滹沱河流域湿地植被的数量分类和排序

应用TWINSPAN和DCA相结合的方法,对滹沱河流域湿地植被74个样方进行分类和排序,将湿地植被分为16个群丛。DCA排序第一轴反映土壤含水量梯度,第二轴反映土壤类型的变化。主要优势种的DCA排序图与样方的DCA排序图有很大的相似性,优势种的分布格局在很大程度上决定着植物群丛的分布格局。     

结合多个环境因子的模糊数学排序

模糊数学排序是近年来引入植被分析的一个新方法,它可以结合环境因子,综合生态信息,受到生态学者的喜爱。最早的模糊数学排序用一个环境因子,后来可以将两个或三个环境因子结合在一个排序图上。但当环境因子多于三个时,排序难以完成。这就限制了该方法的实际应用,因为植被研究所得到的环境数据往往是一个庞大的矩阵。本文仅用除趋势对应分析（ＤＣＡ）综合环境因子信息,然后再进行模糊数学排序,这样环境因子的数目理论上讲没有限制,模糊数学排序的功能得以扩展。我们用该方法对英国北威尔士山地草甸１６６个样方４９个种的植被数据和８个环境因子数据进行了分析。结果较好地描述了草甸植被和环境因子之间的关系,生态意义明确．     

锦屏水电站植被数量分类与排序

以锦屏梯级水电站大河湾段植被为研究对象,以河流流向为基础布置样方,将50个样方物种重要值及其环境因子进行TWINSPAN数量分类和DCA排序,结果显示:(1)由TWINSPAN数量分类将植被划分为7种类型,雅致雾水葛(Pouzolzia elegans)灌草群落为该区域的主要群落.(2)以TWINSPAN数量分类为基础的DCA二维排序图将样方分为6个生态类型,DCA 二维排序图横轴从左至右海拔高度逐渐降低;排序纵轴由下至上坡度逐渐升高.(3)以TWINSPAN数量分类在DCA排序图中有明确的分布范围和界限,DCA排序与TWINSPAN数量分类结合使用,能很好反映群落与环境因子间的生态关系.     

汾河河口湿地植被数量分类与排序

在群落样方调查基础上,采用双向指示种分析（TWINSPAN）和除趋势对应分析（DCA）对汾河入河口湿地植被群落进行了数量分类和排序。TWINSPAN将78个样方分为18个群丛,并论述了各群丛的群落学特征。DCA排序结果反映了植物群落类型与环境梯度水分之间的关系,表明影响群丛分布格局的主导生态因子为土壤水分。     

中条山中段植物群落数量分类与排序研究

在群落样方调查基础上,采用双向指示种分析法（TWINSPAN）和除趋势对应分析（DCA）对中条山中段植物群落进行了数量分类和排序。TWINSPAN将53个样方分为14组,根据植被分类的原则划分为14个群丛,论述了各群丛的群落学特征。53个样方的DCA排序结果反映了植物群落类型与环境梯度之间的关系,表明影响群丛分布格局的主导生态因子为海拔高度、水分和热量。DCA排序将65个种分为5个种组,各种组在排序轴上的位置反映了种组成员的生态适应性及其在群落中的重要性和更新生态位。     

长江故道湿地植被的数量分类与排序

采用双向指示种分析法（TWINSPAN）和除趋势对应分析法（DCA）对长江故道湿地植被做分类和排序研究。TWINSPAN分类将湿地植被234个样方分为28个群丛,论述了各群丛的群落学特征。DCA排序结果反映了植物群落类型与环境梯度之间的关系,表明影响群丛分布格局的主导生态因子为生境的水分条件。TWINSPAN数量分类在DCA排序图中有较为明确的分布范围和界限,两者的结合使用,能很好地反映群落与环境因子间的生态关系。     

