Conservation Of Vegetation Research Articles

Balancing ecosystem integrity and cultural values at sacred Lake Hora, Ethiopia: The need for conservation of wetland vegetation

AbstractAlthough macrophytes represent important habitats for the plankton communities of shallow lakes and ponds, the role of littoral macrophyte patches in deep crater lakes is not well described. The objective of the present study was to investigate the role of littoral macrophyte vegetation in structuring phytoplankton and zooplankton communities and, therefore, sustaining ecological integrity in a deep tropical crater lake (Hora Lake, Ethiopia). The lake has a surface area of 1.03 km2 and a mean depth of 16.5 m. The area surrounding the lake is a prime location for the celebration of the Oromo thanksgiving festival (Irreecha), which is inscribed by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as an intangible cultural heritage, and also considered sacred by the Oromo people. Measurements of physical, chemical and biological parameters were conducted at fifteen sampling sites in both the littoral and central parts of the lake during the dry and wet seasons in 2017. A total of 28 phytoplankton and 19 zooplankton genera were identified. The phytoplankton and zooplankton communities were dominated by cyanobacteria and rotifers, respectively, at the open water sites. The wetland vegetation was found to be important in reducing potentially toxic and unsightly cyanobacteria. The submerged and emergent vegetation also served as refugia for zooplankton during the wet and dry seasons, respectively. Crustaceans accounted for about 30–45% of the total zooplankton abundance within the vegetation fringes. Their abundance decreased to 5% in the non‐vegetated areas, wherein the community was dominated by rotifers. As the population around the lake, particularly during the festival, may damage the aquatic vegetation, their access to the shoreline should be regulated for conservation and sanitary reasons (e.g. to reduce cyanobacteria growths).

Dual Influence of Climate Change and Anthropogenic Activities on the Spatiotemporal Vegetation Dynamics Over the Qinghai‐Tibetan Plateau From 1981 to 2015

AbstractClimate change and human activities have already caused degradation in a large fraction of vegetation on the Qinghai‐Tibetan Plateau (QTP). Many studies report that climate variability instead of overgrazing has been the primary cause for large‐scale vegetation cover changes on the QTP, for example, Lehnert et al., 2016, https://doi.org/10.1038/srep24367. However, it remains unclear how human activities (mainly livestock grazing) regulate vegetation dynamics under climate change. This paper takes the AVHRR/GIMMS Normalized Difference Vegetation Index (NDVI) as an indicator to analyze the growth status of vegetation zones in the QTP, which has highly sensitive to climate change. The spatiotemporal dynamics of vegetation growth between 1981 and 2015 were analyzed. The dual effects of climate change and human activities were examined by correlation analyses of data from 87 meteorological stations and economic statistical data of the QTP. Results show that: (a) The vegetation in central and southwestern QTP with high altitudes was improving due to the warm‐humid climate trend. An increase in temperature and a reduction in the harsh frigid climate at high altitudes due to global warming has resulted in expansions of the vegetated areas, with the NDVI showing a concordant increase. (b) The degraded areas were mainly confined to the northern and eastern QTP, which have high human and livestock population densities. In comparison to gently changing climate regimes, anthropogenic activities such as chronic concentration of population and livestock in the valleys with a less harsh climate exerts a much stronger pressure on vegetation. The study indicates that the anthropogenic pressures are much more intensive than the impact of climate change and are critical for the conservation and sustainable management of the QTP vegetation.

Asymmetrical cooling effects of Amazonian protected areas across spatiotemporal scales

Amazonian protected areas (PAs) play an important role in maintaining the regional and global ecosystem services, biodiversity and climate change mitigation. The effects of Amazonian PAs on climate change mitigation mainly focus on the carbon sequestration benefits. The biophysical effects of PAs on regulating the local energy budgets, and hence changing local climate, however, are often ignored. Using multiple satellite observation datasets, we evaluated the effects of Amazonian PAs on land surface temperature (LST) and the biophysical mechanisms of PAs on surface albedo and evapotranspiration (ET). We showed that Amazonian PAs have a cooling effect on local LST in relative to nearby croplands and non-protected areas (non-PAs) with the same land cover as PAs. The asymmetrical cooling effects of Amazonian PAs between daytime and nighttime, and between the dry and wet seasons sustain lower diurnal and seasonal temperature ranges, respectively, than non-PAs and croplands. The protected forests have stronger cooling effects, and more effectively moderate the diurnal and seasonal temperature ranges than the protected savannas due to the higher effects on surface albedo and ET. The non-PAs show weaker cooling effect than PAs, indicating reduced thermal buffering effect in non-PAs. Our results highlighted the great potential of natural vegetation in PAs versus non-PAs and croplands in buffering local thermal environment and the necessity of natural vegetation conservation in Amazon region.

