Browsing by Subject "drought"
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Item Agricultural Drought and Moisture Excesses in Minnesota(Minnesota Agricultural Experiment Station, 1960-05) Blake, G. R.; Allred, E. R.; van Bavel, C. H. M; Whisler, F. D.Item Data and Code for Mechanistic links between physiology and spectral reflectance enable pre-visual detection of oak wilt and drought stress(2024-01-04) Sapes, Gerard; Schroeder, Lucy; Scott, Allison; Clark, Isaiah; Juzwik, Jennifer; Montgomery, Rebecca; Guzman Q., J. Antonio; Cavender-Bares, Jeannine; gsapes@ufl.edu; Sapes, Gerard; University of Minnesota; University of Florida; Northern Research Station, USDA Forest ServiceTree mortality due to global change-including range expansion of invasive pests and pathogens- is a paramount threat to forest ecosystems. Oak forests are among the most prevalent and valuable ecosystems both ecologically and economically in the United States. There is increasing interest in monitoring oak decline and death due to both drought and the oak wilt pathogen (Bretziella fagacearum). We combined anatomical and ecophysiological measurements with spectroscopy at leaf, canopy, and airborne levels to enable differentiation of oak wilt and drought, and detection prior to visible symptom appearance. We performed an outdoor potted experiment with Quercus rubra saplings subjected to drought stress and/or artificially inoculated with the pathogen to detect and distinguish both types of stressors. We also performed a field experiment where we validated the capacity of spectral reflectance models to predict physiological status and distinguish oak wilt from healthy trees. The data and code provided here address these goals.Item Data set used in publication titled: All the light we cannot see: Climate manipulations leave short and long-term imprints in spectral reflectance of trees(2024-12-10) Stefanski, Artur; Butler, Ethan B.; Williams, Laura J.; Bermudez, Raimundo; Guzman, J. Antonio; Larson, Andrew; Townsend, Philip A.; Montgomery, Rebecca A.; Cavender-Bares, Jeannine; Reich, Peter B.; astefans@uwsp.edu; Stefanski, Artur; ASCENDAnthropogenic climate change, particularly changes in temperature and precipitation, affects plants in multiple ways. Because plants respond dynamically to stress and acclimate to changes in growing conditions, diagnosing quantitative plant-environment relationships is a major challenge. One approach to this problem is to quantify leaf responses using spectral reflectance, which provides rapid, inexpensive, and nondestructive measurements that capture a wealth of information about genotype as well as phenotypic responses to the environment. However, it is unclear how warming, and drought affect spectra. To address this gap, we used an open-air field experiment that manipulates temperature and rainfall in 36 plots at two sites in the boreal-temperate ecotone of northern Minnesota, USA. We collected leaf spectral reflectance (400-2400 nm) at the peak of the growing season for three consecutive years on juveniles (two to six years old) of five tree species planted within the experiment. We hypothesized that these mid-season measurements of spectral reflectance capture a snapshot of the leaf phenotype encompassing a suite of physiological, structural, and biochemical responses to both long- and short-time scale environmental conditions. We show that the imprint of environmental conditions experienced by plants hours to weeks before spectral measurements is linked to regions in the spectrum associated with stress, namely the water absorption regions of the near-infrared and shortwave infrared. In contrast, the environmental conditions plants experience during leaf development leave lasting imprints on the spectral profiles of leaves, attributable to leaf structure and chemistry (e.g., pigment content and associated ratios). Our analyses show that after accounting for baseline species spectral differences, spectral responses to the environment do not differ among the species. This suggests that building a general framework for understanding forest responses to climate change through spectral metrics may be possible, likely having broader implications if the common responses among species detected here represent a widespread phenomenon. Consequently, these results demonstrate that examining the entire spectrum of leaf reflectance for environmental imprints in contrast to single features (e.g. indices and traits) improves inferences about plant-environment relationships, which is particularly important in times of unprecedented climate change.Item Drought tolerance of consumer turfgrass seed mixtures and blends(2018-11) Sessoms, Florence; Sandor, Dan; Horgan, Brian; Bauer, SamIncreased use of water for irrigation has become a concern in the Twin Cities especially during seasonal drought when demand for fresh water is highest. Homeowners could improve water conservation by choosing the right type of turfgrass species to meet their expectations. The objectives of this study were to evaluate the drought tolerance