02863nas a2200241   4500008004100000020001400041245008600055210006900141300001400210490000700224520215000231653001302381653002802394653002202422653001802444653001902462653001802481100001902499700002102518700002002539700002302559856003902582       2017                        eng d  a1939-558200aAnnual precipitation regulates spatial and temporal drivers of lake water clarity0 aAnnual precipitation regulates spatial and temporal drivers of l  a632 - 6430 v273 aUnderstanding 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.10aland use10aland-water interactions10alandscape ecology10aprecipitation10aremote sensing10aWater quality1 aRose, Kevin, C1 aGreb, Steven, R.1 aDiebel, Matthew1 aTurner, Monica, G.  uhttp://dx.doi.org/10.1002/eap.147102495nas a2200253   4500008004100000020001400041245009100055210006900146260001100215300001100226520172200237100001901959700001301978700002001991700002702011700001802038700002302056700002402079700002202103700001702125700002102142700003002163856004802193       2017                        eng d  a1435-062900aThe Influence of Legacy P on Lake Water Quality in a Midwestern Agricultural Watershed0 aInfluence of Legacy P on Lake Water Quality in a Midwestern Agri  c2017//  a1 - 153 aDecades 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.1 aMotew, Melissa1 aChen, Xi1 aBooth, Eric, G.1 aCarpenter, Stephen, R.1 aPinkas, Pavel1 aZipper, Samuel, C.1 aLoheide, Steven, P.1 aDonner, Simon, D.1 aTsuruta, Kai1 aVadas, Peter, A.1 aKucharik, Christopher, J.  uhttp://dx.doi.org/10.1007/s10021-017-0125-002044nas a2200181   4500008004100000245012700041210006900168260001500237300001600252490000700268520140700275100002601682700002201708700002401730700003001754700002501784856005301809       2016                        eng d00aNitrogen Fertilization Effects on Productivity and Nitrogen Loss in Three Grass-Based Perennial Bioenergy Cropping Systems0 aNitrogen Fertilization Effects on Productivity and Nitrogen Loss  c2016/03/18  ae0151919 - 0 v113 a<p>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 (N<sub>2</sub>O) emissions and nitrate (NO<sub>3</sub><sup>-</sup>) 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 (<italic>Panicum virgatum</italic>) monoculture, a 5-species native grass mixture and an 18-species restored prairie responded to annual fertilizer applications of 56 kg N ha<sup>-1</sup> in a field-scale agronomic trial in south-central Wisconsin over a 2-year period. We observed greater fertilizer-induced N<sub>2</sub>O emissions and sub-rooting zone NO<sub>3</sub><sup>-</sup> 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.</p>1 aDuran, Brianna, E. L.1 aDuncan, David, S.1 aOates, Lawrence, G.1 aKucharik, Christopher, J.1 aJackson, Randall, D.  uhttp://dx.doi.org/10.1371%2Fjournal.pone.015191901818nas a2200325   4500008004100000245007300041210006900114260001500183490000800198520083700206100001801043700002601061700002201087700002301109700001701132700002301149700002001172700002701192700001801219700002401237700001601261700001901277700001701296700002301313700002201336700002901358700002001387700002101407856006401428       2015                        eng d00aPlanetary boundaries: Guiding human development on a changing planet0 aPlanetary boundaries Guiding human development on a changing pla  c2015/02/130 v3473 aThe 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.1 aSteffen, Will1 aRichardson, Katherine1 aRockström, Johan1 aCornell, Sarah, E.1 aFetzer, Ingo1 aBennett, Elena, M.1 aBiggs, Reinette1 aCarpenter, Stephen, R.1 ade Vries, Wim1 ade Wit, Cynthia, A.1 aFolke, Carl1 aGerten, Dieter1 aHeinke, Jens1 aMace, Georgina, M.1 aPersson, Linn, M.1 aRamanathan, Veerabhadran1 aReyers, Belinda1 aSörlin, Sverker  uhttp://www.sciencemag.org/content/347/6223/1259855.abstract01595nas a2200385   4500008004100000020001400041245005100055210005100106300001400157490000600171520062000177100002200797700001800819700001600837700001400853700001800867700001900885700001700904700001400921700001900935700001600954700001500970700001700985700001301002700001801015700001601033700001701049700001601066700001601082700002001098700001501118700001901133700001701152856004001169       2012                        eng d  a2071-105000aGeneral Resilience to Cope with Extreme Events0 aGeneral Resilience to Cope with Extreme Events  a3248-32590 v43 aResilience 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.1 aCarpenter, S., R.1 aArrow, K., J.1 aBarrett, S.1 aBiggs, R.1 aBrock, W., A.1 aCrepin, A., S.1 aEngstrom, G.1 aFolke, C.1 aHughes, T., P.1 aKautsky, N.1 aLi, C., Z.1 aMcCarney, G.1 aMeng, K.1 aMaler, K., G.1 aPolasky, S.1 aScheffer, M.1 aShogren, J.1 aSterner, T.1 aVincent, J., R.1 aWalker, B.1 aXepapadeas, A.1 ade Zeeuw, A.  uhttp://dx.doi.org/10.3390/su4123248