Remotely sensing the ecological influences of ditches in Zoige Peatland, eastern Tibetan Plateau

Zhang, Wenjiang; Lu, Qifeng; Song, Kechao; Qin, Gengsheng; Wang, Yan; Wang, Xin; Li, Jun; Liu, Guodong; Li, Hua

doi:10.1080/01431161.2014.939779

Cited by 31 publications

(14 citation statements)

References 20 publications

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“…In the 1970s, to alleviate the population pressure, large-scale trench draining was performed to expand the pasture to meet the grazing demands. The drainage of the trenches deteriorated the water-holding capacity of the wetlands, which is difficult to recover, accelerating the dewatering and shrinkage of marshes and posing a serious threat to the safety and stability of the local ecology [68]. Urban and construction land as a whole did not adversely influence the ecological risk in the study area.…”

Section: Mechanisms Of Influence On the Ecological Riskmentioning

confidence: 90%

Ecological Risk Assessment and Impact Factor Analysis of Alpine Wetland Ecosystem Based on LUCC and Boosted Regression Tree on the Zoige Plateau, China

Hou

Gao

et al. 2020

Remote Sensing

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The Zoige Plateau is typical of alpine wetland ecosystems worldwide, which play a key role in regulating global climate and ecological balance. Due to the influence of global climate change and intense human activities, the stability and sustainability of the ecosystems associated with the alpine marsh wetlands are facing enormous threats. It is important to establish a precise risk assessment method to evaluate the risks to alpine wetlands ecosystems, and then to understand the influencing factors of ecological risk. However, the multi-index evaluation method of ecological risk in the Zoige region is overly focused on marsh wetlands, and the smallest units of assessment are relatively large. Although recently developed landscape ecological risk assessment (ERA) methods can address the above limitations, the final directionality of the evaluation results is not clear. In this work, we used the landscape ERA method based on land use and land cover changes (LUCC) to evaluate the ecological risks to an alpine wetland ecosystem from a spatial pixel scale (5 km × 5 km). Furthermore, the boosted regression tree (BRT) model was adopted to quantitatively analyze the impact factors of ecological risk. The results show the following: (1) From 1990 to 2016, the land use and land cover (LULC) types in the study area changed markedly. In particular, the deep marshes and aeolian sediments, and whereas construction land areas changed dramatically, the alpine grassland changed relatively slowly. (2) The ecological risk in the study area increased and was dominated by regions with higher and moderate risk levels. Meanwhile, these areas showed notable spatio-temporal changes, significant spatial correlation, and a high degree of spatial aggregation. (3) The topographic distribution, climate changes and human activities influenced the stability of the study area. Elevation (23.4%) was the most important factor for ecological risk, followed by temperature (16.2%). Precipitation and GDP were also seen to be adverse factors affecting ecological risk, at levels of 13.0% and 12.1%, respectively. The aim of this study was to provide more precise and specific support for defining conservation objectives, and ecological management in alpine wetland ecosystems.

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Section: Mechanisms Of Influence On the Ecological Riskmentioning

confidence: 90%

Ecological Risk Assessment and Impact Factor Analysis of Alpine Wetland Ecosystem Based on LUCC and Boosted Regression Tree on the Zoige Plateau, China

Hou

Gao

et al. 2020

Remote Sensing

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“…Previous studies have documented apparent impacts from ditching and drainage activities in the 1970s on Zoige wetland hydrology [17,19,26], while this effect may be overestimated as suggested by a recent field investigation in 2012. A recent field survey found that most of these ditches were nearly filled with silt deposits up to the ground surface, indicating a general decline in drainage impacts from these ditches since they were first constructed in the 1970s [48]. Moreover, as the WR and BR basins were both dug by similar ditch densities, i.e., 0.060 km¨km´2 and 0.066 km¨km´2, respectively [28,49], the similar ditching densities minimize potential impacts on differences between the WR and BR basins and cannot fully explain the observed hydrological differences between the two basins from 1985 to 2007.…”

Section: Impact Of Human Activities On the Hydrology Response Of The mentioning

confidence: 99%

Hydrological Response of Alpine Wetlands to Climate Warming in the Eastern Tibetan Plateau

