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。     

Advances in ecological studies of epiphytes using canopy cranes

Forest canopies are one of the most species-rich habitats, but among the least explored in the biosphere. They play a crucial role in the process of material and energy exchange between the forest and atmosphere. Individual ecosystem members (e.g., epiphytes) and the ecological function of canopies have been given insufficient attention because of inaccessibility. Canopy cranes have been successfully used to guarantee non-destructive and reiterated sampling of epiphytes, thus offering a top-down perspective of the entire canopy. These cranes have become the symbol of canopy research and enable epiphyte research. Globally, western developed countries have conducted many studies of diversity and spatial distributions of epiphytes using canopy cranes, thus accumulating an abundance of valuable results. This review summarizes the structure, development history, and distribution of canopy cranes as well as general information about international canopy research organizations. Ecological studies of epiphytes performed around the world using these canopy cranes are also reviewed. Additionally, the development of canopy ecology and the construction of canopy cranes in China are introduced briefly. In analyzing current research trends in ecological studies of epiphytes in China and globally, the following aspects were considered: biodiversity, spatial patterns and maintenance mechanisms, ecological adaptations of epiphytes, their relationship with canopy animals, and their responses to climate change.     

无人机调查白鹤种群数量和越冬分布

白鹤(Leucogeranus Leucogeranus)是国家Ⅰ级重点保护野生动物,唯一一种极度濒危(CR)鹤类,分布和种群数量是评估其濒危程度的重要参数。无人机调查作为目前生态学研究的一个重要调查方法,为查明白鹤的越冬分布、种群数量及幼鸟比例,于2022年1月使用地面监测结合无人机调查的方法在江西、山东、安徽、湖南、湖北等地的湖泊和农田中开展越冬白鹤调查。野外调查共记录白鹤5607只,网络信息检索在调查区域外的8个地点记录白鹤9只,合计记录越冬白鹤5616只。其中江西鄱阳湖记录到越冬白鹤4813只,占总数的85.7%,主要分布在康山垦殖场、五星垦殖场和成新垦殖场;山东黄河三角洲记录到越冬白鹤625只,占总数的11.1%。安徽、湖南、湖北分别记录到越冬白鹤34,63和72只。对部分群体的白鹤幼鸟数量进行统计,4680只白鹤中,记录到幼鸟674只,幼鸟比例为14.4%,其中湖南越冬白鹤幼鸟比例最高,达28.6%,山东越冬白鹤幼鸟比例最低,为11.5%。调查刷新了白鹤种群数量,证实了山东黄河三角洲是目前除江西鄱阳湖外最重要的白鹤越冬地,缓解了白鹤越冬期过度集中的压力。基于本研究结果,我们...     

No down-regulation of leaf photosynthesis in mature forest trees after three years of exposure to elevated CO2

The photosynthetic responses of six species of mature forest trees to long-term exposure to elevated CO2 (ca. 530 ppm) were determined at the Swiss Canopy Crane (SCC) site near Basel, Switzerland. In the third year of growth in elevated CO2, using web-FACE technology, net photosynthesis (As) in fully sunlit, upper canopy foliage was stimulated by ca. 40% compared to ambient controls. This enhancement did not differ from the instantaneous increase in As found in ambient-grown leaves that were temporarily measured at elevated CO2. A complete lack of down-regulation of photosynthesis was found in all species and in both the early and the late growing season. Neither was leaf nitrogen content significantly affected by long-term exposure to elevated CO2. Our results document a persistent enhancement in leaf level photosynthesis in response to elevated CO2 in mature forest trees over a period of three years. Circumstantial evidence suggests that the additional assimilates feed into large sinks other than stem and shoot growth.     

