Die antizipierte Varianz: ein Werkzeug für die Optimierung von Waldinventuren | The anticipated variance: a tool for the optimization of forest inventory

2003 ◽  
Vol 154 (3-4) ◽  
pp. 117-121 ◽  
Author(s):  
Daniel Mandallaz
Keyword(s):  
Spatial Distribution ◽  
Forest Inventory ◽  
Random Sampling ◽  
Poisson Model ◽  
Simple Algebra ◽  
Simple Random Sampling ◽  
Two Stage ◽  
Two Phase ◽  
Forest Inventories ◽  
Mathematical Review

This paper gives a non-mathematical review of the concept of anticipated variance which allows to solve entirely the optimisation problem for two-phase two-stage forest inventories with cluster or simple random sampling, in the sense that the anticipated variance is minimised for given costs. The anticipated variance is the average of the design-based variance under a local Poisson-model for the spatial distribution of the trees. The resulting sampling rules have a clear intuitive background and require only simple algebra to be implemented. The required parameters can be estimated from any pre-existing two-phase inventory. An example based on the Swiss National Inventory illustrates the method.

Forest inventory with optimal two-phase two-stage sampling schemes based on the anticipated variance

1999 ◽  
Vol 29 (11) ◽  
pp. 1691-1708 ◽  
Author(s):  
Daniel Mandallaz ◽  
Ronghua Ye
Keyword(s):  
Spatial Distribution ◽  
Forest Inventory ◽  
Poisson Model ◽  
Optimal Sampling ◽  
Two Stage ◽  
Two Phase ◽  
Sampling Schemes ◽  
One Stage ◽  
Sampling Procedures

This work presents optimal sampling schemes for forest inventory. The sampling procedures are optimal in the sense that they minimize the anticipated variance for given costs or conversely, the anticipated variance is the average of the design-based variance under a local Poisson model for the spatial distribution of the trees. The resulting optimal inclusion rules are either probability proportional to size, in one-stage procedures, or a combination of probability proportional to prediction and probability proportional to error, in two-stage procedures. Best feasible approximations of the exact optimal sampling schemes are also given.

scholarly journals Evaluation of forest inventory processes in a forest under concession in the southwestern Brazilian Amazon

2019 ◽  
Vol 49 (2) ◽  
pp. 91-96
Author(s):  
Felipe KAUAI ◽  
Ana Paula Dalla CORTE ◽  
Vinicius CYSNEIROS ◽  
Allan Libanio PELISSARI ◽  
Carlos Roberto SANQUETTA
Keyword(s):  
Forest Inventory ◽  
Random Sampling ◽  
Basal Area ◽  
Stand Density ◽  
Simple Random Sampling ◽  
Relevant Information ◽  
Cluster Sampling ◽  
Two Stage ◽  
Wood Volume ◽  
Management Plans

ABSTRACT Forest inventory procedures are of utmost importance to studies of wood volume stocks, and forest structure and diversity, which provide relevant information to public policies, management plans and ecological research. The present work focused on the performance of inventory techniques in the Amazon region to evaluate wood volume stocks with higher levels of accuracy while maintaining sampling intensity fixed. Two sampling processes were assessed: simple random sampling and two-stage cluster sampling. The processes were evaluated through the allocation of sampling units with different dimensions, and the effectiveness of the generated estimators was analyzed as a function of stand density and basal area. Simple random sampling resulted in the smallest errors, reaching 9% when all species were sampled together. The method depicted forest phytosociological parameters with greater sensitivity, whereas two-stage cluster sampling produced the least accurate estimators and presented slower responses to variation in phytosociological parameters.

On the error of estimates from successive forest inventories with SPR

1987 ◽  
Vol 17 (5) ◽  
pp. 442-447
Author(s):  
Tiberius Cunia
Keyword(s):  
Forest Inventory ◽  
Random Sampling ◽  
Regression Coefficients ◽  
Partial Replacement ◽  
Forest Inventories ◽  
Continuous Forest ◽  
Regression Functions ◽  
The Given ◽  
Linear Regressions ◽  
Continuous Forest Inventory

The approach used by Cunia to combine the error from sample plots with the error from volume or biomass tables when Continuous Forest Inventory (CFI) estimates of current values and growth are calculated is extended to the CFI systems using Sampling with Partial Replacement (SPR). The formulae are derived for the case of SPR on two measurement occasions when (i) volume or biomass tables are constructed from linear regressions for which an estimate of the covariance matrix of the regression coefficients is known, and (ii) the sample plots or points are selected by random sampling independently of the given volume or biomass regression functions.

scholarly journals ANALISA KELAYAKAN USAHATANI JAGUNG DI KABUPATEN CIAMIS

2017 ◽  
Vol 1 (2) ◽  
pp. 139
Author(s):  
Ai Husnul Khotimah
Keyword(s):  
Random Sampling ◽  
Simple Random Sampling ◽  
Two Stage ◽  
Cluster Random Sampling

