Core Ideas Effectiveness of EEFs varied greatly with their modes of action, soils, and management factors. NIs, DIs, and CRFs reduced N2O emissions by 38, 30, and 19%, respectively, compared with conventional N fertilizers. NIs increased overall crop yields by 7% compared with conventional N fertilizers. DIs might provide added benefits over NIs in alkaline soils, coarse‐textured soils, and irrigated systems. Enhanced efficiency fertilizers (EEFs) have the potential to reduce N2O emissions and improve crop productivity, but the impact of soil and management conditions on their effectiveness is not clear. We conducted a meta‐analysis to evaluate the effectiveness of different EEF types in reducing N2O emissions in three cereal production systems: rice (Oryza sativa L.), corn (Zea mays L.), and wheat (Triticum aestivum L.). We also compared EEF efficacy across soil and management conditions for corn and wheat systems. Results showed that the effect of EEFs on N2O emissions and crop yields varied greatly with their modes of action, soil types, and management conditions. Nitrification inhibitors (NIs), double inhibitors (DIs: urease plus nitrification inhibitors), and controlled‐release N fertilizers (CRFs) consistently reduced N2O emissions compared with conventional N fertilizers across soil and management conditions (grand mean decreases of 38, 30, and 19%, respectively). The DIs more effectively reduced N2O emissions in alkaline soils than did NIs, but the trend was reversed in acidic soils. Urease inhibitors also reduced N2O emissions compared with conventional N fertilizers in coarse‐textured soils and irrigated systems. Overall crop yields increased by 7% with the addition of NIs alone. Compared with conventional N fertilizers, DIs also increased crop yields in alkaline soils, coarse‐textured soils, and irrigated systems. However, CRFs had no effect on crop yields. Overall, this study suggests that NIs or DIs can reduce N2O emissions while improving crop yields. Growers should select EEFs based on their soil and management conditions to maximize their effectiveness.

Summary1. Many rangelands evolved under an interactive disturbance regime in which grazers respond to the spatial pattern of fire and create a patchy, heterogeneous landscape. Spatially heterogeneous fire and grazing create heterogeneity in vegetation structure at the landscape level (patch contrast) and increase rangeland biodiversity. We analysed five experiments comparing spatially heterogeneous fire treatments to spatially homogeneous fire treatments on grazed rangeland along a precipitation gradient in the North American Great Plains. 2. We predicted that, across the precipitation gradient, management for heterogeneity increases both patch contrast and variance in the composition of plant functional groups. Furthermore, we predicted that patch contrast is positively correlated with variance in plant functional group composition. Because fire spread is important to the fire-grazing interaction, we discuss factors that reduce fire spread and reduce patch contrast despite management for heterogeneity. 3. We compared patch contrast across pastures managed for heterogeneity and pastures managed for homogeneity with a linear mixed effect (LME) regression model. We used the LME model to partition variation in vegetation structure to each sampled scale so that a higher proportion of variation at the patch scale among pastures managed for heterogeneity indicates patch contrast. To examine the relationship between vegetation structure and plant community composition, we used constrained ordination to measure variation in functional group composition along the vegetation structure gradient. We used the meta-analytical statistic, Cohen's d, to compare effect sizes for patch contrast and plant functional group composition. 4. Management for heterogeneity increased patch contrast and increased the range of plant functional group composition at three of the five experimental locations. 5. Plant functional group composition varied in proportion to the amount of spatial heterogeneity in vegetation structure on pastures managed for heterogeneity. 6. Synthesis and applications. Pyric-herbivory management for heterogeneity created patch contrast in vegetation across a broad range of precipitation and plant community types, provided that fire was the primary driver of grazer site selection. Management for heterogeneity did not universally create patch contrast. Stocking rate and invasive plant species are key regulators of heterogeneity, as they determine the influence of fire on the spatial pattern of fuel, vegetation structure and herbivore patch selection, and therefore also require careful management.

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Rangeland management, like most disciplines of natural resource management, has been characterized by human efforts to reduce variability and increase predictability in natural systems (steady-state management often applied through a command-and-control paradigm). Examples of applications of traditional command and control in natural resource management include wildfire suppression, fences to control large ungulate movements, predator elimination programs, and watershed engineering for flood control and irrigation. Recently, a robust theoretical foundation has been developed that focuses on our understanding of the importance of variability in nature. This understanding is built upon the concept of heterogeneity, which originated from influential calls to consider spatial and temporal scaling in ecological research. Understanding rangeland ecosystems from a resilience perspective where we recognize that these systems are highly variable in space and time cannot be achieved without a focus on heterogeneity across multiple scales. Most people view averages as basic reality and variation as a device for calculating a meaningful measure of central tendency ……. Central tendency is a harmful abstraction and variation stands out as the only meaningful reality-Stephen Jay Gould-Full House: The Spread of Excellence from Plato to DarwinWe highlight the broad importance of heterogeneity to rangelands and focus more specifically on (1) animal populations and production, (2) fire behavior and management, and (3) biodiversity and ecosystem function. Rangelands are complex, dynamic, and depend on the variability that humans often attempt to control to ensure long-term productivity and ecosystem health. We present an ecological perspective that targets variation in rangeland properties-including multiple ecosystem services-as an alternative to the myopic focus on maximizing agricultural output, which may expose managers to greater risk. Globally, rangeland science indicates that heterogeneity and diversity increase stability in ecosystem properties from fine to broad spatial scales and through time.

