模拟不同源株密度,探讨潮滩湿地生境异质性及源株密度对互花米草定居、生长和扩散的影响。结果表明:1)生境异质性及源株密度均对互花米草存活率、株高及种群增长率有极显著影响(P0.01)。2)至生长季末,植被区内互花米草存活率、株高均显著高于前沿光滩(P0.05)。此外,淤泥质潮滩植被区内互花米草株高、种群增长率也显著高于粉砂质潮滩植被区(P0.05)。3)互花米草入侵植被区不受源株密度的限制,但随源株密度增加,互花米草种群增长率显著降低(P0.05),而株高无显著差异(P0.05);在光滩区,只有高源株密度才可入侵成功。4)异质生境的冲淤动态、淹水时间和淹水深度是影响互花米草存活和生长的主要环境因子。丰富了河口湿地互花米草入侵力的机理研究,也为我国开展互花米草防控及海岸带保护、修复和管理提供了科学依据,具有重要的理论和实践意义。     

石漠化生境对三叶木通生长及生理特性的影响

石漠化生境土层浅薄、干旱贫瘠,许多植物难以生存。三叶木通作为石漠化生境适生物种之一,探究其对石漠化生境的应答机制对综合治理石漠化生境具有一定的理论和实际意义。在贵州省贵阳市花溪区和安顺市关岭县两地分别选取石漠化生境和普通生境(对照)种植三叶木通,并进行为期一年的观察,探究石漠化生境对三叶木通根、茎、叶等不同器官的生长和生理特性的影响,并利用主成分分析出三叶木通在石漠化生境的主要响应指标。结果显示,与对照相比,石漠化生境下的三叶木通表现出如下特征：(1)植株较矮、茎较细、叶片数较少等生物量的减少,使其适应石漠化生境;(2)叶片叶绿素a/b (Chla/b)和相对含水量(RWC)呈现降低趋势,从而使叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和水分利用率(WUE)均呈下降趋势,胞间CO₂浓度(Ci)呈升高趋势,利于适应石漠化生境;(3)丙二醛(MDA)含量和叶片相对电导率(RC)呈现升高趋势,说明石漠化生境对三叶木通细胞膜系统造成损伤(氧化损伤和渗透损伤),而通过其根中过氧化氢酶(CAT)、茎中过氧化物酶(POD)和叶片中超氧化物歧化酶(SOD)活性升高...     

人为干扰栖息地退化对潮间带中华鲎幼鲎种群数量的影响

栖息地退化是中华鲎（Tachypleus tridentatus）面临的主要威胁因素。然而,人类活动和中华鲎栖息地退化之间的关系研究尚且不足。为了厘清人类活动对中华鲎幼鲎栖息地退化的影响,以北部湾潮间带为研究范围,于2014、2017和2020年对潮间带中华鲎幼鲎丰度进行随机样方法调查,并获取对应年份遥感影像（分辨率30m）作为数据源,借助GIS空间分析、景观格局分析和人为干扰度指数（human disturbance index,HDI）模型,量化评估人为干扰对北部湾潮间带中华鲎幼鲎栖息地景观格局及种群丰度的影响。结果表明：（1）2014-2020年,北部湾潮间带幼鲎栖息地退化严重,无干扰类型景观面积逐渐减少,大部分转化为养殖;（2）北部湾潮间带人为干扰逐渐加强,无干扰等级HDI指数面积不断减少,潮间带大部分面积HDI指数呈增强趋势;（3） HDI指数与幼鲎种群丰度呈显著负相关性,HDI指数高值斑块不适合幼鲎生存。依据HDI指数动态变化及空间分布,可为潮间带中华鲎幼鲎种群栖息地景观格局优化及鲎人工放流增殖选址等保护行动提供理论依据。     

