共查询到19条相似文献，搜索用时 62 毫秒
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鸳鸯(Aix galericulata)为雁形目、鸭科的中型鸭类,属国家二级重点保护野生动物,其国内主要繁殖地在东北地区。2018年12月—2019年6月,在四川省广元市剑阁县观察到一鸳鸯种群留居及繁殖情况。此鸳鸯种群共23只(12♂,11♀)。分别对两个洞穴巢和1号巢中的4枚卵行了测量。卵为椭圆形,色白,平均重量37.92 g,平均长、短径为52×38 mm。由于鸮类的入侵,导致1号巢鸳鸯卵失孵而繁殖失败。此前在四川省还未有对野外环境下鸳鸯繁殖的研究报道,这为鸳鸯种群在南方省份的留居与繁殖地增加了新的纪录。 相似文献
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鸳和鸯鸳鸯,鸳指雄鸟,鸯指雌鸟,属雁形目,鸭科的鸟类。鸳鸯是一种雌雄异色的鸟类,所谓雌雄异色指的就是雄鸟和雌鸟长得不一样,雄鸳鸯是羽色最鲜艳华丽的野鸭,雌鸳鸯则颜色淡雅。它们繁殖季节成对活动,非繁殖期多成小群活动。 相似文献
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<正>记录鸳鸯798只!2023年度冬季第一次鸳鸯科学调查数据显示,在京越冬鸳鸯数打破自2019年开展鸳鸯种群数量调查以来的最高纪录。北京市野生动物救护中心的2023年度冬季第一次鸳鸯科学调查显示,共记录到鸳鸯798只,其中雄性457只,雌性341只。各调查点中鸳鸯数量较多的是颐和园108只,紫竹院148只,玉渊潭288只,各点的数量均为自2019年开展调查以来的最高值。 相似文献
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棕背Ｐｉｎｇ Ｃｌｅｔｈｒｉｏｎｏｍｙｓ ｒｕｆｏｃａｎｕｓ的种群密度与森林鼠害的发生呈正相关关系，而棕背Ｐｉｎｇ种群数量的消长与种群的繁殖关系极为密切。本调查研究结果表明，棕背Ｐｉｎｇ种群的繁殖能力主要在成年组，成年组个体的繁殖强度最高，在繁殖期间占主导地位。从繁殖特点可见一年内只有一个繁殖高峰期，且集中于春季，属前峰型；抗生育药剂对棕背Ｐｉｎｇ雌雄两性害鼠的繁殖强度的影响是显著的，能够大幅度地 相似文献
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姜灿荣 《中南林业调查规划》2008,27(4):37-39
阐述了金钟山国家级自然保护区自然资源重点保护对象即黑颈长尾雉、苏铁、鸳鸯西南种群以及其他野生生物资源现状,并对保护区的面积适宜性、科学价值、经济和社会价值等保护属性进行了分析评价。 相似文献
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Rafael F. del Castillo Sonia Trujillo Argueta Cuauhtémoc Sáenz-Romero 《Forest Ecology and Management》2009
We present an overview of recent studies carried out on Pinus chiapensis (Mart.) Andresen (Pinus strobus var. chiapensis Mart.) and provide management and conservation recommendations. Because of its wood quality, and being commonly used by 12 ethnic groups, this pine is an outstanding forest resource at mid-altitude humid mountains of southern Mexico and Guatemala. P. chiapensis appears to be a distinctive species, closely related with North American white pines, and a potential valuable resource for establishing breeding programs with such species. P. chiapensis is the most abundant tree species in early successional stands of the tropical montane cloud forest playing a key role in ecosystem regeneration particularly in areas managed under slash-and-burn practices. However, many natural stands of this pine are severely reduced. Molecular studies based on isozymes and DNA markers reveal low genetic diversity, the lowest compared with its closest relatives (P. ayacahuite, P. monticola and P. strobus). Heterozygosity and seed viability increase significantly with population size, and inbreeding depression appears to significantly decrease seed viability, suggesting the involvement of genetic factors on population decline. Low population size is associated with both lack of perturbation in well-preserved habitats and high deforestation rates in severely disturbed habitats. Conservation and management practices require preserving and restoring connections between suitable habitats to enhance gene flow between populations, and on careful programs that monitor and control slash-and-burn practices. Restoration practices should use seeds from as many tree sources as possible to reduce inbreeding risks. Spline climate models predict significant increases in temperature, decreases in precipitation and consequently an increase of aridity along the range of P. chiapensis. Thus, assisted migration would be needed to match present genotypes to forecasted climate changes. 相似文献
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《Forest Ecology and Management》2006,236(1):76-84
The importance of early successional habitats for breeding and post-breeding birds has received recent attention. Common early successional habitats in the eastern United States are regeneration after timber harvests, utility right-of ways and reclaimed surface mines. Few studies, however, have compared the characteristics of these with regard to avian habitat use. We conducted a passive mist-netting study to assess the breeding and post-breeding avian communities associated with these land uses in the Cumberland Mountains of eastern Tennessee. We used analysis of variance to compare the vegetation structure among these habitat types and discriminant function analyses to illustrate differences in vegetation structure and bird abundance among habitats. We banded 1562 individuals of 40 species (1.08 birds/net-hour). The percent cover of saplings, forbs and grass differed among habitat types, but there was no detectable difference in shrub cover. Vegetation structure allowed good discrimination between habitat types (Wilks’ λ = 0.16), specifically in differentiating clearcuts from surface mines and right-of-ways. Although the three habitat types had several avian species in common, the abundance of 12 species differed substantially among habitat types, and their species abundance patterns allowed for excellent discrimination between these habitat types (Wilks’ λ = 0.08). We conclude that these three early successional habitat types are different with regard to vegetation structure and avian community assemblage. These differences are important for local and landscape-scale conservation planning for both early and late successional avian species. 相似文献
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Washington J. Gapare 《New Forests》2014,45(3):311-331
