Permanent Wetlands Research Articles

The future of temporary wetlands in drylands under global change

ABSTRACT The Andalusian International University held a workshop entitled Temporary wetlands’ future in drylands under the projected global change scenario in March 2020 in Baeza, Spain, with 26 participants from 10 countries. The workshop objectives were to promote international cooperation and scientific exchange on the conservation and protection of temporary wetlands. The participants highlighted the extreme conditions that temporary and permanent wetlands, ponds, and shallow lakes are currently facing and predicted a dismal future for these systems due to climate change. To foster a holistic view of these ecosystems, the workshop included wetland watersheds. It was concluded that the main threats are those affecting water quality and quantity as well as egg-seed banks, species population dynamics, and food webs. The inherent characteristics of waterbodies in drylands, including high resilience and resistance to harsh conditions, are already negatively impacted by direct human actions and climate change. Another threat is the time lag between scientific warnings about threats and the social and political concern leading to mitigating actions. Thus, more effective actions to protect and conserve temporary wetlands are essential. Research networks could help stimulate the necessary conservation actions, but the global recession due to the COVID-19 pandemic will pose a challenge as economies are burdened with urgent expenditure. This special issue of the journal Inland Waters is the outcome of the workshop presentations and is composed of the ensuing papers on wetlands in drylands.

Multi-method biodiversity assessments from wetlands in Grand Teton National Park

A cost-efficient approach to long-term monitoring is to focus on one species or group of organisms as indicators of ecological condition. Through the use of autonomous monitoring technologies, monitoring programs can efficiently expand the biological community surveyed and inferences made. Amphibians have been monitored in Yellowstone and Grand Teton national parks by the Greater Yellowstone Inventory and Monitoring Network (GRYN) since 2006, yet other taxa dependent on wetlands have not been systematically studied. Our main aim was to explore what additional insights we could gain about wetland biodiversity by combining GRYN’s amphibian surveys with multiple autonomous technologies. We deployed wildlife cameras and acoustic recorders (for audible and ultrasonic sounds) at 4 permanent wetlands in Grand Teton National Park, WY during early and late summer 2017 and used descriptive metrics to summarize our findings. During GRYN’s surveys, 3 of 4 native amphibians were detected. With autonomous monitoring tools, we also documented avian and mammalian communities and detected changes in the degree of activity over the summer. Combining multiple, complementary technologies with field-based surveys provides a more comprehensive picture of wetland biodiversity and enhances insights about ecological condition and change.

Vegetation Changes in Response to Climatic Factors and Human Activities in Jilin Province, China, 2000–2019

Dynamic change in vegetation is an integral component of terrestrial ecosystems, which has become a significant research area in the current context of global climate warming. Jilin Province in northeast China is an ecologically fragile area, and there is an urgent need to understand its vegetation changes and responses to both climatic factors and human activities. The normalized difference vegetation index (NDVI) was used to analyze trends in vegetation growth, and indicated significant growth overall. The NDVI of different vegetation cover types is increasing, indicating that the vegetation is continuously greening, and in descending order, the growth trends were grassland (0.0035/year) > permanent wetland (0.0028/year) > cropland (0.0027/year) > forest land (0.0022/year) > barren land (−0.0001/year). Grassland and cropland vegetation types included the most severely degraded areas, with fluctuating NDVI values. Precipitation was the main positive controlling climatic factor of NDVI in the western regions of the study area, while average temperature was the main factor in the eastern regions. Precipitation was the main climatic control factor for grassland and cropland, while forest land was limited by precipitation and average temperature. Barren land and permanent wetland were slightly negatively correlated with precipitation. From 2000 to 2019, the residual values for NDVI increased from −0.0121 to 0.0116, and the impact of human activities on vegetation changed from negative to positive. By 2019, the proportion of positively affected zones was as high as 94.01%, and the negatively affected zones were mainly distributed across transitional areas of cropland and grassland, and urban and built-up land and forest land.

Larval development and survival of pond-breeding anurans in an agricultural landscape impacted more by phytoplankton than surrounding habitat.

