Vegetation Community Structure Research Articles

Spatial-temporal shifts in submersed aquatic vegetation community structure resulting from a selective herbicide treatment in Lake Sampson, Florida, USA

Thayer J, Enloe S, Prince C, MacDonald G, Leary J. 2024. Spatial-temporal shifts in submersed aquatic vegetation community structure resulting from a selective herbicide treatment in Lake Sampson, Florida, USA. Lake Reserv Manage. xx:xx-xx. Submersed aquatic vegetation (SAV) is a major ecological component of Florida’s shallow lake systems. Hydrilla (H; Hydrilla verticillata [L.F.] Royle) is a nonnative, invasive SAV dominating many of these lakes and a high management priority in conservation. Lake Sampson is a shallow 776-ha lake in north Florida dominated by hydrilla since the 1980s, with native Illinois pondweed (P; Potamogeton illinoensis Morong) and American eelgrass (V; Vallisneria americana Michx.) historically represented. In March 2021, an in-water treatment of the herbicide florpyrauxifen-benzyl was administered to the littoral zone covering 46% of the lake surface. Five months after treatment (MAT), H infestations were reduced by 99%, recruitment by 69%, and invasions to cohabitating native populations by 90%. Conversely, total combined P populations increased occupancy from 15% to 23%, while V populations exhibited only a slight decrease in occupancy, going from 19% to 18%. By 17 MAT, hydrilla infestations, recruits, and invasions had all increased, while native populations started to retract from earlier gains. Moreover, surveys revealed a significant shift in SAV communities to shallower depths that were immediate 1 month after treatment and sustained 17 months later with the posttreatment reduction of hydrilla exclusively occupying deeper water. Posttreatment changes in water quality were apparent and possibly influential to SAV community dynamics. Although this in-water herbicide treatment exhibited good selectivity and reduced hydrilla competition, unintended side effects in water quality may have impeded the long-term succession of resilient native SAV communities that could compete with the recovery of hydrilla.

BIODIVERSITAS GASTROPODA DI HUTAN MANGROVE SEGARA ANAKAN CILACAP

Segara Anakan is a lagoon surrounded by swamp forest with a mud substrate. Several biota live in it, one of which is Gastropods. This biota has slow movements and is relatively sedentary. The aim of research on gastropod biodiversity is to describe the diversity and dominance of their species. The research was conducted in July-September 2021. The research method used was a survey with a purposive random sampling technique at three stations taking into account differences in vegetation community structure. Station 1 (St 1) is in the eastern part of Segara Anakan with vegetation that dominates Aegiceras corniculatum; Station 2 (St 2) is in the middle of Segara Anakan with vegetation that dominates Nypa fruticans; Station 3 (St 3) is in the western part of Segara Anakan with vegetation dominating Sonneratia alba. Each station is determined by nine different sampling points once every month. The results showed that the Potamididae and Neritidae families were most commonly found at all stations during the study. The highest abundance is found in St 3, namely 1433 ind/m2, the lowest in St 1, namely 545 ind/m2. The diversity index in the medium category is at St 1 (1.05) and St 3 (1.59), while the low category is at St 2 (0.85). The dominance index in the medium category is at St 2 (0.55), and in the low category at St 1 (0.47) and St 3 (0.28). Factors that influence differences in abundance, diversity and dominance are adaptation, food and environmental conditions in which they live.

Effect of invasive species on forest composition in tropical dry forest: a case study of invasion by Gliricidia sepium

Ecological concerns caused by biological invasion have been considered an inevitable threat to global sustainability. The superior competitive ability of invasive plant species (IPS) has an impact on vegetation composition and loss of native flora. Recognising IPS at an early stage would significantly contribute to controlling invasive plants, protecting biodiversity and formulating appropriate strategies. Most of the studies available on invasive plants are descriptive and largely confined to non-woody species. The present study focused on the alien Gliricidia sepium, a tree species, to determine the invasive potential of its distribution in tropical dry deciduous forests of Central India. Forty square plots (25 × 25 m) were laid out at each uninvaded and invaded forest to enumerate phytosociological attributes to determine the impact of G. sepium on vegetation composition and community structure. Higher density (37.2 individuals ha−1), basal area (6.32 m2 ha−1) and importance value index (95.8) contributed by G. sepium clearly showed the suppression of seedlings, saplings and trees of native forest species at the invaded sites in terms of species richness, cover and other attributes as compared to at the uninvaded sites. Further, other invasive attributes such as higher seed production, dieback phenomenon, higher coppicing power and higher growth rate as observed during the study clearly affirmed the early speculation that the species might be invasive. The species has a strong potential to spread vigorously and may gradually become invasive throughout the country as already reported from various parts of India. In the present study area, G. sepium was introduced due to restoration and plantation programmes and our findings indicate its negative impact on the native vegetation. Thus, we strongly recommend the avoidance of this species for both plantation and restoration programmes, especially for Indian forests. The study helps in early recognition and rapid monitoring of G. sepium to control its spread throughout the country.