Nonlocal interactions between vegetation induce spatial patterning

Vegetation pattern provides useful signals for vegetation protection and can be identified as an early warning of desertification. In some arid or semi-arid regions, vegetation absorbs water through nonlocal interaction of roots. In this study, we present a vegetation model with nonlocal interaction which is characterized by an integral term with a kernel function. Mathematical analysis provides the conditions for the generation of stationary pattern. Numerical simulations exhibit different spatial distributions of vegetation. Densities of vegetation and water show an inverse relationship at same spatial locations due to water transport mechanism. The results reveal that the interaction intensity and the shape of the kernel function can cause the transition of vegetation pattern. Specifically, the vegetation biomass increases as the interaction intensity decreases or as the nonlocal interaction distance increases. We demonstrate that the nonlocal interactions between roots of vegetation is a key mechanism for the formation of vegetation pattern, which provides a theoretical basis for the preservation and restoration of vegetation.

Investigating Relationships between Runoff–Erosion Processes and Land Use and Land Cover Using Remote Sensing Multiple Gridded Datasets

Climate variability, land use and land cover changes (LULCC) have a considerable impact on runoff–erosion processes. This study analyzed the relationships between climate variability and spatiotemporal LULCC on runoff–erosion processes in different scenarios of land use and land cover (LULC) for the Almas River basin, located in the Cerrado biome in Brazil. Landsat images from 1991, 2006, and 2017 were used to analyze changes and the LULC scenarios. Two simulations based on the Soil and Water Assessment Tool (SWAT) were compared: (1) default application using the standard model database (SWATd), and (2) application using remote sensing multiple gridded datasets (albedo and leaf area index) downloaded using the Google Earth Engine (SWATrs). In addition, the SWAT model was applied to analyze the impacts of streamflow and erosion in two hypothetical scenarios of LULC. The first scenario was the optimistic scenario (OS), which represents the sustainable use and preservation of natural vegetation, emphasizing the recovery of permanent preservation areas close to watercourses, hilltops, and mountains, based on the Brazilian forest code. The second scenario was the pessimistic scenario (PS), which presents increased deforestation and expansion of farming activities. The results of the LULC changes show that between 1991 and 2017, the area occupied by agriculture and livestock increased by 75.38%. These results confirmed an increase in the sugarcane plantation and the number of cattle in the basin. The SWAT results showed that the difference between the simulated streamflow for the PS was 26.42%, compared with the OS. The sediment yield average estimation in the PS was 0.035 ton/ha/year, whereas in the OS, it was 0.025 ton/ha/year (i.e., a decrease of 21.88%). The results demonstrated that the basin has a greater predisposition for increased streamflow and sediment yield due to the LULC changes. In addition, measures to contain the increase in agriculture should be analyzed by regional managers to reduce soil erosion in this biome.

Aboveground litter input alters the effects of understory vegetation removal on soil microbial communities and enzyme activities along a 60-cm profile in a subtropical plantation forest

