Abiotic and Landscape Factors Constrain Restoration Outcomes Across Spatial Scales of a Widespread Invasive Plant

The natural recolonization of native plant communities following invasive species management is notoriously challenging to predict, since outcomes can be contingent on a variety of factors including management decisions, abiotic factors, and landscape setting. The spatial scale at which the treatment is applied can also impact management outcomes, potentially influencing plant assembly processes and treatment success. Understanding the relative importance of each of these factors for plant community assembly can help managers prioritize patches where specific treatments are likely to be most successful. Here, using effects size analyses, we evaluate plant community responses following four invasive Phragmites australis management treatments (1: fall glyphosate herbicide spray, 2: summer glyphosate herbicide spray, 3: summer imazapyr herbicide spray, 4: untreated control) applied at two patch scales (12,000 m2 and 1,000 m2) and monitored for 5 years. Using variation partitioning, we then evaluated the independent and shared influence of patch scale, treatment type, abiotic factors, and landscape factors on plant community outcomes following herbicide treatments. We found that Phragmites reinvaded more quickly in large patches, particularly following summer herbicide treatments, while native plant cover and richness increased at a greater magnitude in small patches than large. Patch scale, in combination with abiotic and landscape factors, was the most important driver for most plant responses. Compared with the small plots, large patches commonly had deeper and more prolonged flooding, and were in areas with greater hydrologic disturbance in the landscape, factors associated with reduced native plant recruitment and greater Phragmites cover. Small patches were associated with less flooding and landscape disturbance, and more native plants in the surrounding landscape than large patches, factors which promoted higher native plant conservation values and greater native plant cover and richness. Herbicide type and timing accounted for very little of the variation in native plant recovery, emphasizing the greater importance of patch selection for better management outcomes. To maximize the success of treatment programs, practitioners should first manage Phragmites patches adjacent to native plant species and in areas with minimal hydrologic disturbance

Invasive Phragmites australis Management Outcomes and Native Plant Recovery Are Context Dependent

The outcomes of invasive plant removal efforts are influenced by management decisions, but are also contingent on the uncontrolled spatial and temporal context of management areas. Phragmites australis is an aggressive invader that is intensively managed in wetlands across North America. Treatment options have been understudied, and the ecological contingencies of management outcomes are poorly understood. We implemented a 5‐year, multi‐site experiment to evaluate six Phragmites management treatments that varied timing (summer or fall) and types of herbicide (glyphosate or imazapyr) along with mowing, plus a nonherbicide solarization treatment. We evaluated treatments for their influence on Phragmites and native plant cover and Phragmites inflorescence production. We assessed plant community trajectories and outcomes in the context of environmental factors. The summer mow, fall glyphosate spray treatment resulted in low Phragmites cover, high inflorescence reduction, and provided the best conditions for native plant recruitment. However, returning plant communities did not resemble reference sites, which were dominated by ecologically important perennial graminoids. Native plant recovery following initial Phragmites treatments was likely limited by the dense litter that resulted from mowing. After 5 years, Phragmites mortality and native plant recovery were highly variable across sites as driven by hydrology. Plots with higher soil moisture had greater reduction in Phragmites cover and more robust recruitment of natives compared with low moisture plots. This moisture effect may limit management options in semiarid regions vulnerable to water scarcity. We demonstrate the importance of replicating invasive species management experiments across sites so the contingencies of successes and failures can be better understood

Application of adaptive multivariable Generalized Predictive Control to a HVAC system in real time

This paper presents the application of a Multivariable Generalized Predictive Controller (MGPC) for simultaneous temperature and humidity control in a Heating, Ventilating and Air- Conditioning (HVAC) system. The multivariable controlled process dynamics is modeled using a set of MISO models on-line identified from measured input-output process data. The controller synthesis is based on direct optimization of selected quadratic cost function with respect to amplitude and rate input constraints. Efficacy of the proposed adaptive MGPC algorithm is experimentally demonstrated on a laboratory-scale model of HVAC system. To control the airconditioning part of system the designed multivariable predictive controller is considered in a cascade dual-rate control scheme with PID auxiliary controllers

How to restore Phragmites-invaded wetlands

Phragmites grows in tall, dense stands that shade out native plants. It spreads rapidly and overtakes important habitat for shorebirds and waterfowl, reducing the availability of nesting, loafing, and foraging areas. Phragmites makes large areas of wetlands inaccessible to wildlife and humans alike

Asymmetric constraints with polytopic sets in MPC with application to coupled tanks system

