Influences of Shifted Vegetation Phenology on Runoff Across a Hydroclimatic Gradient

Abstract

Climate warming has changed vegetation phenology, and the phenology-associated impacts on terrestrial water fluxes remain largely unquantified. The impacts are linked to plant adjustments and responses to climate change and can be different in different hydroclimatic regions. Based on remote sensing data and observed river runoff of hydrological station from six river basins across a hydroclimatic gradient from northeast to southwest in China, the relative contributions of the vegetation (including spring and autumn phenology, growing season length (GSL), and gross primary productivity) and climatic factors affecting the river runoffs over 1982–2015 were investigated by applying gray relational analysis (GRA). We found that the average GSLs in humid regions (190–241 days) were longer than that in semi-humid regions (186–192 days), and the average GSLs were consistently extended by 4.8–13.9 days in 1982–2015 period in six river basins. The extensions were mainly linked to the delayed autumn phenology in the humid regions and to advanced spring phenology in the semi-humid regions. Across all river basins, the GRA results showed that precipitation (r = 0.74) and soil moisture (r = 0.73) determine the river runoffs, and the vegetation factors (VFs) especially the vegetation phenology also affected the river runoffs (spring phenology: r = 0.66; GSL: r = 0.61; autumn phenology: r = 0.59), even larger than the contribution from temperature (r = 0.57), but its relative importance is climatic region-dependent. Interestingly, the spring phenology is the main VF in the humid region for runoffs reduction, while both spring and autumn growth phenology are the main VFs in the semi-humid region, because large autumn phenology delay and less water supply capacity in spring amplify the effect of advanced spring phenology. This article reveals diverse linkages between climatic and VFs, and runoff in different hydroclimatic regions, and provides insights that vegetation phenology influences the ecohydrology process largely depending on the local hydroclimatic conditions, which improve our understanding of terrestrial hydrological responses to climate change.

Attributing trend in naturalized streamflow to temporally explicit vegetation change and climate variation in the Yellow River basin of China

“…Recent studies have increasingly focused on the effect of vegetation phenology and growth on runoff. It is found that earlier spring phenology and delayed autumn phenology promote a longer growing season and can increase the period for plant transpiration, potentially resulting in larger transpiration and might reduce the river runoff (Piao et al, 2019;Geng et al, 2020;Wu et al, 2012;Chen et al, 2022). These results were consistent with the negative effect of the intra-annual temporal pattern of LAI associated with the phenology change on runoff simulated by the VIC model, considering explicit vegetation dynamics in this study.…”

“…6). Since phenology determines the start and end time of vegetation growth and is highly sensitive to climate change (Liang and Schwartz, 2009;Fu et al, 2019), climate warming has played an important role in advancing the spring phenology and delaying autumn phenology, and consequently extended the length of the vegetation growing period across the globe (Piao et al, 2019;Menzel et al, 2020), especially for the semiarid and semihumid regions of China (Wu et al, 2016;Chen et al, 2022). In addition, the variations in micro-topography from slope land into flat terrace significantly increase soil moisture (Bai et al, 2019), which could also inevitably alter interannual change and intra-annual temporal pattern of LAI.…”

Review of vegetation phenology trends in China in a changing climate

“…Future investigations for vegetation phenology could pay more attention to the following aspects: (1) Previous studies have focused on the response of vegetation phenology to climate change, while the feedback of vegetation phenology on the climate system is relatively rare and thus need more investigations (Penuelas et al, 2009). In addition, recent studies found that the hydrological cycle was also tightly associated with vegetation phenology (Chen et al, 2022;Geng et al, 2020), but its mechanisms are still largely unclear. Therefore, the effects of vegetation phenology on eco-hydrological processes at global and watershed scales need further studies.…”

A comprehensive evaluation of hydrological processes in a second‐generation dynamic vegetation model

“…On the other, key hydrological fluxes and states such as evapotranspiration (ET), soil moisture content and runoff generation are critically dependent on the structures and dynamics of plant communities (Brown et al, 2010; Gerten et al, 2004). For example, runoff is significantly affected by plant‐related processes and factors such as canopy interception (Tao et al, 2020), rooting strategy (Collins & Bras, 2007), leaf area (Zhai & Tao, 2021), phenology (Chen et al, 2022), and transpiration (Li et al, 2020). Likewise, afforestation and the recovery of forests from disturbances could reduce runoff by increasing ET, whereas deforestation often increases runoff (Sun et al, 2006).…”