scholarly journals Effects of Catastrophic Insect Outbreaks on the Harvesting Solutions of Dahurian Larch Plantations

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Qi Jin ◽  
Lauri Valsta ◽  
Kari Heliövaara ◽  
Jing Li ◽  
Youqing Luo ◽  
...  
Keyword(s):  
Poisson Process ◽  
Average Rate ◽  
Optimal Harvesting ◽  
Insect Damage ◽  
Dahurian Larch ◽  
Land Value ◽  
Individual Tree ◽  
Pest Outbreaks ◽  
Bare Land ◽  
Bare Land Value

Optimal harvesting under pest outbreak risk was studied on a set of even-aged Dahurian larch (Larix gmelinii) stands in northeastern Inner Mongolia, China. The effects of catastrophic pest outbreaks caused by the Siberian moth (Dendrolimus sibiricus) on the economic harvesting plan are compared through both deterministic and stochastic cases. Stand simulation is based on an individual-tree growth system. A scenario approach is applied when simulating the effects of catastrophic pest outbreaks. Insect damage is assumed to be a Poisson process with an average rate of 0.1 per year. One hundred scenarios of insect damage are created using the Poisson process to simulate the distribution of bare land value of each of the optimal regimes. Numerical results show that the optimal rotation is shortened with an increasing probability of a catastrophe. The average bare land values in the stochastic case are approximately 14.8% to 22.9% lower. Numbers of thinnings are decreased for most plots when seeking a highest bare land value, compared to the deterministic optima. If given a constant thinning rate, increasing risk-taking shortens the optimum rotation, as the model set used.

Optimizing continuous cover and rotation forestry in mixed-species boreal forests

2020 ◽  
Vol 50 (11) ◽  
pp. 1138-1151
Author(s):  
Vesa-Pekka Parkatti ◽  
Olli Tahvonen
Keyword(s):  
Interest Rate ◽  
Tree Species ◽  
Boreal Forests ◽  
Large Diameter ◽  
Land Value ◽  
Mixed Species ◽  
Harvest Timing ◽  
Bare Land ◽  
Level Problem ◽  
Bare Land Value

We study the management of mixed-species boreal forests and tree species composition in a stand-level economic–ecological, size-structured model. The model includes ecological tree species interaction, a detailed harvesting cost module, optimal harvest timing, and optimization between continuous cover and rotation forestry. Optimization is solved by applying a trilevel structure in which the optimal rotation is the highest-level problem, harvest timing is the mid-level problem, and thinning intensity is the lowest-level problem. Given realistic regeneration costs and a 3% interest rate, continuous cover forestry is optimal and may include up to a 40% fraction of broadleaves. A low interest rate and low regeneration cost together with the presence of light-demanding Scots pine (Pinus sylvestris L.) favours rotation forestry. Eurasian aspen (Populus tremula L.) decreases the bare-land value but is optimal to fell without utilization only when it has no commercial value. Overyielding in terms of cubic metre output does not reveal the economically preferable species combination. Managing single-species stands by removing other species that are naturally regenerated decreases the economic outcome by 35%–44%. Felling noncommercial trees without utilization shows that the economically optimal solution avoids high-grading. Maintaining the number of large-diameter trees beyond the level that maximizes profitability implies only minor losses. Omitting thinning decreases the bare-land value up to 73%.

An analysis of forest property tax burdens under a land and reforestation tax system: a western Washington case study

1990 ◽  
Vol 20 (5) ◽  
pp. 554-565
Author(s):  
B. Bruce Bare
Keyword(s):  
Current System ◽  
Property Tax ◽  
Land Value ◽  
Ad Valorem Tax ◽  
Tax Base ◽  
Tax System ◽  
Bare Land ◽  
Western Washington ◽  
Bare Land Value ◽  
Ad Valorem

A per acre property tax model is proposed for taxing plantation-grown timber in western Washington State. The taxable assets consist of the bare land value plus the reforestation investment necessary to establish the timber stand. Under this system, an annual ad valorem property tax, or a harvest yield tax that substitutes for all, or part, of the annual ad valorem tax is levied on the full value of the tax base. Thus, unlike the traditional case where an annual property tax is levied on modified bare land and timber values to reduce the deferred yield bias associated with long-lived timber crops, the tax base under the proposed system requires no comparable modification. A variety of input scenarios are used to compare the numerical consequences of applying the proposed tax system with those of a land only, a land plus timber, and a harvest yield tax system; all levied at full value. Further comparisons with Washington's existing forest tax system, which is composed of an annual ad valorem property tax on a legislatively mandated statutory bare land value and a 5% harvest yield tax imposed in lieu of an annual ad valorem property tax on maturing timber, demonstrates how highly modified Washington's current system has become to accommodate forest owners and temper the deferred yield bias the property tax theoretically fosters.

scholarly journals Long-Term Projections of the Natural Expansion of the Pine Wood Nematode in the Iberian Peninsula

