Quantifying the impacts of river hydrology on riparian vegetation spatial structure: Case study in the lower basin of the Tarim River, China

Abstract

River hydrology largely determines the species composition and spatial distribution of riparian vegetation. However, it is difficult to determine the riparian vegetation spatial pattern that is only influenced by river hydrology due to the complex impacts of other influencing factors in field environments. We investigated the spatial structure of riparian vegetation in the lower basin of the Tarim River in hyper-arid western China, where distinct geomorphic and climatic features exclude the influences of factors other than river hydrological factors on the spatial structure of riparian vegetation. Landsat 8 Operational Land Imager remotely sensed data were used to identify the different vegetation types and obtain the vegetation leaf area index (LAI) in the study area. Our results showed that the overall vegetation LAI exhibited a negative exponential declining trend with distance from the river, but this relationship was different for the different vegetation types, exhibiting a negative exponential relationship for the Populus woodlands and a Gaussian-type relationship for the Tamarix shrublands. The average width of the riparian vegetation decreased along the river by a negative power function. The average vegetation LAI decreased linearly along the river. The quantitative data we obtained regarding the river-induced variation in the riparian vegetation cover with the distance from the river channel would particularly be useful for modelling riparian vegetation dynamics and distributions.

Effects of Distinguishing Vegetation Types on the Estimates of Remotely Sensed Evapotranspiration in Arid Regions

“…Vegetation in arid regions is relatively sparse and their spatial structure is usually simple. As a result, it is easy and feasible to distinguish different vegetation types by using remote sensing images [41,66,67], and some effective classification methods with high accuracy have been proposed [68,69]. Therefore, the estimation method based on specific vegetation type proposed in this study is feasible in practical applications.…”

“…The riparian forests in the arid areas of northwestern China are typically composed of two vegetation types: Tamarix ramosissima (shrub vegetation) and Populus euphratica (arbor vegetation) [41,42]. They are often characterized by discontinuous and plaque-like distribution in space, and have different water-consumption characteristics [31,32].…”

Comparison of Remotely Sensed Evapotranspiration Models Over Two Typical Sites in an Arid Riparian Ecosystem of Northwestern China

“…According to the meteorological observations from the Tikanlik Weather Station, the average annual temperature is 10.5 • C, the annual precipitation is between 17 and 40 mm, and the potential evaporation is approximately 3000 mm yr −1 [6,37]. The vegetation is sparse and dominated by Tamarix ramosissima (T. ramosissima) and Populus euphratica (P. euphratica), which are typical phreatophytes, and belong to shrub and arbor forests, respectively [21,38]. Due to poor water conditions, the vegetation coverage and species richness of plant communities in the study area are relatively low [11].…”

Relationships between Plant Communities and Environmental Factors in an Extremely Arid Area: A Case Study in China

“…The plants were divided into 3 species groups. There were 7 species in group I (species 1, 2, 11, 15, 18, 22, and 24), 6 species in group II (5, 9, 20, 23, 27, and 31), and 19 species in group III (3,4,6,7,8,10,12,13,14,16,17,19,21,25,26,28,29,30, and 32). The occurrence frequency of most species in group III was low.…”

“…The soil sediment concentration is high, the corrosion resistance is poor, and the scouring effects of the water and wind erosion are relatively strong. These factors have meant that the topography is unstable [12]. Precipitation in the basin is rare, but evaporation is strong, soil texture is poor, the plant material accumulation process is very slow, and productivity is low [13].…”