Impacts of Grazing on Vegetation and Soil Physicochemical Properties in Northern Yinshan Mountain Grasslands

The grasslands at the northern foot of the Yinshan Mountains are an integral component of the northern grassland ecosystem in China. The ecosystem in this region has low stability and poor resistance to disturbance. In this study, experiments were conducted to evaluate the possible changes in vegetation community structure and soil physicochemical properties due to overgrazing in the grasslands. Completely randomized group experiments were designed with grazing intensity as the single-factor study was conducted using natural grassland located in Xilamuren (in Inner Mongolia, northern China) as the study area. Three blocks were created, each having four plots of different grazing intensities and each block having an area of 100 m × 100 m. The experiments were conducted to evaluate the possible variances both in the structure of the vegetation community and the soil physicochemical properties resulting from overgrazing in the grasslands at the northern foot of Yinshan Mountain. The results were as follows: The importance values of dominant species, such as Heteropappus altaicus and Artimisia gmelinii, exhibited varying degrees of change with an increase in the grazing intensity. The surface vegetation cover decreased significantly with an increase in the grazing intensity. The increasing grazing intensity led to a significant increase in the content of very coarse sand grains in the soil. Severe grazing increased the exposed surface area, intensified the effects of blowing wind and scouring action of water, and led to the coarsening of topsoil particles. At 0–5 cm depth, the bulk density of soil exhibited an increasing tendency with an increase in the grazing intensity. The organic matter content of the soil in the heavily grazed plots decreased by 11.74%, 11.00%, and 14.08%, respectively, when compared to that in the 0–40 cm soil layer with no grazing, light grazing, and moderate grazing. The results emphasized the importance of managing grazing intensity for soil and vegetation restoration. Thus, the effects of short-term grazing (for example, 5 years) on vegetation community composition and species diversity may be less pronounced. This study contributes to our understanding of pasture management and the restoration of grassland species diversity.

Influence of aspect on vegetation dynamics: insights into the understory vegetation diversity of the dry temperate forests of South Waziristan Agency, Pakistan

The dry temperate forests of Pakistan exhibit rich diversity of understory floral species. These important and endemic plant species play a pivotal role in ecosystem functioning and providing livelihoods to the forest communities. South Waziristan, located in the southwest of Pakistan, is known for its rare pure stands of Pinus gerardiana Wallichex. D. Don forests. The rapidly expanding population and current state of affairs are leading to deforestation and causing disturbance to the understory vegetation of this valuable forest. The current study aims to fill the currently scanty information present in the literature regarding the diversity status of understory vegetation in P. gerardiana forests. Data of understory vegetation diversity were gathered for the northern and southern aspects of the forest. A 50 m2 sampling plot along with the placement of fifty 1x1m2 quadrats on both sites were laid out to determine species dominance, diversity, and evenness using Simpson, Shanon, Marglef, and Buzas–Gibson indices. The study depicted 612 individuals of about 29 species representing 23 families from the study site. The most abundant species in all of the sites was Salvia Glutinosa cccIV = 0.52. The southern aspect depicted the lowest diversity, but had high species dominance. Allium carolinianum DC. in this site was the most important species (IV = 0.74). The most abundant species were medicinal plants (75%), followed by edible plants (25%). Aspect had a significant effect on the understory vegetation and different categories of plants with respect to their diversity, dominance, and evenness as predicted by the various diversity indices. This study provides essential insight in to the florisitic diversity and community structure of the fragile pine nut understory vegetation in South Waziristan, which was hitherto not available. It was concluded that the southern aspect of understudy dry temperate forests depicted lower diversity and density as compared with the northern aspect. But it was observed that the southern aspect more specifically had more density and diversity of medicinal plants. It is therefore the need of the hour that conservation of these species from grazing and unsustainable harvesting must be ensured to sustain the livelihood of the inhabitants.

Does stand density affect understory vegetation and soil properties of differently aged Robinia pseudoacacia plantations?

