A drought-induced pervasive increase in tree mortality across Canada's boreal forests

Peng, Changhui; Ma, Zhuguo; Lei, Xiangdong; Zhu, Qiuan; Chen, Huai; Wang, Weifeng; Liu, Shirong; Li, Weizhong; Fang, Xiuqin; Zhou, Xiaolu

doi:10.1038/nclimate1293

Cited by 701 publications

(571 citation statements)

References 29 publications

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“…Limited seed availability and slow hydrological changes could result in relatively slow transitions. However, in southern continental areas, changes such as warming-induced drought stress (12,36), insect outbreaks, and fire could result in catastrophic collapse into a treeless steppe consistent with observations (3). Change will also differ depending on the local trends in climate.…”

Section: Discussionsupporting

confidence: 84%

Thresholds for boreal biome transitions

Scheffer¹,

Hirota

Holmgren

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

310

295

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Although the boreal region is warming twice as fast as the global average, the way in which the vast boreal forests and tundras may respond is poorly understood. Using satellite data, we reveal marked alternative modes in the frequency distributions of boreal tree cover. At the northern end and at the dry continental southern extremes, treeless tundra and steppe, respectively, are the only possible states. However, over a broad intermediate temperature range, these treeless states coexist with boreal forest (∼75% tree cover) and with two more open woodland states (∼20% and ∼45% tree cover). Intermediate tree covers (e.g., ∼10%, ∼30%, and ∼60% tree cover) between these distinct states are relatively rare, suggesting that they may represent unstable states where the system dwells only transiently. Mechanisms for such instabilities remain to be unraveled, but our results have important implications for the anticipated response of these ecosystems to climatic change. The data reveal that boreal forest shows no gradual decline in tree cover toward its limits. Instead, our analysis suggests that it becomes less resilient in the sense that it may more easily shift into a sparse woodland or treeless state. Similarly, the relative scarcity of the intermediate ∼10% tree cover suggests that tundra may shift relatively abruptly to a more abundant tree cover. If our inferences are correct, climate change may invoke massive nonlinear shifts in boreal biomes.remote sensing | tipping point | resilience | permafrost | wildfire T he boreal forest is one of the most extensive biomes on Earth.Together with tundra, it is warming more rapidly than other biomes-approximately twice as fast as the global average (1). Warming has already caused extensive thawing of permafrost, accompanied with changes in hydrology, which are likely driving changes in vegetation, wildfires, and insect outbreaks (2, 3). Despite these major changes, the potential response of boreal systems to further climate change is poorly understood. One of the big questions is whether boreal biomes will change gradually, as assumed by most dynamic vegetation models (4, 5), or might have tipping points where changing conditions can invoke critical transitions.Many factors, including fire, insects, climate, permafrost, and human land use, play a role in vegetation dynamics in the boreal region (2, 3, 6, 7). However, although detailed studies have revealed separate mechanisms, an understanding of large-scale stability properties and dynamics cannot easily be constructed from these separate elements. To address the question of potential critical transitions, we therefore complement the existing studies by analyzing the distribution of tree cover densities on continental scales. Tree cover is admittedly a rather crude descriptor of the vegetation state. However, it is one of the most defining characteristics not only for the structure of the landscape, but also for functional characteristics such as carbon storage and albedo.Our central goal is to determine whether the frequ...

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Section: Discussionsupporting

confidence: 84%

Thresholds for boreal biome transitions

Scheffer¹,

Hirota

Holmgren

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

310

295

View full text Add to dashboard Cite

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“…In this study, we investigated the influence of droughts on NPP in Northeast China. However, drought can trigger many ecosystem disturbances (Hanson and Weltzin, 2000;Westerling et al, 2006), such as wildfires, disease, pest attack, increased mortality, or re-growth (Allen et al, 2010;Peng et al, 2011;vander Molen et al, 2011;Ma et al, 2012). Wildfire is a dominant disturbance in Northeast China (Tao et al, 2013;Wu et al, 2014).…”

Section: Uncertainties and Implicationsmentioning

confidence: 99%

Effects of drought on net primary productivity: Roles of temperature, drought intensity, and duration

Sun¹,

Zhao²,

Wang

2016

Chin. Geogr. Sci.

