Patterns Of Plant Succession Research Articles

基于地学信息图谱的重庆岩溶石漠化植被恢复演替研究

PDF HTML阅读 XML下载 导出引用 引用提醒 基于地学信息图谱的重庆岩溶石漠化植被恢复演替研究 DOI: 10.5846/stxb201411122233 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（41201436） Quantifying vegetation restoration in a karst rocky desertification area in Chongqing based on Geo-informatic Tupu Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:重庆岩溶石漠化区的植被恢复演替动态变化研究对于该地区的石漠化治理和生态恢复具有十分重要的指导意义。而多时相的遥感数据和地学图谱分析法为植被恢复的研究提供了一种动态性和综合性的研究方法。以重庆市中梁山的典型植被恢复区为例，在基于1996、2001、2007和2013年4期遥感影像解译分类的基础上，采用“空间代替时间”的生态学植被演替研究方法，建立重庆市中梁山区退耕还林前后的植被恢复演替图谱，并结合地学图谱的相关分析方法，得到该区的植被恢复演替动态格局演变规律，体现了空间信息科学技术、生态学方法和地学信息图谱分析法在植被恢复演替研究中的有效结合。结果表明：（1）运用BP神经网络和BP算法进行分类，分类精度达到87.42%，比传统监督分类提高了5.57%。（2）自2002年全国范围内的“退耕还林（草）”工程全面启动后，该区域植被恢复演变特征明显，耕地面积明显减少而植被面积明显增加。（3）从2001-2013年，植被演替在该时期内依然存在着进展演替和逆向演替两个方向。虽然逆向演替比例仅占到18.63%，但它却使该区的演替研究变得复杂。（4）质心反映了各植被类型在恢复演替过程中的聚散与迁移，1996-2013年，马尾松群落和落叶阔叶林群落的质心变化较小，其他植被群落的质心都有很明显的变化。 Abstract:Karst rocky desertification (KRD) has become one of the most important ecological and environmental problems in China, and the control of rocky desertification has been listed as a goal of both social development and national environmental managment projects. However, patterns of plant succession in the process of KRD reversal activities are still unclear. Understanding plant dynamics is important for both the theory and practice for successful ecosystem restoration. We used multi-temporal, remotely sensed images and a Geo-informatic Tupu method to investigate the succession patterns of vegetation restoration at Zhongliang Mountain in Chongqing, Southwest China. This region is a typical KRD vegetation restoration area, with a rich diversity of regional vegetation types. In this study, remotely sensed images for four different time periods (1996, 2001, 2007, and 2013), representing four different stages in vegetation succession, were selected and analyzed using back-propagation (BP) neural network models for interpretation and classification. This resulted in maps of vegetation restoration based spatial structure rather than time series images, captured before and after the Grain for Green project, and thus, established information about principles for vegetation restoration succession in the region. Thereafter, the maps were analyzed using Geo-informatic Tupu to identify the dynamic patterns of vegetation restoration succession in the region. Our results indicate the following. (1) The BP neural network model provides an efficient vegetation classification method in the Zhongliang Mountain region. The overall accuracy of the (BP) neural network classification was 87.42%, which was 5.57% higher than traditional supervised methods. (2) Since 2002, a series of ecological restoration projects, including the Grain for Green project (the conversion of cropland into forest or pasture), have been implemented in this region, leading to a reduction in the area of farmland and an increase in the area of natural vegetation. The positive trends observed in the study site are interpreted as being the result of human-induced restoration. Comparing vegetation change in the different sub-regions of the study site, the most significant vegetation changes occurred on farmland that was located in the valley and foothills of Zhongliang Mountain. In contrast, regions with moderate change included the acid and the alkaline soil areas at higher elevations of Zhongliang Mountain. Here, the Masson pine community and kashiwagi community, respectively, are dominant. These communities have effective energy and nutrient conversion capabilities and form stable ecosystems that moderate changes in the natural succession of vegetation. (3) The Zhongliang Mountain communities were classified into two different stages, forward succession and reverse succession, during the period 2001-2013. In 18.63% of the region, reverse succession occurred, resulting in complex patterns of vegetation change. (4) Analysis of changes in vegetation structure was performed based on the centroid shifting method. From 1996 to 2013, the centroid of the Masson pine community and deciduous broad-leaved forest communities changed only slightly, while changes observed in other vegetation types were more marked. The Tupu method quantified the spatial pattern, distribution, and change processes of vegetation in different successional stages. It appears that the Tupu method can identify the state of each image element in each sampling time and achieve an integration of Space-Property-Process, providing a strong scientific basis and technical means for vegetation restoration in karst rocky desertification regions. 参考文献 相似文献 引证文献

Pattern of Plant Succession from Eutrophic Lake to Ombrotrophic Bog in NE Poland Over the Last 9400 Years Based on High-Resolution Macrofossil Analysis

This article describes vegetation history and plant succession in Lakes Kojle and Perty (NE Poland) and in the surrounding peatlands during the last 9400 cal. BP. Vegetation changes were reconstructed based on high-resolution plant macrofossil analysis of three sediment cores. The changes in vegetation and the course of succession found in the studied lakes and peatlands resulted largely from regional climate changes. Climate cooling that took place approximately 5000 cal. BP resulted in an increase in Picea abies cover in the vicinity of the lakes, as well as in the appearance of Nuphar pumila and Potamogeton alpinus in the lakes. A further increase in Picea abies approximately 3500 cal. BP coincided with the development of an ombrotrophic bog at one site. During the period under study, the aquatic plant species that persisted for the longest time at one site were Najas marina and Nymphaea alba, and the shortest-term residents were Potamogeton spp.

