TY - JOUR T1 - Annual precipitation regulates spatial and temporal drivers of lake water clarity JF - Ecological Applications Y1 - 2017 A1 - Rose, Kevin C A1 - Greb, Steven R. A1 - Diebel, Matthew A1 - Turner, Monica G. KW - land use KW - land-water interactions KW - landscape ecology KW - precipitation KW - remote sensing KW - Water quality AB - Understanding how and why lakes vary and respond to different drivers through time and space is needed to understand, predict, and manage freshwater quality in an era of rapidly changing land use and climate. Water clarity regulates many characteristics of aquatic ecosystems and is responsive to watershed features, making it a sentinel of environmental change. However, whether precipitation alters the relative importance of features that influence lake water clarity or the spatial scales at which they operate is unknown. We used a dataset of thousands of north temperate lakes and asked: (1) How does water clarity differ between a very wet versus dry year? (2) Does the relative importance of different watershed features, or the spatial extent at which they are measured, vary between wet and dry years? (3) What lake and watershed characteristics regulate long-term water clarity trends? Among lakes, water clarity was reduced and less variable in the wet year than in the dry year; furthermore, water clarity was reduced much more in high-clarity lakes during the wet year than in low-clarity lakes. Climate, land use/land cover, and lake morphometry explained most variance in clarity among lakes in both years, but the spatial scales at which some features were important differed between the dry and wet years. Watershed percent agriculture was most important in the dry year, whereas riparian zone percent agriculture (around each lake and upstream features) was most important in the wet year. Between 1991 and 2012, water clarity declined in 23% of lakes and increased in only 6% of lakes. Conductance influenced the direction of temporal trend (clarity declined in lakes with low conductance), whereas the proportion of watershed wetlands, catchment-to-lake-area ratio, and lake maximum depth interacted with antecedent precipitation. Many predictors of water clarity, such as lake depth and landscape position, are features that cannot be readily managed. Given trends of increasing precipitation, eliminating riparian zone agriculture or keeping it <10% of area may be an effective option to maintain or improve water clarity. VL - 27 SN - 1939-5582 UR - http://dx.doi.org/10.1002/eap.1471 IS - 2 ER - TY - JOUR T1 - The Influence of Legacy P on Lake Water Quality in a Midwestern Agricultural Watershed JF - Ecosystems Y1 - 2017 A1 - Motew, Melissa A1 - Chen, Xi A1 - Booth, Eric G. A1 - Carpenter, Stephen R. A1 - Pinkas, Pavel A1 - Zipper, Samuel C. A1 - Loheide, Steven P. A1 - Donner, Simon D. A1 - Tsuruta, Kai A1 - Vadas, Peter A. A1 - Kucharik, Christopher J. AB - Decades of fertilizer and manure applications have led to a buildup of phosphorus (P) in agricultural soils and sediments, commonly referred to as legacy P. Legacy P can provide a long-term source of P to surface waters where it causes eutrophication. Using a suite of numerical models, we investigated the influence of legacy P on water quality in the Yahara Watershed of southern Wisconsin, USA. The suite included Agro-IBIS, a terrestrial ecosystem model; THMB, a hydrologic and nutrient routing model; and the Yahara Water Quality Model which estimates water quality indicators in the Yahara chain of lakes. Using five alternative scenarios of antecedent P storage (legacy P) in soils and channels under historical climate conditions, we simulated outcomes of P yield from the landscape, lake P loading, and three lake water quality indicators. Legacy P had a significant effect on lake loads and water quality. Across the five scenarios for Lake Mendota, the largest and most upstream lake, average P yield (kg ha−1) varied by −41 to +22%, P load (kg y−1) by −35 to +14%, summer total P (TP) concentration (mg l−1) by −25 to +12%, Secchi depth (m) by −7 to +3%, and the probability of hypereutrophy by −67 to +34%, relative to baseline conditions. The minimum storage scenario showed that a 35% reduction in present-day loads to Lake Mendota corresponded with a 25% reduction in summer TP and smaller reductions in the downstream lakes. Water quality was more vulnerable to heavy rainfall events at higher amounts of P storage and less so at lower amounts. Increases in heavy precipitation are expected with climate change; therefore, water quality could be protected by decreasing P reserves. SN - 1435-0629 UR - http://dx.doi.org/10.1007/s10021-017-0125-0 JO - Ecosystems ER - TY - JOUR T1 - Nitrogen Fertilization Effects on Productivity and Nitrogen Loss in Three Grass-Based Perennial Bioenergy Cropping Systems JF - PLoS ONE Y1 - 2016 A1 - Duran, Brianna E. L. A1 - Duncan, David S. A1 - Oates, Lawrence G. A1 - Kucharik, Christopher J. A1 - Jackson, Randall D. AB -