子午岭地区植被恢复演替过程与环境因子的分类与排序

在野外实地调查基础上,采用双向指示种分析法(TWINSPAN)和除趋势对应分析(DCA)对子午岭地区植物群落进行了数量分类和排序。结果显示:(1)TWINSPAN将50个样方划分为14个群系;DCA排序结果与TWINSPAN分类结果相互印证。(2)第一排序轴上显示出植被由草地、灌丛到森林的恢复演替系列,在此演替过程中土壤中的速效磷逐渐减少,全氮和有机质逐渐增加;第二排序轴反映环境因子的梯度不明显,但植被的演替过程会受到海拔、坡度的影响。研究表明,随着植被恢复演替的进展群落结构在变化,乔木层的重要值增加,所在群落中的全氮、速效磷、有机质等亦呈现规律性变化。     

丹江口库区滩涂与入库支流植被与土壤种子库: 水传播潜力探讨

为了探索库区滩涂与入库支流土壤种子库与植被的关系, 以及物种通过水传播扩散的潜力, 对丹江口库区内4条支流及其入库滩涂的地表植被和土壤种子库进行了调查。结果显示, 支流地表植被和种子库的物种多样性高于库区滩涂, 汉江库区滩涂和支流的地表植被与种子库均有较高的物种相似性。DCA排序和TWINSPAN聚类可以明显地将支流的植被和种子库样方与滩涂的植被和种子库样方分到不同的样方组, 结合物种排序图可以清楚地发现, 流入汉江库区支流的植被和种子库的物种组成与滩涂的植被和种子库的物种组成有密切联系。汉江库区滩涂0-15 cm的土层内都有种子萌发, 而丹江库区种子库中只有狗牙根(Cynodon dactylon)一种植物, 且仅存在于0-5 cm土层。研究结果表明, 繁殖体通过支流向滩涂的水传播作用对植被建立有积极贡献。     

草海国家级自然保护区水生植物群落的数量分类与排序分析

在群落样方调查的基础之上,采用双向指示种分析法（TW INSPAN）和除趋势对应分析（DCA）对草海国家级自然保护区水生植物群落进行分类和排序。TW INSPAN将50个样方分为17组,根据植被分类的原则划分为17个群丛,论述了各个群丛的群落学特征。50个样方的DCA排序结果反映了植物群落类型与环境梯度之间的关系,表明影响群落分布格局的主导生态因子为水分条件,第一轴反映了各个群落类型所在的水分条件梯度。排序结果与分类结果较吻合,反映出植物群落类型和物种分布随环境因子梯度变化的趋势。     

广东亚热带部分森林群落排序分析

本文应用极点排序、主坐标分析和位置向量排序等3种排序技术,对广东亚热带11个森林群落进行排序。探索了这3种方法在广东亚热带植被分析上的应用效果;经过对排序结果的分析,说明了11个森林群落的相互关系,在一定程度上揭示了植被变化的生态学原因。     

东南亚沿海与内陆植被对洪水事件响应的稳定性差异

为探讨东南亚沿海与内陆地区植被对洪水事件的响应差异,基于东南亚2000-2018年MODIS卫星遥感数据和洪水数据,通过比较东南亚洪水发生区域,共确定自2000年来影响最大、破坏程度相近的2个沿海洪水事件、2个内陆洪水事件以及1个沿海内陆洪水事件。以Google Earth Engine为数据处理平台,利用Sen+Mann-Kendall趋势法分析了2000-2018年研究区NDVI变化,发现5个研究区19年间NDVI均呈现出上升趋势,平均增速为0.013/10a,沿海与内陆植被在时空演变格局上无明显差异;基于灾害植被破坏指数的分析发现,内陆与沿海植被在洪水影响下的植被破坏指数分别为0.29与-0.25,植被破坏面积分别占比为14.29%与18.11%,内陆植被破坏程度小于沿海地区。同时,排除人类干扰强烈的耕地与人造地表,沿海研究区植被生态系统对洪水事件的抵抗力指数为88.15,明显强于内陆地区的28.89。草地表现出最强的抵抗力,其次为林地;而在植被恢复力方面,表现出相反的趋势。人类活动影响降低了内陆地区洪水灾害对植被的破坏。研究东南亚沿海与内陆植被对单次洪水事件的差异响应,排除内陆与沿海地区洪水事件累计影响,能够为东南亚沿海与内陆植被抵抗洪水灾害提出有针对性的建议。     

