Funding information National Science Foundation, Grant/Award Numbers: 1354900, 1441188; Purdue University Abstract Wetlands play an important role in watershed eco-hydrology. The occurrence and distribution of wetlands in a landscape are affected by the surface topography and the hydro-climatic conditions. Here, we propose a minimalist probabilistic approach to describe the dynamic behaviour of wetlandscape attributes, including number of inundated wetlands and the statistical properties of wetland stage, surface area, perimeter, and storage volume. The method relies on two major assumptions: (a) wetland bottom hydrologic resistance is negligible; and (b) groundwater level is parallel to the mean terrain elevation. The approach links the number of inundated wetlands (depressions with water) to the distribution of wetland bottoms and divides, and the position of the shallow water table. We compared the wetlandscape attribute dynamics estimated from the probabilistic approach to those determined from a parsimonious hydrologic model for groundwater-dominated wetlands. We test the reliability of the assumptions of both models using data from six cypress dome wetlands in the Green Swamp Wildlife Management Area, Florida. The results of the hydrologic model for groundwater-dominated wetlands showed that the number of inundated wetlands has a unimodal dependence on the groundwater level, as predicted by the probabilistic approach. The proposed models provide a quantitative basis to understand the physical processes that drive the spatiotemporal hydrologic dynamics in wetlandscapes impacted by shallow groundwater fluctuations. Emergent patterns in wetlandscape hydrologic dynamics are of key importance not only for the conservation of water resources, but also for a wide range of eco-hydrological services provided by connectivity between wetlands and their surrounding uplands.

Wetlandscape hydrologic dynamics driven by shallow groundwater and landscape topography

Assessing the safe operating space of aquatic macrophyte biomass to control the terrestrialization of a grass-type shallow lake in China.

Abstract This paper presents development of the paleolake Starowlany existing in the Eemian Interglacial (MIS 5e) in north - eastern Poland. The lake history is based on Cladocera analysis. The paleolake Starowlany is located in the central part of the Sokółka Hills, approximately 9 km north of the town of Sokółka in the North Podlasie Lowland. The sediments studied filled a southern part of a tunnel valley formed during the Warta Glaciation. The coring was carried out with a geological drilling and constituted a part of the frame work aimed at preparing the Sokółka sheet for the Detailed Geological Map of Poland in scale 1:50000. The core was 7 m long. Peaty silt, peats and organic silt were present at the depth of 4.0-6.6 m, under deluvial sands, tills and silt. Organic series was over lain by a clayey silt with no glacial cover. Cladocera analysis was conducted with 20 samples from a depth interval 6.6-4.1 m. Remains of 17 species of Cladocera were found, representing the families: Chydoridae, Sididae and Bosminidae. A vast majority of them were the littoral species. In the paleolake Starowlany four development zones were distinguished that reflected changes as regards temperature, trophic levels and changes of water level in the lake. The paleolake existed from the early until the middle Eemian. The high est water level and the most favorable conditions for zooplankton development occurred in zones SCZ I and II. The highest trophic level took place in SCZ III (middle Eemian). In the late Eemian the water level dropped and the paleolake was transformed into a wetland. At certain points, the higher water level enabled existence of a few Cladocera species. The reasons for disappearance of the paleolake Starowlany included a local decrease in ground water levels as well as morphometric and geological characteristics of the lake.

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History of Development and Terrestrialization of Lake Starowlany in the Eemian Interglacial Based on Cladocera Analysis (Sokόłka Hills, Ne Poland)

Eutrophication is threatening biodiversity and ecosystem functions in inland water bodies and estuaries world-wide. Phosphorus (P) export from arable land by e.g. leaching is a major contributor to eutrophication, with high P leaching losses from long-term manured mineral soils and cultivated organic soils (Histosols). The forms of P present in these soils and their role in P mobilisation were examined in this thesis. Spectroscopic techniques (P K-edge XANES and 31P-NMR) were combined with extensive analysis of chemical and physical soil properties to characterise P in two cultivated fen peats profiles and the profile of a long-term manured mineral soil . Risk of P leaching from these soils was determined in rainfall simulation studies using 20-cm topsoil columns.

Topsoil P content (P-pstot) was with around 40 mmol kg-1 similar in the three profiles and thereby clearly elevated as compared to the P-pstot content in the sub soil of the profiles (maximum 20 mmol kg-1). When accounting for the higher bulk density the mineral sol profile was however substantially richer in total P than the organic profiles. Organic profiles were dominated by organic P (P-org) and the highest P-pstot proportion (80%) was observed in the topsoil, which was attributed to peat subsidence and transformation of mineral fertiliser P into organic P by soil microbiota and crops. According to P K-edge XANES, 20-40% of P in the organic soils was inorganic and primarily adsorbed to Al-(hydr)oxides.

Long-term manuring resulted in accumulation of inorganic P in the mineral topsoil. Up to 70% of total P was adsorbed to Fe-(hydr)oxides and Al-minerals. Most remaining topsoil P was present as secondary amorphous calcium phosphates. In the subsoil, the dominant P species was crystalline apatite, which declined in abundance towards the soil surface, reflecting soil weathering. Organic P content was very low throughout the mineral profile, consisting primarily of phosphate monoesters.

The rainfall simulation experiments indicated a risk of high P leaching from the manured mineral soil and cultivated Histosol, with cumulative P load mobilised from topsoil of 10 and 15 kg P ha-1, respectively. Phosphorus leaching was found to be driven by processes involving mobilisation of inorganic phosphate adsorbed to Fe or Al mineral surfaces, which was high relative to the size of the leachable P pool. This may reflect competition between phosphate and organic anions for sorption sites.

There was no indication that P-org is currently contributing to P leaching from Histosols, but continued soil subsidence over time will eventually lead to microbial mineralisation of organic soil P, increasing the availability of leachable inorganic P forms.

Phosphorus speciation in Swedish arable soils with high leaching potential

https://dspace.library.uu.nl/bitstream/handle/1874/298524/thesis.JvDeelen.pdf;sequence=2

Management in freshwater ponds and shallow lakes in the Netherlands: A review of the effects on emergent vegetation diversity and terrestrialisation

Terrestrialization is the process by which a water body changes from a wetland to a terrestrial ecosystem. Many factors contribute to the process, including climate change and macrophyte expansion. Among such factors, water level and eutrophication result in quantitative and qualitative changes on macrophyte communities, while expansion of macrophytes can accelerate the rate of terrestrialization by bioaccumulation. The siltation of sand also greatly contributes to terrestrialization. Here, the water quality, water level, siltation of sand, and vegetation of Baiyangdian Lake were analyzed to assess the terrestrialization characteristics of this lake and understand its terrestrialization process.

Aijuan Guo

Papers

Four terrestrialization characteristics of Baiyangdian Lake, China