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 849
Author(s):  
Begoña de la Fuente ◽  
Santiago Saura
Keyword(s):  
Iberian Peninsula ◽  
Tree Species ◽  
Average Rate ◽  
Limiting Factor ◽  
Pine Wood Nematode ◽  
Individual Tree ◽  
Pine Wood ◽  
Pine Tree ◽  
Informative Content

The invasive pine wood nematode (PWN), Bursaphelenchus xylophilus, causal agent of pine wilt disease, was first reported in Europe, near Lisbon, in 1999, and has since then spread to most of Portugal. We here modelled the spatiotemporal patterns of future PNW natural spread in the Iberian Peninsula, as dispersed by the vector beetle Monochamus galloprovincialis, using a process-based and previously validated network model. We improved the accuracy, informative content, forecasted period and spatial drivers considered in previous modelling efforts for the PWN in Southern Europe. We considered the distribution and different susceptibility to the PWN of individual pine tree species and the effect of climate change projections on environmental suitability for PWN spread, as we modelled the PWN expansion dynamics over the long term (>100 years). We found that, in the absence of effective containment measures, the PWN will spread naturally to the entire Iberian Peninsula, including the Pyrenees, where it would find a gateway for spread into France. The PWN spread will be relatively gradual, with an average rate of 0.83% of the total current Iberian pine forest area infected yearly. Climate was not found to be an important limiting factor for long-term PWN spread, because (i) there is ample availability of alternative pathways for PWN dispersal through areas that are already suitable for the PWN in the current climatic conditions; and (ii) future temperatures will make most of the Iberian Peninsula suitable for the PWN before the end of this century. Unlike climate, the susceptibility of different pine tree species to the PWN was a strong determinant of PWN expansion through Spain. This finding highlights the importance of accounting for individual tree species data and of additional research on species-specific susceptibility for more accurate modelling of PWN spread and guidance of related containment efforts.

Optimal structure and development of uneven-aged Norway spruce forests

2011 ◽  
Vol 41 (12) ◽  
pp. 2389-2402 ◽  
Author(s):  
Olli Tahvonen
Keyword(s):  
Steady State ◽  
Interest Rate ◽  
Norway Spruce ◽  
Large Scale ◽  
Size Structure ◽  
Basal Area ◽  
Growth Conditions ◽  
Optimal Harvesting ◽  
Tree Model ◽  
Individual Tree

Optimal harvesting of Norway spruce ( Picea abies (L.) Karst.) forests is studied applying an individual-tree model for uneven-aged management. Optimization is carried out by gradient-based, large-scale interior point methods. Assuming volume maximization and natural regeneration, it is optimal to apply uneven-aged management. Under artificial regeneration, the result is the reverse. Economically optimal solutions with a 20-year harvesting interval produce an annual sawn timber output of 4.4–2.4 m3·ha–1 depending on thermal zone and interest rate. Before harvest basal area varies between 18 and 12 m2·ha–1 and the diameter of harvested trees between 15 and 33 cm. In contrast with the classic inverted J-structure, optimal steady-state size structure resembles a serrate form. Profitability of even- and uneven-aged management is compared assuming that the initial stand state represents an optimal uneven-aged steady state. A switch to even-aged management is optimal given the most favorable growth conditions and interest rate below 1%–2%. In other cases, it is economically optimal to continue uneven-aged management although volume output remains lower than under even-aged management.

Economic Aspects of the Forest Regeneration Delay Decision

1985 ◽  
Vol 9 (2) ◽  
pp. 91-94 ◽  
Author(s):  
Thomas J. Straka ◽  
James E. Hotvedt
Keyword(s):  
Real World ◽  
Forest Regeneration ◽  
Forest Stand ◽  
Economic Aspects ◽  
Expectation Value ◽  
Land Expectation Value ◽  
Bare Land ◽  
Bare Land Value ◽  
The Cost ◽  
Delay Decision

Abstract Regeneration lag, the cost resulting from a delay in reestablishment of a forest stand, represents an important opportunity cost̶the cost of the foregone opportunity to grow timber over the period of the delay. The land expectation value (Le) criterion is used to evaluate the costs associated with one-time-only and perpetual lags. Significant decreases in wealth, or bare land value, were found using a simplified example with real-world cost and price data. Changes in required land bases resulting from regeneration delays were also reviewed. The additional land requirements resulting from scheduled delays in regeneration can be costly.

scholarly journals Dynamics of land use and land cover changes in Huluka watershed of Oromia Regional State, Ethiopia

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Gemechu Shale Ogato ◽  
Amare Bantider ◽  
Davide Geneletti
Keyword(s):  
Land Use ◽  
Sustainable Development ◽  
Land Cover ◽  
Water Body ◽  
Average Rate ◽  
Land Cover Changes ◽  
Cultivated Land ◽  
Forest Land ◽  
Planning And Management ◽  
Bare Land