Robinia pseudoacacia is the most important tree species used for afforestation on the Chinese Loess Plateau. However, most R. pseudoacacia plantations face environmental problems due to inappropriate initial densities. The sustainable development of R. pseudoacacia plantations is challenging due to significant knowledge gaps regarding the appropriate stand densities for maximizing ecological benefits. Herein, R. pseudoacacia plantations of three age classes—young, middle-aged, and mature—were sampled in the loess hilly-gully region of northern Shaanxi Province, China. Based on stand density, R. pseudoacacia plantations in each age class were categorized as low (<1000 trees ha−1), medium (1000–1500 trees ha−1), and high (>1500 trees ha−1) density. We analyzed the effects of stand density on soil physicochemical properties, understory vegetation community structure, and ecosystem multifunctionality. In young stands, a medium stand density significantly increased the Shannon-Wiener index, species richness, and above-ground biomass of herbaceous communities. In middle-aged stands, stand density had no significant effects on understory diversity, whereas medium-density stands showed increased understory above-ground biomass. In mature stands, low-density stands significantly increased understory above-ground biomass and species richness of herbaceous communities. In all age classes, stand density did not significantly affect shrubby community composition, but herbaceous communities shifted compositionally towards shade-tolerant and drought-tolerant species as stand density increased. In the soils of young and middle-aged stands, organic carbon, ammonium nitrogen, nitrate nitrogen, available phosphorus, and water content were highest in medium-density stands, whereas in mature stands, these variables were highest in low-density plantations. In young, middle-aged, and mature stands, the ecosystem multifunctionality indices were highest at densities of 1000–1500, 1000–1500, and < 1000 trees ha−1, respectively. We concluded that the effects of stand density on ecosystem functions in R. pseudoacacia plantations varied with stand age. Our findings highlight a need to implement age-based stand density management strategies for R. pseudoacacia plantations to improve their ecological benefits.

Identification of mangrove species based on substrate characteristics in Borimasunggu Village, Labakkang District, Pangkep Regency

Mangroves are coastal ecosystems that have many benefits, including the ecological benefits of being a source of nutrients for marine life (aquatic biota) and a source of food for land biota. This study aimed to determine the species composition and community structure of mangrove vegetation based on the substrate type and the relationship between mangrove density and substrate texture in Borimasunggu Village, Labakang District. This research was carried out from July to August 2021 in the Borimasunggu Village, Labakkang District, Pangkep Regency. The research method is purposive random sampling which is divided into 3 stages. At each station, 3 transects/plots are determined. The study results found 3 mangrove species in Borimasunggu Village, Labakang District, based on the type of substrate, namely Rhizophora stylosa, Avicennia alba, and Sonneratia alba species. Relative Frequency (RFi) in Borimasunggu Sub-District, Labakang District, was found for all species equally, namely 33.33, the highest relative cover (RCi) was the species Rhizophora stylosa, which was 39.25, and the lowest Relative Coverage (RCi) was the mangrove species Sonneratia alba, which was 26,15. While the highest Significance Value (INP) is the mangrove species Rhizophora stylosa, which equals 148.66%, and the lowest Important Value (INP) is the mangrove species Sonneratia alba, which is equal to 70.59%. The highest relative density (RDi) was found in the mangrove species Rhizophora stylosa, which was 74.07% with a clay substrate type, followed by Avicennia alba 14.81% and Sonneratia alba 11.11% with a dusty clay substrate types.

Assessment of Carbon Reduction Benefits of A/O-Gradient Constructed Wetland Renovation for Rural Wastewater Treatment in the Southeast Coastal Areas of China Based on Life Cycle Assessment: The Example of Xiamen Sanxiushan Village

The enhancement of carbon sequestration and emissions reduction has emerged as a primary concern in China’s rural regions. Nevertheless, numerous completed rural wastewater treatment facilities necessitate retrofitting due to suboptimal operational conditions. Consequently, evaluating the greenhouse gas (GHG) emissions impact and carbon reduction advantages of rural wastewater treatment facility retrofitting is essential. Existing research predominantly focuses on urban wastewater treatment plants, with minimal attention given to GHG emissions impact during the construction and demolition stages of wastewater treatment facilities. In this investigation, we developed a life cycle assessment (LCA)-based evaluation model to appraise the GHG emissions impact and carbon reduction benefits of retrofitting rural wastewater treatment facilities. We examined a renovation project in Sanxiushan Village, Xiamen City, Fujian Province, incorporating the integrated plant treatment technology of constructed wetlands. Our findings indicate that retrofitting offers significant advantages in terms of GHG emissions reduction, even when accounting for implicit GHG emissions. The establishment of supplementary terraced constructed wetlands and landscape greening can yield more substantial carbon reduction benefits. Moreover, we discovered that implicit GHG emissions during the construction stage can be mitigated by employing local, recycled, and low-carbon materials. Modifying vegetation community structure and prioritizing vegetation species selection can enhance the carbon storage capacity of plants, reducing overall life cycle GHG emissions and augmenting emissions reduction benefits. The evaluation model developed in this study can facilitate the promotion of low-carbon construction and operation of rural wastewater treatment facilities.

