Classification and ordination of plant formations in the Pantanal of Brazil

Classification and ordination of plant formations are presented for a seasonally flooded plain of the Brazilian Pantanal. Phytosociological data were collected on 10 physiognomically distinct formations during the rainy, flood, and dry seasons. The degree of association among plant species was measured with Jaccard similarity index, and both Jaccard similarity index and Bray Curtis distance index were employed to classify sample units into similar groups. The ordination of plant species and sample units were performed with Correspondence Analysis. Four groups of plant formations were significantly distinct on a quantitative basis: marsh ponds/waterlogged basins, short grasslands, tall grassland/scrub, and forest-edges. These formations were ordered along a gradient of topographic relief from depressions with permanent standing water (marshes) through flats subject to seasonal flooding (grasslands and scrub) and mounds of sandy soil above the flood level (forests). Although hydroperiod appears to be one of the most important variables, the distribution of plant species within wetlands is most probably explained by the interaction of many additional factors. A few plant species could be used as indicators of the local hydrological and edaphic conditions, e.g., Eleocharis elegans, Aeschynomene fluminensis, Hydrolea spinosa, and Hymenachne amplexicaulis for marsh ponds, and Caperonia castaneifolia, Diodia kuntzei, and Eleocharis acutangula for waterlogged basins. The procedure presented in this study could be developed as a tool for the inventory and management of the Pantanal and other palustrine wetland habitats.     

An assessment of the aquatic and wetland vegetation of the Upper Mississippi River

Illinois, Iowa, Minnesota, Missouri, and Wisconsin have strong botanical traditions that have resulted in a macrophyte literature which documents the identity, taxonomy, floristics, and ecology of aquatic macrophytes and wetland vegetation of the Upper Mississippi River and its floodplain. These findings are reviewed with respect to floristics, vegetation dynamics (patterns, history, production and management), and environmental changes that impact vegetation. Aspects requiring future study are noted to direct subsequent investigations.     

Prediction of potential macrophyte development in response to restoration measures in an urban riverine wetland

Wetland restoration efforts require practical models for predicting the effects of various measures on ecosystem structure and function. The present study examined the species diversity and abundance of macrophytes in relation to hydrological parameters in the Alluvial Zone National Park along the Austrian Danube with a main focus on the Lobau, an urban riverine wetland within the city limits of Vienna. A macrophyte regression model was developed based on the output of a 2D hydraulic model for different wetland management options. These management options describe possible rehabilitation measures by re-connecting the riverine wetland with the Danube. Stepwise multiple regressions revealed that the most important predictors of macrophyte diversity and abundance were water velocity at bankfull discharge (maximum water velocity) and size of shallow water areas (<1 m depth) during the growing season. Macrophyte abundance and diversity increased with decreasing water velocity and increasing shallow water area. These parameters integrate information about environmental features such as nutrients, light availability and hydrological disturbance for macrophytes and explained between 65 and 85% of the macrophyte distribution in an analysis. The model results enabled us to predict quantitatively the development and spatial distribution of macrophytes for different management options in this urban riverine wetland. These predictions suggest that partial reconnection could be a compromise solution at the scale of the whole riverine wetland, increasing the availability of suitable aquatic habitats and diversifying the types of existing wetland water bodies to establish potential new habitats for macrophyte species.     

Spatial variability of the soil seed bank in a heterogeneous ephemeral wetland system in semi-arid Australia

Soil seed banks are an important component of plant community diversity in ephemeral wetlands, allowing many species to persist through unpredictable periods of flood and drought. Spatial variation of extant vegetation in such habitats commonly reflects patterns of flood history and often varies predictably between broadly differing hydro-geomorphic habitat types. Here we investigate whether spatial variation of soil seed banks is similarly controlled by fluvial processes at this scale. Results are presented from a seedling emergence trial using samples collected from a range of habitat types, and at different scales within these, in the ephemeral Narran Lakes system in semi-arid Australia. Composition and structure of soil seed banks varied significantly between habitat types reflecting broad differences in flood frequency. As predicted, germinable seed abundance was found to be highest in intermediately flooded habitats. Variability in soil seed bank composition at a local scale was also found to be influenced by hydrology with greater spatial heterogeneity evident in the river channel as well as amongst the least frequently inundated riparian and floodplain habitats.     

