Detection of alpine tree line change with high spatial resolution remotely sensed data

Abstract

This study examined vegetation distribution and tree line change in the Sangong River watershed in the Tianshan Mountains, Xinjiang, China, using aerial photographs from 1962 and 1981 and a QuickBird image from 2006. An object-oriented classification method was used to map vegetation distribution, and the postclassification comparison approach was used to detect vegetation change. The results were linked to digital elevation model data for exploring the relationships between vegetation distribution/expansion and topographic factors. It shows that Schrenkiana is mainly distributed in the region with elevations less than 2,600 m, but its tree line can reach 2,880 m. Sabina is mainly distributed in the region with elevations within 2,600 to 2,900 m, and its highest elevation can be 3,270 m. Approximately 73% of Schrenkiana areas are distributed in aspects of 0 to 45 deg and 270 to 360 deg and 52% of Sabina areas are in aspects of 45 to 90 deg and 225 to 270 deg. The Schrenkiana expansion is mainly distributed in slopes of 20 to 40 deg (accounting for 82%) and aspects of 0 to 90 deg and 270 to 315 deg (accounting for 77%). The elevation of Schrenkiana tree lines increased by 2 to 3 m from 1962 to 2006 and of Sabina increased by 7 to 12 m from 1981 to 2006. Both Schrenkiana and Sabina expansion is mainly located in vegetation frontiers. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Integrating remote sensing and demography for more efficient and effective assessment of changing mountain forest distribution

“…However, of the studies highlighted here, only seven (Allen and Walsh, 1996;Bharti et al, 2012;Dinca et al, 2017;Hill et al, 2007;Luo and Dai, 2013;Mihai et al, 2017;Resler et al, 2004) provide a quantitative accuracy assessment of the classification produced, either through a traditional confusion table with percent accuracy or through regression as in Hill et al (2007). In some cases (e.g.…”

“…Allen and Walsh, 1996;Hill et al, 2007), assessment of distribution change (e.g. Bharti et al, 2012;Luo and Dai, 2013;Mihai et al, 2017), and to better understand how environmental factors act to influence variation in treeline position and structure over differing geographic scales (Weiss et al, 2015).…”

“…Single characteristics such as canopy cover (Hill et al, 2007;Král, 2009), species (Bharti et al, 2012;Luo and Dai, 2013) or height (Mathisen et al, 2014) have been used as well as combinations of such characteristics to return structural classifications of the treeline (Table 1). The definition of treeline ecotone used requires careful consideration since the choices made can impact on any interpretation of the change estimated and the subsequent utility of distribution maps.…”

“…Consequently, a variety of approaches have been taken to construct a data set that can be used to train classification algorithms and validate maps. Allen and Walsh (1996) and Luo and Dai (2013) used field datasets that identified forest structural classes, bolstered by additional photo interpreted plots to train and validate their classifications. Mihai et al (2017) took advantage of existing national forest inventory data in combination with data from the Global Forest Cover product (Hansen et al, 2013) to create their training and validation data.…”

Remotely-Sensed Identification of a Transition for the Two Ecosystem States Along the Elevation Gradient: A Case Study of Xinjiang Tianshan Bogda World Heritage Site

“…RS and GIS technologies have been introduced into the study of the alpine tree line. Remotely-sensed classification information and digital elevation models (DEM) were used to extract the demarcation elevation of the alpine tree line, which greatly improved the efficiency and comprehensiveness of the study of alpine tree line locations [21,[25][26][27][28]. However, there are still some problems in the study of demarcation elevation.…”