Changes in litter input and understory vegetation due to climate change and human activities affect belowground processes in plantation forests. However, it is unclear whether and how aboveground litter interacts with understory vegetation for their effects on soil microbial communities and functions, especially in deep soils. A field manipulation experiment was conducted, including four treatments of understory vegetation removal plus aboveground litter removal (UVR + ALR), understory vegetation preservation plus aboveground litter addition (UVP + ALA), UVR + ALA, and UVP + ALR in a subtropical Chinese fir (Cunninghamia lanceolata) plantation. After seven years of continuous treatment, the soil samples along a 60-cm profile were used to evaluate microbial community compositions, major microbial enzyme activities, and several physicochemical properties in the four treatments. UVR resulted in significant negative effects on microbial biomass and enzyme activities at different soil layers with or without litter input, but it did not change the soil microbial communities such as F/B, G+/G−. Compared with ALR, ALA amplified the negative understory vegetation removal effects (UVREs) on β-D-cellobioside (CB), β-N-acetylglucosaminidase (NAG), and leucine aminopeptidase (LAP) activities, but did not affect UVREs on total soil PLFAs. Lesser negative UVREs on β-1,4-glucosidase (BG), LAP, and acid phosphatase (AP) activities were observed in top soils compared to deep soils in the ALR treatment. UVREs on soil microbial biomass were not significantly different among soil depths. These results indicate that aboveground litter and soil depth altered UVREs on soil physicochemical properties, primarily through soil microbial biomass and enzyme activities. UVREs were generally more sensitive to major enzyme activities than microbial biomass and were interactively influenced by aboveground litter and soil depth due to synergistic effects within soil ecosystems. This study highlights the integrated feedbacks of microbial structures and functions along soil profiles in response to litter and vegetation interactions in subtropical forests.

Incidence of gastric cancer and risk factors in Suzhou cohort

Objective: To describe gastric cancer incidence in Suzhou cohort, explore the environmental risk factors of gastric cancer in Suzhou, and provide appropriate suggestions for gastric cancer prevention and control. Methods: The participants were from the Suzhou cohort of China Kadoorie Biobank. Baseline survey was conducted from 2004 to 2008, followed by long-term follow-up until December 31, 2013. After the exclusion of those who had been previously diagnosed with peptic ulcer and malignant tumor reported at baseline survey and gastric cancer within six months after enrollment, a total of 50,136 participants were included. Cox proportional risk models were used to identify risk factors of gastric cancer and their hazard ratios in Suzhou. The effect modifications of gender on the association between risk factors and gastric cancer were analyzed. Results: In the follow-up of 7.19 years (median), 374 gastric cancers cases occurred. The standardized incidence was 94.57 per 100 000 person-years. Multivariate Cox proportional risk model analysis found that age (10 years old as a age group, HR=2.20, 95%CI: 1.92-2.53, P<0.001), current smoking (HR=1.84, 95%CI: 1.10-3.07 P=0.020), consumption of preserved vegetables weekly (HR=2.28, 95%CI: 1.28-4.07, P=0.005) and daily (HR=2.05, 95%CI: 1.16-3.61, P=0.013) were risk factors for gastric cancer. Female (HR=0.44, 95%CI: 0.25-0.76, P=0.003) and refrigerator use (10 years as a limit, HR=0.85, 95%CI: 0.74-0.97, P=0.016) were protective factors for gastric cancer. Further analysis showed that there was heterogeneity between males and females in the association between refrigerator use years and the incidence of gastric cancer (P=0.009), and there was an interaction effect between gender and refrigerator use on the incidence of gastric cancer (P=0.010). Conclusions: The incidence of gastric cancer in Suzhou cohort was high. The risk factors of gastric cancer varied. There was a synergistic interaction effect between gender and refrigerator use years on the incidence of gastric cancer.

Effectiveness of protected areas edges on vegetation greenness, cover and productivity on the Tibetan Plateau, China

Protected areas (PAs) are the cornerstones of global vegetation conservation efforts, but growing evidence showed the limited effectiveness of PAs in some regions. Recent attempts to quantify conservation efficiency were mainly focused on vegetation coverage, overlooking other vegetation characteristics, such as greenness and productivity. Here, using multiple indices of vegetation status from satellite observations and a windows search strategy, we measured the conservation efficiency of nature reserves (NRs, the primary category of PAs in China) edge on vegetation greenness, cover, and productivity on the Tibetan Plateau. The results showed that NRs’ edges performed a weak, but significant role in vegetation growth. Over 40% of the areas showed a positive impact of NRs’ edge on vegetation growth in different degrees. However, about 10% of the areas located on NRs’ edge showed a noticeable opposite effect on greenness, cover, and productivity. Compared to some climatic and socio-economic factors (e.g., population density and air temperature), fragmented landscapes and landforms are more likely to inhibit conservation efficiency. The findings of this work can help better understand PAs’ role in securing vegetation conservation and optimize the design of PAs for preventing vegetation losses.