Carbon Sequestration Characteristics Under Natural Vegetation Restoration in Ziwuling Area of the Loess Plateau

The aim of this study was to analyze the carbon sink effect under natural vegetation restoration and the influence of changes in vegetation community characteristics on ecosystem carbon density in ecologically fragile areas of the Loess Plateau. In this study, the changes in carbon sequestration of a vegetation-soil system under eight successional stages[slope cropland, abandoned cropland for 10 years, abandoned cropland for 20 years, Sophora davidii (Franch.) Skeels., Betula platyphylla Suk., Pinus tabulaeformis Carr., Quercus wutaishanic Mary+P. tabulaeformis Carr mixed forests, and Q. wutaishanic Mary] in Ziwuling area over 150 restoration periods were investigated using the common method of spatial and temporal substitution. This study also discussed the relationship between changes in vegetation community characteristics and vegetation-soil system carbon density. The results showed that the community coverage of the investigated vegetation fluctuated from 85% in the slope cropland stage to 100% in the arbor stage. The number of species, Margalef index, Shannon-Wiener index, Pielou index, and Simpson index initially increased rapidly, then declined slowly until becoming stable, and reached a peak in the middle of the succession (B. platyphylla Suk.). The biomass and carbon density of vegetation components (above-ground biomass, below-ground roots, and litter) increased exponentially during the succession, i.e., increased slowly before B. platyphylla Suk. but increased significantly in B. platyphylla Suk. and P. tabulaeformis Carr.(P<0.05). The biomass and carbon density reached the maximum values of 27858.08 g·m-2 and 13232.51 g·m-2, respectively, in Q. wutaishanic Mary+P. tabulaeformis Carr mixed forests and tended to be stable in the late succession stage. Soil organic carbon density showed a power function relationship with vegetation restoration, with the greatest increase in the stages of abandoned cropland for 10 years and B. platyphylla, but no significant changes in the subsequent stages (P>0.05). In the early succession stage, the carbon density of the farmland ecosystem was the lowest (4395.70 g·m-2), whereas the other seven stages increased by 55.54%, 40.37%, 69.96%, 202.48%, 326.35%, 357.43%, and 351.07%, respectively, compared with the farmland ecosystem. Community coverage, Margalef index, Shannon-Wiener index, above-ground biomass, root biomass, and litter biomass were significantly positively correlated with vegetation-soil system carbon density (P<0.05). The carbon sink effect of long-term natural restoration in Ziwuling Region was significant, and the carbon density of the vegetation-soil system under interspecific competition tended to be stable in the late succession stage. Dynamic changes in the vegetation community structure and plant diversity during the succession process increased vegetation carbon density and soil carbon density. This study helps to clarify the carbon sink effect of natural vegetation restoration in ecologically fragile areas of the Loess Plateau and provides a theoretical basis for promoting natural forest conservation and achieving carbon neutrality.

Quality of riparian habitat and its influence on water quality in some ecosystems of waterfalls and springs in Bawean Island

This study aims to evaluate the quality of riparian habitats based on the index of riparian quality (QBR), quality of riparian tree vegetation (community structure and Naturalness index), and anthropogenic activity (Hemeroby Index) and their relationship to water quality in some waterfall and spring ecosystems on Bawean Island. This Ex Post Facto study was conducted on six waterfall ecosystems (Candi, Putri, Suwari, Talomon, Laccar and Kuduk Kuduk) and two spring water ecosystems (Kuduk Kuduk and Laccar). Analysis of riparian tree vegetation at each location was observed from three plots with size 50 x 50 m2. The physics chemical quality of water observed at each location included pH, dissolved oxygen/DO, total suspended solid/TSS, total Kjeldahl nitrogen/TKN, and biochemical oxygen demand/BOD. The results showed that the quality of the riparian habitat affected the water quality.

