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Growing demand for food from finite agricultural lands requires the optimization of agricultural management, including the potential interactive effects of these practices on ecosystems. We experimentally examined the interactive and temporal effects of three ranching practices (pasture management intensity, livestock grazing, and prescribed fire) on soil nutrients in 40 geographically-isolated seasonal wetlands. Wetlands were embedded in a subtropical ranch, and the long-term experiment used a factorial design with wetlands as experimental units. Soils (0–15 cm) were collected three times over 9 years; at experiment start (2007), one year after prescribed burns started (2009), and seven years later (2016). Samples were analyzed for soil bulk density, organic matter (OM), total nitrogen (N), carbon (C), and phosphorous (P). A lag effect was observed in response to fire; differences were not observed in 2009, but were detected in 2016 after multiple fire cycles had occurred. Rangeland practices showed 2- and 3-way interactive effects, especially for total P and N stocks. Total P increased most in the wetlands embedded within highly managed, grazed, and burned pastures (2.31 ± 0.76 g m −2 yr −1 ), consistent with legacy effects of historical fertilizer application, cattle activity, and ash deposit due to fire. Wetlands in semi-natural and burned pastures had the lowest rates of soil N storage (5.13 ± 7.33 g m −2 yr −1 ) compared to all other treatments (24.5 ± 10.8 g m −2 yr −1 ). Total C stocks were not significantly impacted by ranching practices throughout the study. In summary, ranching practices can additively and interactively alter soil nutrient stocks after a time lag, and legacy effects of P application still impact wetlands decades later. Our study is one of few focused on ranchland wetlands and shows that wetlands in highly managed, grazed, and/or burned pastures can sequester soil P and N, playing an important role in nutrient processing for agricultural landscapes and watersheds. [ABSTRACT FROM AUTHOR]

Greater understanding of land management effects on species richness and composition is needed to manage biodiversity-related ecosystem services in agricultural ecosystems. Here we studied responses of vascular plants, macroinvertebrates, and ectothermic vertebrates to local and regional factors in two ranchland management intensities (semi-natural and highly-managed). Samples were collected in 40 separate wetlands embedded in the two management intensities. Based on community assembly theory, we expected a shift from regional to local-based factors as predictors of communities where local conditions become more limiting. We also expected highly managed ranchlands to most strongly “filter” community membership to become more homogeneous. Both predictions were supported though results sometimes differed among taxa. Wetland communities embedded in highly managed pastures were more homogeneous and significantly different from those in semi-natural pastures. Overall, regional factors related to propagule dispersal were most important in semi-natural pastures, and local factors (especially nutrients) were most important in highly managed pastures. However, some community metrics were consistently affected most by local or regional factors regardless of land use intensity. For instance, vegetation richness and vertebrate composition were consistently influenced by local factors, whereas macroinvertebrate composition was consistently influenced by regional factors. Based on our results, biodiversity conservation will be most effective if management efforts focus on improving local habitat conditions in highly managed areas, and on preserving regional heterogeneity in more natural areas. Taxon-specific conservation strategies should account for taxon-specific sensitivities to local and regional processes. [ABSTRACT FROM AUTHOR]

Abstract: Semi-natural grasslands have become increasingly important to conservation in both temperate and subtropical regions due to their diversity and escalating pressures toward conversion or abandonment. As more semi-natural grasslands are incorporated into conservation easements or other protected areas, questions arise about appropriate management for maintaining biodiversity. We conducted an 8year split-plot experiment on the effect of season of burn and nutrient status on plant composition in semi-natural grassland released from ranchland management. Our objective was to find alternative approaches to manage semi-natural grasslands under varying nutrient enrichment when typical ranch management is ceased. We predicted that: (1) burning at high fertility would counteract competitive exclusion and increase diversity and that this increase would be greatest in the historical fire season (summer) to which species are adapted; and (2) that plant composition in plots released from disturbance would shift to greater abundance of competitive species, including shrubs, which would displace smaller grass and forb species and result in reduced diversity. Total species richness and graminoid richness were lowest in unburned, ungrazed plots. Graminoid richness was greatest in winter burned-grazed plots (due mainly to sedges) and forb richness was greatest in summer burn plots. In unburned plots, after 5years, a native shrub, Eupatorium capillifolium (Lam.) Small, and native forb, Lachnanthes caroliniana (Lam.) Dandy, became abundant and grasses declined. Winter burn plots were dominated by a small shrub, Euthamia graminifolia (L.) Nutt. var. hirtipes (Fernald) C. and J. Taylor. Our experiment suggests that maintaining grassland structure and reducing shrub cover in grasslands released from typical ranchland management in subtropical Florida requires burning, and that summer is the most beneficial season of burn to reduce shrub encroachment and encourage both graminoid and forb richness. [Copyright &y& Elsevier]