Soil seed bank study of Hirmi woodland vegetation: Implications for restoration and conservation of natural vegetation, in Tigray, Northern Ethiopia

Soil seed bank (SSB) is an important component in the process of rehabilitating degraded lands by forecasting the future vegetation cover of a given area. The present study was conducted in Hirmidryland vegetation, Tigray, Northern Ethiopia; to investigate the soil seed bank under different land use types in the vegetation ecosystem. A total of 128 soil samples were taken from eight points of four land use types (Shrubland, forest, grassland and bare land) and four soil layers (litter layer, 0–3 cm, 3–6 cm and 6–9 cm depth). Each sample plots measured 15 cm x 15 cm (225cm2). The density, composition and vertical distribution of seedlings were computed. A total of 58 species representing 51 genera and 22 families were recovered from the soil seed bank. Of these, 86.2% of them were herbs. The total density of soil seed banks from all land-use types was 3,116.7seeds/m2. The highest species composition was recorded in the shrubland and the least number of species were recorded in the bare land. Poaceae, Asteraceae, Fabaceae and Lamiaceae were among the plant families with high species composition that accounted for 60.35% of the total. Oplismenus burmannii, Woodfordia uniflora, Rhus retinorrhoea and Pennisetum glaucifolium were among the species with high density. The highest Jaccard's coefficient of similarity was revealed between soil seed bank of forest and shrubland whereas the least similarity was recorded between forest land and bare land. The soil seed bank result from all land use types in the study area showed that the regeneration potential of the woody species were poor. Hence, this study underscores other restoration approaches such as growing seedlings of woody species and plantation, direct seeding in the degraded ecosystem and preventing selective cutting of the matured woody species are recommended.

EVALUASI KEMAMPUAN LAHAN PADA LAHAN TANAMAN CENGKEH DAN KAKAO MENUJU PERTANIAN BERKELANJUTAN

The research purposed to know the land capability class and study the Sustainable Agricultural Management with Agroforestry systems on the land of PT. Fructi Agri Sejati Dusun Komboh, Sambirejo Village, Kec. Wonosalam, Kab. Jombang. One of the ways to manage sustainable agricultural land is by utilizing land according to the land capability class. Land use must be balanced between land use and conservation efforts to maintain the balance of the ecosystem and the preservation of the physical condition the land. The application of agroforestry systems have included one way of the sustainable agricultural systems. The results showed that the land capability class for Clove and Cocoa was class VI with limiting factor is the slope. Land use based on land capability class for clove and cocoa plants, are: 1) Nature Reserve, 2) Forestry, 3) Limited grass, and 4) Fairly good grass. The land use is sought to be as close as possible to the characteristics of the nature reserve and to adjust the slope level, by mechanical and vegetative conservation.

The benefits of coastal adaptation through conservation of foreshore vegetation

AbstractDue to rising sea levels and projected socio‐economic change, global coastal flood risk is expected to increase in the future. To reduce this increase in risk, one option is to reduce the probability or magnitude of the hazard through the implementation of structural, Nature‐based or hybrid adaptation measures. Nature‐based Solutions in coastal areas have the potential to reduce impacts of climate change and can provide a more sustainable and cost‐effective alternative to structural measures. In this paper, we present the first global scale assessment of the benefits of conserving foreshore vegetation as a means of adaptation to future projections of change in coastal flood risk. In doing so, we extend the current knowledge on the economic feasibility of implementing global scale Nature‐based Solutions. We show that globally foreshore vegetation can contribute to a large decrease in both absolute and relative flood risk (13% of present‐day and 8.5% of future conditions in 2080 of global flood risk). Although this study gives a first proxy of the flood risk reduction benefits of conserving foreshore vegetation at the global scale, it shows promising results for including Nature‐based and hybrid adaptation measures in coastal adaptation schemes.

