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1.
Integrating cellular automata,artificial neural network,and fuzzy set theory to simulate threatened orchards: application to Maragheh,Iran 总被引：1，自引：0，他引：1
Urbanization processes challenge the growth of orchards in many cities in Iran. In Maragheh, orchards are crucial ecological, economical, and tourist sources. To explore orchards threatened by urban expansion, this study first aims to develop a new model by coupling cellular automata (CA) and artificial neural network with fuzzy set theory (CA–ANN–Fuzzy). While fuzzy set theory captures the uncertainty associated with transition rules, the ANN considers spatial and temporal nonlinearities of the driving forces underlying the urban growth processes. Second, the CA–ANN–Fuzzy model is compared with two existing approaches, namely a basic CA and a CA coupled with an ANN (CA–ANN). Third, we quantify the amount of orchard loss during the last three decades as well as for the upcoming years up to 2025. Results show that CA–ANN–Fuzzy with 83% kappa coefficient performs significantly better than conventional CA (with 51% kappa coefficient) and CA–ANN (with 79% kappa coefficient) models in simulating orchard loss. The historical data shows a considerable loss of 26% during the last three decades, while the CA–ANN–Fuzzy simulation reveals a considerable future loss of 7% of Maragheh’s orchards in 2025 due to urbanization. These areas require special attention and must be protected by the local government and decision-makers. 相似文献
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A re-evaluation of the threat status of New Zealand's marine invertebrates was undertaken in 2009, following earlier review of New Zealand's Threat Classification System and subsequent refinement of the national criteria for classifying threat of extinction to New Zealand's flora and fauna. Sufficient information was available to enable 295 marine invertebrate taxa to be fully evaluated and assigned to a national threat category. The 10 taxa at most risk of extinction (‘nationally critical’) were the giant seep clam Calyptogena sp., the primitive acorn barnacle Chionelasmus crosnieri, O'Shea's vent barnacle Volcanolepas osheai, the stalked barnacle Ibla idiotica, the four-blotched umbrella octopus Cirroctopus hochbergi, the roughy umbrella octopus Opisthoteuthis chathamensis, the giant squid Idioteuthis cordiformis, the large-egged polychaete Boccardiella magniovata and two gravel maggots, Smeagol climoi and Smeagol manneringi. The key threatening processes identified for marine invertebrates were fishing and land-use associated impacts such as sedimentation. We identified no taxa that had improved in threat status as a result of past or ongoing conservation management action, nor any taxa that had worsened in threat status because of known changes in their distribution, abundance or rate of population decline. We evaluated a small fraction of New Zealand's marine invertebrate fauna for their threat status. Many taxa remain ‘data deficient’ or unlisted. In addition to the most threatened taxa, we recommend these taxa and their habitats as priorities for further survey and monitoring. 相似文献
3.
The threat status of 74 freshwater and estuarine fish present in New Zealand was determined. Fifty-one native taxa were ranked of which 67% were considered Threatened or At Risk. A single species was classified as Extinct, the New Zealand grayling, which has not been observed since the 1920s. Four taxa were classified in the highest threat category, Nationally Critical, and a further 10 taxa as Threatened (Nationally Endangered or Nationally Vulnerable). Twenty taxa were ranked in the At Risk group with the majority ranked as Declining. Endemic galaxiids (Galaxiidae) dominated the Threatened and At Risk taxa. The majority (68%) belonged to the Galaxias genus, comprising 81% of recognised taxa in this genus and all five species in the genus Neochanna were also ranked as Threatened or At Risk. In addition to 51 native taxa, a further three fish species were considered colonists and 20 introduced species were classified as naturalised, although two of these are considered rare. The majority of the Threatened species occur in the Canterbury and Otago regions where a suite of rare non-migratory galaxiids exist. Threat mechanisms that were identified as causal in the decline of freshwater fish species were the impact of introduced fish species, declining water quality, effects of water abstraction, loss of habitat via land-use change and land-use activities, and river modifications. 相似文献
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Pablo E. Meretta Nahuel E. Farias Maximiliano Cledón Carlos Renato Rezende Ventura 《Marine Ecology》2016,37(6):1423-1433
The sea star Asterina stellifera has declined during the last decade and is currently abundant only in the southern limit of its former range. We surveyed this population over 5 years to model individual growth and explore the relationship of changes in local abundance with variation in environmental factors and the reproductive status of individuals. Our results show that A. stellifera is a species with slow growth and a relatively long lifespan. Contrary to expectations for temperate species, growth rates were fairly constant through the year and therefore models including seasonal oscillations were inappropriate. The abundance of this species increased significantly from early spring to early summer, likely due to augmented activity and small‐scale aggregation during the reproductive season that affected our estimates of abundance. No significant recruitment occurred during the 5 years studied. The lack of recruitment during long periods and the slow individual growth rates make A. stellifera particularly vulnerable to local extinction. This study was performed prior to the arrival in the study area of the invasive kelp Undaria pinnatifida and side‐gilled sea slug Pleurobranchaea maculata, species that threaten the community structure where A. stellifera lives. Therefore, the information reported here will be essential to assessing the impacts of these exotic species on this sea star population. 相似文献
6.
