A comparison distance sampling methods for estimating the plant density and canopy cover in different inventory net (Case study: Manesht and ghalarang forest of ilam, Iran)
Year: 2024
Type: article
Abstract: Background and objectives: Forest inventories can be conducted in various ways.While it is possible to survey an entire area to obtain and collect information, this method is not suitable for large areas due to the high costs and excessive time required.To address this issue, the sampling method is commonly employed.Numerous studies have been conducted to evaluate the accuracy and validity of sampling methods.Although, the effectiveness of distance methods has been confirmed in some instances, there are also cases where these methods have been flawed.Among the most important factors influencing the accuracy of estimates derived from these methods is the spatial distribution pattern of individual trees.Analyzing and assessing the precision of different tree sampling measurement methods can assist researchers in making informed decisions regarding vegetation measurement and evaluation. Materials and methods:The protected area of Manshet and Qalarang is located in the northern part of Ilam Province.For this study, 87 hectares of the 33,000-hectare area were selected based on cost and opportunity.The positions of 100% of the trees and the characteristics of the tree crowns were measured and recorded using a GPS device.This information was then entered into a Geographic Information System (GIS) as a point layer, employing a systematic method that began with a random point.In this study, we applied five distance methods (nearest individual, nearest neighbor, second nearest neighbor, joint-point, and point-centered quarter method) to estimate plant density and canopy cover based on various systematic sample sizes (100×100, 150×150, 200×100, and 200×200 meters).The number of samples (71, 34, 34, and 18) collected from the 87 hectares in Manshet and Qalarang, Ilam Province, was compared to assess the accuracy of full calibration.Results: One of the most significant factors influencing the precision of estimates in sampling methods is the spatial distribution pattern of trees.In this study, Clarke and Evans' indices were employed to analyze changes in the spatial arrangement of trees.The calculated numerical value of this index was 0.417, indicating a clustered distribution pattern of the trees.The results demonstrated that among the various distance sampling methods with different inventory networks, the second-nearest neighbor method at a systematic sample of 200 × 200 m and the point-centered quarter method at 200 × 100 m and 150 × 150 m were the most suitable for this region.This is because these methods provided acceptable estimates based on an accuracy threshold of ±10.Conclusion: This study indicates that the methods of distance measurement in the Zagros forest demonstrated good precision and can be applied in other research and practical areas as well.
DOI: 10.61186/jfer.4.1.69
Author: Amir Modaberi
Institution: Ilam University
Language: English
Subfield: Nature and Landscape Conservation
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: hybrid
OpenAlex ID: W4410926648