Jaynes' information theory formalism of statistical mechanics is applied to the stationary states open, non-equilibrium systems. First, it shown that probability distribution pΓ underlying microscopic phase space trajectories Γ over a time interval length τ satisfies ∝ exp(τσΓ/2kB) where σΓ time-averaged rate entropy production Γ. Three consequences this result are then derived: (1) fluctuation theorem, which describes exponentially declining deviations from second law thermodynamics as → ∞;...

Recently the author used an information theoretical formulation of non-equilibrium statistical mechanics (MaxEnt) to derive fluctuation theorem (FT) concerning probability second law violating phase-space paths. A less rigorous argument leading variational principle maximum entropy production (MEP) was also given. Here a more and general mathematical derivation MEP from MaxEnt is presented, relationship between FT thereby clarified. Specifically, it shown that allows orthogonality property...

Summary Optimization models of stomatal conductance ( g s ) attempt to explain observed behaviour in terms cost‐‐benefit tradeoffs. While the benefit opening through increased CO 2 uptake is clear, currently nature associated cost(s) remains unclear. We explored hypothesis that maximizes leaf photosynthesis, where cost arises from nonstomatal reductions photosynthesis induced by water stress. analytically solved two cases, CAP and MES, which reduced potential leads carboxylation cap acity...

A carbon-flow model for managed forest plantations was used to estimate carbon storage in UK differing Yield Class (growth rate), thinning regime and species characteristics. Time-averaged, total (at equilibrium) generally the range 40–80 Mg C ha−1 trees, 15–25 above- belowground litter, 70–90 soil organic matter 20–40 wood products (assuming product lifetime equalled rotation length). The rate of during first most 2–5 year−1. sensitivity analysis revealed following processes be both...

Summary Based on short‐term experiments, many plant growth models – including those used in global change research assume that an increase temperature stimulates respiration ( R ) more than photosynthesis P ), leading to the / ratio. Longer‐term however, have demonstrated is relatively insensitive temperature. We show both types of response may be reconciled within a simple substrate‐based model acclimation temperature, which effectively limited by supply carbohydrates fixed through...

Abstract A new model of stomatal conductance is proposed which combines the essential features Ball–Berry–Leuning (BBL) and Tardieu–Davies (TD) models within a simple spatially aggregated picture guard cell function. The thus provides coherent description responses to both air soil environments. also presents some novel not included in either BBL or TD models: sensing intercellular (rather than leaf surface) CO 2 concentration; an explanation all three observed regimes (A, B C) response...

Experimental evidence indicates that the stomatal conductance and nitrogen concentration ([N]) of foliage decline under CO2 enrichment, percentage growth response to elevated is amplified water limitation, but reduced limitation. We advance simple explanations for these responses based on an optimisation hypothesis applied a model annual carbon-nitrogen-water economy trees growing at CO2-enrichment experiment Oak Ridge, Tennessee, USA. The shown have optimum leaf [N], area index (LAI), where...

Is Maximum Entropy Production (MEP) a physical principle? In this paper I tentatively suggest it is not, on the basis that MEP equivalent to Jaynes’ (MaxEnt) inference algorithm passively translates assumptions into macroscopic predictions, as applied non-equilibrium systems. MaxEnt itself has no content; disagreement between predictions and experiment falsifies assumptions, not MaxEnt. While remains be shown rigorously indeed for systems arbitrarily far from equilibrium, work in progress...

Summary Photosynthetic rate is concurrently limited by stomatal limitations and nonstomatal (NSLs). However, the controls on NSLs to photosynthesis their coordination with control different timescales remain poorly understood. According a recent optimization hypothesis, depend leaf osmotic or water status are coordinated so as maximize photosynthesis. Drought notching experiments were conducted Pinus sylvestris , Picea abies Betula Pendula Populus tremula seedlings in glasshouse conditions...

