Aquatic Vegetation Loss and Its Implication on Climate Regulation in a Protected Freshwater Wetland of Po River Delta Park (Italy)

Aquatic vegetation loss caused substantial decrease of ecosystem processes and services during the last decades, particularly for the capacity of these ecosystems to sequester and store carbon from the atmosphere. This study investigated the extent of aquatic emergent vegetation loss for the period 1985–2018 and the consequent effects on carbon sequestration and storage capacity of Valle Santa wetland, a protected freshwater wetland dominated by Phragmites australis located in the Po river delta Park (Northern Italy), as a function of primary productivity and biomass decomposition, assessed by means of satellite images and experimental measures. The results showed an extended loss of aquatic vegetated habitats during the considered period, with 1989 being the year with higher productivity. The mean breakdown rates of P. australis were 0.00532 d−1 and 0.00228 d−1 for leaf and stem carbon content, respectively, leading to a predicted annual decomposition of 64.6% of the total biomass carbon. For 2018 the carbon sequestration capacity was estimated equal to 0.249 kg C m−2 yr−1, while the carbon storage of the whole wetland was 1.75 × 103 t C (0.70 kg C m−2). Nonetheless, despite the protection efforts over time, the vegetation loss occurred during the last decades significantly decreased carbon sequestration and storage by 51.6%, when comparing 2018 and 1989. No statistically significant effects were found for water descriptors. This study demonstrated that P. australis-dominated wetlands support important ecosystem processes and should be regarded as an important carbon sink under an ecosystem services perspective, with the aim to maximize their capacity to mitigate climate change.

Diversity of Macro Invertebrates and Their Habitat Characteristics in Lan-Kuu Freshwater Wetland, Myanmar

Lan-Kuu freshwater wetland of Auk SaThar in Mingin Township, Sagaing Region was investigated for its species composition, relative abundance, and diversity of aquatic macro-invertebrates from June 2020 to January 2021. This wetland has water throughout the year and is used by many local people for fishing and trapping birds. Thirty macro invertebrates’ species belonging to 28 genera, 19 families, 11 orders, 5 classes, and 3 Phyla were identified and recorded. These species belonged to the orders Hemiptera (23%), Coeleoptera and Odonata (14% each), Orthoptera, Architaenioglossa and Sorbeoconcha (10% each), Lepidoptera (7%), and Hymenoptera, Araneae, Decapoda, and Opithopora (3%). Among the collected specimens Dytiscus verticalis accounted for the highest number of individuals while the least number of individuals were Arocatus rusticus. Average relative abundance indicated 9 species as ‘uncommon’, 14 species as ‘common’ and 7 species as very common in the studied wetland. According to the Shannon index, the diversity of macro-invertebrates recorded in Lan-Kuu freshwater wetland, Myanmar, was high, (2.746-3.016), and so was the evenness (0.888-0.956).

Geochemical and sedimentary constraints on the formation of the Venta Micena early Pleistocene site (Guadix-Baza Basin, Spain)

Despite the paleontological relevance of the terrestrial Early Pleistocene Venta Micena bonebed (Baza Basin, Spain), it lacks a comprehensive geochemical/sedimentological study. Here, we demonstrate that the 1.5-m-thick Venta Micena limestone formed in a relatively small freshwater wetland/pond located at the periphery of the large saline Baza paleolake. Two microfacies are observed, with high and low contents of invertebrate fossils, and which originated in the centre and margin of the wetland, respectively. X-ray diffraction (XRD) mineralogy and paleohydrological characterization based on ostracod and bulk-rock geochemistry (δ13C and δ18O) indicate that the limestone reflects a general lowstand of the Baza lake, permitting the differentiation of freshwater wetlands that were fed by adjacent sources. Conversely, during highstands, the Baza lake flooded the Venta Micena area and the freshwater fauna was replaced by a saline one. Bulk-rock isotopic data indicate that the lower interval C1 of the limestone (bone-rich in marginal settings) displays general negative values, while the upper interval C2 (bone free) displays less negative values. The bones of predated mammals accumulated in the marginal areas, which were flooded and buried by recurring water-table fluctuations. Lake dynamics played a critical role in bone accumulation, which was previously considered as representing a hyena den.

Anthropogenic impacts on Late Holocene land-cover change and floristic biodiversity loss in tropical southeastern Asia

Southern China and Southeast Asia witnessed some of their most significant economic and social changes relevant to human land use during the Late Holocene, including the intensification and spread of rice agriculture. Despite rice growth being associated with a number of earth systems impacts, how these changes transformed tropical vegetation in this region of immense endemic biodiversity remains poorly understood. Here, we compile a pollen dataset incorporating ∼150,000 identifications and 233 pollen taxa to examine past changes in floral biodiversity, together with a compilation of records of forest decline across the region using 14 pollen records spanning lowland to mountain sites. Our results demonstrate that the rise of intensive rice agriculture from approximately 2,000 y ago led not only to extensive deforestation but also to remarkable changes of vegetation composition and a reduction in arboreal diversity. Focusing specifically on the Tertiary relic tree species, the freshwater wetland conifer Glyptostrobus (Glyptostrobus pensilis), we demonstrate how key species that had survived changing environmental conditions across millions of years shrank in the face of paddy rice farming and human disturbance.

Nitrous Oxide Emission from a Flooded Tropical Wetland across a Vegetation and Land Use Gradient

Whereas wetland ecosystems are among the most vital natural carbon sinks, they are also important sources of nitrous oxide (N2O), a highly potent greenhouse gas. However, due to differences in wetland characteristics, N2O emission is likely to vary across wetland types. We investigated the: 1) influence of vegetation community (Typha latifolia; Typha, Phragmites mauritianus; Phragmites and Cyperus papyrus; Papyrus) in a natural tropical freshwater wetland, and 2) impact of converting a natural tropical freshwater wetland into a rice paddy wetland on N2O emission. Results showed that N2O emission (µg m− 2 h− 1) from the natural wetland did not vary significantly (p > 0.05) among the vegetation communities during both the dry and wet seasons (Typha = 0.6 ± 1.6 [SE] and 0.5 ± 1.4, Phragmites = 0.5 ± 1.7 and 0.4 ± 1.5, Papyrus = 0.5 ± 1.3 and 0.5 ± 1.5, respectively). These emission rates insignificantly differed (p > 0.05) from those recorded in the rice paddy wetland (dry season = 0.7 ± 2.8 and wet season = 0.6 ± 2.7). There was no significant correlation (p > 0.05) between soil physico-chemical characteristics and N2O emission. We concluded that vegetation community does not affect N2O emission from a natural tropical freshwater wetland under continuous flooding. Similarly, under continuous flooding and no fertilization conditions, converting a natural tropical freshwater wetland into a rice paddy wetland does not influence N2O emission. We roughly estimated total annual N2O emissions (T yr− 1) and their carbon dioxide equivalents (CO2e; T yr− 1) from all Uganda’s natural and rice paddy wetlands as: natural wetlands = 115.1 ± 342.8 (CO2e = 30,501.5 ± 90,842) and rice paddy wetlands = 0.9 ± 2.7 (CO2e = 242.5 ± 707.6).