Asymmetric constraints have not received sufficient attention in the MPC literature, possibly due to the popularity of ellipsoidal terminal regions, which for asymmetric constraints would give conservative results. The work here adopts low-complexity polyhedra for which invariance and feasibility under asymmetric constraints can be handled through the use of Farkas' lemma and related results. The paper embeds these results into an MPC law based on a dual mode prediction strategy and proposes algorithms for the systematic design of the polytopic terminal sets. The efficacy of the results is illustrated through application to a coupled tanks system. Copyright © 2004 John Wiley and Sons, Ltd

Constrained predictive control of linear distributed parameter systems

The model predictive control problem with guaranteed stability for a class of linear distributed parameter systems with simultaneous amplitude and rate control constraints is investigated. The approach is developed using a finite dimensional, input-output modelling technique for distributed parameter systems based on a distributed output projection onto a finite basis set. The paper employs a dual mode prediction strategy in conjunction with the projection-based state space system description and proposes algorithms for the design of polyhedral positive invariant and feasible sets which serve as terminal target sets for predicted states. An extension to predictive control with integral action is described. The proposed algorithms are shown to work well by means of both simulations and experimental results. © 2004 Taylor and Francis Ltd

Asymmetric constraints with polyhedral sets in MPC with application to coupled tanks system

Asymmetric constraints have not received sufficient attention in the MPC literature possibly due to the popularity of ellipsoidal terminal regions, which for asymmetric constraints would result in conservative results. The work here adopts low complexity polyhedra for which invariance and feasibility under asymmetric constraints can be handled through the use of Farkas' lemma and related results. The paper embeds these results into a MPC law based on a dual mode prediction strategy and proposes algorithms for the systematic design of the polyhedral terminal sets. The efficacy of the results is illustrated through application to a coupled tanks system

Real-time implementation of multiple model based predictive control strategy to air/fuel ratio of a gasoline engine

Growing safety, pollution and comfort requirements influence automotive industry ever more. The use of three-way catalysts in exhaust aftertreatment systems of combustion engines is essential in reducing engine emissions to levels demanded by environmental legislation. However, the key to the optimal catalytic conversion level is to keep the engine air/fuel ratio (AFR) at a desired level. Thus, for this purposes more and more sophisticated AFR control algorithms are intensively investigated and tested in the literature. The goal of this paper is to present for a case of a gasoline engine the model predictive AFR controller based on the multiple-model approach to the engine modeling. The idea is to identify the engine in particular working points and then to create a global engine's model using Sugeno fuzzy logic. Opposite to traditional control approaches which lose their quality beside steady state, it enables to work with satisfactory quality mainly in transient regimes. Presented results of the multiple-model predictive air/fuel ratio control are acquired from the first experimental real-time implementation on the VW Polo 1390 cm3 gasoline engine, at which the original electronic control unit (ECU) has been fully replaced by a dSpace prototyping system which execute the predictive controller. Required control performance has been proven and is presented in the paper

Hidden Players—Meiofauna Mediate Ecosystem Effects of Anthropogenic Disturbances in the Ocean.

Humans have used, and had effects on, marine ecosystems throughout history. As the human population and its economic activities increase, these effects intensify. Yet, our awareness and understanding of the long‐term, pervasive effects of anthropogenic disturbances on the seafloor, and the resident meiofauna, is far from complete. This chapter summarises research on the responses of marine meiofauna to the most widespread anthropogenic disturbances, including bottom-fishing, pollution, introduction of invasive species, and climate change. Anthropogenic disturbance and natural environmental dynamics interact to cause changes in the response of meiofauna species, either in the short-term, through effects on growth and development, or in the long-term, through genetic selection. Species-specific sensitivity to disturbance can propagate to community-level responses, mediated by shifts in interspecific interactions. Meiofauna responses to anthropogenic disturbance are commonly nonlinear and depend on the environmental context in which the disturbance occurs, on the scales at which meiofauna responses are observed, and on the extent to which the disturbance creates novel environments that differ from those to which the resident meiofauna are adapted. Although responses of meiofauna assemblages to anthropogenic disturbance are complex, in general severe disturbance leads to dominance by opportunistic species. The widespread replacement of habitat-specific ecological specialists by broadly-adapted ecological generalists and opportunists often results in biotic and functional homogenisation of once disparate biotas. Their small size, their life history characteristics, and their phylogenetically and functionally diverse species pool, all suggest that meiofauna are resilient, and there is little evidence for the local extinction of meiofauna from anthropogenically disturbed seafloor habitats. It therefore seems likely that meiofauna have the ability to adapt, and thrive, in response to most environmental changes. New horizons for future meiofauna research pertain to the extent to which the resistance or resilience of meiofauna to anthropogenic disturbance buffers ecosystem functioning against further change