平茬密度对荒漠草原人工柠条林间生境的影响

合理平茬对柠条林更新复壮及科学利用具有重要意义。以宁夏荒漠草原6 m带距人工柠条林(中间锦鸡儿,Caragana intermedia)林间草原为研究对象,研究了全平(QP)、隔一带平茬两带(G1P2)、隔一带平茬一带(G1P1)、隔两带平茬一带(G2P1)、未平茬(WP)五种密度(间距)平茬后柠条林间植被和土壤性状、小气候和土壤风蚀特征等变化。结果表明:(1)G2P1处理下林间植被物种总数、密度、高度和地上生物量最高,物种丰富度、多样性指数以G1P1、G2P1较高。(2)0—40 cm土壤容重以G1P1、G2P1较低,但机械组成无明显变化规律;土壤有机质、速效钾、全氮和速效氮以G2P1最高,但速效磷G1P1最高;土壤平均含水量以G2P1较高,达到8.33%,G1P2和WP最低,WP水分垂直变异系数最大。(3)处理间气温和风速无显著差异;风蚀量以QP、G1P2和WP较高,G1P1与G2P1较小。研究认为,适宜的密度平茬对人工柠条林间生境有改善作用,宁夏荒漠草原人工柠条林平茬时可采取隔两带平茬一带的方式。     

Potential effects of El Niño-South Oscillation (ENSO) on growth of the American crocodile, Crocodylus acutus (Crocodylia: Crocodilydae) in captivity

Temperature affects growth rate of crocodiles. However, no information exists about the effects of temperature by El Niño-South Oscillation (ENSO) on crocodiles. In this paper, we present information about the effect of ENSO on total length and body mass of Crocodylus acutus in captivity during 1997–2001. We did not observe differences in total length among years, but we did so in body mass. Furthermore, we observed that warm episodes of ENSO were associated with a higher average total length and cold episodes represented a higher average of body mass. Sea surface temperature (SST) was significantly related with total length; however, the relationship between SST and body mass was unclear. We suggest that ENSO effects on growth rates of crocodiles need to be considered as an important factor on the management of captive populations.     

基于MaxEnt与ArcGIS的云南榧树潜在生境分析

为明确国家二级保护树种—云南榧树(Torreya yunnanensis)的潜在生境分布区和保护现状,利用50个云南榧树的存在记录点和7个对其分布影响较高的主导环境因子(最冷季平均降水量、降水季节性变异系数、年温差范围、土壤容重、土壤类型、坡向和下层土壤中的百分比粘土)运用最大熵模型(MaxEnt)和地理信息系统(ArcGIS 10.2)模拟其在云南省的潜在生境的分布状况,并将其模拟结果与现有的云南省自然保护区的范围进行叠加分析。研究结果显示：(1)MaxEnt模型对云南榧树潜在生境的模拟的结果所表现出的精度高(AUC=0.977)。(2)云南榧树在云南省的潜在分布区主要集中在三江并流区,云南榧树潜在生境在云南省自然保护区内主要分布在高黎贡山(2364.35 km~2, 58.35%)、白马雪山(846.46 km~2, 31.66%)和云岭(625.55 km~2, 82.42%)自然保护区。(3)最冷季平均降水量(>75.58 mm)、降水季节性变异系数(<64.28)、年温差(24.08—26.40℃)是影响云南榧树在云南省潜在生境分布的主要气候因子。(4)金沙江可能...     

Effects of fine-grain habitat complexity on egg parasitism by three species of Trichogramma

Effects of microhabitat complexity on host foraging by three species of Trichogramma (T. deion, T. ostriniae, and T. pretiosum) were evaluated under simulated stored product conditions. All three species have been considered as potential biological control agents for the Indianmeal moth, Plodia interpunctella, in retail stores and warehouses. Trials were conducted with single naïve female parasitoids in 10-cm Petri dishes that were either empty, contained flour, or contained millet. Empty 15-cm Petri dishes, which served as a surface area control, comprised a fourth treatment. Females were allowed to forage for sentinel egg disks for 2 h, after which percentages of parasitism and egg mortality were computed. In addition, behavioral observations were made on a subset of the trials. Trichogramma deion parasitized more eggs than the other two species in the empty dishes and in the dish containing flour. For T. deion, rates of parasitism and egg mortality were significantly greater in both the small and large empty dishes than in the small dishes containing flour or millet. Parasitism was consistently low for all three species in the grain-filled dishes. Among species, T. ostriniae spent the most time walking, while T. pretiosum was the most sedentary. In addition, T. pretiosum spent significantly more time on the first egg visited compared with subsequent eggs. T. deion may be the best-suited for use as a biological control agent for P. interpunctella. However, the potential negative effects of fine-grain habitat complexity should be taken into account when developing a release protocol for Trichogramma spp.     

