Economics

This work investigates the impact of global climate change on the sustainable growth of forest, namely, on its aggregated characteristics such as the number of trees, the basal area, and the amount of carbon sequestrated in the stand. The forest dynamics is described by a nonlinear size-structured population model. The existence of a steady state regime is proven and explicit formulas for the aggregated characteristics are obtained. A numeric simulation on realistic data illustrates and extends the analytic results obtained.

The paper analyzes nonlinear optimal control of integral-differential equations that describe the optimal management of a forest taking into account intra-species competition and carbon sequestration. The objective function includes the revenues from timber production, operational expenses, and the net benefits from carbon sequestration. A dual system is derived and a necessary extremum condition is established.

The Kyoto Protocol allows Annex I countries to deduct carbon sequestered by land use, land-use 2 change and forestry from their national carbon emissions. demonstrated 3 that the objectives of maximizing timber and carbon sequestration are not complementary. Based on 4 this finding, this paper develops a model that takes into account the underlying biophysical and 5 economic processes, and determines empirically the optimal selective management regime. The results 6 show that sequestration costs are significantly lower than previous estimates. 7 8

The Kyoto protocol allows Annex I countries to deduct carbon sequestered by land use, land-use change and forestry from their national carbon emissions. demonstrated that the objectives of maximizing timber and carbon sequestration are not complementary. Based on this finding, this paper determines the optimal selective management regime taking into account the underlying biophysical and economic processes. The results show that the net benefits of carbon storage only compensate the decrease in net benefits of timber production once the carbon price has exceeded a certain threshold value. The sequestration costs are significantly lower than previous estimates.

Age-structured and size-structured population models with a distributed harvesting control are considered and their qualitative behaviors are compared. The maximum principle and bang-bang structure of the optimal control are established for a sizestructured forestry model with carbon sequestration benefits.

We present a theoreticai model to determlnc the optinral managementofasize-distribrrtedforest.Thedecisionnrode}isgil'enin form of a distributed optirnal control problem that cannot be solved analytically.Thus,thepapelpresentsarrrrrrrericaltechniquethatal]or'n's transforming tt'" t"igitttot distributecl control problem into arr ordirrarv control problem. The"methocl has the aclvantage that it does not require progralnmlng numerical algorithms btt ratlier can be implernented u'ith standard .o-ltt"'"iut optiJization packages such as GA\'{S' The empirical application of our model for the case of forest management allolvs deterrnining the selective cutting regime lr'hen carborr sequestration is taken into account'

The Kyoto protocol and subsequent agreements allow Annex I countries to deduct carbon sequestered by land use, land-use change and forestry from their national carbon emissions. From this point of view the determination of the optimal logging regime in the presence of timber and carbon sequestration benefits is of utmost importance. demonstrated that the objectives of maximizing timber and carbon sequestration are not complementary. They show that management regimes that maintain a continuous canopy cover and mimic, to some extent, regular natural forest disturbance are likely to achieve the best combination of wood yield and carbon storage expressed in biophysical units. Based on this finding, this paper determines the optimal selective cutting regime taking into account the underlying biophysical and economic processes. By varying the price for sequestered carbon, this paper establishes the corresponding optimal management regime with respect to the number of young trees to be planted, the size and number of trees to be cut, and the amount of CO 2 sequestered in the long run. The results show that the net benefits of carbon storage only compensate the decrease in net benefits of timber production once the carbon price has exceeded a certain threshold value which in turn depends on the permanence rate of the sequestered carbon in the wood products.

Este artículo presenta un modelo teórico para determinar el régimen de tala selectiva óptimo en un bosque irregular, donde los árboles están distribuidos por diámetros. La ecuación de movimiento del modelo económico está gobernada por una ecuación diferencial parcial, que describe la evolución de la masa forestal a lo largo del tiempo. Con el fin de encontrar la solución del problema de control óptimo con parámetros distribuidos resultante se propone una técnica de solución numérica conocida como "Escalator Boxcar Train", utilizada en Biología para el estudio de la dinámica de poblaciones estructuradas. En la parte empírica se determina la tala selectiva óptima de una masa forestal irregular, es decir, la tala selectiva que maximiza el valor actual de los beneficios obtenidos de la producción de madera de una parcela de pino silvestre, en un horizonte infinito, y se compara la tala selectiva óptima con la tala rasa.

Future climate changes will affect among other aspects forest ecosystems, through its impact on tree growth and productivity. The management of fast-growing species can be adapted more easily to climate change, since rotation periods are short. However, the adaption of the management of slow-growing species to climate changes is more challenging because trees need many years to grow before they reach their commercial size, and consequently any changes in temperature or precipitation may have clear implications on the profitability of forests. In comparison with the existing literature, different future climate change scenarios and the economic model are not considered separately but incorporated in an integrated forest management model. In particular, the paper determines the optimal selective logging regime of a size-distributed forest in the presence of climate change and analyzes the economic implications of the management changes in comparison with the business as usual strategy.