Forest Resource Dynamics Research Articles

Modelling the Dynamics of Carbon Storages for Pinus densata Using Landsat Images in Shangri-La Considering Topographic Factors

Accurate estimation of forest carbon storage is essential for understanding the dynamics of forest resources and optimizing decisions for forest resource management. In order to explore the changes in the carbon storage of Pinus densata in Shangri-La and the influence of topography on carbon storage, two dynamic models were developed based on the National Forest Inventory (NFI) and Landsat TM/OLI images with a 5-year interval change and annual average change. The three modelling methods used were partial least squares (PLSR), random forest (RF) and gradient boosting regression tree (GBRT). Various spectral and texture features of the images were calculated and filtered before modelling. The terrain niche index (TNI), which is able to reflect the combined effect of elevation and slope, was added to the dynamic model, the optimal model was selected to estimate the carbon storage, and the topographic conditions in areas of change in carbon storage were analyzed. The results showed that: (1) The dynamic model based on 5-year interval change data performs better than the dynamic model with annual average change data, and the RF model has a higher accuracy compared to the PLSR and GBRT models. (2) The addition of TNI improved the accuracy, in which R2 is improved by up to 10.48% at most, RMSE is reduced by up to 7.32% at most, and MAE is reduced by up to 8.89% at most, and the RF model based on the 5-year interval change data has the highest accuracy after adding TNI, with an R2 of 0.87, an RMSE of 3.82 t-C·ha−1, and a MAE of 1.78 t-C·ha−1. (3) The direct estimation results of the dynamic model showed that the carbon storage of Pinus densata in Shangri-La decreased in 1987–1992 and 1997–2002, and increased in 1992–1997, 2002–2007, 2007–2012, and 2012–2017. (4) The trend of increasing or decreasing carbon storage in each period is not exactly the same on the TNI gradient, according to the dominant distribution, as topographic conditions with lower elevations or gentler slopes are favorable for the accumulation of carbon storage, while the decreasing area of carbon storage is more randomly distributed topographically. This study develops a dynamic estimation model of carbon storage considering topographic factors, which provides a solution for the accurate estimation of forest carbon storage in regions with a complex topography.

Above-Ground Biomass Estimation for Coniferous Forests in Northern China Using Regression Kriging and Landsat 9 Images

Accurate estimation of forest above-ground biomass (AGB) is critical for assessing forest quality and carbon stocks, which can improve understanding of the vegetation growth processes and the global carbon cycle. Landsat 9, the latest launched Landsat satellite, is the successor and continuation of Landsat 8, providing a highly promising data resource for land cover change, forest surveys, and terrestrial ecosystem monitoring. Regression kriging was developed in the study to improve the AGB estimation and mapping using the Landsat 9 image in Wangyedian forest farm, northern China. Multiple linear regression (MLR), support vector machine (SVM), back propagation neural network (BPNN), and random forest (RF) were used as the original models to predict the AGB trends, and the optimal model was used to overlay the results of kriging interpolation based on the residuals to obtain the new AGB predictions. In addition, Landsat 8 images in Wangyedian were used for comparison and verification with Landsat 9. The results showed that all bands of Landsat 8 and Landsat 9 maintained a high degree of uniformity, with positive correlation coefficients ranging from 0.77 to 0.89 (p < 0.01). RF achieved the highest estimation accuracy among all the original models based on the two data sources. However, kriging regression can significantly reduce the estimation error, with the root mean square error (RMSE) decreasing by 55.4% and 51.1%, for Landsat 8 and Landsat 9, respectively, compared to the original RF. Further, the R2 and the lowest RMSE for Landsat 8 were 0.88 and 16.83 t/ha, while, for Landsat 9, they were 0.87 and 17.91 t/ha. The use of regression kriging combined with Landsat 9 imagery has great potential for achieving efficient and highly accurate forest AGB estimates, providing a new reference for long-term monitoring of forest resource dynamics.

Temporal changes in Oak forests over last three decades in western Himalaya, India

The distribution and dynamics of forest resources provide basis for management and conservation planning. Long-term data and information is important to improve our understanding on spatial and temporal variations of a particular ecosystem. In view of this, distribution and dynamics of temperate forests was assessed for last three decade in the western Himalaya (Uttarakhand). Comparative assessment of existing data and information on Oak species (Quercus leucotrichophora) found in Uttarakhand is performed with present status of forest to provide the consequence of climate change and anthropogenic disturbances. Results of the study reveals a significant increase in tree density of majority of the species studied. Total Basal Area (TBA) of targeted Oak forests has significantly increased (p<0.01) over the last three decades. There exists a significant increase in tree, saplings and seedling density of Q. leucotrichophora and Q. lanuginosa. The density of tree of Q. floribunda increased significantly, while saplings and seedlings declined; this indicates poor regeneration of the species. The ecological condition of Q. semecarpifolia is alarming due to huge decline in the number of saplings, and complete absence of seedlings. The changes in the forest dynamics is attributed to environmental perturbations and anthropogenic pressures.