Disturbance and Succession in Early to Mid-Holocene Northern English Forests: Palaeoecological Evidence for Disturbance of Woodland Ecosystems by Mesolithic Hunter-Gatherers

Forest succession can be monitored in the present, modelled for the future, but also reconstructed in the past on the records of forest history, including through the use of palaeo-ecological techniques. Longer-term records from pollen data can show changes over centennial and millennial timescales that are impacted by climate, migration or soil development. Having knowledge of previous phases of post-disturbance seral stages of woodland regeneration however, as after fire, can provide insights regarding successional process and function over short-term decadal timescales. The aim of this paper is to test the high-resolution pollen record as a source of new insights into processes of succession, assisted by the supplementary data of microscopic charcoal analyses. On short-term timescales, multiple phases of forest disturbance and then recovery have been identified in early to mid-Holocene peat records in northern England, many from the uplands but also from lowland areas. We identify and describe a typology of recovery patterns, including the composition and rate of recovery, and then test the processes and factors that impacted on different seral trajectories, concentrating on fire disturbance which might have had a natural origin, or might have been caused by pre-agricultural Mesolithic hunter-gatherers. Factors considered include the spatial location and intensity of the fire event, the duration of the disturbance phase, the structure and dynamics of the successional regeneration vegetation communities and the pre-disturbance tree cover. Data from examples of fire disturbance of woodland have been examined from both upland and lowland sites in northern England and indicate that they had different successional pathways after disturbance. Fire disturbances in the denser lowland forests were mostly single burn events followed by natural successions and regeneration to forest, whereas fire disturbances in the upland woods usually showed continued or repetitive fire pressure after the initial burning, arresting succession so that vegetation was maintained in a shrub phase, often dominated by Corylus, for an extended period of time until disturbance ceased. This creation of a kind of prolonged, almost plagioclimax, ‘fire-coppice’ hazel stage suggests controlled rather than natural successional pathways, and strongly suggests that Mesolithic foragers were the fire starters in the upland English woodlands where hazel was naturally common and could be maintained in abundance in later-stage successions, along with other edible plants, for human use. All post-fire seral stages would have been attractive to game animals, providing a reliable food source that would have been of great benefit to hunter-gatherer populations.

Influence of fine-scale habitat characteristics on sage-grouse nest site selection and nest survival varies by mesic and xeric site conditions

AbstractResource managers and scientists across western U.S. agencies seek methodologies for identifying environmental attributes important to both wildlife conservation and broad-scale land stewardship. The Greater Sage-Grouse (Centrocercus urophasianus; hereafter, sage-grouse) exemplifies a species in need of this broad-scale approach given widespread population declines that have resulted from loss and degradation of habitat from natural and anthropogenic disturbances. These include agricultural land conversion, conifer expansion, energy development, and wildfire coupled with ecological conversion by invasive plants such as cheatgrass (Bromus tectorum). Development of habitat assessments and conservation actions for sage-grouse benefit from studies that link demographic responses to habitat selection patterns. To address this, we examined nest survival of sage-grouse in relation to fine-scale habitat patterns (i.e., field-based habitat measurements) that influenced nest site selection, using data from nests of telemetered females at 17 sites over 6 years in Nevada and northeastern California, USA. Importantly, sites spanned mesic and xeric average precipitation conditions that contributed substantially to vegetation community structure across cold desert ecosystems of the North American Great Basin. Vegetative cover immediately surrounding sage-grouse nests was important for both nest site selection and nest survival, but responses varied between mesic and xeric sites. For example, while taller perennial grasses were selected at xeric sites, we found no evidence of selection for perennial grass at mesic sites, indicating a functional response to availability of habitat features between hydrographic regions. Furthermore, perennial grass height and forb height both had positive effects on nest survival at xeric sites, but we found varying effects at mesic sites. We emphasize that precipitation conditions driving ecosystem productivity vary regionally among sagebrush communities, shaping vegetation structure and suitable habitat conditions for nesting sage-grouse.