The destruction of freshwater habitat is a major contributor to biodiversity loss in aquatic ecosystems. However, created or restored wetlands could partially mitigate aquatic biodiversity loss by increasing the amount of available habitat across a landscape. We investigated the impact of surrounding terrestrial habitat and water quality variables on suitability for two species of pond-breeding amphibians (bullfrogs [Lithobates catesbeianus] and Blanchard's cricket frogs [Acris blanchardi]) in created permanent wetlands located on an agricultural landscape. We examined tadpole growth and survival in field enclosures placed in ponds surrounded by agricultural, forested, or grassland habitats. We also evaluated the potential for carryover effects of the aquatic environment on terrestrial growth and overwinter survival of cricket frog metamorphs. We found that habitat adjacent to ponds did not predict tadpole growth or survival. Rather, phytoplankton abundance, which showed high variability among ponds within habitat type, was the only predictor of tadpole growth. Cricket frogs emerged larger and earlier from ponds with higher phytoplankton abundance; bullfrogs were also larger and at a more advanced developmental stage in ponds with higher levels of phytoplankton. Overwinter survival of cricket frogs was explained by size at metamorphosis and there were no apparent carryover effects of land use or pond-of-origin on overwinter growth and survival. Our results demonstrate that created ponds in human-dominated landscapes can provide suitable habitat for some anurans, independent of the adjacent terrestrial habitat.

Delimitation and classification of coastal wetlands: Implications for the environmental management of the Colombian Continental Caribbean

This article describes the cartographic layer construction process of Colombian Caribbean coastal wetlands at a scale of 1:100,000 and the results obtained in terms of their quantification and typing. Two cartographic layers were constructed and subsequently joined, one of the permanent water bodies and another of temporary water bodies and associated coverages. The layers were generated by multitemporal analysis of 45 Landsat 8-OLI satellite images, based on the NDVI index, uncertainty models by superposition of cartographic attributes, and a flood frequency consultation model on ALOS PALSAR 1 images. As a result, 576,279 ha of coastal wetlands were delimited (1.9 % of total wetlands in Colombia), of which 20.4 % are within protected areas. The cartographic legend makes it possible to typify wetlands based on the coverage and temporality of water bodies; discriminates permanent wetlands (42.7 %) with five categories and temporary wetlands (57.3 %) with 15 categories, mostly distributed in seven large complexes. This study is the first description of the colombian Caribbean coastal wetlands based on a cartographic construction, is methodologically replicable, and will support decision-making in the planning of colombian Caribbean coastal areas, especially for risk management and ecosystem-based adaptation to climate change.

Pre-Columbian fire management and control of climate-driven floodwaters over 3,500 years in southwestern Amazonia

In landscapes that support economic and cultural activities, human communities actively manage environments and environmental change at a variety of spatial scales that complicate the effects of continental-scale climate. Here, we demonstrate how hydrological conditions were modified by humans against the backdrop of Holocene climate change in southwestern Amazonia. Paleoecological investigations (phytoliths, charcoal, pollen, diatoms) of two sediment cores extracted from within the same permanent wetland, ∼22 km apart, show a 1,500-y difference in when the intensification of land use and management occurred, including raised field agriculture, fire regime, and agroforestry. Although rising precipitation is well known during the mid to late Holocene, human actions manipulated climate-driven hydrological changes on the landscape, revealing differing histories of human landscape domestication. Environmental factors are unable to account for local differences without the mediation of human communities that transformed the region to its current savanna/forest/wetland mosaic beginning at least 3,500 y ago. Regional environmental variables did not drive the choices made by farmers and fishers, who shaped these local contexts to better manage resource extraction. The savannas we observe today were created in the post-European period, where their fire regime and structural diversity were shaped by cattle ranching.