Penelitian ini bertujuan untuk mengetahui: (1) Besarnya biaya dan penerimaan pada usahatani jagung di Kabupaten Ciamis (2) R/C ratio pada usahatani jagung. Metode yang digunakan dalam penelitian ini adalah metode survai dengan mengambil kasus pada komoditi jagung di Kabupaten Ciamis. Teknik penarikan sampel dilaksanakan menggunakan two stage cluster random sampling untuk sampel area dan strata simple random sampling untuk sampel petani. Data yang diperoleh dianalisa secara deskriptif. Usahatani jagung dianalisis dengan analisis biaya, pendapatan dan R/C. Hasil penelitian menunjukkan bahwa usahatani jagung di Kabupaten Ciamis sudah mulai pada usahatani komersial, dengan teknik budidaya yang masih konvensional, yang pelaksanaannya dipadukan dengan budidaya ternak. R/C yang didapat sebesar 2,22 menunjukkan bahwa usahatani jagung di Kabupaten Ciamis menguntungkan.

scholarly journals SISTEMA DE INVENTÁRIO FLORESTAL PARA SERINGAL NATIVO

FLORESTA ◽  
2002 ◽  
Vol 32 (1) ◽  
Author(s):  
José de Arimatéa Silva ◽  
Sylvio Péllico Netto
Keyword(s):  
Forest Inventory ◽  
Random Sampling ◽  
Rubber Tree ◽  
Basal Area ◽  
Simple Random Sampling ◽  
Inventory System ◽  
Stratified Random Sampling ◽  
Stage Number ◽  
Second Stage ◽  
Two Stages

Este trabalho teve como objetivo desenvolver um Sistema de Inventário Florestal para seringal nativo. Aplicou-se a Amostragem Inteiramente Aleatória (AIA), em dois estágios: colocação de seringa, no primeiro, e estrada de seringa, no segundo. Foram estimados: número de seringueiras por estrada (N), área basal das seringueiras da estrada (G) e volume da porção explorada do fuste (V). Realizou-se uma pós-estratificação, considerando-se estradas de centro e de margem, aplicando-se a Amostragem Estratificada (AE). Comparou-se a AIA com a AE, com base na eficiência relativa. Os resultados revelaram as seguintes estimativas para as médias estratificadas: N=100; G=19,00 m², V= 62,8 m³. Concluiu-se que a AE revelou-se mais eficiente que a AIA para estimar as variáveis analisadas. Propõe-se que um sistema de inventário para seringal nativo deve combinar: informações de um censo das colocações; um processo de amostragem estratificada; e um método de amostragem cuja unidade de amostra é a estrada de seringa. Forest Inventory System for Rubber Trees Abstract Forest Inventory System for rubber trees. This work had as objective to develop an Inventory System for native rubber tree areas. The Simple Random Sampling (SRS) was applied in two stages: the setting, in the first, and the rubber trees tracks, in the second stage. Number of rubber trees per track (N), basal area of the rubber trees track (G) and volume of the stem portion explored (V) were the parameters estimated. A post-stratification was become fulfilled, considering itself center tracks and river side tracks, applying itself it Stratified Random Sampling (STRS). It was compared SRS with the STRS, on the basis of the relative efficiency. The results showed the following estimates for the stratified means: N=100; G=19,00 m², V = 62,8 m³. It was concluded that the STRS showed more efficient than the SRS to estimate the analyzed variables. It is considered that an Inventory System for native rubber tree areas must match: information of a census of the settings; a process of Stratified Random Sampling; and a sampling method whose unit of sample is the rubber tree track.

Forest inventory: further results for optimal sampling schemes based on the anticipated variance

2001 ◽  
Vol 31 (10) ◽  
pp. 1845-1853 ◽  
Author(s):  
Daniel Mandallaz ◽  
Adrian Lanz
Keyword(s):  
Forest Inventory ◽  
Optimal Allocation ◽  
Optimality Criterion ◽  
Second Phase ◽  
Optimal Sampling ◽  
Two Stage ◽  
Two Phase ◽  
Sampling Density ◽  
Sampling Schemes ◽  
Inclusion Probabilities

This work presents optimal allocation rules for two-phase, two-stage sampling schemes in which the sampling density and the costs of the second phase can vary over domains. The optimality criterion is based on the anticipated variance. It also gives an improved version of discrete approximation for the resulting inclusion probabilities. An example illustrates the theory.

Forest inventory estimation with mapped plots

2004 ◽  
Vol 34 (2) ◽  
pp. 493-497 ◽  
Author(s):  
Paul C Van Deusen
Keyword(s):  
Forest Inventory ◽  
Random Sampling ◽  
Simple Random Sampling ◽  
Mean Squared Errors ◽  
Additional Work ◽  
Fixed Area ◽  
Plot Design

Procedures are developed for estimating means and variances with a mapped-plot design. The focus is on fixed-area plots, and simulations are used to validate the proposed estimators. The mapped-plot estimators for means and variances are compared with simple random sampling estimators that utilize only full plots. As expected, the mapped-plot estimates have smaller mean squared errors than the simple random sampling estimates. The theory for fixed-area plots is easy to apply, although additional work is required to map plots in the field. Corresponding theory for variable plots is developed but not tested with simulations. The difficulty of applying these methods to variable plots is greater, but not prohibitive.