characteristics of consumer-available turfgrass seed mixtures and blends and to examine the effect of mowing height on drought tolerance and recovery from drought.Item The Effect of Atmospheric Sulfate Deposition on Mercury Biogeochemistry in an Experimental Peatland: Impacts, Recovery, and Natural Variability(2014-07) Coleman Wasik, JillElevated mercury deposition resulting from human activities has caused wide-spread mercury contamination of aquatic systems around the world. Peatlands are generally considered to be sinks for mercury deposited to the landscape, but also act as biogeochemical reactors wherein inorganic mercury is transformed into bioaccumulative, organic methylmercury (MeHg). Recent, short-term investigations have demonstrated that sulfate deposition alone can increase MeHg production in, and flux from, peatlands through the stimulation of sulfate-reducing bacteria, a group of known mercury methylators. However, over longer periods of time the interaction between the biogeochemical cycles of mercury and sulfur is complicated by variability in climate, hydrology, and sulfur and mercury deposition rates. These complexities were addressed by experimentally altering sulfate-loading to a 2.5-ha peatland in northern Minnesota over eight years. The peatland was initially divided into control and experimental treatments and sulfate was added to the latter three times each field season in simulated rainfall events. Porewaters were sampled before and after each sulfate addition and peat samples were collected five times from sites located within the raised central bog and along the peatland margins. The lagg margin is generally considered to be the primary site of mercury methylation in peatlands. However, sulfate addition caused more pronounced and persistent increases in MeHg in the central bog sites, relative to the margin sites, demonstrating that sulfate delivery to the central bog can greatly expand the areal extent of mercury methylation in peatlands. MeHg production also responded to sulfate release following severe summer drought. The increase was much higher in experimental-treatment sites than in control sites suggesting that the experimental treatment was "primed" to quickly respond to new sulfate inputs. In early 2006 sulfate addition was halted to the upgradient one-third of the original experimental treatment in order to monitor how MeHg production changed as sulfate deposition declined. Although drought appeared to slow the recovery process by increasing sulfate availability and mobilizing MeHg, three years after sulfate additions ceased MeHg in the recovery treatment was significantly lower than in the experimental treatment. This indicates that MeHg production in peatlands formerly affected by elevated sulfate deposition may return to background conditions and highlights the potential benefits that further controls on atmospheric sulfur emissions may have on MeHg production in peatlands and consequent mercury burdens in aquatic foodwebs. The long-term nature of this study allowed for an in-depth exploration of the effects that hydrologic flucutations on mercury cycling in peatlands and calls attention to the potential negative consequences that changing precipitation patterns and evapotranspirative demands may have on MeHg production in these systems.Item Evaluation of fine fescues as alternative golf course fairway turfgrasses(2016-05) Reiter, MaggieIn the cool-season region of the United States, golf courses traditionally grow high-input grasses like creeping bentgrass (Agrostis stolonifera, L.), Kentucky bluegrass (Poa pratensis, L.), annual bluegrass (Poa annua, L.), and/or perennial ryegrass (Lolium perenne, L.) on fairways. Grass species exist that are more sustainable than those currently being used for golf course fairway turf. Low-input fine fescue species could be able to withstand the pressure from typical turfgrass disease and stresses while producing acceptable turf and excellent playing quality with fewer overall inputs of pesticides, water, and fertilizer. Little research has been conducted on these species in a fairway setting, so golf course managers have been hesitant to use fine fescues. This project conducted research to overcome these barriers and thus begin using low-input fine fescues for fairways on golf courses throughout the northern United States. The objective of the first experiment was to evaluate fine fescue species’ performance as fairway turfgrass under an acute drought. Field trials were conducted at two locations under a rainout shelter. Mixtures that contained large proportions (>33%) of Chewings fescue [Festuca rubra ssp. commutata (Thuill.) Nyman] had the greatest green cover at the end of the drought period. The marginal effects summary revealed no significant differences among species success after drought. Overall, this study found that fine fescues can provide acceptable turf quality and playability on golf course fairways resulting in lower irrigation inputs. The objectives of the second project were to determine the effect of the plant growth regulator