Properties of Young and Mature 'Valencia' Oranges Related to Selective Harvest by Mechanical Means

1972 ◽  
Vol 15 (2) ◽  
pp. 0235-0238 ◽  
Author(s):  
G. E. Coppock
Keyword(s):  
Selective Harvest

108 years of change in spatial pattern following selective harvest of aPinus ponderosastand in northern Arizona, USA

2009 ◽  
Vol 20 (1) ◽  
pp. 79-90 ◽  
Author(s):  
A.J. Sánchez Meador ◽  
M.M. Moore ◽  
J.D. Bakker ◽  
P.F. Parysow
Keyword(s):  
Spatial Pattern ◽  
Northern Arizona ◽  
Selective Harvest

scholarly journals Impact of Distance between Strip Roads on Productivity and Costs of a Forwarder in Commercial Thinning of Pinus Taeda Stands

2020 ◽  
Vol 41 (2) ◽  
pp. 243-249
Author(s):  
Oscar Manuel de Jesús Vera Cabral ◽  
Eduardo da Silva Lopes ◽  
Carla Krulikowski Rodrigues ◽  
Afonso Figueiredo Filho
Keyword(s):  
Pinus Taeda ◽  
Value Added ◽  
Wood Products ◽  
Production Costs ◽  
Working Cycle ◽  
Time Motion ◽  
Commercial Thinning ◽  
Selective Harvest ◽  
Thinning Operations ◽  
The Impact

Demand for higher value-added wood products stimulates research for new, mainly mechanized, thinning operations in order to increase productivity and reduce production costs. In this context, the aim of this study was to evaluate the impact of distance between strip roads on forwarder productivity and costs of thinning operations in Pinus taeda stands. The study was carried out in 10-year-old Pinus taeda stands located in Parana State, Brazil. Two thinning methods were evaluated: (1) TH5: systematic harvest in every fifth tree row and selective harvest in adjacent rows; and (2) TH7: systematic harvest in every seventh tree row and selective harvest in adjacent rows. Working cycle times, productivity and costs were determined through a time-motion study of the forwarder. The additional variables evaluated were wood assortments (industrial wood and energy wood) and extraction distances (50, 100, 150 and 200 m), and mean values were compared between thinning methods using t tests for independent samples (α=0.05). Loading and unloading elements consumed the most time in the working cycle, with lower participation time in TH7 due to greater availability of logs along the strip roads (higher pile volumes), influencing total cycle time up to the mean distance of 150 m for both assortments. TH7 consequently showed 6% higher productivity, its energy yield was 5.3% lower and its production cost was 3.0% lower.

Investigating Contemporary Evolution via Size-Selective Harvest

2009 ◽  
Vol 71 (3) ◽  
pp. 151-155 ◽  
Author(s):  
Joseph H. Allen ◽  
Jill Wold
Keyword(s):  
Contemporary Evolution ◽  
Selective Harvest

scholarly journals Global Stability Analysis and Optimal Control of a Harvested Ecoepidemiological Prey Predator Model with Vaccination and Taxation

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Chao Liu ◽  
Qingling Zhang ◽  
Jinna Li
Keyword(s):  
Optimal Control ◽  
Stability Analysis ◽  
Global Stability ◽  
Interaction Mechanism ◽  
Prey Population ◽  
Predator Population ◽  
Optimal Control Strategy ◽  
Global Stability Analysis ◽  
Selective Harvest ◽  
Predator Model

We propose an ecoepidemiological prey predator model, where selective harvest effort on predator population is considered. Vaccination and taxation are introduced as control instruments, which are utilized to control number of susceptible prey population and protect predator population from overexploitation, respectively. Conditions which influence nonnegativity and boundedness of solutions are studied. Global stability analysis around disease-free equilibrium is discussed based on robust Bendixson criterion, which is theoretically beneficial to studying coexistence and interaction mechanism of population within harvested ecoepidemiological system. By using Pontryagin’s maximum principle, an optimal control strategy is derived to maximize the total discounted net economic revenue to society as well as protect prey population from infectious disease. Numerical simulations are carried out to show the consistency with theoretical analysis.

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