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Northeast China has experienced frequent droughts over the past fifteen years. However, the effects of droughts on net primary productivity (NPP) in Northeast China remain unclear. In this paper, the droughts that occurred in Northeast China between 1999 and 2013 were identified using the Standardized Precipitation Evapotranspiration Index (SPEI). The NPP standardized anomaly index (NPP-SAI) was used to evaluate NPP anomalies. The years of 1999, 2000, 2001, and 2007 were further investigated in order to explore the influence of droughts on NPP at different time scales (3, 6, and 12 months). Based on the NPP-SAI of normal areas, we found droughts overall decreased NPP by 112.06 Tg C between 1999 and 2013. Lower temperatures at the beginning of the growing season could cause declines in NPP by shortening the length of the growing season. Mild drought or short-term drought with higher temperatures might increase NPP, and weak intensity droughts intensified the lag effects of droughts on NPP.

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“…As in all other ecosystems, tropical forests too face a wide range of disturbances of variable duration, intensity and frequency. Long-term vegetation monitoring has been undertaken in various tropical forests around the world (Rees et al 2001;Laurance et al 2004;Weckel et al 2006;Marimon et al 2012;van den Berg et al 2012;Ge et al 2013), and an increasing number of studies have shown that forests have undergone dynamic widespread directional shifts in composition and structure (Enquist and Enquist 2011;Feeley et al 2011;Peng et al 2011;Fauset et al 2012;Kucbel et al 2012). Long-term monitoring of permanent forest plots provides data to assess aboveground standing biomass stock and C dynamics and assesses the response of the forest to the environmental drivers such as elevated temperature, CO 2 fertilization, increase in incoming solar radiation and nitrogen enrichment (Bhat and Ravindranath 2011).…”

Section: Introductionmentioning

confidence: 99%

Tree Diversity Changes over a Decade (2003-2013) in Four Inland Tropical Dry Evergreen Forest Sites on the Coromandel Coast of India

Elumalai¹,

Parthasarathy²

2016

Journal of Forest and Environmental Science

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Forest tree diversity inventory and its periodical monitoring are important to understand changes in tree population structure and to provide information useful for biodiversity conservation and reserve management. In a long-term forest dynamics program in Indian tropical dry evergreen forest, this communication deals with tree diversity changes at decadal interval. The initial inventory of tree diversity was carried out in 2003, in four tropical dry evergreen forest sites -(much disturbed sites Shanmuganathapuram -SP and Araiyapatti -AP and moderately disturbed sites -Karisakkadu -KR and Maramadakki -MM) on the Coromandel Coast of peninsular India, by establishing four 1ha permanent plots, one in each site. In 2013, the four plots were re-inventoried for tree diversity (≥10 cm gbh) changes which yielded 56 species from 46 genera and 26 families. The studied forest sites are threatened by disturbance due to multiple reasons; cutting of trees inside of the forest, grazing by goats, construction of temple approach road, and some aspects cultural attachment of local people like constructing new, additional strctures of temple by denuding a portion of forest etc.. Tree species richness over a decade increased by four species in site SP, two species in site AP, and one species in site KR, but decreased by one species in site MM. Tree density decreased drastically by 480 (28.92%) and 102 (12.63%) stems ha -1 respectively in sites SP and AP, but moderately increased by 82 (12.09%) stems ha -1 in site KR and 26 in ten years. The long-term forest monitoring data will be valuable to understand forest dynamics and for conservation and management of this and similar tropical forests.

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A drought-induced pervasive increase in tree mortality across Canada's boreal forests

Cited by 701 publications

References 29 publications

Thresholds for boreal biome transitions

Thresholds for boreal biome transitions

Effects of drought on net primary productivity: Roles of temperature, drought intensity, and duration

Tree Diversity Changes over a Decade (2003-2013) in Four Inland Tropical Dry Evergreen Forest Sites on the Coromandel Coast of India

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