Planning for reserve adequacy in dynamic landscapes; maximizing future representation of vegetation communities under flood disturbance in the Pantanal wetland

Aim Using a probabilistic modelling framework, we aimed to incorporate landscape spatiotemporal dynamics into reserve design. We employed a spatially explicit stochastic model, which integrates both hydrological and biological processes, to simulate the wetland’s biological succession. Location Pantanal wetland (with 140,000 km²) between Brazil, Bolivia and Paraguay. Methods We used the reserve design software Marxan to optimize the current and future representation (up to 50 years) of 20% of five plant communities with maximum reliability (i.e. smallest uncertainty). The Kappa statistic was used to compare selection frequencies of individual sites through a set of planning timeframes (5, 17, 25 and 50 years) and the likely pattern of biological succession over these periods. Results Solutions based on static vegetation distributions were significantly dissimilar from solutions based on the expected modelled changes resulting from the flood disturbance and succession dynamics. Increasing the required reliability of biodiversity outcomes resulted in more expensive reserve solutions. We demonstrated the flexibility of probabilistic decision‐making methods to illuminate the trade‐offs between reliability and efficiency of site selection. Main conclusions Considering the importance of habitat heterogeneity to the principles and practice of systematic conservation planning, it is notable that landscape dynamics have not been a central theme in conservation planning. In the case of the Pantanal hydrosere, acknowledging and planning for temporal dynamics required an ability to model succession and define acceptable levels of outcome reliability, but ultimately improved the long‐term Adequacy of resulting reserve networks.     

Past vegetation changes in the Brazilian Pantanal arboreal–grassy savanna ecotone by using carbon isotopes in the soil organic matter

Measurements of the organic carbon inventory, its stable isotopic composition and radiocarbon content were used to deduce vegetation history from two soil profiles in arboreal and grassy savanna ecotones in the Brazilian Pantanal. The Pantanal is a large floodplain area with grass-dominated lowlands subject to seasonal flooding, and arboreal savanna uplands which are only rarely flooded. Organic carbon inventories were lower in the grassy savanna site than in the upland arboreal savanna site, with carbon decreasing exponentially with depth from the surface in both profiles. Changes in ¹³C of soil organic matter (SOM) with depth differed markedly between the two sites. Differences in surface SOM ¹³C values reflect the change from C₃ to C₄ plants between the sites, as confirmed by measurements of ¹³C of vegetation and the soil surface along a transect between the upland closed-canopy forest and lowland grassy savanna. Changes of ¹³C in SOM with depth at both sites are larger than the 3–4 per mil increases expected from fractionation associated with organic matter decomposition. We interpret these as recording past changes in the relative abundance of C₃ and C₄ plants at these sites. Mass balances with ¹⁴C and ¹³C suggest that past vegetational changes from C₃ to C₄ plants in the grassy savanna, and in the deeper part of the arboreal savanna, occurred between 4600 and 11 400 BP, when major climatic changes were also observed in several places of the South American Continent. The change from C₄ to C₃, observed only in the upper part of the arboreal savanna, was much more recent (1400 BP), and was probably caused by a local change in the flooding regime.     

Freshwater and wetland plant communities of Loch Lomond

Information on the aquatic and wetland vegetation of Loch Lomond, Scotland, is summarised for the period 1957–90. Aquatic macrophyte growth is estimated to occupy about 1% of the loch's total surface area, being limited to the 0–10 m euphotic zone, and probably excluded from much of this area by wave disturbance and unsuitable substrates. Aquatic vegetation is however abundant in sheltered bays and less-exposed shorelines, particularly in the South Basin of the loch. Although Littorella uniflora (L.) Aschers is the commonest, ubiquitous, submerged plant of the loch, three separate euhydrophyte communities have been identified within the loch. One of these is characterised by abundant stands of Elodea canadensis Michx., which appears to have invaded Loch Lomond some time between 1967–88, and has rapidly spread throughout the loch.     

Ant communities,environmental characteristics and their implications for conservation in the Brazilian Pantanal

Studies about processes determining biodiversity in Pantanal are urgently needed and the use of invertebrates for this purpose may be an efficient tool. The purpose of this paper is to verify whether ants could be used to predict human impacts on Pantanal, assessing how environmental characteristics of gallery forest influence arboreal ant species richness. Specifically, we tested the hypotheses that: (i) resource availability (estimated by tree density) and (ii) diversity of environmental conditions (estimated by structural heterogeneity) positively influence arboreal ant species richness and composition. Ants were sampled in a gallery forest in the Miranda River. Ant species richness did not respond to tree density, but increased with structural heterogeneity. Species composition was affected both by tree density and structural heterogeneity. The species list produced in the present study showed a high similarity between arboreal ant faunas of Cerrado and Pantanal, which are contiguous biomes. The relationship of ant species richness with heterogeneity, as well as the observed changes of species composition with tree density and heterogeneity may be explained by the presence of a variation of environmental conditions, which create several micro-habitats in the forest. The response of the ant community can reflect human impacts on the forests of the studied region, which are usually modified to create patches for sport fishing and by pathways used in ecotourism.     