Abstract Background Land use and land cover changes in urbanized watersheds of developing countries like Ethiopia are underpinned by the complex interaction of different actors, driving forces, and the land itself. Land conversion due to residential development, economic growth, and transportation is identified as the most serious environmental pressure on urbanized landscapes of the world. It results in the degradation of natural vegetation and significant increases in impervious surfaces. The purpose of the study was to analyze spatio-teporal changes in land use and land cover in the Huluka watershed with implications to sustainable development in the watershed. Results Forest land, cultivated land, urban built-up, bush/shrub land, bare land, grassland, and water body were identified as the seven types of land use and land cover in the Huluka watershed. Forest land decreased by 59.3% at an average rate of 164.52 ha/year between 1979 and 2017. Bush/ shrub land decreased by 68.2% at an average rate of 318.71 ha/year between 1979 and 2017. Grassland decreased by 32.7% at an average rate of 228.65 ha/year between 1979 and 2017. Water body decreased by 5.1% at an average rate of 1.06 ha/year between 1979 and 2017. Urban built-up area increased by 351% at an average rate of 16.20 ha/year between 1979 and 2017. Cultivated land increased by 105.3% at an average rate of 692.76 ha/year between 1979 and 2017. Bare land increased by 41.9% at an average rate of 4.00 ha/year between 1979 and 2017. Infrastructural and agricultural expansion, increased demand for wood, local environmental and biophysical drivers, rapid human population growth, economic drivers, technological drivers, policy and institutional drivers, and local socio-cultural drivers were perceived by residents as drivers of land use and land cover changes. Increased flooding risk, increased soil erosion, increased sedimentation into water resources like lakes and rivers, decrease in soil fertility, loss of biodiversity, loss of springs, decrease in annual rainfall, and increase in heat during the dry season were perceived by residents as negative local effects of land use and land cover changes. Conclusions Changes in land use and land cover in the study water shade imply the need for integrating sustainable watershed planning and management into natural resources management strategies. In other words, practices of appropriate land use planning and management, family planning, participatory planning and management, appropriate environmental impact assessment (EIA), and proper planning and management of development projects and programmes are of paramount importance to promote sustainable development in the Huluka watershed and beyond.

scholarly journals The Poisson process is the universal law of cancer development: driver mutations accumulate randomly, silently, at constant average rate and for many decades, likely in stem cells

2017 ◽  
Author(s):  
Aleksey V. Belikov ◽  
Alexey D. Vyatkin ◽  
Sergey V. Leonov
Keyword(s):  
Stem Cells ◽  
Probability Distribution ◽  
Poisson Process ◽  
Old Age ◽  
Average Rate ◽  
Age Distribution ◽  
Cancer Development ◽  
Driver Mutations ◽  
Erlang Distribution ◽  
Universal Law

AbstractBackgroundIt is assumed that cancers develop upon acquiring a particular number of (epi)mutations in driver genes, but the law governing the kinetics of this process is not known. We have recently shown that the age distribution of incidence for 20 most prevalent cancers of old age is best approximated by the Erlang probability distribution. The Erlang distribution describes the probability of several successive random events occurring by the given time according to the Poisson process, which allows to predict the number of critical driver events.ResultsHere we show that the Erlang distribution is the only classical probability distribution that can adequately model the age distribution of incidence for all studied childhood and young adulthood cancers, in addition to cancers of old age.ConclusionsThis validates the Poisson process as the universal law describing cancer development at any age and the Erlang distribution as a useful tool to predict the number of driver events for any cancer type. The Poisson process signifies the fundamentally random timing of driver events and their constant average rate. As waiting times for the occurrence of the required number of driver events are counted in decades, it suggests that driver mutations accumulate silently in the longest-living dividing cells in the body - the stem cells.

Lectures on the Poisson Process

2017 ◽  
Author(s):  
Günter Last ◽  
Mathew Penrose
Keyword(s):  
Poisson Process

Applying the Anderson-Darling Test to Suicide Clusters

Crisis ◽  
2013 ◽  
Vol 34 (6) ◽  
pp. 434-437 ◽  
Author(s):  
Donald W. MacKenzie
Keyword(s):  
Poisson Process ◽  
Goodness Of Fit ◽  
Small Samples ◽  
Massachusetts Institute Of Technology ◽  
Homogeneous Poisson Process ◽  
Cornell University ◽  
The Difference ◽  
Suicide Clusters ◽  
Institute Of Technology ◽  
Anderson Darling

Background: Suicide clusters at Cornell University and the Massachusetts Institute of Technology (MIT) prompted popular and expert speculation of suicide contagion. However, some clustering is to be expected in any random process. Aim: This work tested whether suicide clusters at these two universities differed significantly from those expected under a homogeneous Poisson process, in which suicides occur randomly and independently of one another. Method: Suicide dates were collected for MIT and Cornell for 1990–2012. The Anderson-Darling statistic was used to test the goodness-of-fit of the intervals between suicides to distribution expected under the Poisson process. Results: Suicides at MIT were consistent with the homogeneous Poisson process, while those at Cornell showed clustering inconsistent with such a process (p = .05). Conclusions: The Anderson-Darling test provides a statistically powerful means to identify suicide clustering in small samples. Practitioners can use this method to test for clustering in relevant communities. The difference in clustering behavior between the two institutions suggests that more institutions should be studied to determine the prevalence of suicide clustering in universities and its causes.

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