Landscape transformation after irrigation development in and around a semi-arid wetland ecosystem

The objectives of this study are to determine the spatial and temporal land use/cover changes in a semi-arid agricultural basin (Develi Basin) after the implementation of an irrigation project and to understand how these changes affected the wetlands (Sultan Marshes) located in the basin. The changes were determined using multitemporal Landsat Thematic Mapper and Landsat 8 Operational Land Imager imagery taken in 1987, 1998, 2007, and 2013. The images were classified into six information classes (grasslands/shrublands, croplands, permanent wetlands, water bodies, barren, and urban/built-up) using a hybrid classification method. Post-classification change detection was applied to determine the changes between different years. Overall, the accuracy of the classified images ranged from 85 to 94%. Grasslands/shrublands covered the largest area in the basin (63% in 2013), followed by croplands (32% in 2013). The area covered by water bodies, permanent wetlands, barren, and urban/built-up was 5% (in 2013). From 1987 to 2013, croplands expanded by 56%, while grasslands/shrublands declined by 15%. The areas occupied by water bodies decreased by 88% and permanent wetlands decreased by 4%. Urban/built-up areas expanded by 140%. The hydrologic regime of the Sultan Marshes wetland changed, which resulted in declines in water volumes by 85% and in water inflows by 55% from 2000 to 2015. Climatic variations during the 1987–2013 period were low and there was no apparent trend in precipitation and air temperature, which ruled out climatic conditions as one of the drivers of wetland changes. Economic and institutional factors supported the expansion of irrigated agriculture and animal husbandry in the basin and accelerated the expansion of croplands and conversion to industrial and fodder crops and orchards from traditional non-irrigated crops. Expansion of croplands and irrigated agriculture were the major drivers of the changes in the Sultan Marshes.

Corrigendum: Extrapolation and Uncertainty Evaluation of Carbon Dioxide and Methane Emissions in the Qinghai-Tibetan Plateau Wetlands Since the 1960s

Wetlands are important modulators of atmospheric greenhouse gas (GHGs) concentrations. However, little is known about the magnitudes and spatiotemporal patterns of GHG fluxes in wetlands on the Qinghai-Tibetan Plateau (QTP), the world’s largest and highest plateau. In this study, we measured soil temperature and the fluxes of carbon dioxide (CO2) and methane (CH4) in an alpine wetland on the QTP from April 2017 to April 2019 by the static chamber method, and from January 2017 to December 2017 by the eddy covariance (EC) method. The CO2 and CH4 emission measurements from both methods showed different relationships to soil temperature at different timescales (annual and seasonal). Based on such relationship patterns and soil temperature data (1960-2017), we extrapolated the CO2 and CH4 emissions of study site for the past 57 years: the mean CO2 emission rate was 1096.59 mg C m-2 h-1 on different measurement methods and timescales, with the range of the mean emission rate from 421.17 to 1754.99 mg C m-2 h-1, while the mean CH4 emission rate was 32.99 mg C m-2 h-1, with the ranges of the mean emission rate from 16.95 to 46.25 mg C m-2 h-1. The estimated regional CO2 and CH4 emissions from permanent wetlands on the QTP were 94.29 and 2.37 Tg C year-1, respectively. These results indicate that uncertainties caused by measuring method and timescale should be fully considered when extrapolating wetland GHG fluxes from local sites to the regional level. Moreover, the results of global warming potential showed that CO2 dominates the GHG balance of wetlands on the QTP.

Comparison of sampling methods for benthic macroinvertebrates in forested wetlands

Forest wetlands are biodiversity hotspots that perform functions of vital ecological importance, but they are among the world's most threatened ecosystems. Due to their high diversity of habitats and species, the study of their benthic macroinvertebrate communities is challenging, and there is no consensus on which sampling methods allow a better representation of these communities. Here we compared the performance of 3 sampling methods (hand net, corer and litterbags) in 2 temporary and 3 permanent forested wetlands in southern Chile, which were bimonthly sampled throughout a year, with 108 samples per wetland. Our results indicated that the greatest abundance and diversity were collected with the hand net, followed by the litterbags and the corer. The composition of communities collected by the hand net and litterbags were more similar between them than that of communities collected by the corer (where Chironomidae and Oligochaeta were common). We suggest that the combined use of the hand net and corer could provide a good representation of macroinvertebrate communities in forest wetlands, as they would allow recording most of the diversity, including taxa that are both sensitive and tolerant to stressors.