• The teabag index (TBI) was adopted to quantify subtropical wetland decomposition. • Land-use intensification, grazing, and fire interactively affected decomposition. • Hydrology and climate contributed to spatial–temporal variation in decomposition. • TBI is a useful indicator to inform wetland ecosystem service management. Understanding how global change drivers and their interactions affect decomposition in wetlands embedded in agricultural landscapes remains challenging, especially in tropical and subtropical biomes, which are disproportionately important for global carbon cycling yet with high uncertainties. In a long-term whole-ecosystem experiment, we used a widely-adopted indicator of decomposition, the Teabag Index (TBI), to investigate individual and interactive effects of surrounding land-use intensity, cattle grazing, and prescribed fire on seasonal wetland decomposition (i.e., decay rate k , and stabilization factor S) in an exemplar subtropical landscape in central-south Florida, USA. We ask: (1) How do land-use intensity and management practices affect the decomposition in seasonal wetlands? (2) How does wetland decomposition vary with hydrological gradient and seasonal climatic condition? (3) What are the dominant direct and indirect pathways through which land-use intensity and management practices affect wetland decomposition? Our results showed that, overall, surrounding land-use intensity exerted much stronger effects on litter decomposition compared to grazing and prescribed fire, and cattle grazing reduced decomposition rate k. There was a complex three-way interaction among land-use intensity, grazing and fire on the stabilization factor S – a proxy related to carbon sequestration potential. Grazing-fire interactive effects on S only existed in wetlands embedded in intensively-managed landscapes, where grazing reduced S in burned wetlands but did not affect S in unburned wetlands. Decay rate k showed profound temporal variation primarily driven by seasonal climatic conditions (especially precipitation), whereas S varied spatially along the hydrological gradient. Our structural equation modeling (SEM) analyses further revealed that effects on k were also indirectly manifested through changes on soil C/N, C/P, and pH, while effects on S were manifested through alterations in soil C/P ratio, pH, soil nutrients and water content. Our TBI results suggest that anthropogenic environmental changes, including land-use intensification, livestock introduction and fire suppression, could compromise carbon sequestration potential in tropical and subtropical seasonal wetlands. Our research highlights the importance of considering landscape context in wetland management and demonstrates the use of TBI as an indicator to quantify and inform combinations of land management and agricultural practices could conserve wetlands and sustain their vital functions and services, especially from the lens of promoting carbon storage and nutrient retention services. [ABSTRACT FROM AUTHOR]