基于MaxEnt模型的雅砻江冬麻豆生境适宜性评价

雅砻江冬麻豆（Salweenia bouffordiana）是近年发现的西南特有冬麻豆属新濒危种,主要分布于四川新龙县的雅砻江河谷。开展其生境适宜性评价及其影响因素分析是对其有效保护的前提和基础。基于2015年8月在雅砻江河谷调查获得的55个分布点,结合24个环境变量数据,利用最大熵模型分析影响雅砻江冬麻豆生境的主要环境因子及其适宜生境预测。结果表明：（1）AUC（曲线下面积）值高于0.9,模型具有较高的准确度,适宜于雅砻江冬麻豆的生境适宜性预测和评估;（2）年均温、最湿月降水、昼夜温差月均值和距河流距离是影响雅砻江冬麻豆生境的最主要环境变量,其最适生境环境变量组合为年均温7.9℃、最湿月降水120-124 mm、昼夜温差月均值13.8℃以及距河流距离33 m;（3）雅砻江冬麻豆的潜在适宜和次适宜生境面积分别约为4.83×10³ hm²和2.37×10⁴ hm²,但仅约7.56×10² hm²的潜在适宜生境和3.28×10³ hm²的潜在次适宜生境位于现有自然保护区管辖范围内。雅砻江冬麻豆的潜在适生区主要沿雅砻江河谷呈狭长的条带状分布,现存区受人类活动影响大,未有生物学地位定级,应尽快确定其生物学保护地位,建立保护小区或社区保护地进行就地保护。     

基于生态位模型的艾比湖鹅喉羚生境评价

明确物种生境空间分布格局及其与环境因素的关系,对了解该物种的生境需求和适宜生境空间分布至关重要。生境评价和预测是对物种进行有效保护的基础。以鹅喉羚(Gazella subgutturosa)为研究对象,以其重要栖息地新疆博州艾比湖国家级湿地自然保护区为研究区域,选取115个鹅喉羚分布点数据和23个环境变量因子,应用MAXENT模型分析其生境空间分布及主要影响因子,划分了鹅喉羚在研究区域的适宜生境,并对它的栖息地特征进行了分析。探讨了鹅猴羚生境选择与环境因子的关系。结果表明:气温日较差是影响鹅喉羚生境分布的主要环境因子。植被类型,坡度和最干月降水量对艾比湖鹅喉羚的生境选择影响不大。除了温度和降水在内的19项生物气候变量是鹅猴羚选择生境的重要因素之外,海拔和坡向等地形特征也影响鹅猴羚的生境选择性。鹅喉羚的高度适宜生境区主要分布在研究区域的北部和东部,中度及低度适宜生境区则分布于高度适宜生境区的边缘,而非适宜生境区主要集中在西部地区。研究不仅提供了鹅喉羚在艾比湖的实际分布状况及其栖息地特征,也为鹅喉羚在栖息地方面的研究,即鹅猴羚的栖息地选择和环境因子的关系方面提供了一个重要的依据。     

Assessing determinants of community biomass composition in two-species plant competition studies