The environmental and ecological determinants of elevated Ross River Virus exposure in koalas residing in urban coastal landscapes

Koala populations in many areas of Australia have declined sharply in response to habitat loss, disease and the effects of climate change. Koalas may face further morbidity from endemic mosquito-borne viruses, but the impact of such viruses is currently unknown. Few seroprevalence studies in the wild exist and little is known of the determinants of exposure. Here, we exploited a large, spatially and temporally explicit koala survey to define the intensity of Ross River Virus (RRV) exposure in koalas residing in urban coastal environments in southeast Queensland, Australia. We demonstrate that RRV exposure in koalas is much higher (> 80%) than reported in other sero-surveys and that exposure is uniform across the urban coastal landscape. Uniformity in exposure is related to the presence of the major RRV mosquito vector, Culex annulirostris, and similarities in animal movement, tree use, and age-dependent increases in exposure risk. Elevated exposure ultimately appears to result from the confinement of remaining coastal koala habitat to the edges of permanent wetlands unsuitable for urban development and which produce large numbers of competent mosquito vectors. The results further illustrate that koalas and other RRV-susceptible vertebrates may serve as useful sentinels of human urban exposure in endemic areas.

Estimation of Water Coverage in Permanent and Temporary Shallow Lakes and Wetlands by Combining Remote Sensing Techniques and Genetic Programming: Application to the Mediterranean Basin of the Iberian Peninsula

This work aims to validate the wide use of an algorithm developed using genetic programing (GP) techniques allowing to discern between water and non-water pixels using the near infrared band and different thresholds. A total of 34 wetlands and shallow lakes of 18 ecological types were used for validation. These include marshes, salt ponds, and saline and freshwater, temporary and permanent shallow lakes. Furthermore, based on the spectral matching between Landsat and Sentinel-2 sensors, this methodology was applied to Sentinel-2 imagery, improving the spatial and temporal resolution. When compared to other techniques, GP showed better accuracy (over 85% in most cases) and acceptable kappa values in the estimation of water pixels (κ ≥ 0.7) in 10 of the 18 assayed ecological types evaluated with Landsat-7 and Sentinel-2 imagery. The improvements were especially achieved for temporary lakes and wetlands, where existing algorithms were scarcely reliable. This shows that GP algorithms applied to remote sensing satellite imagery can be a valuable tool to monitor water coverage in wetlands and shallow lakes where multiple factors cause a low resolution by commonly used water indices. This allows the reconstruction of hydrological series showing their hydrological behaviors during the last three decades, being useful to predict how their hydrological pattern may behave under future global change scenarios.

Water use efficiency in terrestrial ecosystem over East Asia: Effects of climate regimes and land cover types

Water use efficiency (WUE) is an environmental factor to account for the metabolism of terrestrial ecosystems using various climate systems and vegetation types. It is estimated by the ratio of gross primary productivity (GPP) to evapotranspiration (ET), the largest carbon and water fluxes with respect to plant respiration. In this study, the WUE was calculated using GPP and ET from the community land model version 4.0 (CLM4.0), inclusive of the prognostic carbon-nitrogen model in the community earth system model (CESM). The estimated WUE in East Asia was analyzed for climate zones, land cover types, and water- and energy-limited zones, with aridity index (AI). Spatial variations from 2001 to 2015 in annual WUE gradually increased as latitude decreased, though small year-to-year differences appeared between monthly GPP and ET. Monthly WUE was lower in summer than fall because the water loss rate in summer was higher than the carbon assimilation increase. The WUE under arid conditions (AI<0.5) was lower than under humid conditions. The GPP, ET, and WUE were higher in the forest, savannas, cropland, and permanent wetland with dense vegetation or abundant water resources than in other land cover types. The WUE was lower in water-limited zones than in energy-limited zones due to the low amount of water to use for the physical processes of GPP and ET. Based on this study, we identified general spatial and temporal variations of carbon fluxes in East Asia with various climate zones and land cover types.

