Publications by authors named "Meili Wen"

5 Publications

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Understanding the complex environmental management through a len of food-water-ecosystem nexus: Insights from an ecosystem restoration hotspot in dryland.

Sci Total Environ 2021 Apr 15;783:147029. Epub 2021 Apr 15.

Guangdong Open Laboratory of Geospatial Information Technology and Application, Guangzhou Institute of Geography, Guangdong Academy of Sciences, Guangzhou 510070, PR China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, PR China.

The Ecosystem Restoration Project (ERP) is a critical and urgent practice to achieve the land degradation neutrality (LDN) targets. However, an insufficient understanding of the balance between contrasting sectors of the food-water-ecosystem nexus results in ineffectiveness in supporting complex environmental management (CEM), leading to undesirable ERP failures. The Ordos Plateau case identified the nexus evolution and the non-linear interactions between sectors, which were expected to support adaptive strategy formulations for CEM and achieve win-win outcomes. Revegetation in drylands substantially boosted ecosystem restoration, alleviating soil erosion. However, the excessive reliance on returning cropland to woodland and grassland has caused a significant loss of arable and grazing land. During the initial period of ERPs, this exacerbated decline in grain and meat productivity. In addition, aggressive revegetation activities have also reduced runoff yield and depleted soil water resources. Water scarcity is recognized as the most challenging issue in dryland ecosystem restoration, heavily influencing the interactions between sectors and threatening the long-term sustainability of ERPs. To accommodate for regional water carrying capacity, ERPs should adopt and properly allocate the use of suitable plant species with a proven anti-drought capability and high survival ratios without additional human interventions. In addition, the evolution regimes, driving factors, critical thresholds, and complex feedbacks between the nexus sectors should be fully understood to address the water resources constraints and reconcile trade-offs. This would enable the prevention of ecosystem shifts to undesirable failures and inform timely and cost-effective CEM to achieve the LDN targets.
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http://dx.doi.org/10.1016/j.scitotenv.2021.147029DOI Listing
April 2021

Exploring soil erosion trajectories and their divergent responses to driving factors: a model-based contrasting study in highly eroded mountain areas.

Environ Sci Pollut Res Int 2021 Mar 20;28(12):14720-14738. Epub 2020 Nov 20.

Guangdong Open Laboratory of Geospatial Information Technology and Application, Guangzhou Institute of Geography, Guangdong Academy of Sciences, Guangzhou, 510070, People's Republic of China.

Soil erosion threatens environmental sustainability worldwide. Exploring the trajectories of soil erosion and associated drivers is of great significance for combating land degradation. This study selected the highly eroded Loess Plateau (LP) and Karst Plateau (KP) as contrasting regions to monitor soil erosion dynamics. Monitoring was performed by applying the Revised Universal Soil Loss Equation based on a GIS platform and multi-source input data to investigate associated drivers. The results established that soil erosion in both regions was substantially reduced by ecological restoration projects and significant land use/cover conversions. Landscape and geomorphological variables were found to be the dominant factors controlling soil erosion in the LP and KP, as they influenced land use patches and geomorphological patterns, respectively. The correlations between fragmentation metric indices and soil erosion indicated that the appropriately intensive fragmentation in the LP could mitigate or prevent soil erosion by disturbing its formation and transportation and ultimately positively influenced soil erosion control. Geomorphological patterns were also determinative factors, particularly for the KP, where almost all geomorphological variables were significantly correlated with the erosion modulus. Owing to the peculiar landform and landscape conditions in karst areas and loess hilly-gully areas, geomorphological and landscape variables should be considered when determining the main factors affecting soil erosion processes and integrated into the forecasting model to improve the accuracy of the simulation. The findings of this study are expected to (i) improve the efficacy of soil erosion control and (ii) promote the sustainable planning and management of land and soil resources.
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http://dx.doi.org/10.1007/s11356-020-11703-1DOI Listing
March 2021

Ecological restoration is not sufficient for reconciling the trade-off between soil retention and water yield: A contrasting study from catchment governance perspective.

Sci Total Environ 2021 Feb 2;754:142139. Epub 2020 Sep 2.