小尺度高寒湿地放牧干扰格局——以纳帕海湿地为例

高寒湿地放牧干扰强烈,是其生态系统退化的主因。湿地植被生物量空间格局不仅能够反映自然因素的作用,也能够体现地域放牧等人类活动的主要特征,因此常作为表征放牧干扰格局的主要度量方法。但尺度效应导致的植被生物量影响要素在不同空间尺度下存在较大差异,尤其是针对面积为几十至几百km²范围的小尺度高寒湿地而言,自然因素和放牧等人为干扰对其植被地上生物量的共同作用特征仍不明确,缺乏针对该类型湿地的合理评估模式。以滇西北国际重要湿地纳帕海为例,在排除其它人为干扰的条件下,通过植被地上生物量的空间异质性特征来表征其放牧干扰格局,并以该案例为基础提出一种小尺度高寒湿地放牧干扰格局评估模式。研究尝试基于详细地面植被调查,获得潜在植被地上生物量,利用调查同时期高分定量遥感方法(法国PLEIADES卫星数据结合实测植被地上生物量建模)获得实际植被地上生物量,并使用潜在与实际植被地上生物量之差的空间异质性特征表示纳帕海湿地放牧干扰格局。该评估模式可以有效减少对于小尺度湿地放牧干扰数据的依赖,同时减少牛羊马等大牲畜散养带来的空间分布随机性。研究结果显示纳帕海湿地放牧干扰对湿地植被地上生物量的影响严重,影响比例约为93.5%。研究发现水文等自然因素和放牧等人为干扰分别决定纳帕海湿地植被地上生物量的上限和下限,并基于此提出四方面干扰调控策略。     

Mercury accumulation in sediment cores and along food chains in two regions of the Brazilian Pantanal

The Pantanal is a 140,000 km² floodplain wetland stretching acrosswestern Brazil and parts of Bolivia and Paraguay. Gold mining withmercury (Hg) amalgamation has thrived since 1980 along its northern rim. We quantified Hg accumulation in sediment cores (N = 5) and food chainsin this general region of the northern Pantanal and in a reference region,200 km deeper into the wetland (Acurizal). Cores were dated with²¹⁰Pb and ¹³⁷Cs using direct gamma-assay. Total Hg wasanalyzed by cold-vapor atomic fluorescence using a gold-meshpre-concentration trap. Average pre-1940 Hg accumulation in cores wasnot significantly different (N = 5, p= 0.14) between both regions andcomparable with rates calculated for global reference sites. Post gold-rushHg (post-1980) deposition averaged 55 ± 11.3 g m^-2yr^-1 in the northern impacted region and was more than 1.5 timeshigher than the post-1980 rate in Acurizal, implying a regional Hg effectof gold mining. Post-1980 Hg accumulation in Acurizal, in turn, was 2.1times the rate reported for a global reference during that time period,suggesting an additional basin-wide effect over such reference sites. Bycombining our core data with assessments of the size of the impacted areaand the amount of Hg released to the region since 1980, we estimated thatonly 2–8% of this Hg was recovered as a sedimentary signal. Theremainder of the Hg was lost to the atmosphere, downstream areas, orstored in biota. Hg concentrations in surface sediments in the northernPantanal (45.5 ± 5.5 ng g_dry ^-1) were significantlyhigher than those in our reference region (29.1 ± 0.7ng g_dry ^-1). Hg levels in primary producers were alsoelevated in the northern Pantanal. Eichhornia crassipes rootscontained 2.7–3.0 times more mercury than shoots in both regions and Salvinia auriculata, suggested as a biological monitor for Hg pollution,contained almost four times more mercury in the northern Pantanal (90.7± 9.1 ng g_dry ^-1) than in Acurizal (24.5 ± 3.3ng g_dry ^-1). Plant grazers and scavengers, such as apple snails(Pomacea sp.) and adult water beetles (Fam. Hydrophilidae), werelow in Hg, confirming previous data showing that the channeling of mercuryfrom lower to higher trophic levels along herbivorous links was inefficientcompared to transfer along carnivorous links. Collections of 12–16individuals of four species of Characidae (Aphyocharax sp., Tetragonopterus sp., Serrasalmus spiropleura and Pygocentrisnattereri) in both regions showed elevated Hg body burdens in bothpiranhas S. spiropleura and P. nattereri from the northernPantanal (149.9 ± 84.2 and 302.2 ± 159.1ng g_dry ^-1, respectively). Fish length for each species was notstatistically different between regions. P. nattereri length correlatedsignificantly (p<0.001) with Hg content in both regions, but the slopeof the regression in the northern Pantanal was 2.6 times the slope for theAcurizal collection, indicating an elevated rate of biomagnification in theHg-impacted region. Signals of Hg use in mining can be quantified insediment core chronologies and biological tissues, although species atdifferent trophic levels show dissimilar impacts. Mechanisms involved in Hgmagnification along food chains deserve more attention, particularly intropical regions where the threat of chronic exposure to this neurotoxinmay have the greatest implications for biodiversity.     