Species diversity of the Okavango Delta, Botswana

In the Okavango Delta (about 28,000 km2) the number of identified species is 1,300 for plants, 71 for fish, 33 for amphibians, 64 for reptiles, 444 for birds, and 122 for mammals. The local occurrence of different species of these taxonomic groups in the Okavango Delta is mainly due to a hydrological gradient from permanent streams and swamps to seasonal floodplains, riparian woodlands, and dry woodlands. This level of species diversity is normal for the southern African region, and all analyzed aquatic groups are composed of ubiquitous species with an additional significant proportion of species originating from northern, more tropical systems. Cyclical variations in climate over thousands of years have created a huge wetland complex in the upper Zambezi and Okavango Rivers during wet phases. This wetland complex has fragmented into the Okavango Delta and other large wetlands in Zambia during dry phases. There are no endemic species in the Okavango Delta while the South-central African wetland complex is a centre of endemism. Species diversity of the Okavango Delta is a consequence of this unique environment, with dynamic shifts in flooding patterns that in turn force constant changes in patterns of plant succession and dependent animals. Temporal variations in flooding also cause accumulation and sudden mobilization of nutrients which are readily used by well adapted plant species. As a consequence, locally high biological productivity occurs, which in turn results in high numbers of grazing mammals.

Altered Fire Regimes Affect Landscape Patterns of Plant Succession in the Foothills and Mountains of Southern California

In the southern California foothills and mountains, pronounced and complex topographic gradients support fire regimes that vary over short distances. We used LANDIS, a spatially explicit landscape model of disturbance and plant succession, to examine the resilience of dominant plant species, representing different disturbance response strategies, to the effect of varying fire rotation intervals (FRI). The simulated fire regimes represented natural, current and very long FRIs for the foothill shrublands less than 1,400 m (90, 30 and 150 years) and montane forest greater than 1400 m (30, 150, 500 years). The 30-year FRI allowed obligate resprouting shrubs to dominate over obligate seeders, whereas the 90-year FRI resulted in a stable spatial distribution of both of these shrub functional types. This is consistent with the literature that suggests that shifts in shrubland composition are most likely to result from human-caused increases in fire frequency at the low-elevation urban-wildland interface. An ecotone conifer, Pinus coulteri, showed dramatic shifts in distribution under different FRIs, and retreated to the portion of the landscape representing its temporal regeneration niche. Both low and high frequency fire maintained the fire tolerant dominant pine (P. jeffreyi) in the montane zone. This contradicts the literature that suggests that a high frequency ground fire regime is required for the persistence of a pine-dominated forest, but is consistent with studies showing that conifer forests in the western U.S. have experienced, and are resilient to, a broad range of natural FRIs that include low frequency, high intensity crown fires.

Effects of a Specialist Herbivore (Altica Subplicata) on Salix Cordata and Sand Dune Succession

Although effects of insect herbivory on host plant growth and reproduction are well documented, few studies have examined how decreases in host plant fitness might influence community—level patterns, such as plant succession. The purpose of this study was to examine how a specialist flea beetle, Altica subplicata, influences (1) the growth and survivorship of its host plant, sand—dune willow (Salix cordata), and consequently, (2) patterns of plant succession on sand dunes. Growth and mortality of S. cordata were compared over a 3—yr period in experimental plots in which host plants were either protected from beetle feeding (with mesh cages) or exposed to beetle feeding (without cages). The changes in the abundance and biomass of other plant species in these experimental plots were also monitored for the 3—yr period. Growth rates of host plants were significantly influenced by the herbivore exclusion treatment. Plants protected from beetle feeding added 2.2 times as much height and 2.0 times as much diameter as did plants exposed to beetle feeding. Differences between growth rates of plants with and without beetles were greater on the west dune, which had significantly greater amounts of beetle damage, than on the east dune. Furthermore, within plots exposed to beetle feeding, areas with greater amounts of beetle damage had significantly lower height and diameter growth rates than did areas with lesser amounts of beetle damage. A separate experiment showed that mesh cages per se did not influence height growth, diameter growth, or number of shoots added over a 2—yr period. Plant mortality was also strongly affected by the herbivore exclusion treatment. Eighty—four percent of the plants that died over the 3—yr period of the study were in plots with beetles present. Mortality was 3x and 6x higher for plants with beetles than for plants without beetles on the east and west dune, respectively. On the west dune, which had higher beetle damage and plant mortality, the amount of beetle damage incurred by plants explained 88% of the variation in plant mortality. Herbivory on S. cordata also had significant, indirect effects on the changes in abundance of neighboring, non—host plants. For both monocot and dicot herbs, there were greater increases in numbers of plants in plots with beetle feeding than in plots with beetles absent, but only on the west dune with its greater beetle damage. Numbers of herbaceous monocots and herbaceous dicots increased 2.5 times and 1.5 times more, respectively, in plots with beetles than in plots without beetles. The changes in abundance of other Salix plants displayed the same trends, but differences were not statistically significant. In contrast, other woody plants showed significantly greater decreases in abundance in plots with beetles than in plots without beetles on the west dune. Individual plant species displayed both positive and negative changes in abundance in response to exclusion of herbivores from S. cordata. Biomass of two common herbaceous monocots (Juncus spp.) increased more in plots with beetles present, but for the most common herbaceous dicots (Aster and Solidago spp.), increases were greater in plots with beetles absent. Biomass of Salix myricoides, the most common other willow, on the east dune increased more in plots with beetles than in plots without beetles. In general, species that did not show differential increases in abundance also did not show differential growth to already—present plants. After 3 yr of herbivore exclusion, there were no significant differences in species richness, species diversity, or species evenness in plots with and without beetles. Thus, herbivory on S. cordata caused increases in the abundance of herbaceous plants and decreases in the abundance of other woody plants, but over 3 yr did not influence overall species diversity. It appears that selective herbivory by Altica subplicata directly decreases growth and increases mortality of S. cordata and that damage of this single plant species also exerts an indirect impact on the patterns of plant succession on sand dunes.