A Test of Cluster Sampling in Forest Inventories

1975 ◽  
Vol 5 (2) ◽  
pp. 269-272 ◽  
Author(s):  
G. M. Bonnor
Keyword(s):  
Random Sampling ◽  
Sampling Design ◽  
Simple Random Sampling ◽  
Cluster Sampling ◽  
Field Sampling ◽  
Forest Inventories ◽  
Straight Line ◽  
Time Required ◽  
Variance Estimates ◽  
The Given

During a recent pilot survey in Newfoundland, forest data were collected using a stratified, one-stage cluster-sampling design. The data were analyzed to determine if, within the stratified framework, cluster sampling would be more efficient than simple random sampling. Each cluster consisted of five point-samples located in a straight line. For the analysis, volume and variance estimates were determined from clusters of 1,2,3,4 and 5 points. During the survey, records were kept of the time required to complete various field-sampling tasks. These were used in lieu of cost data in the analysis. Results indicated that, for the given conditions, simple random sampling was more efficient than cluster sampling. However, relatively small changes in the conditions would make cluster sampling more efficient.

scholarly journals Damage in Khaya ivorensis caused by Trigona spinipes in Brazilian savannah

2017 ◽  
Vol 1 (1) ◽  
pp. 40 ◽  
Author(s):  
Rebecca Silva de Moura ◽  
Kellen Rabello de Souza ◽  
Daniel Da Silva Souza ◽  
Gabriel Mendes Santana ◽  
Guilherme Murilo De Oliveira ◽  
...  
Keyword(s):  
Forest Inventory ◽  
Random Sampling ◽  
Sampling Method ◽  
Simple Random Sampling ◽  
First Record ◽  
Apical Part ◽  
African Mahogany ◽  
Brazilian Savannah ◽  
Apical Bud

Trigona spinipes (Dog bee) attack the apical bud of Khaya ivorensis causing atrophy and budding which provoke branches that will depreciate the shaft if not handled. Damage to the culture of K. ivorensis has been reported for Brazil, but never before for the Brazilian savannah. The aim of this study was to survey the dog bee attack and report as first record the presence and damage caused in the African mahogany plantations in the Brazilian savannah. The area has about of 16.6 hectares of African mahogany monoculture in the municipality of Piracanjuba, Goiás. It has been used 21 plots of 400 m², pre-defined and simple random sampling method, in which was carried out forest inventory and observation sprouts the apical part of the stem and consequent artificial pruning of sprouts. Also performing were viewed bees in foraging of activity by cutting the shoots of K. ivorensis. In planting, 6.14% of the trees had regrowth and this percentage may indicate the number of attacked trees. The total trees with regrowth is a large quantity of trees which may develop with problems, generating more than one stem or branch, thereby preclude the affected wood is used for furniture.  

scholarly journals Geostatistics as a tool to reduce the sampling effort in forest inventories

2021 ◽  
pp. 174-179
Author(s):  
Myrcia Minatti ◽  
Carlos Roberto Sanquetta ◽  
Sylvio Péllico Neto ◽  
Ana Paula Dalla Corte ◽  
Vinicius Costa Cysneiros
Keyword(s):  
Forest Inventory ◽  
Ordinary Kriging ◽  
Simple Random Sampling ◽  
Exponential Model ◽  
Indicator Kriging ◽  
Sampling Effort ◽  
Thematic Maps ◽  
Visual Interpretation ◽  
Forest Inventories ◽  
Geostatistical Techniques

Geostatistics is one of the tools applied to investigate the spatial variability of forests to reduce costs and recognize the best productivity areas for planning. This study aimed to test the performance of geostatistical techniques in reducing the sampling effort in forest inventories. For this purpose, we used the height of dominant trees as a discriminator of the homogeneous strata to obtain a better representation of the productivity within the forest stands. We carried out the study in Pinus taeda L. stands in the Center-South of Paraná, Brazil, by using plots from a forest inventory allocated with the systematic process. Then, we tested three models to determine the site curves (Schumacher, Chapman-Richards 2, and 3 coefficients) with the thirty-seventh year being the reference age. To model the spatial patterns of the dominant height, we used the ordinary kriging, and, after that, we generated the thematic maps of the site classes. Similarly, we used the indicator kriging which allowed obtaining the probabilities of high, medium, and low productivity sites. The processing of the stratified sampling, with the support of the visual interpretation of the images, allowed us to define five strata according to productivity. Results showed that ordinary kriging is effective in defining the productivity classes. Along with geostatistical techniques, it produces more homogeneous strata and reduces the errors of the forest inventory. Moreover, the best-selected model was the Chapman-Richards (3 coefficients) for the site curves. The exponential model was the best model to identify the best areas of the probability of occurrence of sites with higher productivity. The efficiency of indicative kriging generated thematic maps to delimit the likely locations of the most promising sites. Overall, geostatistics proved to be efficient concerning error when compared to simple random sampling.

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