Attack rates on artificial caterpillars in urban areas are higher than in suburban areas in Colombia

Abstract Growing urban expansion can alter ecological processes within trophic networks. Predation on herbivores is known to vary with the size of the area covered by vegetation, successional stage, altitude and predator community structure; however there are gaps in understanding how this occurs in urban and suburban environments. The purpose of this study was to determine whether predation pressure on artificial models of caterpillars varied with the degree of urbanisation and type of substrate. Artificial caterpillars were placed on two types of substrates (leaf vs. stem) in two areas of the city (urban vs. suburban). Total predation was measured as the number of models with evidence of attack by predators, with the predation rate estimated on a weekly basis. Predation was affected by the degree of urbanisation, being higher in urban (x̄ = 9.88%; SD = 4.09%, n = 8) than suburban areas (x̄ = 5.75%, SD = 4.21%, n = 8). Attack marks were observed in 23.8% (n = 125) of artificial caterpillars. The weekly predation rate on leaves (x̄ = 9.63%, SD = 5.95%, n = 8) was higher than that on stems (x̄ = 6%, SD = 4.2%, n = 8). These results suggest that the incidence of predation might vary with the degree of urbanisation and by the type of substrate on which prey organisms are found.

金沙江下游典型库区消落带植被恢复模式

PDF HTML阅读 XML下载 导出引用 引用提醒 金沙江下游典型库区消落带植被恢复模式 DOI: 10.5846/stxb202202160364 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（U2102209）；中国三峡建工（集团）有限公司技术服务项目（JG/18103B-4B-5B-6B） Vegetation restoration pattern of water-level-fluctuation zone in two cascaded reservoirs in the lower Jinsha River 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:消落带植被分布、生活型、多样性的调查研究显著促进了消落带植被恢复技术的进步，然而相邻两梯级库区消落带植被分布的差异以及植被群落特征的年际变化并不明确。此外，金沙江下游部分区域表现出一定的干热特征，其影响下的消落带植被群落特征有待深入了解。基于2019年和2021年向家坝和溪洛渡库区消落带植被调查结果，分析表明：（1）金沙江下游消落带按照下垫面特性主要分为硬岩型、软岩型、松软堆积型3种类型，坡度平缓的松软堆积型消落带是植被恢复的主要类型；（2）整体上，消落带优势植被类型是一年生和多年生草本，单优势种、少优势种群落较为普遍，两个库区消落带优势种重要值差异显著，植被生活型较少；（3）向家坝、溪洛渡库区消落带在分别经历6次和8次周期性水淹后，消落带植被分布与群落物种多样性特征变化不显著，表明消落带植被群落结构相对稳定。综上说明向家坝、溪洛渡两个相邻的梯级库区消落带植被恢复需要以灌草为主，且具有不同的潜在恢复模式，因此需要对应采取不同的恢复策略。研究对于科学指导金沙江下游梯级水电站库区消落带植被恢复具有重要意义。 Abstract:The investigation and research on the distribution, life-forms, and diversity of the vegetation have greatly promoted the progress of the restoration technology of the vegetation in water-level-fluctuation zone of the reservoir area. However, previous studies did not answer the question of how the distribution of vegetation in the riparian zone differed between two cascade reservoirs and the associated interannual variation of vegetation community characteristics. In addition, some areas in the lower Jinsha River belong to hot-dry valleys. The vegetation of the water-level-fluctuation zone in the reservoir areas of the lower Jinsha River is partly affected by the high temperature and arid climate, which would have a certain influence on the vegetation community characteristics of the water-level-fluctuation zone. That is, in the area of the lower Jinsha River, it is still unclear how the distribution of vegetation in the water-level-fluctuation zone in two cascaded reservoir areas and their interannual change. In 2019 and 2021, the vegetation communities of the neighboring Xiangjiaba and Xiluodu reservoir areas were investigated, respectively. The results showed that:(1) there were mainly three types of water-level-fluctuation zone in the lower Jinsha River:type of hard rock, type of soft rock, and type of loose and soft sedimentary zones with soil or sediments accumulated. Plants were mainly distributed in the loose and soft sedimentary zones with gentle slopes; (2) Overall, the dominant vegetation in the sedimentary zones were annual and perennial herbaceous plants. The single dominant species and less dominant species communities were common. Due to the periodic inundation and dry heat, the vegetation in the zone had a zonal distribution along the water level elevation. Significant differences in the important values of dominant species in the two reservoirs. Generally, a relatively few vegetation life types were found in the studied areas; (3) The vegetation community index of the zone in Xiangjiaba and Xiluodu reservoirs did not change significantly after six and eight periodic inundations, indicating that the vegetation community structure of the zone was relatively stable in the two-year time scale. Combining the differences in the important values of dominant species in the two reservoir areas, different vegetation restoration patterns of the water-level-fluctuation zone of Xiangjiaba and Xiluodu reservoirs were clarified. In summary, it is suggested that the restoration of vegetation in the fallout zone of Xiangjiaba and Xiluodu, two adjacent terrace reservoirs, needs to be dominated by irrigation and grass, and has different potential restoration patterns, so different restoration strategies need to be adapted accordingly. The study is of great significance for scientific guidance on the restoration of vegetation in the fallout zone of the reservoir area of the lower Jinsha River. 参考文献 相似文献 引证文献

Increasing tidal inundation corresponds to rising porewater nutrient concentrations in a southeastern U.S. salt marsh.