Major challenges exist for applied gene conservation of forest genetic resources in native habitats of the Mexican and Central American Pines, Pinus radiata and the Southern US pines. They include population decline and population structure changes, due to forest removal, conversion of forest land to other uses, fires, climate change, diseases and pests. However, tree breeders continue to struggle with methods that would meaningfully integrate tree breeding and conservation populations. In this review, I will start by outlining the importance of gene conservation in tree breeding programs, then highlight some challenges and opportunities for applied gene conservation programs; and lastly, I share results of a large body of applied research and other activities aimed at genetically characterising the base population of P. radiata in Australia and New Zealand, for the purposes of effective ex situ gene conservation. Main threats for species grown in exotic environments also include introduced diseases and pests, and more recently, climate change. Consequently, movement of genetic material is often restricted and genetic resources of pine species are not readily expanded by further importations from overseas. Therefore, conservation of genetic material currently in these countries is likely to be important for the long-term viability of plantation forestry using pine species. In addition to understanding the largely unpredictable or speculative biological and economic worth of rare alleles, the greatest challenge that we have in ex situ gene conservation is to develop practical approaches for infusing genes from base populations of unimproved material into more advanced-generation breeding programs without greatly affecting productivity gains. Other notable challenges include perceived costs and benefits of gene conservation in the face of increasing privatisation of forest estate. While financial resources for domestication of alternative species are declining, a vast number of existing species and provenance/progeny trials of P. radiata, the Mexican and Central American pines and the Southern US pines provide an excellent gene resource for the future. 相似文献
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Elizabeth A. Roznik Steve A. Johnson Cathryn H. Greenberg George W. Tanner 《Forest Ecology and Management》2009
Many animals exhibit changes in patterns of movement and habitat use as they age, and understanding such ontogenetic shifts is important for ensuring that habitat management is appropriate for all life stages. We used radiotelemetry to study movements and habitat use of juvenile and adult gopher frogs (Rana capito) as they migrated from the same ponds following metamorphosis or breeding. To supplement radiotelemetry data, we also captured adult gopher frogs at drift fences as they left ponds for the terrestrial environment. We directly compared patterns of movement, directional orientation, macrohabitat use (forest type), and microhabitat use (refugia) between the two life stages. Both juveniles and adults moved considerable distances from breeding ponds (up to 691 m) and selected fire-maintained longleaf pine (Pinus palustris) forest over fire-suppressed forest. However, fire-suppressed habitat appeared to be a greater barrier to juveniles than adults. Additionally, we found differences in microhabitat use; both juveniles and adults used underground refuges (e.g., burrows and stump holes) for shelter, but juveniles used such refuges less often than adults. Juveniles also took more time than adults to locate their first refuge after exiting ponds. These differences may reflect the juveniles’ lack of experience in terrestrial habitats. Unlike juveniles, adults are likely more familiar with the locations of specific habitat features (e.g., burrows and ponds) and may take the shortest routes when moving among them, even if it requires moving through fire-suppressed habitat. Previous research has recommended that terrestrial habitats surrounding breeding ponds should be managed with frequent prescribed fire (i.e., 1–3-year intervals) in order to maintain suitable terrestrial habitat for juvenile gopher frogs, and our study suggests that these management practices are also likely beneficial to adults. 相似文献
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Dr. F. Kühlhorn 《Journal of pest science》1983,56(4):67-70
This second part begins with representing the breeding biotops ofC. pipiens. Lighted water is preferred by subspeciesC. p. pipiens and dark water by subspeciesC. p. molestus. Then the ecological requirements of breeding (cleanness, oxygen, temperatures, plants a. o.) are shown. Some behaviour patterns of larvae during the ingestion are described, and the consequence of development of a scum in the breeding area is viewed. Finally the population dynamics of the species in a bavarian region are discussed. The density mainly dependents on abiotic factors, the suitability of breeding biotops and the availability of blood hosts. 相似文献
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Rafa? Kowalczyk Pierre TaberletEric Coissac Alice ValentiniChristian Miquel Tomasz KamińskiJan M. Wójcik 《Forest Ecology and Management》2011,261(4):821-828