Vegetation bioshields for tsunami mitigation: review of effectiveness, limitations, construction, and sustainable management

Coastal vegetation has been widely recognized as a natural method to reduce the energy of tsunami waves. However, a vegetation barrier cannot completely stop a tsunami, and its effectiveness depends on the magnitude of the tsunami as well as the structure of the vegetation. For coastal rehabilitation, optimal planning of natural coastal systems, and their maintenance, we need to quantitatively elucidate the capacity of vegetation to reduce the energy of tsunami waves. The limitations of coastal forests in relation to the magnitude of a tsunami and the maintenance of forests as natural disaster buffer zones have to be understood correctly for effective coastal vegetation planning. Demerits of coastal forests have also been revealed: for example, an open gap in a forest (i.e., a road, river, difference in elevation, etc.) can channel and amplify a strong current by forcing it into the gap. Floating debris from broken trees also can damage surrounding buildings and hurt people. However, many studies have revealed that these demerits can be overcome with proper planning and management of mangroves and coastal forests, and that coastal vegetation has a significant potential to mitigate damage in constructed areas and save human lives by acting as buffer zones during extreme natural events. However, mangrove forests have been damaged by anthropogenic activities (i.e., tourism, shrimp farming, and industrial development), making coastal areas increasingly vulnerable to tsunamis and other natural disasters. The effectiveness of vegetation also changes with the age and structure of the forest. This highlights the fact that proper planning and management of vegetation are required to maintain the tsunami buffering function of coastal forests. Although many government and nongovernmental organizations have implemented coastal vegetation projects, many of them have been unsuccessful due to a lack of proper maintenance. A pilot project in Matara City, Sri Lanka, revealed that participation and support from local authorities and communities is essential to make the planting projects successful. An integrated coastal vegetation management system that includes utilization of the materials produced by the forest and a community participation and awareness program are proposed to achieve a sustainable and long-lasting vegetation bioshield.     

江苏海岸带植被的特征、分布及利用

 江苏海岸带的自然植被基本上为滨海盐土植被,包括陆生、沼生及水生三类植被。另外,海边沙滩有很少量的沙生植被。滨海盐土植被的发生和形成过程,与滨海盐土的成土发育过程密切相关,两者相辅相成。本文论述了海岸带植被的环境条件及其相互关系;详细分析植被的区系组成特点,并作了生活型谱,简要概述群落类型、分布及其演替规律;最后,讨论了盐土植被的利用问题。     

Coastal vegetation planting projects for tsunami disaster mitigation: effectiveness evaluation of new establishments

Coastal vegetation acts as a natural barrier against extreme natural and anthropogenic activities, protecting infrastructure and human lives. Establishment of hard infrastructure for tsunami protection is not feasible in developing countries due to its cost-intensive nature. Coastal vegetation can therefore be a feasible alternative for tsunami and general coastal protection in developing countries. This study investigates the effectiveness of current coastal vegetation projects and reports a pilot-scale vegetation project, which provides insights into the management and sustainability of such projects. Thirty-seven establishments of coastal vegetation for tsunami protection were identified for the study from Hambantota to Colombo along the southern coast in Sri Lanka. Evaluation was carried out to assess whether the coastal vegetation establishments fulfilled the planning objectives, such as vegetation alignment to tsunami direction, tree density and tree species, and whether monoculture or mixed species are grown. The study also assessed continuous maintenance and awareness about coastal vegetation, community participation and long-term institutional support from government, nongovernment groups, academic institutions, and other institutions within an integrated framework. Approximately 50% of the sites were found to be effective in terms of fulfilling the above requirements and had reasonable protection against future tsunami-type events. Continuous maintenance is ensured only for 35% of sites with community participation. The survey also revealed the importance of adopting scientific and nonscientific methods of vegetation establishment and selecting appropriate species and structure of vegetation strips for tsunami protection. It is expected that this will lead to the development of coastal vegetation guidelines for local authorities.     