Salt marshes are ecologically and economically important features of coastal environments that are vulnerable to sea level rise, the rate of which has accelerated in recent decades along the southeastern US Atlantic coast. Increased flooding frequency and duration across the marsh platform is predicted to impact vegetation community structure and overall marsh persistence, but the effect of changing inundation patterns on biogeochemical processes in marsh sediments remains largely unexplored. As part of a long-term monitoring effort to assess how marshes are responding to sea level rise in North Inlet estuary (South Carolina, USA), we collected data on porewater nutrient concentrations from a series of permanent monitoring plots across multiple transects spanning the marsh elevation gradient during the growing season from 2009 to 2019. Additionally, we calculated time inundated for each plot using local water level data and high-resolution elevation measurements to assess the change in time flooded at each plot. Our results indicate that both NH4 and PO4 nutrient concentrations have increased in most permanent plots over the 11-year study period and that nutrient concentrations are higher with increasing proximity to the creek. Spatial patterns in nutrient increases through time are coincident with considerable increases in tidal inundation observed over the marsh platform. Across plots located in the low marsh, porewater NH4 and PO4 concentrations have risen at average rates of 8.96 μM/year and 0.86 μM/year, respectively, and have reached rates as high as 27.25 μM/year and 3.13 μM/year. We suggest that increased inundation time due to rising sea level has altered biogeochemical conditions influencing nutrient availability in marsh porewater, resulting in increases that likely have relevance for larger scale nutrient cycles as well as marsh ecosystem stability and function.

Ecophysiological Effects of Groundwater Drawdown on Phreatophytes: Research Trends during the Last Three Decades

A systematic synthesis of phreatophytes’ responses to groundwater drawdown would provide a more complete picture of groundwater-related research aimed at the sustainable management of groundwater-dependent ecosystems amid climate change. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the ecophysiological effects of groundwater drawdown on phreatophytes and methodological approaches were synthesized from peer-reviewed articles published from 1988 to 2022. The highest relative count of studies was found in arid and semi-arid high-income countries, such as Australia and North America (18–24%), while the lowest relative count to no data was found in hyper-arid countries, such as north African countries (0–3.65%). The groundwater depth effects on phreatophyte ecophysiology had the highest relative count (53.65%), followed by large-scale tree plantation effects on the groundwater characteristics (44.37%) and groundwater depth and biological invasion relationship (1.99%). The results revealed that as the groundwater depth increased, the phreatophytic vegetation growth, productivity, and community structure decreased across the ecosystem types. A groundwater withdrawal also had a significant impact on the physiology of the phreatophytes, specifically on the transpiration rate, xylem water potential, hydraulic conductance, and photosynthetic rate. Many of the reviewed studies concluded that large-scale tree plantations can deplete groundwater resources due to an increased evapotranspiration rate. Further, species’ diversity, evenness, dominance, composition, and distribution, as well as the Normalized Difference Vegetation Index (NDVI), are commonly measured parameters in the reviewed studies through vegetation and groundwater monitoring. Amid applied and contemporary problems, this synthesis may provide researchers with cues to conduct studies relevant to the integrated and sustainable conservation and management of groundwater-dependent ecosystems, particularly in data-poor, hyper-arid countries.

Species composition and vegetation structure of mangrove forest in Baskara Bakti Village, Central Bangka Regency, Bangka Belitung

Mangrove ecosystem has a strategic function as a buffer for coastal areas, marine conservation, mitigates climate change and global warming. Bangka Belitung is an archipelagic province with many coastal areas, including mangrove ecosystems. This study aims to determine the quality of the mangrove ecosystem by analyzing the structure, composition, and health index of mangroves in the mangrove forest ecosystem in Baskara Bakti Village, Central Bangka Regency. Data were collected through observations at several sampling points used to analyze species composition, vegetation community structure, and environmental physicochemical conditions using stratified random sampling with an observation plot size of 10 m x 10 m and canopy cover determination using the hemispherical photography method. The study results show that the composition of mangrove vegetation in the study area consisted of 5 true mangrove species and 6 associated mangrove species. Rhizophora apiculata is the species with the highest Important Value Index of 91.87%. The mangrove community showed a good health condition with an average value of 50.41%. Environmental parameters that directly influence the mangrove forest ecosystem include temperature, water pH, dissolved oxygen (DO), and salinity. Planting and enrichment of mangrove species need to conserve sustainable mangrove ecosystems.