A method is proposed for assessing the relative importance of species identity, neighbour species influence and environment as determinants of change in community biomass composition in two-species short-term competition experiments. The method is based on modelling the differences in relative growth rates (RGR) of species (hence called the RGRD method). Using a multiple regression approach it quantifies the effects of initial species abundance, species identity and environment on RGRD and hence on change in community biomass composition. The RGRD approach is relatively simple to use and deals readily with statistical difficulties associated with correlated responses between species from the same stand. It can be easily adapted to analyse sequential harvest data. An example based on data from two-species mixtures of the annual species Stellaria media and Poa annua is used to illustrate the method. The main determinant of change in community biomass composition was species identity, reflected in the difference in growth rates between the species. Change in community composition was not, in general, significantly affected by the influence of neighbours or fertiliser level. The unimportance of the influence of neighbours in affecting the composition of these communities contrasts with the strong role of intra- and interspecific competition in determining the size of individuals of both species (Connolly et al. in Oecologia 82:513–526, 1990).     

官山自然保护区白颈长尾雉季节性生境选择

2009年10月至2010年11月,2015年7月至11月在江西官山自然保护区对白颈长尾雉不同生活史阶段的(繁殖期、育雏期、繁殖后期)生境选择进行了比较研究。调查了6条样线上的126个样方,选取与其生境相关的17个因子进行了观察与测量。研究结果表明,不同生活史阶段各生境选择样方负荷绝对值较大的因子在各主成分中的序位不尽相同,即生境选择的主要生态因子随生活史阶段而变化。卡方检验及单因素方差分析,结果显示,各生活史阶段,白颈长尾雉对林型、坡向、坡度、灌木高度、草本高度和水源距离6个生态因子上无显著差异(P≥0.05),其余11个生态因子两两之间存在显著差异或极显著差异。典则判别结果显示,白颈长尾雉在不同生活史阶段在生境选择上存在一定程度的重叠,又有较为明显的差异。逐步判别表明,在不同生活史阶段,白颈长尾雉生境选择差异上有一系列的生态因子发挥作用,依照贡献值的大小依次为草本数量、落叶层盖度、乔木盖度、海拔和乔木数量,由这5个变量构成的方程对生境选择差异的正确区分率为80.3%。繁殖期和越冬期食物条件是影响白颈长尾雉生境选择的主要因素,而育雏期则为隐蔽条件。     

基于MaxEnt模型的秦岭山地斑羚生境适宜性评价

生境适宜性评价对野生动物的保护与管理具有重要意义。为了解陕西秦岭地区斑羚(Naemorhedus griseus)的生境状况,利用2011—2013年间在秦岭地区采集的斑羚分布点数据,通过MaxEnt模型对陕西秦岭地区的斑羚生境进行适宜性评价。结果表明,陕西秦岭地区的斑羚适宜生境面积约为9800 km~2,占秦岭山地面积的17%,主要位于秦岭中西部区域;次适宜生境面积约为6940 km~2,占秦岭面积的12%,主要位于适宜生境的周边区域。海拔、月均昼夜温差和年降雨量是影响陕西秦岭地区斑羚生境适宜性的主要环境变量,而人类干扰对生境适宜性的影响较小。陕西秦岭地区的斑羚偏好于选择1800—3000 m的中高海拔区间、年降水量为750—850 mm、月均昼夜温差8℃左右的环境。明确了斑羚适宜生境在秦岭的分布状况及关键环境影响因子,可为下一步制定濒危动物保护和生境管理提供理论依据。     

Influence of culture temperature on the growth,biochemical composition and fatty acid profiles of six Antarctic microalgae