The economics of the Sylvo-Cynegetic equilibrium

This work aims at modeling the economics of the sylvo-cynegetic equilibrium in commercial forests, as defined by forestry authorities, with respect to uncertain damages to plantation stands caused by the overabundance of ungulate species. After presenting the stochastic optimal control framework, in which the dynamics of forest resources and the population dynamics of big game species are both considered, we apply the stochastic control to an updated version of the well-known Gordon-Schaefer bioeconomic model. Our results show that the equilibrium can be achieved through the use of a joint control divided between regeneration works and hunting regimes. Furthermore, we find that, in equilibrium, the investment in forestry works ought to be equal to the willingness to undertake the resource stock stabilization in uncertainty. The investment should amount no more than 20% of total costs engaged in a forestry management plan.

Approximating Forest Resource Dynamics in Peninsular Malaysia Using Parametric and Nonparametric Models, and Its Implications for Establishing Forest Reference (Emission) Levels under REDD+

Forest reference (emission) levels (FREL/FRLs) are baselines for REDD+, and 34 countries have submitted their FREL/FRLs to UNFCCC by January 2018. Most of them used simple historical average without considering the stages of forest transition. This research suggested that the period of calculating FREL/FRLs of simple historical average should be properly chosen if these countries are occupying multiple stages or sub-stages of forest transition. Moreover, as a case study, this research applied both parametric and nonparametric models to approximate forest area dynamics with regard to per capita GDP in Peninsular Malaysia from 1971 to 2016. This research found that, in the case of Peninsular Malaysia, among the parametric models, the biexponential model outperformed the other growth models, while two of the nonparametric models i.e. Friedman local averaging and Nadaraya–Watson kernel smoothing models are the best among all the models on the basis of their RSS, RMSE, and MAE indices. Based on the results of our leave-last-five-out CV, however, the research found that the biexponential and Nadaraya–Watson kernel smoothing models performed best, although the performance of the other two nonparametric models remains unknown. Nonparametric model results indicated that Peninsular Malaysia experienced four sub-stages since 1971 and each sub-stage had different linear trends, yet it still did not reach the turning point of forest transition. This research also found that a linear projection using historical deforestation data when the per capita GDP level reached US$8000 was appropriate for setting FREL/FRLs.

International trade, urbanization and forest resource dynamics

Based on BT model (Brander and Taylor 1997, 1998), this paper extends and introduces private ownership, and takes into account of the relationship between international trade, urbanization and forest degradation in the context of forest resource products as consumer goods and intermediate inputs. In an autarky economy, the level of urbanization is positively related to forest degradation. When the economic entity is opening to outer world, and under a diversified production pattern, different trade patterns of products have different impact on forest degradation; and under a professional production pattern, international trade will lead the urbanization level to evolve in two extreme directions. When urbanization level reaches 0, the forests degenerate even become depleted; when urbanization level reaches 1, the forest resources are perfectly protected.

Особенности роста популяции елипод пологом березняков в южной тайге Русской равнины