Virulence of entomopathogenic nematodes (Rhabditida: Steinernematidae, Heterorhabditidae) against Tipula paludosa (Diptera: Tipulidae), a turfgrass pest on golf courses

The European crane fly (ECF), Tipula paludosa Meigen feeds on leaves, crowns, and roots of cool-season turfgrasses causing damage to residential lawns and golf courses. A laboratory study was conducted to determine the susceptibility of ECF larvae to four commercial entomopathogenic nematode (EPN) species (Heterorhabditis marelatus, H. megidis, Steinernema carpocapsae and S. feltiae). The virulence of four S. feltiae isolates recovered from golf courses in Quebec and Ontario were also compared to a commercial strain. LC₅₀ values of EPN against late instar ECF larvae were 152, 562, 763, and 3584 for S. feltiae, H. megidis, H. marelatus and S. carpocapsae, respectively. When non-feeding (without grass seedling), ECF larvae mortalities decreased for all nematode species and concentrations tested. At 25°C, LC₅₀ values for the two most virulent indigenous S. feltiae were 129 and 187 nematodes/larva, not different from the commercial strain. At 5°C, the commercial S. feltiae was more effective than both BIC14A and RE6A isolates against ECF larvae. However, at 15°C, BIC14A was the most virulent at the low concentration of 200 IJs/larva.     

Biological control of Tipula paludosa (Diptera: Nematocera) using entomopathogenic nematodes (Steinernema spp.) and Bacillus thuringiensis subsp. israelensis

Tipula paludosa (Diptera: Nematocera) is the major insect pest in grassland in Northwest Europe and has been accidentally introduced to North America. Oviposition occurs during late August and first instars hatch from September until mid-October. Laboratory and field trials were conducted to assess the control potential of entomopathogenic nematodes (EPN) (Steinernema carpocapsae and S. feltiae) and Bacillus thuringiensis subsp. israelensis (Bti) against T. paludosa and to investigate whether synergistic effects can be exploited by simultaneous application of nematodes and Bti. Results indicate that the early instars of the insect are most susceptible to nematodes and Bti. In the field the neonates prevail when temperatures tend to drop below 10 °C. S. carpocapsae, reaching >80% control, is more effective against young stages of T. paludosa than S. feltiae (<50%), but the potential of S. carpocapsae might be limited by temperatures below 12 °C. Mortality of T. paludosa caused by Bti was not affected by temperature even at 4 °C but the lethal time increased with decreasing temperatures. Synergistic effects of Bti and EPN against T. paludosa were observed in 3 out of 10 combinations in laboratory assays but not in a field trial. The potential of S. carpocapsae was demonstrated in field trials against early instars in October reaching an efficacy of >80% with 0.5 million nematodes m⁻² at soil temperatures ranging between 3 and 18 °C. Results with Bti were strongly influenced by the larval stage and concentration. Against early instars in autumn between 74 and 83% control was achieved with 13 kg ha⁻¹ Bti of 5,700 International Toxic Units (ITUs) and 20 kg ha⁻¹ of 3,000 ITUs. Applications in spring against third and fourth instars achieved between 0 and 32% reduction. The results indicate that application of Bti and nematodes will only be successful and economically feasible during the early instars and that the success of S. carpocapsae is dependent on temperatures >12 °C. Synergistic effects between S. carpocapsae and Bti require more detailed investigations in the field to determine maximal effect.     

丹顶鹤性活动的声行为研究

丹顶鹤繁殖期的性活动可分为雄鹤求偶、雌鹤对雄性求偶的应答、两性交配和交配完结4个阶段,其相应的鸣声模式分别为雄性的求偶鸣声、雌性对雄性求偶的应答声和两性的对鸣声、两性对唱的交配声和两性的高声合唱。4个阶段鸣声都是以基本音的主频率(PF)为主音的单音调声,前3个阶段都带数个近似fn=nf0(f0=FP)关系的低幅值谐频成分。第4个阶段带数个近似fn=nf0(f0=FP)关系的高幅值谐频成分;品质因数(Q3dB)多半为4～6,声脉冲重复频率(RFP)一般为150～180Hz,而第2阶段声的RFP一般为180～260Hz。雄性鸣声的每个单次叫声中含有的音节数较少,一般不超过4个;而雌性鸣声比较复杂。每个单次叫声中含有的音节数较多,一般都在7～8个以上;但雌雄鸣声的每个音节都是由3个声脉冲组成。雄鹤鸣唱声频率变化范围较小,而雌鹤鸣唱声频率变化形式是由低到高达到高峰后又开始下降。4个阶段的鸣声都具有较好共鸣。只有第2阶段发声运动较快。而且发现雄鹤鸣唱单次鸣叫声的音节数“增多”。各阶段鸣声特性均存在差异,不同配偶间均存在显著差异,研究结果表明丹顶鹤雌雄都具有不同的鸣声,且其性活动过程中不同的鸣声行为具有较高的个体识别信号潜能。另外,求偶鸣叫声和求偶应答与对鸣声在性活动鸣声中起着决定性的作用。     