Zhang

Song

et al. 2016

Remote Sensing

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Alpine wetlands in the Tibetan Plateau (TP) play a crucial role in the regional hydrological cycle due to their strong influence on surface ecohydrological processes; therefore, understanding how TP wetlands respond to climate change is essential for projecting their future condition and potential vulnerability. We investigated the hydrological responses of a large TP wetland complex to recent climate change, by combining multiple satellite observations and in-situ hydro-meteorological records. We found different responses of runoff production to regional warming trends among three basins with similar climate, topography and vegetation cover but different wetland proportions. The basin with larger wetland proportion (40.1%) had a lower mean runoff coefficient (0.173˘0.006), and also showed increasingly lower runoff level (´3.9% year´1, p = 0.002) than the two adjacent basins. The satellite-based observations showed an increasing trend of annual non-frozen period, especially in the wetland-dominated region (2.64 day¨year´1, p < 0.10), and a strong extension of vegetation growing-season (0.26-0.41 day¨year´1, p < 0.10). Relatively strong increasing trends in evapotranspiration (ET) (~1.00 mm¨year´1, p < 0.01) and the vertical temperature gradient above ground surface (0.043˝C¨year´1, p < 0.05) in wetland-dominant areas were documented from satellite-based ET observations and weather station records. These results indicate recent surface drying and runoff reduction of alpine wetlands, and their potential vulnerability to degradation with continued climate warming.

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“…However, previous studies [22,23] provided no solid evidence on whether artificial ditches truly contribute to the degradation of peatlands in the Zoige Basin. The loophole may be attributed to the highly variable nature of peat hydrological properties (e.g., water table), such that even within a small area (less than 2500 m 2 ), characterizing the spatial variations of these properties requires high-resolution topographic data and high-density samples [24,25].…”

Section: Introductionmentioning

confidence: 97%

Characterizing Hydrological Connectivity of Artificial Ditches in Zoige Peatlands of Qinghai-Tibet Plateau

Gao

You

2018

Water

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Peats have the unique ability of effectively storing water and carbon. Unfortunately, this ability has been undermined by worldwide peatland degradation. In the Zoige Basin, located in the northeastern Qinghai-Tibet Plateau, China, peatland degradation is particularly severe. Although climate change and (natural and artificial) drainage systems have been well-recognized as the main factors catalyzing this problem, little is known about the impact of the latter on peatland hydrology at larger spatial scales. To fill this gap, we examined the hydrological connectivity of artificial ditch networks using Google Earth imagery and recorded hydrological data in the Zoige Basin. After delineating from the images of 1392 ditches and 160 peatland patches in which these ditches were clustered, we calculated their lengths, widths, areas, and slopes, as well as two morphological parameters, ditch density (Dd) and drainage ability (Pa). The subsequent statistical analysis and examination of an index defined as the product Dd and Pa showed that structural hydrological connectivity, which was quantitatively represented by the value of this index, decreased when peatland patch areas increased, suggesting that ditches in small patches have higher degrees of hydrological connectivity. Using daily discharge data from three local gauging stations and Manning’s equation, we back-calculated the mean ditch water depths (Dm) during raining days of a year and estimated based on Dm the total water volume drained from ditches in each patch (V) during annual raining days. We then demonstrated that functional hydrological connectivity, which may be represented by V, generally decreased when patch areas increased, more sensitive to changes of ditch number and length in larger peatland patches. Furthermore, we found that the total water volume drained from all ditches during annual raining days only took a very small proportion of the total volume of stream flow out of the entire watershed (0.0012%) and this nature remained similar for the past 30 years, suggesting that during annual rainfall events, water drained from connected ditches is negligible. This revealed that the role of connected artificial ditches in draining peatland water mainly takes effect during the prolonged dry season of a year in the Zoige Basin.

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Remotely sensing the ecological influences of ditches in Zoige Peatland, eastern Tibetan Plateau

Cited by 31 publications

References 20 publications

Ecological Risk Assessment and Impact Factor Analysis of Alpine Wetland Ecosystem Based on LUCC and Boosted Regression Tree on the Zoige Plateau, China

Ecological Risk Assessment and Impact Factor Analysis of Alpine Wetland Ecosystem Based on LUCC and Boosted Regression Tree on the Zoige Plateau, China

Hydrological Response of Alpine Wetlands to Climate Warming in the Eastern Tibetan Plateau

Characterizing Hydrological Connectivity of Artificial Ditches in Zoige Peatlands of Qinghai-Tibet Plateau

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