Temperature Vegetation Dryness Index Estimation of Soil Moisture under Different Tree Species

Abstract

Abstract:The Laoshan forest is the largest forest in Nanjing, and it plays an important role in water resource management in Nanjing. The objectives of this study are to determine if the temperature vegetation dryness index (TVDI) is suitable to estimate the soil moisture and if soil moisture is significantly affected by tree species in the Laoshan forest. This paper calculated the spatial distribution of TVDI using LANDSAT-5 TM data. Sixty-two observation points of in situ soil moisture measurements were selected to validate the effectiveness of the TVDI as an index for assessing soil moisture in the Laoshan forest. With the aid of the three different temporal patterns, which are 10 January 2011, 18 May 2011 and 23 September 2011, this paper used the TVDI to investigate the differences of soil moisture under four kinds of mono-species forests and two kinds of mixed forests. The results showed that there is a strong and significant negative correlation between the TVDI and the in situ measured soil moisture (R ). This means that the TVDI can reflect the soil moisture status under different tree species in the Laoshan forest. The soil moisture under these six types of land cover from low to high is listed in the following order: Eucommia ulmoides, Quercus acutissima, broadleaf mixed forest, Cunninghamia lanceolata, coniferous and broadleaf mixed forest and Pinus massoniana. OPEN ACCESSSustainability 2015, 7 11402

Special Issue Editorial: Earth Observation and Geoinformation Technologies for Sustainable Development

“…Their results indicate that provincial and prefectural regions with more public services per capita and higher population density had more equal public services. Chen et al [19] conduct a study for Laoshan forest in Nanjing based on Landsat-5 TM data to determine whether the temperature vegetation dryness index (TVDI) is suitable to estimate the soil moisture and if soil moisture is significantly affected by tree species. Their analysis shows that there is a strong negative correlation between the TVDI and the in situ measured soil moisture, which underlines that the TVDI can reflect the soil moisture status under different tree species.…”

Estimation of soil moisture across broad landscapes of Georgia and South Carolina using the triangle method applied to MODIS satellite imagery

“…In theory, the wet edge of the conceptual model should form a horizontal line, where land surface or forest canopy temperature is independent of the vegetation index. There are no water stress conditions present along this line where the soil moisture and evapotranspiration capacity are relatively high (Chen et al 2015). However, the wet edge could also have a positive or negative slope depending on the relationship between the vegetation index and the surface temperature assumptions for the landscape and season under study, and where data may be lacking for certain landscape conditions (Sandholt et al 2002;Cho et al 2016).…”

“…A number of earlier studies Wan et al 2004;Sun et al 2008;Li et al 2008;Mallick et al 2009;Wang et al 2010;Chen et al 2011a;Liu et al 2016) have also advocated the use of TVDI for monitoring surface moisture conditions. TDVI has been recently applied to studies of forests in Brazil (Cho et al 2016), Argentina (Holzman et al 2014), and China (Chen et al 2015). The primary advantage of this approach is that TVDI combines the information captured by both vegetation indices and LST, which facilitates wider application of assessments of soil moisture conditions across diverse landscapes.…”

“…Through the triangle method, TVDI values for a landscape are derived. TVDI has been successfully applied in monitoring, and subsequent assessments, of regional droughts Liu et al 2016), and it can be effective in soil moisture status for different types of land uses (Chen et al 2015). The triangle method has been applied to a variety of landscapes, such as western Africa (Sandholt et al 2002), the central region of Spain (de Tomás et al 2014), and northern China .…”

“…Areas near the dry edge represent stressed conditions of limited water availability for plants, and minimal evaporation (when the vegetation index decreases) or minimal transpiration in case of dense vegetation canopy (where the vegetation index is close to 1). Scatter plots are often trapezoidal as well (Chen et al 2015), where the triangle becomes truncated with larger vegetation index values. Through the triangle method, TVDI values for a landscape are derived.…”