trinexapac-ethyl on the performance of fine fescue mixtures when managed as a golf course fairway and identify fine fescue mixtures that perform well under traffic stress. The marginal effects summaries showed hard fescue [Festuca trachyphylla (Hack.) Krajina], slender creeping red fescue [Festuca rubra ssp. litoralis (G.F.W. Meyer) Auquier.], strong creeping red fescue (Festuca rubra ssp. rubra Gaudin), and sheep fescue (Festuca ovina, L.) had the greatest component effect on visual turfgrass quality, and were all statistically similar. Strong creeping red fescue was more susceptible to dollar spot disease (caused by Sclerotinia homoeocarpa F.T. Bennett) than the other species. The third experiment evaluated fine fescue species and mixtures for snow mold resistance on three golf courses in Minnesota. In the spring of 2013, 2014, and 2015, there was no damage from snow mold. These grasses may be resistant to the pathogens; however, our observations in higher cut fine fescue suggest that snow mold and snow scald diseases can be a problem in these grasses. Although the objective to determine if fine fescue fairways require fungicides at currently-recommended application rates to survive winter snow mold pressure was not accomplished, turf quality data taken over 2 years was analyzed. Mixtures maintained significantly better turfgrass quality than any of the five species alone.Item Impact of Drought Stress on Cool-Season Turfgrass: Comparative Analysis of Mixture and Monoculture Responses(2023-11) Turbeville, Jillian; Sessoms, Florence; Watkins, EricThe objective of this study was to determine the performance of mixtures and monocultures capable of withstanding long drought periods under low input management.Item Impact of Drought Stress on Cool-Season Turfgrass: Comparative Analysis of Mixture and Monoculture Responses(2022-11) Turbeville, Jillian; Sessoms, Florence; Watkins, EricWe determined the performance of turfgrass mixtures/monocultures capable of withstanding long drought periods with a low fertility management practice.Item Mechanistic links between physiology and spectral reflectance enable pre-visual detection of oak wilt and drought stress(Proceedings of the National Academy of Sciences, 2024-02) Sapes, Gerard; Schroeder, Lucy; Scott, Allison; Clark, Isaiah; Juzwik, Jennifer; Montgomery, Rebecca; Guzmán Q., J. Antonio; Cavender-Bares, JeannineTree mortality due to global change—including range expansion of invasive pests and pathogens—is a paramount threat to forest ecosystems. Oak forests are among the most prevalent and valuable ecosystems both ecologically and economically in the United States. There is increasing interest in monitoring oak decline and death due to both drought and the oak wilt pathogen (Bretziella fagacearum). We combined anatomical and ecophysiological measurements with spectroscopy at leaf, canopy, and airborne levels to enable differentiation of oak wilt and drought, and detection prior to visible symptom appearance. We performed an outdoor potted experiment with Quercus rubra saplings subjected to drought stress and/or artificially inoculated with the pathogen. Models developed from spectral reflectance accurately predicted ecophysiological indicators of oak wilt and drought decline in both potted and field experiments with naturally grown saplings. Both oak wilt and drought resulted in blocked water transport through xylem conduits. However, oak wilt impaired conduits in localized regions of the xylem due to formation of tyloses instead of emboli. The localized tylose formation resulted in more variable canopy photosynthesis and water content in diseased trees than drought-stressed ones. Reflectance signatures of plant photosynthesis, water content and cellular damage detected oak wilt and drought 13 days before visual symptoms appeared. Our results show that leaf spectral reflectance models predict ecophysiological processes relevant to detection and differentiation of disease and drought. Coupling spectral models that detect physiological change with spatial information enhances capacity to differentiate plant stress types such as oak wilt and drought.Item Multi-Scale Topographic Influences on Tree Growth: A Case Study of Quercus lobata in the Tehachapi Mountains, California(2022-12) Trumper, MatthewComplex topography can facilitate climatic and hydrologic microenvironments that buffer plants against climate change and extreme drought. However, the extent to which topographic position mediates tree growth response to climate remains an open question. Dendrochronology, the study of precisely dated tree rings, has been a valuable tool for assessing tree growth response to climate variability across topographic gradients. In this study, six new tree-ring chronologies were developed from valley oak (Quercus lobata), a long-lived, endemic species in California. Trees were sampled growing in upland and riparian hillslope positions along a 1,300-meter (4,265-feet) elevational transect in the Tehachapi Mountains of California to understand how topography acts as a mediating factor on