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101.
Floral organogenesis of Chloranthus sessilifolius K. F. Wu is described. The inflorescence primordium is dome-like in the beginning and then elongates, and bract primordia
initiate almost decussately. Each floral primordium, arising from the axil of a bract, soon becomes a scale-like structure,
with three primordia of androecial lobes originating from its abaxial part, and the gynoecial primordium in adaxial position.
As the androecial lobes become more distinct, four thecae are already in differentiation, and the gynoecial primordium appears
as a shallow disc. The androecial lobes do not extend their length until the thecae approach maturity and the stigma is differentiated.
The androecial lobes are united at all the stages of development, and the entire androecium falls off as a unit at the end
of anthesis. Based on these results, combined with published evidence from neobotany, palaeobotany and phylogenetic studies,
the morphological nature of the androecium of Chloranthus is further discussed. Our studies support the viewpoint that the androecial structure of Chloranthus may have arisen by splitting of a single stamen with 2 marginal thecae.
Received May 2, 2001 Accepted December 18, 2001 相似文献
102.
There have been considerable advances in our understanding of the tolerance of species interaction networks to sequential extinctions of plants and animals. However, communities of species exist in a mosaic of habitats, and the vulnerability of habitats to anthropogenic change varies. Here, we model the cascading effects of habitat loss, driven by plant extinctions, on the robustness of multiple animal groups. Our network is constructed from empirical observations of 11 animal groups in 12 habitats on farmland. We simulated sequential habitat removal scenarios: randomly; according to prior information; and with a genetic algorithm to identify best‐ and worst‐case permutations of habitat loss. We identified two semi‐natural habitats (waste ground and hedgerows together comprising < 5% of the total area of the farm) as disproportionately important to the integrity of the overall network. Our approach provides a new tool for network ecologists and for directing the management and restoration of multiple‐habitat sites. 相似文献
103.
《农业工程》2014,34(2):106-109
Nature reserve has been served as the important pathway for biodiversity conservation and carbon storage. Global climate change is an indisputable fact and impacted the biodiversity and nature reserve. How nature reserves adapt to climate change has drawn more and more concerns. This research conducted questionnaires of 68 national nature reserves from 24 provincial regions, and the questionnaires showed that all surveyed nature reserves experienced climate change, and 68.57%, 61.43% and 68.57% of nature reserves, respectively, considered warming temperature, precipitation change, and occurrence of extreme climate events as new threats to them. These new factors directly threat the distribution range and survival of endangered species, change of ecosystem function, enhance of pest and disease damages, and directed damage the infrastructures. However, most of the surveyed nature reserves did not consider the systematic monitoring the facts of climate change, and lack actions and strategies of initiative adaptation to climate change. At last, we proposed the strategies for nature reserves to adapt to climate change, including enhancing the monitoring on the impact of climate change, making scientific planning and designing for development of nature reserves, decreasing the pressure through sustainable development, and enhancing the scientific research and the investment to improve the ability of nature reserves to adapt to climate change. 相似文献
104.
In this study we designed, implemented, and evaluated an outreach programme for high-school biology students rooted in the ‘science as inquiry’ approach. Accordingly, students learn about science from experts in the field, as well as through in-class exposure to the history and philosophy of science. Our sample consisted of 11th graders (n?=?497), ages 16–17, attending advanced biology classes. Our goal was to determine whether this programme had a significant effect on students’ understanding of the ‘nature of science’ (NOS) and on their attitudes towards science. Using a controlled pre-post research design, we asked participants to complete a Likert-like questionnaire. Also, we conducted post-programme semi-structured interviews with 35 of the participants. Results show that completion of the programme significantly enhanced participants’ NOS understanding and improved their attitudes towards science. Participants expressed a deep level of NOS understanding and explicitly stated that the field visits to experts’ labs had changed their attitude towards science. We believe that our outreach programme can be adapted for teaching other sciences and for societies worldwide, as long as there is access to university laboratories and researchers willing to interact with young citizens and potential future scientists. 相似文献
105.
We investigated emotional intimacy with nature and life, and intellectual interest in life among South Korean pre-service teachers (N = 114) training in biology education, analysing the differences between these two constructs as well as their relationship to environmental behaviour and sensitivity. In addition, differences in the respondents’ experiences of nature, concerns about environmental problems and willingness to perform environmental education were explored. Four groups of pre-service biology teachers, categorised by the two investigated personal variables, showed different responses for the environment-related characteristics and other variables. Our results suggest that biology teachers should have higher emotional and intellectual interest in nature and life, and a balance between emotional intimacy with nature and life, and intellectual interest in life is needed to prepare them. 相似文献
106.
《植物生态学报》2018,42(7):752
为了明确我国枫香树(Liquidambar formosana)种子与果实表型变异程度和变异规律, 采用方差分析、相关分析和回归分析等方法对36个天然种群枫香树的10个种子与果实的表型性状在种群间和种群内表型变异和地理变异模式进行探讨。研究结果表明, 枫香树平均表型分化系数为57.55%, 种群间的变异是其表型变异的主要来源; 种子和果实表型性状的变异丰富, 变异幅度为10.05%-24.31%, 平均变异系数为15.83%; 不同种群间变异差别明显, 安福种群平均变异系数最大(16.73%), 建阳种群平均变异系数最小(11.48%)。枫香树多数种子与果实表型性状在地理变化上是随机的, 地理相近种群在表型上没有显著相关性。地理气候因子中1月平均气温、海拔和纬度对种子与果实性状起主要的影响。种子与果实性状与海拔相关分析表明, 枫香树种子长宽比随海拔的升高而减小, 种子长宽比可以推测种群所在的海拔高度。探讨枫香树种群表型多样性, 可为野生优异种质的收集、多目标品种选育等工作提供依据。 相似文献
107.