Plant succession in areas of scorched and blown‐down forest after the 1980 eruption of Mount St. Helens, Washington

Abstract. Patterns of plant succession were studied in areas of scorched and blown‐down forest resulting from the 1980 eruption of Mount St. Helens, Washington. Changes in species abundance were observed for 7 years in permanent sample plots representing four post‐disturbance habitats, or site types. Total plant cover and species richness increased with time on all site types. In blown‐down forests supporting snowpack at the time of eruption, understory recovery was dominated by the vegetative regeneration of species persisting through disturbance. In forests without snowpacks, plant survival was poorer. Increases in cover and diversity were dominated first by introduced grasses, then by colonizing forbs characteristic of early successional sites. Epilo‐bium angustifolium and Anaphalis margaritacea showed widespread recruitment and clonal expansion throughout the devastated area. As a result, species composition on previously forested sites converged toward that on formerly clearcut sites, where early serai forbs resprouted vigorously from beneath the tephra.Total plant cover and species diversity were poorly correlated with post‐disturbance habitat and general site characteristics (e.g. distance from the crater, elevation, slope, and aspect). However, distributions of several life‐forms (e.g. low sub‐shrubs and tall shrubs) were strongly correlated with depth of burial by tephra and with cover of tree rootwads. Thus, early community recovery may reflect microsite variation or chance survival and recruitment rather than broad‐scale gradients in environment or disturbance.Recovery of pre‐disturbance composition and structure will undoubtedly be much slower than after other types of catastrophic disturbance. The rate and direction of community recovery will largely depend on the degree to which original understory species survived the eruption.

Abandoned Pastures in Eastern Amazonia. I. Patterns of Plant Succession

(1) Vegetation composition, structure, and biomass accumulation were studied on thirteen forest sites that had been cut and burned, used as cattle pasture, and then abandoned in the eastern Amazon near Paragominas, Para, Brazil. (2) The study sites were of two ages (two to four years and seven to eight years) and had received light, medium or heavy use for up to thirteen years. (3) Forest regenerated vigorously on sites of previously light use. Above-ground biomass accumulation averaged 10 t ha-' y-1 or 80 t after eight years (roughly onequarter of mature forest levels). Tree species richness was also high (about 20 per 100 mi2) and almost all species also occurred in native forest. Moderately grazed pastures also developed forest but biomass accumulation was only 5 t ha'-I y. Tree species richness was also lower than on light-use sites and there were fewer forest trees. Abandoned pastures subjected to heavy use had the least distinct patterns of succession. The single eight-year-old site was dominated by grasses and forbs with fewer than one tree per 100 m2 and an above-ground biomass accumulation of 0 6 t ha-' y1, a value only about 6% of that found on light-use sites. (4) The light-use sites had significantly higher biomass and species richness in both ageclasses than either moderateor heavy-use sites. Site age was a good predictor of aboveground biomass accumulation on lightand moderate-use sites, but not on heavy-use sites. (5) These Amazon ecosystems generally can recover after large-scale pasture disturbances. Only where land has been used too intensively for long periods is reforestation uncertain, but probably less than 10% of the pasture land in northern Para has degraded to this level. Nevertheless, the re-growth forest, regardless of pasture-use history, will not necessarily have the same characteristics of physiognomy or species composition as that originally occupying the site. Moreover, as burning becomes more prevalent in eastern Amazonia, abandoned sites may not develop into forest and the irreversible degradation of the entire regional ecosystem must be contemplated.