tree growth and drought sensitivity. Valley oaks are thought to be highly dependent on groundwater, so I hypothesized that higher groundwater availability at the riparian sites would mediate growth sensitivity to drought. Results showed that tree growth patterns and drought sensitivity varied substantially in association with hillslope position and elevation. Valley oak radial growth showed a consistently weaker response to precipitation at riparian sites, supporting my hypothesis. The influence of hillslope position on drought sensitivity varied with elevation, such that the riparian buffering effect was strongest at the low elevation sites and weaker at higher elevations. At upland sites, precipitation and tree growth covaried on annual to decadal time scales, depending on elevation. The strong topographic influence on valley oak growth and drought sensitivity observed here has implications for climate refugia planning and paleohydrology using this species.Item Plant diversity drives soil microbial biomass carbon in grasslands irrespective of global environmental change factors(Wiley, 2015) Thakur, Madhav Prakash; Milcu, Alexandru; Manning, Pete; Niklaus, Pascal A; Roscher, Christiane; Power, Sally; Reich, Peter B; Scheu, Stefan; Tilman, David; Ai, Fuxun; Guo, Hongyan; Ji, Rong; Pierce, Sarah; Ramirez, Nathaly Guerrero; Richter, Annabell Nicola; Steinauer, Katja; Strecker, Tanja; Vogel, Anja; Eisenhauer, NicoSoil microbial biomass is a key determinant of carbon dynamics in the soil. Several studies have shown that soil microbial biomass significantly increases with plant species diversity, but it remains unclear whether plant species diversity can also stabilize soil microbial biomass in a changing environment. This question is particularly relevant as many global environmental change (GEC) factors, such as drought and nutrient enrichment, have been shown to reduce soil microbial biomass. Experiments with orthogonal manipulations of plant diversity and GEC factors can provide insights whether plant diversity can attenuate such detrimental effects on soil microbial biomass. Here, we present the analysis of 12 different studies with 14 unique orthogonal plant diversity × GEC manipulations in grasslands, where plant diversity and at least one GEC factor (elevated CO2, nutrient enrichment, drought, earthworm presence, or warming) were manipulated. Our results show that higher plant diversity significantly enhances soil microbial biomass with the strongest effects in long-term field experiments. In contrast, GEC factors had inconsistent effects with only drought having a significant negative effect. Importantly, we report consistent non-significant effects for all 14 interactions between plant diversity and GEC factors, which indicates a limited potential of plant diversity to attenuate the effects of GEC factors on soil microbial biomass. We highlight that plant diversity is a major determinant of soil microbial biomass in experimental grasslands that can influence soil carbon dynamics irrespective of GEC.Item Plant diversity effects on grassland productivity are robust to both nutrient enrichment and drought(The Royal Society, 2016) Craven, Dylan; Isbell, Forest; Manning, Pete; Connolly, John; Bruelheide, Helge; Ebeling, Anne; Roscher, Christiane; Van Ruijven, Jasper; Weigelt, Alexandra; Wilsey, Brian; Beierkuhnlein, Carl; De Luca, Enrica; Griffin, John N; Hautier, Yann; Hector, Andy; Jentsch, Anke; Kreyling, Jürgen; Lanta, Vojtech; Loreau, Michel; Meyer, Sebastian T; Mori, Akira S; Naeem, Shahid; Palmborg, Cecilia; Polley, H Wayne; Reich, Peter B; Schmid, Bernhard; Siebenkäs, Alrun; Seabloom, Eric; Thakur, Madhav P; Tilman, David; Vogel, Anja; Eisenhauer, NicoGlobal change drivers are rapidly altering resource availability and biodiversity. While there is consensus that greater biodiversity increases the functioning of ecosystems, the extent to which biodiversity buffers ecosystem productivity in response to changes in resource availability remains unclear. We use data from 16 grassland experiments across North America and Europe that manipulated plant species richness and one of two essential resources—soil nutrients or water—to assess the direction and strength of the interaction between plant diversity and resource alteration on above-ground productivity and net biodiversity, complementarity, and selection effects. Despite strong increases in productivity with nutrient addition and decreases in productivity with drought, we found that resource alterations did not alter biodiversity–ecosystem functioning relationships. Our results suggest that these relationships are largely determined by increases in complementarity effects along plant species richness gradients. Although nutrient addition reduced complementarity effects at high diversity, this appears to be due to high biomass in monocultures under nutrient enrichment. Our results indicate that diversity and the complementarity of species are important regulators of grassland ecosystem productivity, regardless of changes in other drivers of ecosystem function.