Production of moss‐dominated biocrusts to enhance the stability and function of the margins of artificial water bodies
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Ricardo Cruz de Carvalho Patrícia dos Santos Cristina Branquinho 《Restoration Ecology》2018,26(3):419-421
Margins of water reservoirs associated with dams can have high‐frequency tides, promoting soil erosion and nutrient leaching. We propose the use of biocrusts for restoration and ecological engineering purposes, due to their poikilohydric character, to stabilize reservoir margins. We promoted biocrust growth under controlled conditions, testing two types of substrate: native sand and organic substrate. After 2 months, biocrusts grew on organic substrate covering almost all the area, but not on native sand. This fast and easy nature‐based solution for soil stabilization can be used as an environmental engineering tool in highly degraded sites. 相似文献
108.
Elmira Maharramova Irada Huseynova Sandro Kolbaia Michael Gruenstaeudl Thomas Borsch 《分类学与生物多样性》2018,16(1):14-27
We aimed to (i) assess the extant genetic diversity of the riparian relict tree Pterocarya fraxinifolia across its current distribution range in the South Caucasus, including the past refugial areas Colchis and Hyrcan, and (ii) test if a separation of these areas is reflected in its phylogeographic history. Genetic diversity of natural populations was examined using nuclear microsatellite and plastid DNA markers. Spatial genetic structure was evaluated using Bayesian clustering methods and the reconstruction of plastid DNA networks. Divergence times of Colchic and Hyrcanian populations were estimated via divergence dating using a relaxed molecular clock. Allelic richness, private allelic richness, and expected heterozygosity were significantly higher in Hyrcan than in Colchis and the Greater Caucasus, and significant genetic differentiation was revealed between the two groups. Whereas only two plastid haplotypes were detected for the Colchic and Caucasian populations, the Hyrcanian populations displayed 11 different haplotypes. Significant isolation by distance was detected in Hyrcan. The most recent common ancestor of all P. fraxinifolia haplotypes was dated to a time well before a suggested glaciation period in the Caucasus during the late Pliocene (5.98 Ma [11.3–2.48 Ma HPD]). The widespread Colchic haplotype that also occurs along the southern slope of the Greater Caucasus and reaches south-eastern Azerbaijan has appeared more recently (0.24 Ma [1.41–0 Ma HPD]). This diversification pattern of Colchic haplotypes from ancient Hyrcanian haplotypes suggests a colonization of the region from south-east to north-west that predates the last glacial maximum (LGM). Natural populations of P. fraxinifolia show low-to-intermediate levels of genetic diversity and a significant decrease of diversity from Hyrcan to Colchis. However, the genetic differentiation between Colchic-Caucasian and Hyrcanian populations for nuclear markers suggests that independent gene pools existed in both areas at least since the LGM. Particular attention to conservation seems justified for the more diverse Hyrcanian populations. 相似文献
109.
Ruben Girsowicz Oksana Koryachenko Chen Sherman Einav Mayzlish-Gati Tirza Doniger 《Soil & Sediment Contamination》2018,27(3):175-185
The present study evaluated the effect of crude oil contamination on a microbial community in hyper-arid soils. The Evrona Nature Reserve of Israel, situated in the Arava, was exposed twice in the last 40 years to petroleum-hydrocarbon-spill pollution. The first pollution event took place 40 years ago and was never treated, presenting a unique future time-point perspective to the second (2014) contamination event. Soil samples were collected after the second spill, and abiotic properties and bacterial diversity in the sampled soil were analyzed. The results showed that there is a significant decrease over time in the number of observed bacterial species in the contaminated samples, coupled together with bacterial species replacement toward species capable of using source oil as the sole carbon and energy source. The presence of petroleum in soil significantly changed the composition and functional diversity of a microbial community, and the Evrona Nature Reserve is still in the middle of a bioremediation process even 40 years after the crude oil contamination. 相似文献
110.
Sanna Ojalammi 《Anthrozo?s》2018,31(2):233-246
These days zoos often claim that their main objective is the promotion of nature conservation and that they strive to educate their visitors about animals and nature conservation. But how do zoo visitors themselves perceive this emphasis on conservation education? In order to determine how Helsinki Zoo visitors perceive nature conservation during their visit, we undertook a qualitative analysis of 75 structured situational interviews and five autoethnographical visits. Our results show that there was only a limited understanding of nature conservation among the zoo visitors. Their perception follows the typical framing of nature conservation in zoos: conservation projects that embrace captive breeding, in-situ conservation collaboration, and the reintroduction of those species. Moreover, in the Helsinki Zoo case these perceptions may have been influenced by the fact that the zoo did not give concrete advice on how the visitors themselves can contribute to conservation, except in terms of donating money. Framing nature conservation in such ways distances it from visitors’ everyday lives. 相似文献