The Early Bronze Age dendrochronology of Sovjan (Albania): A first tree-ring sequence of the 24th – 22nd c. BC for the southwestern Balkans

The archaeological site of Sovjan is situated on the edge of the Korçë Basin, southeastern Albania. Its remarkably long and well investigated stratigraphic sequence, spanning from the Neolithic till the Iron Age, makes it an important type- and reference-site for the whole region. At different periods of prehistory it was located on the shores of the former Lake Maliq that once filled the Korçë Basin, but was definitely drained in the 1940′s. These permanent wetland conditions on the site allowed for a high degree of preservation of organic material, especially wood. Based on the current knowledge, level 8 of Sovjan contains the best-preserved wooden material of all the Early Bronze Age sites in the Balkans. Through the combination of dendrochronology and Bayesian modelling, i.e. wiggle-matching, a floating 269-years long tree-ring chronology was constructed, with an absolute end-date range falling between 2158 and 2142 cal BC (2σ). It was possible to establish that the dwellings and the trackway associated with the last occupation phase of level 8 are contemporaneous. Additionally, with the help of the new dendrochronological data and based on previously published charcoal dates, the absolute chronology of the subsequent level 7 is being narrowed-down to a range from the mid-22nd to mid-20th c. cal BC (2σ). The Early Bronze Age layers of the archaeological site of Sovjan, which are particularly pertinent for the 3rd millennium chronology of the southwestern Balkans, can now be dated with high precision for the first time and hence offer a major chronological reference point in the region.

Assessing the potential of integrating distribution and structure of permanent open-water wetlandscapes in reclamation design: a case study of Alberta, Canada

Wetlands are multi-functional systems that provide a disproportionatenumber of ecosystem services given the spatial extent they occupy bothnationally and globally. The ecological functioning of these wetlands isdependent on the structure of the landscape, which poses unique challenges whenreclaiming wetlands in areas where resource extraction is occurring. Resource extraction mega-projects requirethat entire wetlandscapes be reclaimed and often involve timelines thatnecessitate the consideration of climate projections to create self-sustaining,naturally appearing wetlandscapes that meet policy objectives. To understandwetlandscape structure and guide reclamation planning and closure permittingevaluation, a random sample of 13,676 1-km2 landscapes weresubselected to identify 1684 permanent open-water wetlandscapes. A parsimoniousset of landscape metrics were applied and compared across levels ofanthropogenic disturbance and across natural regions (i.e., Grassland, Parklandand Boreal). Results demonstrated that permanent open-water wetlands arerelatively rare (12.3% of our total random sample) and typically occupy lessthan 8% of wetlandscapes when present. The majority of wetlands in the study area are lesspermanent and more variable in nature than the permanent open waterwetlandscapes created by megaproject reclamation, which has the potential to alter thedistribution and size of open-water wetlands beyond their natural occurrence.Comparison across disturbance levels and natural regions yield statisticaldifferences among landscape structure. General wetland landscapes representinga combination of disturbance level and natural region can be created for eachmetric to guide reclamation design and closure planning approval.

Cladocera resting egg banks in temporary and permanent wetlands

Cladocerans are important filter-feeders transferring energy up the food web to different invertebrate and vertebrate predators. Along the flood period, cladocerans are one of the primary food sources for juvenile fish in floodplain. Resting egg banks allow cladoceran populations to overcome the environmental stress, related to several limnological changes, including complete drying of temporary wetlands. After drought, resting egg banks influence cladoceran community attributes during the cyclic and successional processes driven by episodic flood events. In this study we compared the taxonomic richness of active (from the water column) and dormant (from the sediment) Cladocera assemblages and analyzed the structure of resting egg banks, comparing the diversity, abundance and apparent viability/unviability of the eggs, between six temporary and six permanent wetlands, located along the Ovens River Floodplain, Victoria, Australia. The qualitative analysis shows higher taxonomic richness in active assemblages from temporary (24 taxa) than permanent (13 taxa) wetlands compared to dormant assemblages present in resting egg banks (9 taxa) from temporary and permanent wetlands. However, richness was influenced by taxonomic level of identification, with the majority of resting eggs only being identified to the taxonomic level of family (i.e. Chydoridae). Total taxa richness within egg banks was similar between wetland types, however, on average higher Shannon’s diversity of resting eggs was found within permanent (1.53) than temporary (0.82) wetlands. This is likely to be due to more stable wetlands not providing appropriate cues to trigger dormancy induction or breakage for specific populations, leading to higher values of evenness in permanent than temporary wetlands. Comparing permanent and temporary wetlands, higher abundance of resting eggs (more than four times) consisting of higher abundance of unviable eggs and similar viable egg abundance to permanent wetlands, was found within temporary wetlands, suggesting that the increased resting egg abundance in temporary wetlands is balanced by the losses due to factors such as predation, parasitism or other physical damage, during the terrestrial phase. Despite resistant outer shell structure, this study highlights that the damage to egg integrity is intensified in wetlands that undergo dry phases. Cladoceran resting egg banks represent the potential assemblage to recover after disturbance events such as drying, and information about these is important to ensure appropriate management and conservation of floodplain biodiversity.