Struktur Komunitas Moluska: Gastropoda dan Bivalvia di Vegetasi Perairan Danau Sentani Papua

Community structure of bivalvia and gastropods nearby water vegetation in Sentani Lake, Papua. Line’s transect and plot methods were used to determining the structure of mollusks and vegetation by using index, diversity, and dominance as parameters. Intentional measurement were carried out on several biological parameters of the waters at 10 sampling points. From the observation and measurments, we obtained seven types of mollusk with 5644 individuals, where six types are belong to gastropods and one type is a member of bivalves. The highest level of mollusk diversity was in Kwadeware, the highest at the inlet of the lake, and were dominated by Melanoides tuberculata and Pomacea canaliculata. In addition, vegetation found in the area observation were water hyacinth (Eichhornia crassipes), water spinach (Ipomoea aquatica), apu wood (Pistia stratiotes), genjer (Limnocharis flava), Hydrilla verticillata, seagrass (Potomogeton malainus), Nymphaea alba, Ceratophyllum demersum, and Nymphoides indica.Key words: gastropods; molluscs; vegetation; Sentani lake

Bird Flight Resistance Analysis and Planning Strategies in Urban Regeneration Areas: A Case Study of a Certain Area in Shenzhen, China

At present, the sharp decline in urban biodiversity worldwide is severe. Conducting biological perspective analysis and proposing space construction solutions during urban regeneration can greatly alleviate the contradiction between urban construction and biodiversity conservation. In this study, birds were taken as biological representatives, and a certain area in Shenzhen with strong conservation needs was used as an example. Based on a thorough analysis of bird status, the minimum resistance model was applied to establish a resistance surface describing the real flight movement of the indicator species and to construct a bird conservation pattern from the flight process of birds. The results show that: (1) bird flight resistance is the lowest in the southern green space and northern woodland around the reservoir in the research region, and the resistance is higher in the central part, but the path of least resistance therein has the potential to become a corridor. (2) From the perspective of the community structure of green space vegetation, the sparse woodland and shrubland in the research region have low resistance and high richness, which are the most ideal green space forms for birds; from the perspective of architecture, bird flight resistance shows a negative correlation with building height and a positive correlation with building density. The final urban regeneration design plan is thus derived, and the validity of the method is verified based on the biodiversity index. This study reveals the possibility of applying bird flight resistance analysis based on the minimum resistance model to small and medium-scale urban regeneration areas, and also provides insight into the correlation between flight resistance and spatial design elements, which can assist decision-makers, planners and developers in spatial design and planning from a biological standpoint.

Structural changes in vegetation coincident with reseeding Elymus nutans can increase perceived predation risk of plateau pikas (Ochotona curzoniae)

The perceived predation risk of animals is often influenced by the structure and complexity of vegetation communities. Plateau pikas (Ochotona curzoniae) are considered a pest species in alpine meadows when their densities exceed a certain threshold. The changes in vegetation structure caused by reseeding Elymus nutans can reduce pika densities, which may result from the increased risk of predation for pikas. However, whether the changes in community structure caused by reseeding of E. nutans is sufficient to alter the perceived predation risk for pikas, remains unknown. In this study, we measured the running speed (spontaneous without stimulation), alert distance (AD) and vigilance to a potential human predator in E. nutans habitat and open habitat by video review to assess perceived predation risk for plateau pikas in the two habitat types. Our results showed that body mass and habitat type influenced the running speed, group size and the habitat type influenced AD, and habitat type and group size influenced vigilance. The running speed of pikas was 1.67 times faster in the E. nutans compared to in open habitat, the AD of pikas was 1.79 times longer in the open than in the E. nutans habitat, and pikas were more vigilant in E. nutans than pikas in open habitat. The shorter AD indicates pikas have poor visibility due to higher vegetation height. The faster running speed and higher vigilance suggest a higher perceived predation risk for pikas in E. nutans habitat. Therefore, we believe that structural changes in vegetation following reseeding of E. nutans can increase the perceived predation risk for pikas, and could be responsible for the decrease in the pika population densities in these areas.