Guangdong Open Laboratory of Geospatial Information Technology and Application, Guangzhou Institute of Geography, Guangzhou 510070, PR China; Key Lab of Guangdong for Utilization of Remote Sensing and Geographical Information System, Guangzhou 510070, PR China. Electronic address:

Ecological restoration program (ERP) is widely recognized as an effective measure to combat land degradation and improve environmental quality. However, inappropriate ERPs lead to trade-offs between soil retention and water yield as well as conflicts of soil and water resources between the midstream and the downstream of catchment. This study aims to assess the efficiency of ERPs in soil erosion control and identify the trade-offs between soil retention and water yield through the lens of runoff and sediment regimes in contrasting catchments of the Loess Plateau (LP) and the Karst Plateau (KP). Although favorable climate and rapid vegetation restoration substantially reduced water erosion in both these areas, the hydrological responses were not the same because of climate differences. In the arid LP, water and energy variables correlated closely with vegetation cover. Excessive afforestation programs in drylands increased vegetation transpiration and soil evaporation, further exhausting soil water resources, and eventually causing water yield reduction. However, soil and water conservation programs (SWCPs) in the humid KP reduced sediment yield substantially, and the runoff remained stable. Significant runoff reduction in the midstream of the Yellow River aggravated water scarcity and threatened the downstream water demand. Meanwhile, sediment load decline in the LP and the KP impacted sediment deposition in the downstream and estuary formation. From the perspective of integrated catchment governance, human interventions including ERP and SWCP should be more sustainable and consider not only the target process at the local scale (intracoupling effect), but also unprecedented non-target process at the regional scale (telecoupling effect). In addition, it should allow for the supply-demand balance of competing soil and water resources to achieve the coordinated development of resources, environment, and production.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142139DOI Listing
February 2021

Unfolding the effectiveness of ecological restoration programs in combating land degradation: Achievements, causes, and implications.

Sci Total Environ 2020 Dec 10;748:141552. Epub 2020 Aug 10.

Guangdong Open Laboratory of Geospatial Information Technology and Application, Guangzhou Institute of Geography, Guangzhou 510070, PR China; Key Lab of Guangdong for Utilization of Remote Sensing and Geographical Information System, Guangzhou 510070, PR China.

Land degradation is one of the most serious environmental problems worldwide. To combat land degradation, China has implemented a series of ecological restoration programs (ERPs). This study selected the northern dryland of China as a case study to examine the efficiency of ERPs, and the response of soil loss to afforestation efforts and climatic conditions was discussed using the principles from the ecological theory of non-linear ecosystem dynamics. Owing to the combined impacts of declining wind speed and rapid vegetation restoration, the soil erosion for the entire region was substantially reduced from 1990 to 2015. However, the rainfall fluctuated considerably, particularly for the period from the late 1990s to early 2000s. Several drought events to some extent inhibited vegetation growth and further offset afforestation efforts, resulting in degradations in vegetation structure and soil retention function, which have been aggravating soil erosion since 2005. In certain representative sandstorm areas, limited increase in rainfall was not enough to promote vegetation growth, and therefore the vegetation cover did not present increasing trends and, in some cases, even declined significantly. The responses in terms of land degradation to climatic conditions and afforestation efforts behaved in a non-linear dynamic manner, providing essential insights into appropriate timings, climate-induced windows of opportunity, and risk in recovering and sustaining ecosystems, and eventually moving towards the land degradation neutrality (LDN) target. The climate-induced windows of opportunity and risk are critical in identifying the time for starting human interventions to mitigate and halt land degradation. Meanwhile, effective investment actions should be taken according to existing environmental conditions and critical thresholds, to achieve LDN at minimum risk and cost.
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http://dx.doi.org/10.1016/j.scitotenv.2020.141552DOI Listing
December 2020

Effects of the interception of litterfall by the understory on carbon cycling in eucalyptus plantations of South China.

PLoS One 2014 24;9(6):e100464. Epub 2014 Jun 24.

Centre of Resource and Environment, Guangzhou Institute of Geography, Guangzhou, China.

For the purposes of forest restoration, carbon (C) fixation, and economic improvement, eucalyptus (Eucalyptus urophylla) has been widely planted in South China. The understory of eucalyptus plantations is often occupied by a dense community of the fern Dicranopteris dichotoma, which intercepts tree canopy leaf litter before it reaches the ground. To understand the effects of this interception of litterfall on C cycling in eucalyptus plantations, we quantified the mass of intercepted litter and the influences of litterfall interception on litter decomposition and soil respiration. The total mass of E. urophylla litterfall collected on the understory was similar to that collected by the traditional litter trap method. All of the eucalyptus litterfall is intercepted by the D. dichotoma canopy. Of the litterfall that was intercepted by D. dichotoma, 20-40% and 60-80% was intercepted by the top (50-100 cm) and bottom (0-50 cm) of the understory canopy, respectively. Intercepted litterfall decomposed faster at the bottom of understory canopy (at the base of the plants) than at the top, and decomposition was slower on the soil surface in the absence of understory than on any location in the understory canopy. Soil respiration was highest when both the understory and litter were present and was lowest when both the understory and litter were absent. These results indicate that litterfall interception changed carbon flow between aboveground and belowground through litter decomposition and soil respiration, which changed carbon cycling in eucalyptus plantations. The effects of the understory on litter decomposition and soil respiration should be considered in ecosystem carbon models.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0100464PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4069015PMC
March 2015