Many species of plants and animals associated with grasslands are rare or declining due to habitat loss and degradation. Although grassland plants and insects evolved in the context of both grazing and fire, the appropriate use of grazing and fire has been debated among those concerned with protecting insect communities. We established an experiment to test insect responses to three grassland management treatments: (1) patch‐burn graze (burning of spatially distinct patches and free access by cattle), (2) graze‐and‐burn (burning of entire tract with free access by cattle), and (3) burn‐only. Because we expected that land‐use legacies could also affect insect abundance and diversity, we evaluated effects of time since fire, grazing history, remnant history (remnant or reconstructed grassland) and pre‐treatment vegetation characteristics, which were assumed to be a legacy of prior land‐use. Butterflies (Lepidoptera), ants (Hymenoptera: Formicidae), and leaf beetles (Coleoptera: Chrysomelidae) were surveyed for three years to compare their responses to each of these treatments as measured by abundance, richness and species diversity. Each of these taxa is relatively diverse and was expected to have the potential to have strong negative responses to grazing and burning, but we predicted more positive responses to patch‐burn grazing. Our results showed that land‐use legacies affected insect abundance, richness and diversity, but treatments did not. Ant abundance was lower in tracts with a history of heavy grazing. Ant species richness was positively associated with pre‐treatment time since fire and vegetation height and negatively associated with pre‐treatment proportion native plant cover. Butterfly abundance was positively associated with pre‐treatment litter cover. Leaf beetle diversity was positively associated with pre‐treatment native plant cover, and leaf beetle abundance was negatively associated with time since fire. Our results indicate that land‐use legacies can exert more influence on grassland insect community composition than current management, but the particular aspects of these land‐use legacies that are important vary across insect taxa. The implications of these finding are that (1) land‐use legacies should garner more attention in grassland management and (2) conservation of grassland insect communities will be improved by taxon‐specific analysis of land‐use legacy variables.

Winter, Stephen L.; Miller, James R.; and Debinski, Diane M., "Temporal variability in aboveground plant biomass decreases as spatial variability increases" (2016 Abstract.Ecological theory predicts that diversity decreases variability in ecosystem function. We predict that, at the landscape scale, spatial variability created by a mosaic of contrasting patches that differ in time since disturbance will decrease temporal variability in aboveground plant biomass. Using data from a multi-year study of seven grazed tallgrass prairie landscapes, each experimentally managed for one to eight patches, we show that increased spatial variability driven by spatially patchy fire and herbivory reduces temporal variability in aboveground plant biomass. This pattern is associated with statistical evidence for the portfolio effect and a positive relationship between temporal variability and functional group synchrony as predicted by metacommunity variability theory. As disturbance from fire and grazing interact to create a shifting mosaic of spatially heterogeneous patches within a landscape, temporal variability in aboveground plant biomass can be dampened. These results suggest that spatially heterogeneous disturbance regimes contribute to a portfolio of ecosystem functions provided by biodiversity, including wildlife habitat, fuel, and forage. We discuss how spatial patterns of disturbance drive variability within and among patches.

Tallgrass prairies of central North America have experienced disturbances including fire and grazing for millennia. Little is known about the effects of these disturbances on prairie ants, even though ants are thought to play major roles in ecosystem maintenance. We implemented three management treatments on remnant and restored grassland tracts in the central U.S., and compared the effects of treatment on abundance of ant functional groups. Management treatments were: (1) patch-burn graze-rotational burning of three spatially distinct patches within a fenced tract, and growing-season cattle grazing; (2) graze-and-burn-burning entire tract every 3 years, and growing-season cattle grazing, and (3) burn-only-burning entire tract every 3 years, but no cattle grazing. Ant species were classified into one of four functional groups. Opportunist ants and the dominant ant species, Formica montana, were more abundant in burn-only tracts than tracts managed with either of the grazing treatments. Generalists were more abundant in graze-and-burn tracts than in burn-only tracts. Abundance of F. montana was negatively associated with pre-treatment time since fire, whereas generalist ant abundance was positively associated. F. montanawere more abundant in restored tracts than remnants, whereas the opposite was true for subdominants and opportunists. In summary, abundance of the dominant F. montana increased in response to intense disturbances that were followed by quick recovery of plant biomass. Generalist ant abundance decreased in response to those disturbances, which we attribute to the effects of competitive dominance of F. montana upon the generalists. Abstract. Tallgrass prairies of central North America have experienced disturbances including fire and grazing for millennia. Little is known about the effects of these disturbances on prairie ants, even though ants are thought to play major roles in ecosystem maintenance. We implemented three management treatments on remnant and restored grassland tracts in the central U.S, and compared the effects of treatment on abundance of ant functional groups. Management treatments were: 1) patch-burn grazerotational burning of three spatially distinct patches within a fenced tract, and growing-season cattle grazing; 2) graze-and-burn -burning entire tract every 3 yrs, and growing-season cattle grazing, and 3) burn-only -burning entire tract every 3 yrs, but no cattle grazing. Ant species were classified into one of four functional groups. Opportunist ants and the dominant ant species, Formica montana, were moreThe final publication is available at Springer via http://dx.doi.org/10.1007/s10841-013-9554-z.2 abundant in burn-only tracts than tracts managed with either of the grazing treatments. Generalists were more abundant in graze-and-burn tracts than in burn-only tracts. Abundance of F. montana was negatively associated with pre-treatment time since fire, whereas generalist ant abundance was positively associated. Formica montana were more abundant in restored tracts than ...

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