Small-sized fish as possible seed dispersers: disclosing novel fish and plant species interactions in the Pantanal wetland

ABSTRACT

Seed dispersion is a critical process to vegetation dynamics which is particularly complex in mosaic-like landscapes as the Pantanal wetlands. We analyzed some aspects of ichthyochory in the Pantanal flooded grasslands. The fish were collected and had their whole intestinal contents removed and submitted to suitable germination conditions for 179 days. We collected 661 specimens belonging to 40 species. Feces from Astyanax lacustris, Poptela paraguayensis, Moenkhausia sanctafilomena and Moenkhausia bonita produced 15 seedlings of herbaceous plant of the species Ludwigia inclinata, Ludwigia leptocarpa and a non-identified monocotyledon. A total of 30.4 g of fecal mass was recovered with a rate of 0.49 seedling.gram^?1. There is a positive relation between the number of seedlings obtained and the amount of fish fecal mass (g). Currently, Pantanal landscape dynamics is under rising pressure of field compartmentalization due to man-made roads which restrains fish transit.     

Dung beetle diversity and functions suggest no major impacts of cattle grazing in the Brazilian Pantanal wetlands

1. Dung beetles perform relevant ecological functions in pastures, such as dung removal and parasite control. Livestock farming is the main economic activity in the Brazilian Pantanal. However, the impact of cattle grazing on the Pantanal's native dung beetle community, and functions performed by them, is still unknown. 2. This study evaluated the effects of cattle activity on dung beetle community attributes (richness, abundance, biomass, composition, and functional group) as well as their ecological functions (dung removal and soil bioturbation) in the Pantanal. In January/February 2016, dung beetles were sampled and their ecological functions measured in 16 sites of native grasslands in Aquidauana, Mato Grosso do Sul, Brazil, 10 areas regularly grazed by cattle and six control ungrazed areas (> 20 years of abandonment). 3. In all, 1169 individuals from 30 species of dung beetles were collected. Although abundance, species richness, and biomass did not differ between grasslands with and without cattle activity, species composition and functional groups differed among systems. Large roller beetles were absent from non‐cattle grasslands, and the abundance, richness, and biomass of medium roller beetles was higher in those systems. 4. Despite causing changes in species/functional group composition, the results of this study show that a density compensation of functional groups in cattle‐grazed natural grasslands seems to have conserved the ecological functions (dung removal and soil bioturbation), with no significant differences between systems. 5. Therefore, these results provide evidence that cattle breeding in natural grasslands of the Brazilian Pantanal can integrate livestock production with the conservation of the dung beetle community and its ecological functions.     

四川省湿地水鸟资源现状与保护

为保护四川省湿地生境及生物多样性提供科学依据,于2014年12月至2018年12月对四川省湿地水鸟资源与栖息地进行了调查。在川西高原区、川西南山地区和四川盆地区共设置调查区域(点) 27个。调查记录湿地水鸟141种,加上以前有记录而本调查没有记录到的24种,四川湿地鸟类共计165种。实地调查到的141种湿地鸟类隶属于11目、23科,分别占全国水鸟目、科、种的73. 33%、65. 71%和43. 79%,其中国家一级保护鸟类7种,二级保护鸟类9种,四川省保护鸟类19种,CITES附录Ⅰ有3种,附录Ⅱ有8种。留鸟20种,夏候鸟23种,冬候鸟41种,旅鸟56种,迷鸟1种。区系组成包括古北界79种(59.57%)、东洋界33种(23.40%)、广布种29种(20.57%)。四川盆地区的物种数和种群数量最丰富,其次为川西高原区。四川盆地区与川西南山地区主要以冬候鸟和旅鸟为主,川西高原区则以夏候鸟为主。四川省湿地水鸟物种丰富,但人类活动导致湿地资源遭到破坏,影响了物种多样性,必须加强保护。     

Aquatic plant community composition and distribution along an inundation gradient at two ecologically-distinct sites in the Pantanal region of Brazil

