Recent shift in Eurasian boreal forest greening response may be associated with warmer and drier summers

Buermann, Wolfgang; Parida, Bikash Ranjan; Jung, Martin; MacDonald, Glen M.; Tucker, Compton J.; Reichstein, Markus

doi:10.1002/2014gl059450

Cited by 107 publications

(93 citation statements)

References 43 publications

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“…The importance of this result depends, in part, on the spatial extent and intensity of precipitation changes across the boreal and Arctic during this century. There is a detectable anthropogenic influence in high-latitude precipitation changes (Wan et al, 2015), but these changes are inconsistent: drier and warmer conditions in boreal Eurasia (Buermann et al, 2014), for example, but growing season length increases in interior Alaska with no increase in precipitation (Wendler and Shulski, 2009). This spatial variability will interact with permafrost thaw dynamics to produce a complex patchwork of soil moisture changes (Zhang et al, 2012;Watts et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

2016

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Abstract. Rapid climatic changes, rising air temperatures, and increased fires are expected to drive permafrost degradation and alter soil carbon (C) cycling in many high-latitude ecosystems. How these soils will respond to changes in their temperature, moisture, and overlying vegetation is uncertain but critical to understand given the large soil C stocks in these regions. We used a laboratory experiment to examine how temperature and moisture control CO 2 and CH 4 emissions from mineral soils sampled from the bottom of the annual active layer, i.e., directly above permafrost, in an Alaskan boreal forest. Gas emissions from 30 cores, subjected to two temperatures and either field moisture conditions or experimental drought, were tracked over a 100-day incubation; we also measured a variety of physical and chemical characteristics of the cores. Gravimetric water content was 0.31 ± 0.12 (unitless) at the beginning of the incubation; cores at field moisture were unchanged at the end, but drought cores had declined to 0.06 ± 0.04. Daily CO 2 fluxes were positively correlated with incubation chamber temperature, core water content, and percent soil nitrogen. They also had a temperature sensitivity (Q 10 ) of 1.3 and 1.9 for the field moisture and drought treatments, respectively. Daily CH 4 emissions were most strongly correlated with percent nitrogen, but neither temperature nor water content was a significant first-order predictor of CH 4 fluxes. The cumulative production of C from CO 2 was over 6 orders of magnitude higher than that from CH 4 ; cumulative CO 2 was correlated with incubation temperature and moisture treatment, with drought cores producing 52-73 % lower C. Cumulative CH 4 production was unaffected by any treatment. These results suggest that deep active-layer soils may be sensitive to changes in soil moisture under aerobic conditions, a critical factor as discontinuous permafrost thaws in interior Alaska. Deep but unfrozen high-latitude soils have been shown to be strongly affected by long-term experimental warming, and these results provide insight into their future dynamics and feedback potential with future climate change.

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Section: Discussionmentioning

confidence: 99%

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

2016

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“…The landscape freeze/thaw (F/T) status derived from satellite microwave observations has been shown to be closely linked with surface energy budget, hydrological activity and vegetation growing-season dynamics due to strong control of surface F/T status on vegetation growth and hydrological cycles [17,33]. In this study, a global F/T Earth System Data Record (FT-ESDR; [34]) derived from satellite passive microwave remote sensing observations was used to assess variations in land surface F/T status and its association with surface hydrology over the study area.…”

Section: Remote Sensing Measurementsmentioning

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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“…The NDVI is sensitive to the cover density of green vegetation due to the differences in reflectance sensitivity to chlorophyll between near-infrared and red spectra [36]. Therefore, NDVI time series have been widely used to characterize vegetation development at different stages, including onset, peak and offset of the growing season [4,[37][38][39]. The GIMMS3g dataset was assembled from different NOAA Advanced Very High Resolution Radiometer (AVHRR) records accounting for various deleterious effects including calibration loss, orbital drift, inter-sensor inconsistency and volcanic eruptions [40].…”

Section: Datasetsmentioning

confidence: 99%

Climatic Controls on Spring Onset of the Tibetan Plateau Grasslands from 1982 to 2008

Zhang

Kimball

et al. 2015

Remote Sensing

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Understanding environmental controls on vegetation spring onset (SO) in the Tibetan Plateau (TP) is crucial to diagnosing regional ecosystem responses to climate change. We investigated environmental controls on the SO of the TP grasslands using satellite vegetation index (VI) from the 3rd Global Inventory Modeling and Mapping Studies (GIMMS3g) product, with in situ air temperature (T a ) and precipitation (Prcp) measurement records from 1982 to 2008. The SO was determined using a dynamic threshold method based on a 25% threshold of seasonal VI amplitude. We find that SO shows overall close associations with spring T a , but is also subject to regulation from spring precipitation. In relatively dry but increasingly wetting (0.50 mm¨year´1, p < 0.10) grasslands (mean spring Prcp = 22.8 mm; T a =´3.27˝C), more precipitation tends to advance SO (´0.146 day¨mm´1, p = 0.150) before the mid-1990s, but delays SO (0.110 day¨mm´1, p = 0.108) over the latter record attributed to lower solar radiation and cooler temperatures associated with Prcp increases in recent years. In contrast, in relatively humid TP grasslands (73.0 mm;´3.51˝C), more precipitation delays SO (0.036 day¨mm´1, p = 0.165) despite regional warming (0.045˝C¨year´1, p < 0.05); the SO also shows a delaying response to a standardized drought index (mean R = 0.266), indicating a low energy constraint to vegetation onset. Our results highlight the importance of surface moisture status in regulating the phenological response of alpine grasslands to climate warming.

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Recent shift in Eurasian boreal forest greening response may be associated with warmer and drier summers

Cited by 107 publications

References 43 publications

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

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

Climatic Controls on Spring Onset of the Tibetan Plateau Grasslands from 1982 to 2008

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