The growth, biochemical composition and fatty acid profiles of six Antarctic microalgae cultured at different temperatures, ranging from 4, 6, 9, 14, 20 to 30 ^∘C, were compared. The algae were isolated from seawater, freshwater, soil and snow samples collected during our recent expeditions to Casey, Antarctica, and are currently deposited in the University of Malaya Algae Culture Collection (UMACC). The algae chosen for the study were Chlamydomonas UMACC 229, Chlorella UMACC 234, Chlorella UMACC 237, Klebsormidium UMACC 227, Navicula UMACC 231 and Stichococcus UMACC 238. All the isolates could grow at temperatures up to 20 ^∘C; three isolates, namely Navicula UMACC 231 and the two Chlorella isolates (UMACC 234 and UMACC 237) grew even at 30 ^∘C. Both Chlorella UMACC 234 and Stichococcus UMACC 238 had broad optimal temperatures for growth, ranging from 6 to 20 ^∘C (μ = 0.19 – 0.22 day^–1) and 4 to 14 ^∘C (μ = 0.13 – 0.16 day^–1), respectively. In contrast, optimal growth temperatures for NaviculaUMACC 231 and Chlamydomonas UMACC 229 were 4 ^∘C (μ = 0.34 day^–1) and 6–9 ^∘C (μ = 0.39 – 0.40 day^–1), respectively. The protein content of the Antarctic algae was markedly affected by culture temperature. All except Navicula UMACC 231 and Stichococcus UMACC 238 contained higher amount of proteins when grown at low temperatures (6–9 ^∘C). The percentage of PUFA, especially 20:5 in Navicula UMACC 231 decreased with increasing culture temperature. However, the percentages of unsaturated fatty acids did not show consistent trend with culture temperature for the other algae studied.     

土地利用变化对生境网络的影响——以苏锡常地区白鹭为例

生境网络对于物种更具有生态意义。研究土地利用变化对生境网络的影响,对破碎景观中种群的扩散和迁徙至关重要。研究结果有助于区域生境网络的恢复和完善,从物种的角度而非景观结构的角度优化生态网络。以城市化快速发展、土地利用变化明显的苏锡常地区为研究区域,优势湿地鸟类白鹭为代表物种,构建物种生境斑块约束条件概念模型,提出按照物种生活习性特征划分、选择生境斑块的方法,并从斑块和网络结构两个视角分析了土地利用变化对生境网络的影响。结果表明:(1)2000—2010年研究区白鹭生境的适宜地类总面积虽有所增加,但主要由于大量新增线性人为干扰致使白鹭生境网络质量下降;(2)白鹭生境网络在研究区不是全区覆盖的回路,基本由宜兴—溧阳片、无锡滨湖片、苏州吴中片和苏州阳澄湖片4个小片网构成,其完整程度按照宜溧片、滨湖片、吴中片、阳澄湖片降次排列;至2010年,宜溧片破坏最为严重,滨湖片和吴中片次之,阳澄湖片受破坏程度相对最弱。总体上,白鹭生境境况在10年间恶化明显,土地利用变化朝着不利于白鹭持续生存的方向发展。     

Ecology of deepwater rice-fields in Bangladesh 5. Mineral composition of the rice plant and other aquatic macrophytes

The mineral composition of deepwater rice (cultivar Kartik Sail) was studied during 1986 in a field near Sonargaon, Bangladesh, which is flooded by water from R. Meghna. Samples were taken four times, once prior to flooding and three times during the flood season. On two of the latter days (10 August = end of first flood peak, 23 September = second flood peak) the study was extended to other components of the ecosystem (sediments + soil, water, other aquatic macrophytes). On 23 September, 32% of the mass of the plant was out of water, 65% in water and 3% in sediment/soil. There were marked differences between elements in their pattern of accumulation by deepwater rice through the season. In comparison with the final totals for each element, about 48% of N, but only 11% of P and 10% of Na had been accumulated by the time the floodwater had arrived. The aquatic roots doubled in mass between the times of the two flood peaks and it is suggested that much of the P taken up by the plant may reach the plant via its aquatic roots after having becoming mobilized and released to the water when sediments become anaerobic. In comparison with other parts of the plant, Na was always much higher in the stem and Zn in the basal roots.Other aquatic macrophytes (weeds) increased from 0.40% of the mass (dry weight) of deepwater rice on 10 August to 4.0% on 23 September. However their content of each element (% dry weight) was considerably higher than that in deepwater rice, so they may at times compete effectively with the rice for nutrients. During the flood period (to 23 September) weeds accumulated 16% of the N accumulated by rice during the same period.