Browsing by Author "Erpay S."

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How good is TanDEM-X 50 m forest/non-forest map? Product validation using temporally corrected geo-browser supplied imagery through Collect Earth
(2023-01-01) Akturk E.; Altunel A.O.; Atesoglu A.; Seki M.; Erpay S.
TanDEM-X Forest/Non-Forest (FNF) map(s) have been one such data focusing on the status of global forest coverage, which has played an essential role in combating climate change. Although the producers have carried out verification and comparison analyses, the need for accuracy assessments in a broader sense creates uncertainties for the users to approve the new data. For this purpose, TanDEM-X 50 m FNF maps were exclusively examined visually through 66,000 test grids within 30 geocells selected from temperate, boreal, and tropical forest zones. Thus, it was aimed to provide product accuracy utilizing visual inspections to the end users of TanDEM-X FNF maps. In addition, Collect Earth (CE) software was used to evaluate the dataset visually, and its advantages or disadvantages were compared with similarly designed studies. Consequently, even though the producers’ data sets were found to have an accuracy of around 85%, it was observed that there were some issues, especially in the definition of the “non-forest” class. CE software was found to be helpful in such studies. However, the dependence of the analyses on geo-browser supplied imagery had some limitations in estimating the accuracy of a new dataset.
Monitoring of Land- Cover/Land- Use changes in Syria by involving the collect earth methodology approach
(2020-12-01) Atesoglu A.; Akturk E.; Rasouli A.; Erpay S.; Ozel H.B.
Land-cover/Land-use (LC/LU) monitoring is important for the ecosystem and climate change intends. The LC/LU change sector plays and will continue to play a crucial role in international efforts for decision making and planning. Monitoring, evaluating and reporting according to international agreements in LC/LU change is still a challenging task difficult task due to government instability, war or conflict situation in some countries. What happened in Syria in recent years is an example of this situation too. In this context, different methods based on remote sensing are used to produce more sensitive and accurate data. Thus, in this study used to Collect Earth methodology, that multi-purpose land monitoring using remote sensing and Geographic information system integrated, for accurately estimating LC/LU change between 2000 and 2018 in Syria. Recently, The Food and Agriculture Organization (FAO) to assist countries in collecting, managing and analysing land-cover and land-use information have released Open Foris Collect Earth software. Besides, there are not enough and current studies for studies in line with the international LC/LU categories and classification principles in Syria. Overall, the article provides basic results which distribution of LC/LU classes according to the Intergovernmental Panel on Climate Change (IPCC), monitoring the current status and change of forest, pasture or woody vegetation, agricultural fields and wetlands, LC/LU change between 2000-2018, habitat loss-gain and revealing the effects of war on the land.
The new natural distribution area of aspen (Populus tremula L.) Marginal populations in pasinler in the Erzurum Province, Turkey, and its stand characteristics
(2018-12-01) özel H.B.; Ayan S.; Erpay S.; Simovski B.
Background and Purpose: Genetic diversity is the basis for adaptation and survival of tree species under changing environmental conditions, representing the key issue of stability and productivity of forest ecosystems. This paper studies the marginal population characteristics and stand dynamics of aspen tree (Populus tremula L.) in natural, pure and mixed forest stands with Scots pine (Pinus sylvestris L.). These populations were observed on founding sites between Timarli Valley and Timan Plateau located in Pasinler in the Erzurum Province in Turkey. Materials and Methods: Three replicated sample sites were established according to a randomised block design with a spacing of approximately 200 m in altitude starting from 1,890 m, which is the natural distribution area of P. tremula, up to 2,460 m, above which this species can no longer thrive. Timarli Valley, Pasinler Erzurum Province, which is the area of research, is located enroute to Timan Plateau, where Scots pines form the alpine tree line ranging up to 2,680 m a.s.l. Results: In this context, aspen trees in this region are the second closest tree species to the tree line after Scots pine, which are found in the subalpine and war zones. In addition, as a result of this study, it has been found out that this species, notwithstanding its natural area of occupancy across Turkey, could thrive up to 2,460 m in altitude and extent of occurrence. Conclusions: A new marginal natural population related to aspen has been found in Pasinler in the Erzurum Province, Turkey, which at the same time indicates that the timberline value in the vertical natural distribution of these species should be updated. Aspen trees, which as pioneer trees play a vital role in the rebuilding or restoring of the ecological balance in forests that over time become degraded because of excessive cutting of trees and erroneous silvicultural interventions should be used in the reclamation of broadleaved and mixed forests in a planned manner. Genetic resources that represent marginal and peripheral populations, both within and outside the natural distribution area, should be established and protected.