Environmental diagnostics in areas with high potential fragility in the Federal District, Brazil

This study aimed to conduct environmental diagnostics of areas with high potential environmental fragility in the Federal District, Brazil. Reclassified thematic maps of soil slope and vulnerability to water erosion were combined to create the soil susceptibility map to water erosion, which, in turn, was combined with the thematic maps of soil use and rain erosivity. The result was then reclassified, giving rise to the potential environmental fragility map. In the places identified with high potential environmental fragility, information was collected by observing the aspects of the physical, biotic, and anthropogenic environmental components of the landscape. Areas with high potential environmental fragility in the Federal District were found. In those locations, the uses and occupations of the soil observed were intensive farming, small rural activities, managed intensive livestock and degraded intensive livestock. Land use and occupation in areas with high potential environmental fragility of the Federal District, with “degraded intensive livestock”, make such sites environmentally fragile since there is a scarcity of non-preserved natural areas and there is no soil conservation method. It was concluded that, for the use and occupation of the soil with high potential environmental fragility areas in the Federal District, which are taken by intensive farming, small rural activities, and managed intensive livestock, the conservation of the natural areas and the vegetative and mechanical soil conservation techniques must be implemented.

Assessing Restoration of Ecosystem Functioning in Brazilian Subtropical and Tropical Streams

AbstractRivers and streams provide many ecosystem services, including provision of food, water purification, and nutrient abatement. Ecosystem functioning, the set of processes that regulate the fluxes of energy and matter, is the backbone of ecosystem services. A myriad of human impacts affects the functioning of running waters. To reduce these impacts, strategies for conservation and recovery of riparian vegetation, as well as direct interventions for stream restoration, have been carried out. However, these actions have been more limited in sub/tropical than in temperate regions. Based on case studies from southeastern Brazil and comparisons with their temperate counterparts, we illustrate and discuss how restoration of riparian canopy cover and stream reconfiguration through the addition of wood can influence two key ecosystem processes: nutrient retention and metabolism. Our findings indicate that the distinctive environmental features of the sub/tropical climate strongly shape the effect of stream restoration on ecosystem functioning. However, as in the temperate climate, effects are rarely monitored for a long time after the restoration, indicating the need for their longer‐term assessment. Understanding how restoration evolves over time to impact the functioning of sub/tropical streams is fundamental for the management and conservation of these strategic water bodies and the relevant ecosystem services they provide.

Vegetation on ex-tin mining in Mempayak village, Manggar district, Belitung regency and its utilization

The former tin mining land in Mempayak Village in Belitung Regency created a basin that becomes water catchment area when it rains and becomes a source of clean air during the dry season. The heavy rain occurred in 2017 brought vast amounts of soil material depending on the ex-mining basins in this village. This study aims to inventory of vegetation that grows and discusses its use by the communities around the Mempayak Village. Vegetation that succeeded in changing 34 species grouped into 20 families and 31 genera. Vegetation in this former tin mining land has benefits as a raw material for making a single drug without mixture (34 species), food (2 species), roofing material (1 species), cutting tools (1 species), chicken feed (1 species), and straws (1 species). Vegetation body parts that are useful for the above purposes include: roots (2 species), petiolus (1 species), shoots (1 species), leaf blades (2 species), young stems (2 species), old stems (2 species), and all parts of the plant body (14 species), and unknown parts of the plant body used by the surrounding community (9 species). The success of vegetation on ex-mining land has been taking place by spending a variety of types and diverse uses by the people of Mempayak Village, Manggar District, Belitung Regency. Efforts to manage the area and manage vegetation are needed to protect the preservation of vegetation on ex-tin mining land and work carried out at high speed.

Habitat selection of large herbivores evidenced as threats to alpine ecosystem

Across the globe, increasing populations of Cervidae have the potential to modify ecosystems. Long-term grazing pressure by deer not only alters vegetation but also affects ecosystem functions and interspecific interactions. It is recognized as a significant factor in ecological degradation. Alpine vegetation (i.e., alpine meadow) is an icon of alpine ecosystems and has thrived for centuries without the presence of large herbivores in Japan. However, in the alpine zone (>2700 m a.s.l.) of the South Alps National Park in central Honshu, Japan, sika deer (Cervus nippon) were first seen in the 1990s; thereafter, the vegetation noticeably changed starting in the 2000s. Nonetheless, virtually no information exists on habitat selection by these alpine sika deer. Here we analyzed (1) the altitudinal movement patterns of alpine sika deer, (2) the significant environmental factors affecting their habitat selection, and (3) estimated the relative probability of their habitat use via resource selection functions (RSF). The mean altitudinal difference between summer and winter home ranges was 1186 m, and the alpine sika deer arrived at the alpine ridgeline in June when the snow cover at >2400 m a.s.l. rapidly decreased. The mean altitude in the summer home range was 2635 ± 135 m. Alpine meadow, followed by Betula forests and tall grasslands, were preferred habitats by deer. The deer also preferred areas where snow melted in late spring and early summer. The deer's core habitat, indicated by higher RSF values (≥0.65), covered 45.2% of the study area, mostly distributed in the alpine zone. Our estimates clearly suggest the urgent need to prioritize specific areas for the conservation of the alpine vegetation in the South Alps National Park in Japan.

