Wyniki wyszukiwania

1

Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik

Obrebowa metoda inwentaryzacji lasu oparta na losowaniu warstwowym

100%

Bruchwald A., Zajaczkowski S.

Sylwan

|

2002

|

tom 146

|

nr 10

13-23

2

Ocena dokładności obrębowej metody inwentaryzacji lasu opartej na losowaniu warstwowym

100%

Bruchwald A., Miscicki S., Dmyterko E., Sterenczak K.

Sylwan

|

2017

|

tom 161

|

nr 11

The aim of the research was to assess the accuracy of the stratified sampling method used to estimate the standing volume of a forest district and to compare it with the accuracy of simple random sampling methods. The paper presents the variability of the variables affecting the accuracy of the stratified sampling method. We attempted to find the ways to increase this accuracy. The research was based on the empirical material collected on approximately 42,000 sample plots with a size of 50−500 m², and with an average of 737 plots per forest district. The standard deviation of the merchantable volume of trees on sample plots ranged from 87 to 213 m³/ha, with an average of 128 m³/ha. The coefficient of variation ranged from 5.3 to 28.5% (the average 40.8%). Using a simple random sampling method, the standard error of the volume ranged from 3.3 to 10.0 m³/ha (the average 4.8 m³/ha) and the relative error – from 1.01 to 3.41% (the average 1.55%). The absolute error of the stratified sampling method under which strata are formed on the basis of the main tree species and its age ranged from 2.9 to 7.4 m³/ha, the average 4.2 m³/ha, and the relative error ranged from 0.65 to 1.95%, 1.02% on average (tab.). The accuracy of the stratified sampling method was by 15% higher than that of the simple random sampling method. We found that the relationship between the volume of a sample plot and the main tree species and its age measured by the correlation coefficient was 0.453 on average. For the relationship between volume and age of stands this coefficient was on average 0.422, while between volume and main tree species – only 0.118. Stand age – as an auxiliary variable in formation of strata – proved to be of moderate usefulness resulting from a small difference in the standing volume of stands in older age classes. Main tree species turned out to be of slight usefulness in formation of strata, therefore it seems reasonable to find some other auxiliary variables to replace it.

3

Analiza dokladnosci obrebowej metody inwentaryzacji lasu opartej na losowaniu warstwowym

100%

Bruchwald A., Wojcik R., Zajaczkowski S.

Sylwan

|

2003

|

tom 147

|

nr 05

13-20

4

Dokładność określenia zasobności na poziomie warstw gatunkowo-wiekowych w obrębowej metodzie inwentaryzacji

84%

Banas J., Drozd M., Bujoczek L., Zieba S., Zygmunt R.

Sylwan

|

2017

|

tom 161

|

nr 09

Statistical representative method of inventory based on stratified sampling is used for elaborate forest management plans in Poland. Strata are created according to the dominant tree species and age of stands. First stratum include stands with age from 21 to 30 years and the interval in the next strata is 10 years. Sample plot size depends on stand age and varies from 0.005 to 0.05 ha. According to the allocation pattern number of samples is proportional to age and total area of stands in a stratum. Diversification of number and size of sample plots has a profound influence of inventory precision in an age classes. The aim of the study is to analyse the accuracy of the stand volume determination on the level of age−species strata. Research was conducted based on the data obtained from periodic forest inventory in seven mountainous forest subdistricts located in the Kłodzko Basin (SW Poland). Norway spruce stands with total area of 39,935.45 ha and 6102 sample plots were chosen for analysis. Sampling fraction, mean number and volume of trees on a sample plot, coefficient of volume variability and standard error of volume were calculated for each stratum in analyzed forest subdistricts. Sample plots with size of 0.005 ha established in young stands (21−30 years) are characterized by small number of trees (4.3−7.6 in average) and the highest coefficient of volume variability (93%). Additionally, because of low age of stands, the number of plots is also small (18 on average), which influences the low precision of volume inventory in this stratum. Standard error of volume was on the mean level of 23% in the youngest age stratum and decreased with age of stands to 5% in the stands of 41−71 years and below this level in the strata with the older stands. Increasing the plot size in the youngest stratum will be effective way to improve accuracy of forest inventory in the method based on stratified sampling.

5

Analiza wielkosci miazszosci uzyskanej z inwentaryzacji zapasu metoda obrebowa w zaleznosci od roznych wariantow obliczen

84%

Borecki T., Pieniak D., Wojcik R.

Sylwan

|

2006

|

tom 150

|

nr 11

22-29

6

Ocena dokladnosci okreslenia zasobnosci drzewostanow w obrebowej metodzie inwentaryzacji zapasu

84%

Nowakowska J., Wojcik R., Sierdzinski Z.

Sylwan

|

2010

|

tom 154

|

nr 08

535-544

7

Obrębowa metoda szacowania użytków trzebieżowych w planowaniu rocznym

67%

Wojcik R.

Rozprawy Naukowe i Monografie. Szkoła Główna Gospodarstwa Wiejskiego w Warszawie

|

2013

|

nr 424

8

Szacunek brakarski

67%

Kusiak W.

Przegląd Leśniczy

|

2015

|

tom 25

|

nr 06-07

9

Szacunki brakarskie - to jeszcze nie produkt docelowy

67%

Drabarczyk J.

Głos Lasu

|

2014

|

nr 07-08

10

Metoda 'obrebowa' - szansa na zmniejszenie pracochlonnosci

67%

Bielawska K.

Głos Lasu

|

2009

|

nr 03

14

11

Nowa metoda szcunkow brakarskich

59%

Bielawska K.

Głos Lasu

|

2009

|

nr 03

12-13

Ograniczanie wyników

Obrebowa metoda inwentaryzacji lasu oparta na losowaniu warstwowym

Ocena dokładności obrębowej metody inwentaryzacji lasu opartej na losowaniu warstwowym

Analiza dokladnosci obrebowej metody inwentaryzacji lasu opartej na losowaniu warstwowym

Dokładność określenia zasobności na poziomie warstw gatunkowo-wiekowych w obrębowej metodzie inwentaryzacji

Analiza wielkosci miazszosci uzyskanej z inwentaryzacji zapasu metoda obrebowa w zaleznosci od roznych wariantow obliczen

Ocena dokladnosci okreslenia zasobnosci drzewostanow w obrebowej metodzie inwentaryzacji zapasu

Obrębowa metoda szacowania użytków trzebieżowych w planowaniu rocznym

Szacunek brakarski

Szacunki brakarskie - to jeszcze nie produkt docelowy

Metoda 'obrebowa' - szansa na zmniejszenie pracochlonnosci

Nowa metoda szcunkow brakarskich