Nutrient Retention in Ecologically Functional Floodplains: A Review

Nutrient loads in fresh and coastal waters continue to lead to harmful algal blooms across the globe. Historically, floodplains—low-lying areas adjacent to streams and rivers that become inundated during high-flow events—would have been nutrient deposition and/or removal sites within riparian corridors, but many floodplains have been developed and/or disconnected. This review synthesizes literature and data available from field studies quantifying nitrogen (N) and phosphorus (P) removal within floodplains across North America and Europe to determine how effective floodplain restoration is at removing nutrients. The mean removal of nitrate-N (NO3−-N), the primary form of N in floodplain studies, was 200 (SD = 198) kg-N ha−1 year−1, and of total or particulate P was 21.0 (SD = 31.4) kg-P ha−1 year−1. Based on the literature, more effective designs of restored floodplains should include optimal hydraulic load, permanent wetlands, geomorphic diversity, and dense vegetation. Floodplain restorations along waterways with higher nutrient concentrations could lead to a more effective investment for nutrient removal. Overall, restoring and reconnecting floodplains throughout watersheds is a viable and effective means of removing nutrients while also restoring the many other benefits that floodplains provide.

Assessing the interaction of land cover/land use dynamics, climate extremes and food systems in Uganda

Rainfed agriculture is Uganda's mainstay across the different regions of its territory. Farmland area has been reported to increase despite agriculture's vulnerability to climate variations. This great interplay among land-use dynamics, climate extremes, and food systems is, however, understudied. The current research, therefore, explores this interaction at both national and regional scales for the period between 2001 and 2017. Following an approach that employs remote sensing datasets on Net Primary Productivity (NPP), land cover types, drought indices, and climate variables, i.e. precipitation, temperature, and evapotranspiration, impacts of climate extremes and land cover changes on food production have been analysed. Similarly, the performance of ten major crops in Uganda over the last 6 decades has been detected using the Regime Shift technique. Key findings, thereof, indicate that NPP in farmlands is sensitive to climate variability, and this sensitivity varies spatially among the regions. Forests and permanent wetlands have been massively changed into farmlands, hence, moving a step forward into offsetting food insecurity but a step backward in preserving ecosystem services, espcially mitigating climate change. Furthermore, the noticeable increase in the total production of the major crops in Uganda seems to be derived mainly by the increase in area harvested affirming the step towards food security. However, the influences, thereof, may aggravate climate change impacts especially through reversing carbon sinks into carbon sources. This reversal could impact the crop yields further. Contrastingly, results from some crops illustrate the potential to increase crop production without necessarily expanding the cropland area. Therefore, Uganda may, instead, consider exploiting the maximum yield potential of crops through, for instance, augmenting rainfed agriculture with irrigation and enforcing effective policies rather than expanding farmland area. These findings collectively contribute further to our understanding of the importance of policies that ensure food security but at the same time preserve a healthy environment.