Mapping native and non-native vegetation in the Brazilian Cerrado using freely available satellite products

Native vegetation across the Brazilian Cerrado is highly heterogeneous and biodiverse and provides important ecosystem services, including carbon and water balance regulation, however, land-use changes have been extensive. Conservation and restoration of native vegetation is essential and could be facilitated by detailed landcover maps. Here, across a large case study region in Goiás State, Brazil (1.1 Mha), we produced physiognomy level maps of native vegetation (n = 8) and other landcover types (n = 5). Seven different classification schemes using different combinations of input satellite imagery were used, with a Random Forest classifier and 2-stage approach implemented within Google Earth Engine. Overall classification accuracies ranged from 88.6–92.6% for native and non-native vegetation at the formation level (stage-1), and 70.7–77.9% for native vegetation at the physiognomy level (stage-2), across the seven different classifications schemes. The differences in classification accuracy resulting from varying the input imagery combination and quality control procedures used were small. However, a combination of seasonal Sentinel-1 (C-band synthetic aperture radar) and Sentinel-2 (surface reflectance) imagery resulted in the most accurate classification at a spatial resolution of 20 m. Classification accuracies when using Landsat-8 imagery were marginally lower, but still reasonable. Quality control procedures that account for vegetation burning when selecting vegetation reference data may also improve classification accuracy for some native vegetation types. Detailed landcover maps, produced using freely available satellite imagery and upscalable techniques, will be important tools for understanding vegetation functioning at the landscape scale and for implementing restoration projects.

Eradication of rabbits from islets is essential for conservation of microinsular vegetation and narrow endangered flora: the case of Medicago citrina (Fabaceae) in s’Espartar islet (Balearic Islands, Western Mediterranean Basin)

The introduction of exotic herbivores to islands is one of the most harmful challenges to the conservation of insular biodiversity, causing the extinction or geographical reduction of many plant species worldwide and motivating conservation actions from environmental managers. Here, we evaluated the recovery of plant communities, specifically the endangered Medicago citrina, on a small islet close to Ibiza (Western Mediterranean Basin) after the complete eradication of introduced rabbits (fully eradicated in 2016). To evaluate the variation of plant richness and coverage, five permanent plots were installed in 2015 to record over five years. Additionally, an exhaustive census geolocating all M. citrina individuals was carried out in 2019. Total vegetation cover, plant richness and Shannon’s diversity index significantly increased throughout the study period. We counted 2,322 M. citrina individuals over 15 cm tall and a large number of seedlings. Therefore, this population not only successfully recovered, but also established the largest population in the entire geographic distribution of this species. The demographic structure is dominated by young individuals and a few large individuals, and the distribution across the island is heterogeneous since the largest spots of individuals were located in ravines where air currents probably provided seeds from plants located in inaccessible cliffs. However, the appearance of the invasive insect Icerya purchasi now threats the population of M. citrina as it feeds on the tissues of adult plants and compromises its development and survival. This study proves the eradication of herbivores is the most efficient way to conserve vulnerable species.

ЗАКАЗНИКИ КАК ФАКТОР СОХРАНЕНИЯ ЭКОСИСТЕМ БАССЕЙНА РЕКИ ОХОТЫ

In the paper it is considered the biological diversity of the plant world in the basin of the Okhota River upper reaches. This biodiversity is very important for preserving the water content in lakes Neck, Khel-Degi and Ueginsky. Its functioning provides preservation of the rare salmon – neiva – habitats, as its population size depends on the stability of natural and climatic conditions and the preservation of forest vegetation in the area.