This paper highlights the quantitative estimates of plant species diversity and ecosystems of the Rohtang Pass,which is one of the most preferred visiting spots by tourists in Himachal Pradesh （H.P.）,India. In spite of high pressure of anthropogenic activities,the Rohtang Pass still harbours a variety of flowering plants with economic value,including various medicinal herbs. In order to observe species diversity in different landscape elements （LSEs）,ground surveys were conducted in nine unique LSEs within the elevation range between 3624 m and 4332 m. Plant community structure in each LSE was studied using stratified random sampling where a total 56 quadrats of 1 m^2 in size for herbs and 7 quadrats of 25 m^2 for shrubs were made. Of the total 50 plant species belonging to 15 families recorded in different random quadrats,24 species were found of medicinal value. Maximum species richness （18） and value of Shannon diversity （H＇=2.2648） were observed on northeast-facing slope in Picrorhiza kurrooa dominated LSE in moist area,followed by Rheum emodi LSE （species richness = 17 and H＇ = 2.4141） distributed on south-facing slope. Maximum values of species richness and Shannon diversity in Rheum emodi LSE were observed between 8 ～ 12 and 1.4797 ～ 2.1911,respectively. Rhododendron anthopogon dominated LSE on northwest-facing slope was found least diverse in terms of species richness where the Simpson index of dominance （D） was 0.4205. The species were equal in abundance in P. kurrooa LSE on east-facing slope and Pleurospermum candollii LSE on north-facing slope,showing the maximum similarity in terms of species distribution between the two LSEs. Low turnover of species across common LSEs gives an idea regarding their limited distribution. Five species of threatened category according to the IUCN criteria were observed in seven LSEs. The largest population of threatened medicinal plants was recorded on northeast and northwest-facing slopes where population density of Bergenia stracheyi （ 相似文献
7.
A spawning site of Galaxias brevipinnis Giinther was located in a New Zealand stream for the first time. It was at the edge of a riffle and only partially submerged. The habitat used for spawning matched that described for G. brevipinnis in Australia. Spawning was estimated to have occurred between late April and early May and the eggs hatched in late May. The species of fish spawning was identified by rearing the eggs through to identifiable juveniles and by DNA sequencing of one individual. 相似文献
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Richard F. Maloney 《新西兰海洋与淡水研究杂志》2013,47(4):505-515
Abundance and species composition of aquatic benthic macroinvertebrates were compared between an area sprayed with the herbicide Grazon (active ingredient triclopyr), and an upstream control site (no triclopyr). Five Surber samples were collected from each of three riffles in control and treatment sites on eight occasions over a 1‐month period. Aquatic invertebrate species composition was similar in treatment and control sites, and did not change over time. The five taxa that made up 91–95% of all invertebrates by abundance did not vary significantly in treatment compared to control riffles. Abundance of three of the 15 most common taxa (>10 individuals per riffle) differed significantly between treatment and control sites over time. However, none of these fluctuations correspond to the presence of known concentrations of triclopyr in water samples, and it is unlikely that the declines resulted from triclopyr. These results are discussed with reference to known lethal concentrations of triclopyr for some invertebrates, and to the effect of floods on invertebrate populations. 相似文献
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MATTHEW W Pearson 《资源与生态学报(英文版)》2020,11(2):171-181
识别某一物种受威胁的原因有助于制定最好的物种恢复计划,基于一般概念的恢复计划可能并不适用于某个特定区域或者某个特定物种的恢复。城市扩张和土地集约化利用就被认为是威胁区域生物多样性的主要人为因素,因此厘清这个威胁过程与受威胁物种的相互作用可以指导物种的恢复工作。在南澳大利亚州,异木麻黄(Allocasuarina robusta)的变化过程为了解该地区过去的土地利用变化及其对生物多样性的影响提供了很好的机会。本文聚焦于土地利用变化与植物标本数据之间的关系,以了解常见物种和受威胁物种之间的关系。随着物种的进化和对环境的适应,所采取的生物多样性恢复保护措施(包括用于识别未来行动的方法)需要与不断变化的环境相适应。同时,不断变化的环境也会对生物多样性产生影响,并进而给土地管理者带来了许多新的问题。传统的物种恢复技术可以减缓威胁过程,例如补充种植就是有充分依据的做法,但是这种做法的意义可能还有待于进一步验证;自然再生对于种群长期生存至关重要,但是在生命力旺盛的异木麻黄中却并没有发生(自然再生情况)。调查异木麻黄的变化情况旨在探索植物标本数据与土地历史利用之间的关系,以指导未来的物种恢复工作。 相似文献
10.
Bruce L. Godfriaux 《新西兰海洋与淡水研究杂志》2013,47(3):473-504
Feeding was examined in 772 snapper, Chrysophrys auratus (Bloch and Schneider), from the western Bay of Plenty, New Zealand. Occurrence, points (bulk), and numbers methods of food analysis were used in the study. Diet was extremely varied, and, by all methods of food analysis, crustaceans, polychaetes, echinoderms, molluscs, and teleosts formed the main snapper food groups, with crustaceans being the most important. Size of snapper, depth, sampling area, and time of day affected the occurrence, volume, and numbers of food items, while sex did not. Seasonal feeding patterns on most species/categories of food varied locally within each sampling area, and there were no uniform seasonal feeding patterns for any food/category in the four sampling areas examined. 相似文献