В статье рассматривается рост ели под пологом южно-таёжных березняков. Анализируется возрастная динамика высоты и объема стволов деревьев ели в зависимости от периода их возобновления. Приводится сравнение основных показателей роста подпологовой ели и древостоев ели, формирующихся без участия мягколиственных пород. Dynamics of forest resources in the center of Russian plain can be characterized by an increase of soft-leaved breed stand square. Spruce population resumes under such stand canopy. These stand often develop spontaneously. This fact shows the relevance of studying the processes of formation of soft-leaved breed stand with spruce growing under their canopy. The aim of this research was to study the growth characteristics of spruce under the canopy of birch forests of the southern taiga. Method of sample-trees was used. In total 400 sample-trees of different habitus were involved. The trees were sawn into segments and the cuts were measured according to the methodology adopted for the analysis of tree trunks. The measurement results were processed with a special program for personal computers. It was identified that tree growth is largely determined by the period of spruces regeneration – Tw (the difference between the age of the birch and spruce age). On the dynamics of growth in the height of the selected three generations for Tw: 1–25, 26–40, 41–50 years. At the age of 35 years the first generation reaches the lower height threshold (6.3 m) of the second tier of the stand. The average height of the second and third tree generations at this age does not exceed the height of the regrowth. For the first two generations the current average-for-the-period height increase reaches its maximum value at the age of 35–40 years, while the second generation significantly inferior to the first one in growth value. For the trees of the first generation the equality of the current average-for-the-period and average height increments observed at the age of 60 years. After that age the changes in the vertical structure of the emerging spruce forest are unlikely. In this generation, at the age of 15 years leading trees start to stand out, the minimum height of these leading trees is equal to 0,7 m. Spruce trees with higher tapering and low marketability of wood dominate in the canopy of birch forests. The growth characteristics of spruce growing under the canopy of birch significantly inferior to the characteristics of spruce, growing in forest stands without the participation of soft-leaved breeds. At the age of 60 years, the average growth in height is 40 % smaller, and average growth in the trunk volume is 80 % less than for trees in stands of II grade of locality spruce, which are the most common in the study region.

Roundwood Trade and its Impact on the Dynamics of Forest Resources in China : A Time Series Approach

Roundwood Trade and its Impact on the Dynamics of Forest Resources in China : A Time Series Approach

Behavioral Modelling in a Decision Support System

Considering the variety of attitudes, objectives and behaviors characterizing forest owners is crucial for accurately assessing the impact of policy and market drivers on forest resources. A serious shortcoming of existing pan-European Decision Support Systems (DSS) is that they do not account for such heterogeneity, consequently disregarding the effects that this might have on timber supply and forest development. Linking a behavioral harvesting decision model—Expected Value Asymmetries (EVA)—to a forest resource dynamics model—European Forestry Dynamics Model (EFDM)—we provide an example of how forest owner specific characterization can be integrated in a DSS. The simulation results indicate that the approach holds promise as regards accounting for forest owner behavior in simulations of forest resources development. Hence, forest owner heterogeneity makes the distribution of forestland on owner types non-trivial, as it affects harvesting intensity and, subsequently, inter-temporal forest development.

Stimulating fuelwood consumption through public policies: An assessment of economic and resource impacts based on the French Forest Sector Model

Stimulating renewable energy is a crucial objective in view of tackling climate change and coping with future fossil fuel scarcity. In France, fuelwood appears to be an important source for the renewable energy mix. Using the French Forest Sector Model, our paper aims to assess the impacts of three policy options to stimulate fuelwood consumption: a consumer subsidy, a producer subsidy and a fixed-demand contract policy. We explored their impacts in terms of five groups of criteria: (1) forest resource dynamics; (2) variations in wood products prices and quantities consumed and produced; (3) trade balance; (4) budgetary costs; and (5) variations in agent surpluses. We show that no policy option is more desirable than another on the basis of all of these criteria and that trade-offs will determine which is the best policy option to be implemented.

Forest Management Policies and Resource Balance in China

Using the latest forest inventory, this article provides a detailed analysis of China's changing forest sector by focusing on new forest trends, forest policy changes, and challenges to achieving a sustainable forest management. The authors analyze the dynamics of forest resources and provide an impact assessment of forest policies on China's forestry development during the past decades. Moreover, the analysis of the forest market highlights substantial disequilibria marked by a limited domestic supply potential and a growing demand for forest products satisfied by increasing imports. Internal and external solutions are explored, and their implications for China and supplying countries are assessed.

Multilevel Modeling of the Forest Resource Dynamics

We examine the theoretical and applications-specific issues relating to modeling the temporal and spatial dynamics of forest ecosystems, based on the principles of investigating dy- namical models. When developing the predictive dynamical models of forest resources, there is a possibility of achieving uniqueness of the solutions to equations by taking into account the initial and boundary conditions of the solution, and the conditions of the geographical environment. We present the results of a computer modeling and predictive mapping for the regional and subregional model of the forest resource dynamics.

Forest Management Policies and Resource Balance in China: An Assessment of the Current Situation

Using the latest forest inventory, this paper provides a comprehensive analysis of China's forest sector by focusing on new forest trends, forest policy changes and challenges to achieve a sustainable forest management. We analyze the dynamics of forest resources and provide an impact assessment of forest policies on China's forestry development over the last decades. Moreover, the analysis of the forest market highlights substantial disequilibria marked by a limited domestic supply potential and a growing demand for forest products satisfied by increasing imports. Internal and external solutions are explored and their implications for China and supplying countries are assessed.