• Phosphorus decreased within a year in highly altered wetlands with grazing and fire. • After a year, phosphorus and ammonia decreased in highly altered wetlands with fire. • After 6 years, only ammonia decreased with grazing removed and fire. • In a lab experiment, plants & detritus released phosphorus & nitrogen after burning. Small, isolated, depressional wetlands increasingly exist in developed landscapes and are highly vulnerable to hydrologic alterations and eutrophication. Globally, grazing lands contain a significant number of these wetlands, and the practices of grazing, prescribed fire and fertilizing have all been shown separately to influence wetland nutrient dynamics. However, wetlands are often exposed to a combination of these practices and the interactive effects have yet to be fully elucidated. The purpose of this study was to examine the effects of pasture management, grazing, and fire on water quality in isolated wetlands on a subtropical ranch in South-Central Florida. We used a factorial experiment on 40 whole wetland ecosystems manipulating grazing (fenced or not) and fire (burned or not) in two pasture types (intensely managed and semi-native). Grab samples of water were collected over 8 years, including one pre-treatment year, at peak growing season, in all wetlands and analyzed for nitrogen and phosphorous. In addition, we conducted a laboratory experiment to simulate the effect of a prescribed burn on water quality using live plant tissue, detritus, and soil taken from grazed and fenced wetlands to investigate the interactions of these practices on short-term responses of water quality. In the field experiment, after one year of experimental treatments, wetlands exposed to both grazing and prescribed burns had relatively low phosphorous in water in intensely managed pastures. After multiple years of treatment only ammonia was reduced with burning and fencing in both pasture-types. In the lab experiment, simulated burning caused a pulse release of phosphorous and a reduction of nitrogen due to volatilization of both live plant tissue and detritus, but the magnitude was influenced by grazing and pasture-type. This study of rangeland management on wetland water quality demonstrates the effect of these practices, especially prescribed burns, on improving nutrient release in agricultural wetlands and shows that management effects on nutrient release varies with historical land use and over time. [ABSTRACT FROM AUTHOR]

Intensification, the process of intensifying land management to enhance agricultural goods, results in "intensive" pastures that are planted with productive grasses and fertilized. These intensive pastures provide essential ecosystem services, including forage production for livestock. Understanding the synergies and tradeoffs of pasture intensification on the delivery of services across climatic regions is crucial to shape policies and incentives for better management of natural resources. Here, we investigated how grassland intensification affects key components of provisioning (forage productivity and quality), supporting (plant diversity) and regulating services (CO 2 and CH 4 fluxes) by comparing these services between intensive versus extensive pastures in subtropical and temperate pastures in the USDA Long-term Agroecosystem Research (LTAR) Network sites in Florida and Oklahoma, USA over multiple years. Our results suggest that grassland intensification led to a decrease in measured supporting and regulating services, but increased forage productivity in temperate pastures and forage digestibility in subtropical pastures. Intensification decreased the net CO 2 sink of subtropical pastures while it did not affect the sink capacity of temperate pastures; and it also increased environmental CH 4 emissions from subtropical pastures and reduced CH 4 uptake in temperate pastures. Intensification enhanced the global warming potential associated with C fluxes of pastures in both ecoregions. Our study demonstrates that comparisons of agroecosystems in contrasting ecoregions can reveal important drivers of ecosystem services and general or region-specific opportunities and solutions to maintaining agricultural production and reducing environmental footprints. Further LTAR network-scale comparisons of multiple ecosystem services across croplands and grazinglands intensively vs extensively managed are warranted to inform the sustainable intensification of agriculture within US and beyond. Our results highlight that achieving both food security and environmental stewardship will involve the conservation of less intensively managed pastures while adopting sustainable strategies in intensively managed pastures. • Intensification did not increase forage productivity in subtropical pastures. • Intensification increased forage productivity in temperate pastures. • Intensification reduced supporting and regulating services in pastures. • Intensification reduced CO 2 sink capacity and increased CH 4 emissions of subtropical pastures. • Intensification increased the global warming potential associated with C fluxes in pastures. [ABSTRACT FROM AUTHOR]