Large herbivores are keystone species in many forest areas, as they shape the structure, species diversity and functioning of those ecosystems. The European bison Bison bonasus has been successfully restored after extinction in the wild at the beginning of 20th century. As free-ranging populations of the species were re-established mainly in forest habitats, knowledge of the impact by the largest European terrestrial mammal on tree stands is essential. This helps to make management and conservation decisions for viable population maintenance of the species in the wild. Using a novel DNA-based method of herbivore diet analysis, the trnL approach (DNA-barcoding), we investigated the influence of different foraging conditions (access to supplementary fodder) on bison diet in winter and its potential impact on woody species. Faecal samples were collected from different bison treatment groups: (1) intensively fed; (2) less intensively fed; (3) non-fed utilising forest habitats; and (4) non-fed utilising agricultural areas surrounding the Forest. These were analysed to estimate the proportion of different plant groups consumed by bison. Bison groups differed significantly in their diet. The amount of woody materials (trees and shrubs) consumed by bison increased with decreasing access to supplementary fodder, ranging from 16% in intensively fed bison to 65% in non-fed bison utilising forest habitats. Inversely, the amount of herbs, grasses and sedges decreased from 82% in intensively fed bison to 32% in non fed bison utilising forest habitats. The species of trees mainly browsed by bison, Carpinus/Corylus, Betula sp. and Salix sp., were of lower economic importance for forest management. The impact of bison on tree species needs further investigation, however, we can predict that browsing by bison, mainly on Carpinus/Corylus, makes an insignificant impact on forestry due to the high and increasing representation of this species in the forest understory. Supplementary feeding has several negative effects on bison ecology and health, therefore reduced and distributed supplementary feeding should be applied as the management practice in the Bia?owie?a Forest. 相似文献
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E. M. Abraham A. P. Kyriazopoulos Z. M. Parissi P. Kostopoulou M. Karatassiou K. Anjalanidou C. Katsouta 《Agroforestry Systems》2014,88(2):287-299
Dactylis glomerata L. is a widespread perennial grass species, which has been reported to be adapted to shaded conditions. Its populations thrive in a variety of environments. However, little information is available concerning the comparative response of its natural populations from contrasting environments under the reduced light intensity conditions that exist in silvopastoral systems. The objective of the present study was to estimate the comparative ability of three populations of D. glomerata from northern, central and southern Greece to grow under full sun, 60 % shade and 90 % shade in terms of their growth characteristics, phenotypic plasticity, dry matter production and nutritive value. Shade reduced tillering and dry matter production, increased tiller height and modified leaf characteristics. Under shade fewer leaves were grown simultaneously on the same tiller, but these were longer and thinner compared to full sun. Differentiation in response to shade among the populations examined of D. glomerata was observed mainly for leaf characteristics. The population from Pertouli (central Greece) responded better, particularly to moderate shade as it had a higher leaf area, longer leaf and higher dry matter production, compared to the others. Evidence for adaptive phenotypic plasticity to moderate shade was suggested only for this population. Additionally, Pertouli had higher nutritive value compared to Taxiarchis (northern Greece) and Crete (southern Greece) under shade. The divergent responses of natural populations of D. glomerata could justify breeding germplasm with enhanced shade tolerance. 相似文献
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A.-M. Dulaurent A.J. Porté I. van Halder F. Vétillard P. Menassieu H. Jactel 《Forest Ecology and Management》2011,261(6):1069-1076
Little attention has been given to the relevance of habitat complementation concept to the population dynamics of insect herbivores. Late instar larvae of the pine processionary moth (PPM) Thaumetopoea pityocampa move in late winter from pine stands, their feeding habitat, to neighbouring habitats where they pupate until next summer. They search for sunny exposed soil which they can find in open areas. We investigated the effect of both forest cover and soil origin, with three matching types (pine stand, broadleaved stand and open area) on the survival of PPM pupae. The microclimatic soil variables which significantly differentiated cover types and soil origins were the maximum temperature and the mean relative humidity in spring, soon after pupation has occurred. A significant effect of the cover type, but not of the soil origin, was detected on the proportion of dead, emerged or diapausing pupae. Open areas were more suitable for pupae survival than forest covers (pine or broadleaved stands), due to warmer and more humid soil conditions. In this study, we provide one of the first examples of habitat complementation for an insect herbivore, as PPM population can benefit from the combination of pine habitats for the feeding of larvae with open habitats for pupation. The presence of broadleaved stands next to pine stands might also represent an ecological trap for PPM pupae, as broadleaved habitats may turn to be less suitable for pupae survival in spring when the apparition of leaves creates cooler conditions. 相似文献