Trójdzielność młodszego dryasu obserwowana w rozwoju roślinności w otoczeniu torfowiska Żabieniec w środkowej Polsce

The Żabieniec mire is located in central Poland on the Łódź Highlands. Paleogeographical and paleoecological research have been being conducted there from a few decades. Organic sediments accumulated during the Eemian Interglacial, Vistulian Glaciation and Holocene reveal a continuous and detailed record of vegetation succession and environmental changes during these periods. Initially, a lake existed there and gyttja constitutes the sediment of the lower part of investigated core. Nowadays, there is still a small area of open water surrounded by mire. The high thickness of organic sediments, which is exceptional for old-glacial areas, enabled palaeoecological analyses and a detailed description of environmental history during the Late Glacial and Holocene. This article presents the pollen analysis record of vegetation development during the Younger Dryas, the last cold period of the Late Glacial. The chronology is based on radiocarbon dating made at the Gliwice Radiocarbon Laboratory of the Silesian University of Technology (Petera-Zganiacz et al. 2022). The course and proportions of dominating taxa and important “cold” species allowed for the division of the diagram into three phases. The first one lasted ca 900 years (50 cm of sediments) and shows a cooling, the development of cold-demanding plant communities, deforestation and an increase in trophy. The cooling of the climate was revealed in higher curves of Juniperus, Poaceae and Artemisia. The presence of pollen grains of light-demanding Hippophaë proved deforestation and dominance of open plant communities. Apart from aforementioned Artemisia, there grew steppe plants like Ephedra distachya and E. fragilis, Helianthemum and some herbs of identified: Chenopodiaceae, Anthemis type, Cichorioidae. Dwarf shrubs developed in wet habitats, namely Betula nana type and Salix polaris type. Dryas octopetala appeared on soil patches rich in calcium carbonate. The second phase lasted not longer than 230 years (50 cm of sediments) and shows preservation of cold-demanding vegetation and high trophy of the lake. This is the phase of stable ex-istence of cold-demanding species. A cold steppe dominated by Poaceae and Artemisia was enriched by many herbal plants represented in pollen types: Gypsophila repens type, Rumex acetosella, Bupleurum, Senecio type, Anthemis type, Cichorioidae. Thalictrum, Valeriana officinalis, Solanum dulcamara, Rumex acetosa developed next to dwarf shrubs of Betula nana and Salix. Exclusively in this phase, there appeared pollen type of Saxifraga hieraciifolia, a plant of calcareous habitats in subarctic regions and high moun-tains. At the same time, Juniperus and steppe elements (Helianthemum, Ephedra) decreased. High curves of Pediastrum and disappearance of spores of Isoëtes revealed high trophy of the lake during this phase. The third phase lasted ca 120 years (30 cm) and shows a decrease in cold- and light-demanding tundra and steppe taxa. There were only single pollen grains of Betula nana, Salix polaris type, Dryas octopetala. Meanwhile, Ephedra, Helianthemum and Gypsophila repens type disappeared. Trophy was clearly decreasing. Significant changes in trophy are suggested mainly based on the presence of Isoëtes, a plant of a very nutrient-poor water. The main changes in trophy are revealed mainly by high curve of oligotrophic Isoëtes found at the end of Allerød and then at the end of the Younger Dryas, while a phase of high tro-phy is marked by growing curves of some varieties of Pediastrum boryanum. Pollen analyses of some sites in Poland suggest that vegetation succession driven by macro-climatic features is significantly modified by local factors such as geomorphology, topography and physico-chemical properties of the ground/ habitat. Periods of cooling and warming at the be-ginning and end of the Younger Dryas have previously been defined in detail for the laminated sediments of Lake Gościąż. Microfacies, isotops and other paleoclimatic analyses done for that site indicated that the decrease in temperature at the beginning of the Younger Dryas and its in-crease at the end lasted, respectively, 180 and 70 years. They are shorter periods than phases of vegetation changes, because the reac-tion of plants and ecosystems development takes more time. Most Younger Dryas pollen diagrams in Poland can be divided into two parts. The first, older one reveals the development of tundra and cold steppe vegetation as a result of the climate cooling. The second shows the disappearance of cold-demanding species and tundra vegetation and the development of plants of warmer climate such as Typha latyfolia and Filipendula. Such a division can be found on diagrams from the Witów, Gościąż, Kaniewo, Łukie sites. Some pollen records, however, show stable curves during the entire Younger Dryas (Perespilno, Imiołki).