In spite of its size and biological significance, we know little about the ecology of the Pantanal, a 140,000 km² floodplain in west-central Brazil. Increasing human pressures make this lack of understanding particularly critical. Using transects and 1 m² circular plots, we documented floristic composition and interacting-environmental conditions associated with littoral herbaceous vegetation along inundation gradients at two ecologically-distinct sites in the Pantanal. We recorded water depth and percent cover for each species in Baía Piuval, a bay in the Bento Gomes River (Mato Grosso), and in a bay in the Acurizal Reserve (Mato Grosso do Sul). Baía Piuval and Acurizal plots contained a total of 22 and 18 macrophyte species, respectively. At both sites Eichhornia azurea and Salvinia auriculata occurred most frequently as dominant or co-dominant species. Chi² analysis, used to quantify zonations along depth gradients, generated four different groups of species ( p < 0.05) for Baía Piuval. For Acurizal, two significantly different groups ( p < 0.05) occurred with an intermediate assemblage of species that could be assigned to either group. Canonical correspondence analysis, used to analyze species distributions, showed a pattern consistent with the Chi² results for Baía Piuval but not for Acurizal. Higher species richness and diversity occurred where dry season and low water levels coincided and richness was generally highest in proximal plots where water depths were lowest. Our results are consistent with the few other plant ecological studies reported for the Pantanal. This study can be considered additive to needed baseline data on biota and ecology of this region of South America.This revised version was published online in March 2005 with corrections to the issue cover date.     

The effects of fire on wetland structure and functioning

Fire is an extensively used wetland management tool in both tropical and temperate areas, but its effects on wetlands are not well understood. The purpose of this paper is to review the effects of fire on wetland hydrology, biogeochemical cycling and vegetation composition, including primary effects that take place during the fire such as combustion of plant material, loss of volatile substances to the atmosphere and deposition of ash on the soil surface, and secondary effects such as alteration of soil pH as a result of ash deposition, exposure of the soil surface to solar radiation, and increased availability of nutrients. Several of the secondary effects are most dramatic immediately after a fire, but become progressively modulated by newly stimulated vegetation growth. The findings suggest that the effects of fire depend upon a wetland's characteristics, including its climatic and hydrological context, as well as upon interactions with other disturbances such as grazing. Thus, similar fire regimes may have dramatically different outcomes. Where knowledge gaps were identified, some general predictions are offered, drawing from comparable ecosystems such as mesic grasslands. These predictions provide potential hypotheses for further research.     

美国湿地植物指示指标由来及应用

该文略述美国湿地植物指示指标由来并以俄亥俄州立大学湿地研究园人工实验湿地为例,详细地列出了该人工湿地建成15年后的植物及美国湿地植物指示。这个实例有助于中国的湿地恢复及保育。     

Degradation stages of the oak forests in the area of Algiers

Long lasting human impact on the natural Mediterranean vegetation is the reason for its degradation. Uncontrolled felling of trees, fire and overgrazing are the most important ecological causes of this process.Geobotanical investigations made in the area of Algiers facilitated the characterization of degradation changes in the structure of vegetation and in the floristic composition in all the degradation stages.Under the influence of the degradation factors, mentioned above, the oak forests, growing on different, more or less calcareous substrates, are transformed into various shrub formations, mainly into many types of maquis and garrigue. The floristic composition of these communities is given in Table 2.Further degradation leads to widespread Cistus-formations and then to palmitto, a formation created by the dwarf palm (Chamaerops humilis).When the anthropopressure becomes stronger even this dwarf palm retreats. Loose swards, replacing the palmitto formation, often cannot stop the subsequent degradation. Bare rock is the extreme, relatively rare stage of forest degradation in this area.The most common form of natural regeneration is the invasion of Pinus halepensis, observed in all degradation stages identified. This pine is also one of trees, most commonly planted on mountain slopes to prevent their erosion.     

西部高寒湿地系统的草地资源保护与优化利用模式研究

西部高寒湿地系统的草地资源保护与优化利用问题,是我国生态环境建设中倍受重视的科学问题。本研究以甘南的高寒湿地为研究对象,分析了高寒草地资源变化的时空分布特征及其在环境条件影响下的增长动态,采用生物控制论方法,组建了草地资源保护模型及草地放牧系统的最优控制模型。依据在甘南玛曲县高寒草地的调查结果,分别对其山地草原化草甸、山地典型草甸和沼泽草甸等草地资源的利用,建立了相应的保护指标。确定了该草地放牧系统的最优牧草资源水平和最优控制量,提出了草地资源优化利用的管理对策与措施,为草地放牧管理提供了优化模式和定量依据。