High productivity of Peneroplis (Foraminifera) including aberrant morphotypes, in an inland thalassic salt pond at Lake Macleod, Western Australia

Abstract Growth variability in extant Peneroplis has drawn attention since early times. There is general agreement that the aberrations in recent populations of Peneroplis are natural and intraspecific. For these reasons, some authors have questioned the systematic relationships among living Peneroplis species. In this study, we explore variation in an exceptionally abundant population of Peneroplis from Pete's Pond, a permanent wetland, within the Lake Macleod Evaporate Basin, Western Australia. The area is unusual because foraminifera are isolated from the nearby ocean, except for a 15-km subterranean karst system that permits a constant delivery of seawater. Pete's Pond water salinities are either less than or at normal seawater levels. The morphological variations identified have been grouped, with morphogroups A, B, and C referred to as variants of the Peneroplis growth pattern, including morphotypes with high flaring and cylindrical uniserial chambers. Morphogroups D and E are referred to as ‘abnormal’ aberrant forms, which show bifurcated serial chambers or a disordered growing style. Variants are the most critical in terms of taxonomic discrimination. Here we recommend the following morphological constraints for species determination of Peneroplis variants: i) degree of involution of early chambers; ii) presence/absence of umbilical depressions, iii) incision of sutures and iv) ornament, including the presence and disposition of small pits or ribs. Aberration in Peneroplis is considered to be linked to strict environmental parameters that have led to optimum shell growth as well as to having a key role in the phylogenesis of Soritoidea through deep time.

Extrapolation and Uncertainty Evaluation of Carbon Dioxide and Methane Emissions in the Qinghai-Tibetan Plateau Wetlands Since the 1960s

Wetlands are important modulators of atmospheric greenhouse gas (GHGs) concentrations. However, little is known about the magnitudes and spatiotemporal patterns of GHGs fluxes in wetlands on the Qinghai-Tibetan Plateau (QTP), the world’s largest and highest plateau. In this study, we measured soil temperature and the fluxes of carbon dioxide (CO2) and methane (CH4) in an alpine wetland on the QTP from April 2017 to April 2019 by the static chamber method, and from January 2017 to December 2017 by the eddy covariance (EC) method. The CO2 and CH4 emission measurements from both methods showed different relationships to soil temperature at different timescales (annual and seasonal). Based on such relationship patterns and soil temperature data (1960–2017), we extrapolated the CO2 and CH4 emissions of study site for the past 57 years: the mean CO2 emission rate was 91.38 mg C m–2 h–1 on different measurement methods and timescales, with the range of the mean emission rate from 35.10 to 146.25 mg C m–2 h–1, while the mean CH4 emission rate was 2.75 mg C m–2 h–1, with the ranges of the mean emission rate from 1.41 to 3.85 mg C m–2 h–1. The estimated regional CO2 and CH4 emissions from permanent wetlands on the QTP were 94.29 and 2.37 Tg C year–1, respectively. These results indicate that uncertainties caused by measuring method and timescale should be fully considered when extrapolating wetland GHGs fluxes from local sites to the regional level. Moreover, the results of global warming potential showed that CO2 dominates the GHG balance of wetlands on the QTP.

Conservation Status and Sex Ratios of the Coahuila Box Turtle (Terrapene coahuila) in the Cuatro Ciénegas Valley of Coahuila, Mexico, 2011–2018

The Coahuila box turtle (Terrapene coahuila) is an endangered species of chelonian endemic to the Cuatro Ciénegas valley in northern Mexico. It is the only aquatic member of the genus Terrapene and is dependent on permanent and seasonal wetlands. Over the past several decades, T. coahuila populations have declined from habitat loss as the wetlands have dried due to human modification of the valley. We conducted a survey of the status of the species from 2011 to 2018, updating previous estimates of population density and overall population size. We also collected data on sex ratio in each of the 8 wetland study areas in the valley and report a strongly male-biased sex ratio. Our results indicate a total population size of approximately 1791 individuals, based on recorded densities from 0.24 to 3.3 individuals/ha among 539.76 ha of suitable habitat in the 8 wetland areas. This estimate is lower than previous studies indicated, implying direct effects of habitat loss on T. coahuila. If habitat loss due to lowering of the water table continues, this species will become extinct. We recommend conservation measures including upgrading the species' International Union for Conservation of Nature Red List status to Critically Endangered, protecting and restoring key wetlands in the valley, and establishing captive assurance colonies in Mexico.