地下水埋深和季节性干旱对古尔班通古特沙漠南缘梭梭生理和生长的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 地下水埋深和季节性干旱对古尔班通古特沙漠南缘梭梭生理和生长的影响 DOI: 10.5846/stxb202101190206 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 新疆维吾尔自治区天山青年计划项目（2020Q025）；国家自然科学基金项目（32171874）；新疆维吾尔自治区自然科学基金项目（2019D01A98） Effects of groundwater depth and seasonal drought on the physiology and growth of Haloxylon ammodendron at the southern edge of Gurbantonggut Desert 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:干旱区因降水稀少，地下水成为荒漠植被重要且稳定的水源。选取古尔班通古特沙漠南缘建群种植物梭梭（Haloxylon ammodendron）为研究对象，通过测量不同地下水埋深（3.45、9.08、10.47、13.27 m和15.91 m）下生长季前期和后期同化枝生理生化指标（黎明水势、正午水势、含水量、氯离子、钠离子、脯氨酸和非结构性碳水化合物）和生长与形态特征（生长速率和胡伯尔值），旨在认识荒漠植物对地下水埋深增加和季节性干旱的响应特征和调节适应机制。结果表明：（1）梭梭应对地下水埋深变化的生理调节对策，是采取先降低后升高黎明前同化枝水势、降低新枝形成期同化枝生长速率、增大胡伯尔值和积累非结构性碳水化合物的策略；（2）梭梭应对生长季大气干旱的生理调节对策，是通过降低黎明前同化枝水势、维持较高胡伯尔值、积累钠离子和消耗淀粉抵御季节性干旱；（3）在大气干旱与地下水水文干旱交互作用下，梭梭是采取降低正午同化枝水势、维持较高的同化枝含水量和积累可溶性糖的生态策略。综上所述，梭梭在响应地下水水文干旱和季节性大气干旱的生理特征间存在差异。研究结果丰富了水文和大气干旱对梭梭生理和生长影响的认知，可以为基于地下水资源管理的干旱区荒漠植被保育提供参考。 Abstract:Groundwater is an important and stable water source for desert vegetation due to the scarcity of precipitation in arid areas. Currently, anthropogenic withdraw of groundwater and climatic drought further limits the water availability for phreatophytic vegetation in arid regions and results in the decline of native vegetation. However, how phreatophytic plant response and adaptation to reduced water availability along the groundwater depth gradient are not clear. Haloxylon ammodendron was widely distributed in northwest arid zone of China and played an important role in desertification control. Groundwater was an important water resource for H. ammodendron. The declining groundwater depth has caused the partially decline even death of H. ammodendron in their native distribution area. In this study, we selected H. ammodendron, one of the main constructive species, at the southern edge of Gurbantonggut Desert as the taget species. In order to understand the response characteristics and regulatory adaptation mechanisms of desert plants to increasing groundwater depth and seasonal drought, we measured physiological and biochemical traits (including predawn water potential, midday water potential, water content, sodium ion, chloride ion, proline and non-structural carbohydrates), growth and morphological characteristics (including growth rate and Huber value) of assimilation branches in the early and late growing season under different groundwater depths (3.45, 9.08, 10.47, 13.27 and 15.91 m). The results showed that:(1) H. ammodendron adopted the strategy of first decreasing and then increasing predawn assimilation branch water potential, decreasing assimilation branch growth rate during new branch formation, increasing the Huber value and accumulating non-structural carbohydrates in response to increase in groundwater depth. (2) With the prolonged drought, H. ammodendron reduced predawn assimilation branch water potential, maintained high Huber values, accumulated sodium ions and consumed starch to resist seasonal drought during the growing season. (3) Reducing midday assimilation branch water potential, maintaining high assimilation branch water content and accumulating soluble sugars are ecological strategies in H. ammodendron to acclimate atmospheric and hydrological drought. In summary, there are differences in the physiological characteristics of H. ammodendron in response to groundwater hydrological drought and seasonally atmospheric drought. The results of the study enriched the knowledge of the effects of hydrological and atmospheric drought on the physiology and growth of H. ammodendron, and provided a reference for the conservation of desert vegetation based on groundwater resource management in arid areas. 参考文献 相似文献 引证文献