Mangrove resilience to climate extreme events in a Colombian Caribbean Island

Extreme events affect coastal vegetation in several ways. They cause massive tree defoliations and mortality that carry changes in vegetation structure and floristic composition. In order to assess these changes in dry tropical forests, coastal vegetation and mangroves in El Rosario archipelago, and their relationship with extreme events between 2002 and 2014, Quickbird and Worldview Satellite images with uneven periodicity were analyzed and the Normalized Difference Vegetation Index (NDVI) was calculated for these vegetation covers. Time series analysis was performed to oceanographic and climate variables such as maximum wind velocity, daily precipitation, significant wave height, peak wave period and maximum and minimum air temperatures. The first two axes of a redundancy analysis explained 65% of data variance (p value ≤ 0.05) and showed that the decrease of the NDVI and extension of beach vegetation were related to increases in wind frequency and intensity. However, mangrove vegetation was benefited by the increase in the frequency of short drought events, although their NDVI decreased when these drought events became longer. Drought events were related to El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) anomalies that had the strongest effects on coastal vegetation and dry forest, as shown by the minimum values of NDVI recorded in 2010. Mangrove vegetation was more resilient to such droughts and strong winds than coastal and dry forest vegetation due to their location along bays or surrounding internal lagoons.     

江苏省海滩植被演替的研究

江苏省海滩植被可分为滨海盐土植被、盐沼植被及海滩沙生植被三个基本类型。本文论述了这些植被类型的演替规律。滨海盐土植被与盐沼植被的演替,外因于土壤盐分含量递减与有机质含量的递增;海滩沙生植被的演替,外因于土壤沙颗粒大小及其相应的土壤含水量的变化,所以海滩植被演替为外因动态演替。     

How widespread is woody plant encroachment in temperate Australia? Changes in woody vegetation cover in lowland woodland and coastal ecosystems in Victoria from 1989 to 2005

Aim Encroachment or densification by woody plants affects natural ecosystems around the world. Many studies have reported encroachment in temperate Australia, particularly in coastal ecosystems and grassy woodlands. However, the degree to which published studies reflect broad-scale changes is unknown because most studies intentionally sampled areas with conspicuous densification. We aimed to estimate changes in woody vegetation cover within lowland grassy woodland and coastal ecosystems in Victoria from 1989 to 2005 to determine whether published reports of recent encroachment are representative of broad-scale ecosystem changes. Location All lowland grassy woodland and coastal ecosystems (c. 6.11 × 10⁵ ha) in Victoria, Australia. Four major ecosystems were analysed: Plains woodlands, Herb-rich woodlands, Riverine woodlands and Coastal vegetation. Methods Changes in woody vegetation cover from 1989 to 2005 were assessed based on state-wide vegetation maps and Landsat analyses of woody vegetation cover conducted by the Australian Greenhouse Office’s National Carbon Accounting System. The results show changes in woody cover within mapped patches of native vegetation, rather than changes in the extent of woody vegetation resulting from clearing and revegetation. Results When pooled across all ecosystems, woody vegetation increased by 18,730 ha from 1989 to 2005. Woody cover within Riverine woodlands and within Plains woodlands each increased by >7000 ha. At the patch scale, the mean percentage cover of woody vegetation in each polygon increased by >5% in all four ecosystems: Riverine woodlands (+9.2% on average), Herb-rich woodlands (+7.6%), Plains woodlands (+6.7%) and Coastal vegetation (+5.9%). Regression models relating degree of encroachment to geographic and climatic variables were extremely weak (r² ≤ 0.026), indicating that most variation occurred at local scales rather than across broad geographic gradients. Main conclusions At the scale of observation, woody vegetation cover increased in all lowland woodland and coastal ecosystems over the 16-year period. Thus, published examples of encroachment in selected coastal and woodland patches do appear to reflect widespread increases in woody vegetation cover in these ecosystems. This densification appears to be associated with changes in land management rather than with post-fire vegetation recovery and is likely to be ongoing and long-lasting, with substantial implications for biodiversity conservation and ecosystem services.     