灰鹤消化系统的形态学观察

本文对灰鹤的消化系统进行了大体解剖和形态学观察,结果表明灰鹤具有发达的舌、小肠、肝脏和胰脏;相对发达的盲肠;但嗉囊不甚发达。     

年龄、集群、生境及天气对鄱阳湖白鹤越冬期日间行为模式的影响

于2012年1—3月和2012年12—2013年3月,采用瞬时扫描法研究了鄱阳湖国家级自然保护区越冬白鹤(Grusleucogeranus)的昼间时间分配模式和日活动节律,分析了年龄、集群大小、生境类型和天气对白鹤越冬行为的影响。结果表明,白鹤越冬期的主要行为有觅食、警戒、理羽、游走、休息和争斗。其中,觅食是鄱阳湖越冬白鹤主要行为,占其昼间活动时间的82.94%;警戒占11.94%,理羽占3.52%,游走占1.88%,休息占0.15%,争斗占0.02%。白鹤在越冬期间的觅食、游走、休息和争斗行为存在明显的昼间节律性,其中游走、觅食和争斗行为在每天的上午和下午各存在1个高峰,休息行为在中午出现一个高峰;警戒和理羽行为则没有显著的昼间节律变化。年龄、集群大小、天气和生境对白鹤的越冬行为具有显著的影响:幼鹤取食的时间显著多于成鹤,而警戒时间则显著的小于成鹤;与家庭群中的个体相比,集体群中的个体取食和争斗时间显著增加,警戒时间显著减少;在天气晴朗时,白鹤的警戒时间显著大于阴天的警戒时间,取食时间则显著少于阴天时白鹤的取食时间;白鹤在大风天气显著增加理羽行为;在有雾的天气会显著增加取食时间,减少警戒时间。在草洲和浅水两种生境中,白鹤的游走和理羽行为存在显著差异,而觅食和警戒行为没有显著的差异,这可能源于草洲和浅水生境相互毗邻,并且具有相同程度的人为干扰。GLM分析结果表明,年龄和集群大小、年龄和生境、集群大小和天气、集群大小和生境、天气和生境对白鹤昼间时间分配模式的影响存在显著交互效应。     

食物资源的枯竭对丹顶鹤营养位的影响

随着扎龙湿地生物资源的迅速减少,在该地栖息的丹顶鹤种群的营养关系可能发生显著的变化.本文使用稳定同位素(δ¹⁵N和δ¹³C)监测食物资源的枯竭对丹顶鹤营养位的影响.结果表明:丹顶鹤种群的δ¹⁵N和δ¹³C的丰度范围分别为6.9‰～8.1‰和-17.8‰～-18.5‰.扎龙湿地系统以大型水禽为食物顶端的食物链长度为3.8±0.2,其中丹顶鹤种群所处的平均营养位为3.1(范围在2.9～3.3).丹顶鹤的δ¹⁵N的丰度近年波动范围为7.4‰～8.8‰(波动幅度1.4,小于营养位发生显著变化的阈值3.4),这说明在该地区活动的丹顶鹤的营养位并没有随着大面积的栖息地和食物资源的消失而发生显著变化.然而,随着本地区生物资源的枯竭,丹顶鹤种群规模迅速减少,当前必须合理解决当地居民从湿地获取生活资源的需求与丹顶鹤觅食之间的矛盾,从而更好地保护这种濒危种群.