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The mechanistic model GO+ describes the functioning and growth of managed forests based upon biophysical and biogeochemical processes. The biophysical and biogeochemical processes included are modelled using standard formulations of radiative transfer, convective heat exchange, evapotranspiration, photosynthesis, respiration, plant phenology, growth and mortality, biomass nutrient content, and soil carbon dynamics. The forest ecosystem is modelled as three layers, namely the tree overstorey, understorey and soil. The vegetation layers include stems, branches and foliage and are partitioned dynamically between sunlit and shaded fractions. The soil carbon submodel is an adaption of the Roth-C model to simulate the impact of forest operations. The model runs at an hourly time step. It represents a forest stand covering typically 1 ha and can be straightforwardly upscaled across gridded data at regional, country or continental levels. GO+ accounts for both the immediate and long-term impacts of forest operations on energy, water and carbon exchanges within the soil–vegetation–atmosphere continuum. It includes exhaustive and versatile descriptions of management operations (soil preparation, regeneration, vegetation control, selective thinning, clear-cutting, coppicing, etc.), thus permitting the effects of a wide variety of forest management strategies to be estimated: from close to nature to intensive. This paper examines the sensitivity of the model to its main parameters and estimates how errors in parameter values are propagated into the predicted values of its main output variables.The sensitivity analysis demonstrates an interaction between the sensitivity of variables, with the climate and soil hydraulic properties being dominant under dry conditions but the leaf biochemical properties being most influential with wet soil. The sensitivity profile of the model changes from short to long timescales due to the cumulative effects of the fluxes of carbon, energy and water on the stand growth and canopy structure. Apart from a few specific cases, the model simulations are close to the values of the observations of atmospheric exchanges, tree growth, and soil carbon and water stock changes monitored over Douglas fir, European beech and pine forests of different ages. We also illustrate the capacity of the GO+ model to simulate the provision of key ecosystem services, such as the long-term storage of carbon in biomass and soil under various management and climate scenarios. [ABSTRACT FROM AUTHOR]

Highlights • A model was developed to evaluate management options under future climate scenarios. • Management systems were evaluated in terms of their nutrient costs. • Nutrient outputs, ecosystem N-P balances, and changes in soil C-N-P were simulated. • Removing harvest residues and reducing rotation length have high nutrient costs. • Climate also has an impact, mainly through an effect of elevated atmospheric CO2. Abstract Intensifying the use of forest biomass to produce fuelwood, through the removal of harvest residues or reductions in rotation length, increases nutrient outputs and can ultimately lead to reduced soil fertility. We developed a modelling approach for the evaluation of different forest management options under future climate scenarios. This approach allows management systems to be evaluated in terms of their nutrient costs by quantifying several variables: nutrient outputs (N, P, K, Ca and Mg) resulting from harvesting, ecosystem N and P balances, and changes in organic C, N and P stocks in the soil. In addition, we calculated a “nutrient cost index” (in kg-harvested-biomass g-exported-nutrients−1). As part of this study, we looked at the effects of harvesting branches, foliage and stumps in addition to tree stems, as well as the effects of changing rotation length in Pinus pinaster , Pseudotsuga menziesii and Fagus sylvatica forest stands, under contrasting Representative Concentration Pathway climate scenarios (RCPs). Comparably to previous studies, our simulations showed that removing harvest residues and, to a lesser extent, reducing rotation length have high nutrient costs. Climate was also found to have an impact, mainly caused by larger amounts of standing tree biomass, and therefore larger biomass harvests and increased nutrient outputs in the scenario which involved elevated atmospheric CO 2. Using contrasting forest management systems and climates, we showed that our modelling approach can be used to guide forest managers in their choice of future silvicultural practices (rotation length, conventional stem-only harvest versus intensive harvest, thinning regime) based on future climate scenarios. Finally, our approach can be used to determine, more accurately than simple allometric relationships, the amounts of nutrients that would need to be applied in order to compensate for losses. [ABSTRACT FROM AUTHOR]

A model for the control of the European grapevine mothLobesia botranaincludes two control methods: insecticides and mating disruption. It yields the combination and schedule of application that minimize cost and losses due to the pest. A simulation is presented for an experimental situation. [ABSTRACT FROM AUTHOR]

The article studies the nutrient transfer mechanism and its control for mixed cropping systems. It presents a mathematical analysis and optimal control of the absorbed nutrient concentration, governed by a transport-diffusion equation in a bounded domain near the root system, satisfying to the Michaelis-Menten uptake law. The existence, uniqueness and positivity of a solution (the absorbed concentration) is proved. We also show that for a given plant we can determine the optimal amount of required nutrients for its growth. The characterization of the optimal control leading to the desired concentration at the root surface is obtained. Finally, some numerical simulations to evaluate the theoretical results are proposed. [ABSTRACT FROM AUTHOR]