Crop, Soil and Environmental Sciences (General)
https://aurora.auburn.edu/handle/11200/49379
2024-03-28T19:12:51ZLinking prescribed fire, nutrient deposition and cyanobacteria dominance through pyroeutrophication in a subtropical lake ecosystem from the mid Holocene to present
https://aurora.auburn.edu/handle/11200/50548
Linking prescribed fire, nutrient deposition and cyanobacteria dominance through pyroeutrophication in a subtropical lake ecosystem from the mid Holocene to present
Prescribed fire (Rx-fire) is a common management tool for many forested ecosystems and promotes tree and forest soil health. Although burned materials from Rx-fire areas can enter adjacent aquatic environments, very few studies have focused on the water quality impacts of increased nutrients on aquatic primary producer communities. Here, we applied paleolimnological techniques on a 170-cm sediment core collected from Ditch Pond, AL, USA, a subtropical lake system located in the Conecuh National Forest where Rx-fire has been the primary management tool for ~90 years. Macroscopic charcoal, nutrients (C, N, P) and photosynthetic pigments were measured throughout the core which spans from the middle Holocene until modern day. Our research questions were: 1) What were the sedimentary nutrient and stoichiometric changes associated with the Rx-Fire period beginning in 1937 CE? and 2) Did these nutrient changes alter historic algae/cyanobacteria groups? Following the onset of Rx-fire, nutrients (C, N, P) increased in deposition in the lake with P showing the greatest proportional increase at over 300%, suggesting that P inputs from Rx-fire are a primary artifact of burning. Photosynthetic pigments showed that increases in nutrients from Rx-fire caused extensive increases in total primary producer abundance and cyanobacteria dominance, called pyroeutrophication. These data suggest a greater need to understand the implications of fire-associated nutrients on aquatic primary producers wherever fire (but especially Rx-fire) is occurring, as well as an increase in collaboration between forest and aquatic ecosystem managers.
Comparison of probabilistic post-processing approaches for improving numerical weather prediction-based daily and weekly reference evapotranspiration forecasts
https://aurora.auburn.edu/handle/11200/50506
Comparison of probabilistic post-processing approaches for improving numerical weather prediction-based daily and weekly reference evapotranspiration forecasts
Reference evapotranspiration (ET0) forecasts play an important role in agricultural, environmental, and water management. This study evaluated probabilistic post-processing approaches, including the nonhomogeneous Gaussian regression (NGR), affine kernel dressing (AKD), and Bayesian model averaging (BMA) techniques, for improving daily and weekly ET0 forecasting based on single or multiple numerical weather predictions (NWPs) from the THORPEX Interactive Grand Global Ensemble (TIGGE), which includes the European Centre for Medium- Range Weather Forecasts (ECMWF), the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS), and the United Kingdom Meteorological Office (UKMO) forecasts. The approaches were examined for the forecasting of summer ET0 at 101 US Regional Climate Reference Network stations distributed all over the contiguous United States (CONUS). We found that the NGR, AKD, and BMA methods greatly improved the skill and reliability of the ET0 forecasts compared with a linear regression bias correction method, due to the considerable adjustments in the spread of ensemble forecasts. The methods were especially effective when applied over the raw NCEP forecasts, followed by the raw UKMO forecasts, because of their low skill compared with that of the raw ECMWF forecasts. The post-processed weekly forecasts had much lower rRMSE values (between 8 % and 11 %) than the persistence-based weekly forecasts (22 %) and the post-processed daily forecasts (between 13 % and 20 %). Compared with the single-model ensemble, ET0 forecasts based on ECMWF multi-model ensemble ET0 forecasts showed higher skill at shorter lead times (1 or 2 d) and over the southern and western regions of the US. The improvement was higher at a daily timescale than at a weekly timescale. The NGR and AKD methods showed the best performance; however, unlike the AKD method, the NGR method can post-process multi-model forecasts and is easier to interpret than the other methods. In summary, this study demonstrated that the three probabilistic approaches generally outperform conventional procedures based on the simple bias correction of single-model forecasts, with the NGR post-processing of the ECMWF and ECMWF–UKMO forecasts providing the most cost-effective ET0 forecasting.
Raw and post-processed ensemble forecasts of crop reference evapotranspiration over the CONUS produced with NWP
https://aurora.auburn.edu/handle/11200/50505
Raw and post-processed ensemble forecasts of crop reference evapotranspiration over the CONUS produced with NWP
Database with raw and post-processed ensembles of summer crop reference evapotranspiration forecasts over the CONUS based on numerical weather predictions (NWP). The forecasts consider single or multi-model NWP from The International Grand Global Ensemble (TIGGE), including the European Centre for Medium-Range Weather Forecasts (ECMWF), the National Centers for Environmental Prediction Global Forecast System (NCEP), and the United Kingdom Meteorological Office forecasts (UKMO). Associated published article available at https://doi.org/10.5194/hess-24-1011-2020
Dataset for: Sediment and Nutrient Transport Through a Reservoir Sequence Along a Large River System
https://aurora.auburn.edu/handle/11200/50504
Dataset for: Sediment and Nutrient Transport Through a Reservoir Sequence Along a Large River System
Reservoirs are highly effective at sequestering both sediments and sediment-bound nutrients, such as silts and phosphorus (P), but are also capable of depositing significant quantities of nutrients with more complex biogeochemical pathways, like nitrogen (N). Because of the growing prevalence of human altered watersheds and regulated rivers, there is a growing need to understand how reservoirs function both individually and as reservoir sequences within large rivers and their watersheds. Models have simulated the overall efficiency and drivers of reservoir nutrient deposition, but few have considered how a sequence of reservoirs alter deposition as an interconnected watershed-sediment-transport-system. In this study, we collected sediment cores from a six-reservoir sequence along a 5th – 6th order stream receiving treated waters from a large metropolitan area in the Southeast United States. Using paleolimnological techniques, we compared nutrient deposition to reservoir morphological qualities and primary producer community structure during the past ~50 years. Our findings suggest phosphorus deposition is associated with reservoir order downstream of the primary nutrient source, nitrogen deposition is linked to reservoir water retention time, and N:P is most strongly linked to reservoir surface area and watershed population density. Our results were strongly influenced by a large upstream and metropolitan nutrient source, fairly common in large rivers, but under different conditions of nutrient loading, reservoirs may express other nutrient depositional patterns.