Nitrogen (N) fertilization can greatly improve plant productivity but needs to be carefully managed to avoid harmful environmental impacts. Nutrient management guidelines aimed at reducing harmful forms of N loss such as nitrous oxide (N2O) emissions and nitrate (NO3-) leaching have been tailored for many cropping systems. The developing bioenergy industry is likely to make use of novel cropping systems, such as polycultures of perennial species, for which we have limited nutrient management experience. We studied how a switchgrass (Panicum virgatum) monoculture, a 5-species native grass mixture and an 18-species restored prairie responded to annual fertilizer applications of 56 kg N ha-1 in a field-scale agronomic trial in south-central Wisconsin over a 2-year period. We observed greater fertilizer-induced N2O emissions and sub-rooting zone NO3- concentrations in the switchgrass monoculture than in either polyculture. Fertilization increased aboveground net primary productivity in the polycultures, but not in the switchgrass monoculture. Switchgrass was generally more productive, while the two polycultures did not differ from each other in productivity or N loss. Our results highlight differences between polycultures and a switchgrass monoculture in responding to N fertilization.

VL - 11 UR - http://dx.doi.org/10.1371%2Fjournal.pone.0151919 IS - 3 ER - TY - JOUR T1 - Planetary boundaries: Guiding human development on a changing planet JF - Science Y1 - 2015 A1 - Steffen, Will A1 - Richardson, Katherine A1 - Rockström, Johan A1 - Cornell, Sarah E. A1 - Fetzer, Ingo A1 - Bennett, Elena M. A1 - Biggs, Reinette A1 - Carpenter, Stephen R. A1 - de Vries, Wim A1 - de Wit, Cynthia A. A1 - Folke, Carl A1 - Gerten, Dieter A1 - Heinke, Jens A1 - Mace, Georgina M. A1 - Persson, Linn M. A1 - Ramanathan, Veerabhadran A1 - Reyers, Belinda A1 - Sörlin, Sverker AB - The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth system. Here, we revise and update the planetary boundary framework, with a focus on the underpinning biophysical science, based on targeted input from expert research communities and on more general scientific advances over the past 5 years. Several of the boundaries now have a two-tier approach, reflecting the importance of cross-scale interactions and the regional-level heterogeneity of the processes that underpin the boundaries. Two core boundaries—climate change and biosphere integrity—have been identified, each of which has the potential on its own to drive the Earth system into a new state should they be substantially and persistently transgressed. VL - 347 UR - http://www.sciencemag.org/content/347/6223/1259855.abstract IS - 6223 JO - Science ER - TY - JOUR T1 - General Resilience to Cope with Extreme Events JF - Sustainability Y1 - 2012 A1 - Carpenter, S. R. A1 - Arrow, K. J. A1 - Barrett, S. A1 - Biggs, R. A1 - Brock, W. A. A1 - Crepin, A. S. A1 - Engstrom, G. A1 - Folke, C. A1 - Hughes, T. P. A1 - Kautsky, N. A1 - Li, C. Z. A1 - McCarney, G. A1 - Meng, K. A1 - Maler, K. G. A1 - Polasky, S. A1 - Scheffer, M. A1 - Shogren, J. A1 - Sterner, T. A1 - Vincent, J. R. A1 - Walker, B. A1 - Xepapadeas, A. A1 - de Zeeuw, A. AB - Resilience to specified kinds of disasters is an active area of research and practice. However, rare or unprecedented disturbances that are unusually intense or extensive require a more broad-spectrum type of resilience. General resilience is the capacity of social-ecological systems to adapt or transform in response to unfamiliar, unexpected and extreme shocks. Conditions that enable general resilience include diversity, modularity, openness, reserves, feedbacks, nestedness, monitoring, leadership, and trust. Processes for building general resilience are an emerging and crucially important area of research. VL - 4 SN - 2071-1050 UR - http://dx.doi.org/10.3390/su4123248 IS - 12 ER -