旅游开发对上海滨海湿地植被的影响

选择上海滨海地区湿地植被为研究对象,采用典型样地与标准样方相结合的调查方法,从属种和生物多样性角度分析不同旅游开发方式对滨海湿地植被的影响。结果如下:(1)根据滨海旅游区水域开放程度,可将开发类型分为封闭式、半封闭式以及开放式3种,不同旅游开发类型对滨海湿地植被影响程度不同;(2)研究区封闭式相比较半封闭式和开放式旅游开发类型,可以提高区域内物种数量,物种数量增加分别增多33和45种,但本地物种所占比例下降,从70%分别下降到26.26%和21.73%;(3)旅游开发封闭性越强,生物多样性越高,封闭式、半封闭式以及开放式旅游开发区域生物多样性Shanno-Winner指数分别为0.92、1.07和1.51,区域内均匀度指数随封闭性增加而有所降低,Shanno-Winner均匀度指数从最高0.71降到最低0.52;(4)滨海湿地植被对不同类型旅游开发响应不同,封闭度越高,区域内植被响应度越强,封闭式、半封闭式以及开放式植被响应指数分别为2.2、2.0和1.8。     

Habitat Use of American Alligators in East Texas

ABSTRACT The American alligator (Alligator mississippiensis) has made a remarkable recovery throughout its range during the last half-century. In Texas, USA, current inland alligator population and harvest management strategies rely on generalized and often site-specific habitat and population data generated from coastal populations, because it is assumed that habitat and demographic similarities exist between inland and coastal populations. These assumptions have not been verified, however, and no studies have specifically examined inland alligator habitat use in Texas. We quantified alligator habitat use in East Texas during 2003–2004 to address this information gap and to facilitate development of regionally specific management strategies. Although habitat was variable among study areas, alligators used habitats with >50% open water, substantial floating vegetation, and emergent vegetation close (<12 m) to dry ground and cover. Adults used habitats further from dry ground and cover, in open water (75–85%), with less floating vegetation (6–22%) than did subadults, which used habitats that were closer to dry ground and cover, with less open water (52–68%), and more floating vegetation (8–40%). Although habitat use mirrored coastal patterns, we estimated alligator densities to be 3–5 times lower than reported in coastal Texas, likely a result of inland habitat deviations from optimal coastal alligator habitat, particularly in the preponderance of open water and floating vegetation. Our findings that 1) inland habitats varied among sites and did not exactly match assumed optimal coastal habitats, 2) alligators used these inland habitats slightly differently than coastal areas, and 3) inland alligator densities were lower than coastal populations, all highlight the need for regionally specific management approaches. Because alligator populations are influenced by habitat quality and availability, any deviations from assumed optimal habitat may magnify harvest impacts upon inland populations.     

The Value of Wetlands in Protecting Southeast Louisiana from Hurricane Storm Surges

The Indian Ocean tsunami in 2004 and Hurricanes Katrina and Rita in 2005 have spurred global interest in the role of coastal wetlands and vegetation in reducing storm surge and flood damages. Evidence that coastal wetlands reduce storm surge and attenuate waves is often cited in support of restoring Gulf Coast wetlands to protect coastal communities and property from hurricane damage. Yet interdisciplinary studies combining hydrodynamic and economic analysis to explore this relationship for temperate marshes in the Gulf are lacking. By combining hydrodynamic analysis of simulated hurricane storm surges and economic valuation of expected property damages, we show that the presence of coastal marshes and their vegetation has a demonstrable effect on reducing storm surge levels, thus generating significant values in terms of protecting property in southeast Louisiana. Simulations for four storms along a sea to land transect show that surge levels decline with wetland continuity and vegetation roughness. Regressions confirm that wetland continuity and vegetation along the transect are effective in reducing storm surge levels. A 0.1 increase in wetland continuity per meter reduces property damages for the average affected area analyzed in southeast Louisiana, which includes New Orleans, by $99-$133, and a 0.001 increase in vegetation roughness decreases damages by $24-$43. These reduced damages are equivalent to saving 3 to 5 and 1 to 2 properties per storm for the average area, respectively.