Bacteria and fungi are primary components in wetland soil microbial communities and provide essential ecosystem functions and services. Understanding responses of bacterial and fungal communities to multiple drivers of environmental change and their interactions is crucial for wetland conservation and management, particularly for those embedded in agricultural landscapes. Yet little is known about effect of agricultural land use and wetland management on soil microbial communities in subtropical seasonal wetlands. Here, we used a long-term whole-ecosystem wetland experiment to examine individual and interactive effects of upland land-use intensification, livestock grazing, and prescribed fire on soil bacteria and fungi. We asked: (1) How do land-use intensification, grazing and fire disturbances interact to alter taxonomic composition and functional potential of wetland soil bacterial and fungal communities? (2) To what extent would these management and disturbance effects on wetland microbial communities manifest through alterations in soil properties? Our results showed that both microbial taxonomic and functional composition are responsive to agricultural land use and wetland management. Upland land-use intensification was the strongest driver (as compared to fire and grazing) in shaping bacterial and fungal community composition. Specifically, land-use intensification increased functional richness of both bacteria and fungi, whereas grazing and fire only interactively affected bacterial functional richness. In addition, responses of bacterial and fungal species diversity to wetland management varied, where grazing and fire reduced fungal species diversity in wetlands embedded in low-intensity managed pastures, but none of these management practices altered bacterial species diversity. Further, we found that pH and secondary nutrients (i.e., Ca and Mg) availability were the most important soil properties that explain how agricultural land use and wetland management drive the composition of bacterial and fungal communities. Our findings suggest that integration of lime application into intensified land uses to neutralize soil pH could facilitate maintenance of microbial diversity and associated functions. Our results highlight the need to comprehensively assess management impacts on soil microorganisms, rather than using a single or few indicators, due to inconsistent responses of bacterial and fungal communities, as well as their varied taxonomic and functional responses. ● Agricultural land use and wetland management have either individual or interactive effects on soil microbial communities. ● Upland intensification exerts stronger effects on wetland soil microbial communities than grazing and fire. ● Fungal diversity is more responsive to land management than bacterial diversity. ● Agricultural management and disturbances can affect potential microbial functions in wetlands. [ABSTRACT FROM AUTHOR]

[Display omitted] • Assessed common metrics with data from 34 cropland, grazing & integrated systems. • Compared production and phenology metrics from eddy covariance, PhenoCam and Landsat. • Correlations among metrics varied across diverse U.S. agroecosystems. • Devised a metric assessment framework to streamline decision making for monitoring. Effective measurement of seasonal variations in the timing and amount of production is critical to managing spatially heterogeneous agroecosystems in a changing climate. Although numerous technologies for such measurements are available, their relationships to one another at a continental extent are unknown. Using data collected from across the Long-Term Agroecosystem Research (LTAR) network and other networks, we investigated correlations among key metrics representing primary production, phenology, and carbon fluxes in croplands, grazing lands, and crop-grazing integrated systems across the continental U.S. Metrics we examined included gross primary productivity (GPP) estimated from eddy covariance (EC) towers and modelled from the Landsat satellite, Landsat NDVI, and vegetation greenness (Green Chromatic Coordinate, G CC) from tower-mounted PhenoCams for 2017 and 2018. Overall, our analysis compared production dynamics estimated from three independent ground and remote platforms using data for 34 agricultural sites constituting 51 site-years of co-located time series. Pairwise sensor comparisons across all four metrics revealed stronger correlation and lower root mean square error (RMSE) between end of season (EOS) dates (Pearson R ranged from 0.6 to 0.7 and RMSE from 32.5 to 67.8) than start of season (SOS) dates (0.46 to 0.69 and 40.4 to 66.2). Overall, moderate to high correlations between SOS and EOS metrics complemented one another except at some lower productivity grazing land sites where estimating SOS can be challenging. Growing season length estimates derived from 16-day satellite GPP (179.1 days) were significantly longer than those from PhenoCam G CC (70.4 days, p adj < 0.0001) and EC GPP (79.6 days, p adj < 0.0001). Landscape heterogeneity did not explain differences in SOS and EOS estimates. Annual integrated estimates of productivity from EC GPP and PhenoCam G CC diverged from those estimated by Landsat GPP and NDVI at sites where annual production exceeds 1000 gC/m−2 yr−1. Based on our results, we developed a "metric assessment framework" that articulates where and how metrics from satellite, eddy covariance and PhenoCams complement, diverge from, or are redundant with one another. The framework was designed to optimize instrumentation selection for monitoring, modeling, and forecasting ecosystem functioning with the ultimate goal of informing decision-making by land managers, policy-makers, and industry leaders working at multiple scales. [ABSTRACT FROM AUTHOR]