Journal Article Conifer Plantations on Drained Peatlands in Britain: a Net Gain or Loss of Carbon? Get access M. G .R. CANNELL, CANNELL 1Institute Terrestrial EcologyBush Estate, Penicuik, EH26 0QB, Scotland Search for other works by this author on: Oxford Academic Google Scholar R. C. DEWAR, DEWAR D. G. PYATT 2Forestry Authority, Northern Research StationRoslin, EH25 9SY, Forestry: An International Forest Research, Volume 66, Issue 4, 1993, Pages 353–369,...

A root-shoot model of partitioning during vegetative plant growth is described, which simulates the transport water, labile nitrogen (N) and carbon (C) through xylem phloem, in C, N water interact to determine growth. It assumed that a fraction (λ) taken up by root passes upwards shoot where it transferred phloem. The remaining (1-λ) directly Phloem translocation C downwards from driven shoot-root gradient concentration, accordance with Munch flow hypothesis. Shoot rates are be functions...

ABSTRACT As trees grow taller, decreased xylem path conductance imposes a major constraint on plant water and carbon balance, is thus key factor underlying forest productivity decline with age. The responses of stomatal conductance, leaf area: sapwood area ratio ( A L : S ) soil–leaf potential gradient (ΔΨ S–L to height growth were investigated in maritime pine trees. Extensive measurements situ sap flow, (non‐gravitational) needle = Ψ − ρ w gh made during 2 years chronosequence four...

We explore the extent to which a simple mechanistic model of short‐term plant carbon (C) dynamics can account for number generally observed phenomena. For an individual, fully expanded leaf, predicts that fast‐turnover labile C, starch and protein pools are driven into approximate or moving steady state is proportional average leaf absorbed irradiance on time‐scale days weeks, even under realistic variable light conditions, in qualitative agreement with general patterns acclimation both...

Photosynthesis of leaves is commonly observed to have a saturating response increases in their nitrogen (N) content, while the plant maintenance respiration more nearly linear over normal range tissue N contents. Hence, for given amount foliage, net primary productivity ( NPP ) may maximum value with respect variations content. Using simple analytically-solvable model , this idea formulated and its broad implications growth are explored at scale closed stand vegetation. The maximum-...

Plant ecologists have proposed a variety of optimization theories to explain the adaptive behaviour and evolution plants from perspective natural selection ('survival fittest'). Optimization identify some objective function--such as shoot or canopy photosynthesis, growth rate--which is maximized with respect one more plant functional traits. However, link between these functions individual fitness seldom quantified there remains uncertainty about most appropriate choice function use. Here,...

The carbon and oxygen stable isotope composition of wood cellulose (delta(13)C(cellulose) delta(18)O(cellulose), respectively) reveal well-defined seasonal variations that contain valuable records past climate, leaf gas exchange allocation dynamics within the trees. Here, we present a single-substrate model for growth to interpret isotopic signals collected in an even-aged maritime pine plantation growing South-west France, where soil flux variables were also monitored. Observed patterns...

Plant responses to global changes in carbon dioxide (CO2), nitrogen, and water availability are critical future atmospheric CO2 concentrations, hydrology, hence climate. Our understanding of those is incomplete, however. Multiple-resource manipulation experiments empirical observations have revealed a diversity responses, as well some consistent patterns. But vegetation models—currently dominated by complex numerical simulation models—have yet achieve consensus among their predicted let...

ABSTRACT An empirical model for stomatal conductance (g), proposed by Leuning (1995, this issue) as a modification of Ball, Woodrow & Berry's (1987) model, is interpreted in terms simple, steady‐state guard cell function. In aperture function the relative turgor between cells and epidermal cells. The correlation g leaf surface vapour pressure deficit Leuning's sensing transpiration rate, via changes gradient total water potential g, CO 2 assimilation rate concentration relationship...

The carbon balance between managed forests and the atmosphere depends critically on frequency intensity of harvesting, lifetime harvested products. To assess more quantitatively nature this dependence, a theoretical analysis, previously applied to storage in trees wood products only, is extended here include forest floor detritus soil. A dimensionless combination parameters model, alpha, with critical value alpha(c), identified such that for alpha < conversion old-growth releases long term....