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Drought Severity in a Changing Climate
Published in Saeid Eslamian, Faezeh Eslamian, Handbook of Drought and Water Scarcity, 2017
Sergio M. Vicente-Serrano, Santiago Beguería, Jesús Julio Camarero
There are a number of recent studies that have related higher tree mortality, including dieback events and growth decline in response to warming-related increase of drought stress [14,15,18,26,64,72,80,130]. Zhao and Running [160] showed at a global scale that between 2000 and 2009 the annual ANPP decreased because of the combined effects of severe drought stress and high temperatures that induced high autotrophic respiration levels, indicating that NPP decreases because of warming-associated drying trends. Peng et al. [94] estimated tree mortality in natural stands throughout Canada’s boreal forests and found that tree mortality rates increased by an overall average of 4.7% per year from 1963 to 2008 associated with a global-change-type drought. Van Mantgem and Stephenson [126] tracked the fates of 21,338 trees in a network of old-growth forest plots in the Sierra Nevada of California and found that the mortality rate increased significantly over the 22 years of measurement (1983–2004) in different taxonomic groups and elevational positions. They attributed this pattern to a temperature-driven increase in drought severity and suggested that these forests may be highly sensitive to temperature-driven drought stress.
Precast segmental bridge construction in seismic zones
Published in Fabio Biondini, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Resilience and Sustainability, 2012
Fabio Biondini, Dan M. Frangopol
Acidification Potential, measured in kg SO2- equivalents. Acidification of soils and waters originates predominantly through the transformation of air pollutants such as sulphur dioxide and nitrogen oxide into acids (H2SO4 und HNO3). This leads to a decrease in the pH-value of rainwater and fog. This “acid rain” harms ecosystems; forest dieback is the most well-known impact. Other damaging effects are nutrients being washed out of soils, an increased solubility of metals into soils, or damage to buildings and building materials (for example metals and natural stones are corroded or disintegrated at an increased rate) (KreiBig & Kümmel 1999).
A Dynamic Model of Forest Carbon Storage in the United States During Climatic Change
Published in Roger A. Sedjo, R. Neil Sampson, Joe Wisniewski, in Forestry, 2020
Brent Sohngen, Robert Mendelsohn
For geographic change, two separate dynamic processes must be considered. First, for forested areas that are changing from one cover type to another (either forest to forest or forest to non-forest), we assume that dieback occurs because ecological conditions change enough to make the old type unfit to continue growing in its original area. Dieback occurs in any area that converts to something else during climate change.
Forests, fire and vegetation change impacts on Murray-Darling basin water resources
Published in Australasian Journal of Water Resources, 2023
Patrick NJ Lane, Richard G Benyon, Rachael H Nolan, Rod J Keenan, Lu Zhang
Eucalypt forests across the MDB are resilient to inter-annual variations in climate, including rainfall. For example, during the prolonged Millennium Drought, there was no evidence of widespread dieback of forests (De Kauwe et al. 2020), although Mac Nally et al. (2011) reported declines in riverine forests and Bergstrom et al. (2021) suggested these forests were on the verge of collapse. Further, experimental studies have shown that eucalypts can maintain transpiration rates during heatwaves which contributes to evaporative cooling, and limits thermal damage (Drake et al. 2018; Griebel et al. 2020). However, some species may maintain transpiration rates under extreme drought, at the risk of incurring failure of the hydraulic system and subsequent tissue death (Marchin et al. 2022). When drought is coupled with heat waves, substantial canopy die-back may occur in eucalypts. This was observed during the 2019/20 drought where large areas of forest were subject to canopy die-back (De Kauwe et al. 2020; Nolan et al. 2021b). Widespread canopy dieback during this drought, but not the Millennium drought, may have been due to the nature of the drought. The drought event in 2019/20 has been described as a ‘flash drought’, i.e. a rapid intensification of drought conditions over a few weeks (Nguyen et al. 2021). Additionally, temperatures were the highest on record (Abram et al. 2021). The rapid intensification of the drought, combined with record high temperatures, led to soil moisture and foliar moisture conditions that were the lowest observed on record (Abram et al. 2021).
Identifying marsh dieback events from Landsat image series (1998–2018) with an Autoencoder in the NIWB estuary, South Carolina
Published in International Journal of Digital Earth, 2020
Huixuan Li, Cuizhen Wang, Jean T. Ellis, Yuxin Cui, Gwen Miller, James T. Morris
The consecutive dieback in 1998–2005 is further examined to explore its spatial extent and subsequent recovery (Figure 8). Dieback clusters in earlier years (1998–2000) are mapped in a yellowish tone, and in later years (2002–2005) the color transitions to a reddish tone (Figure 8(a)). Overall, dieback in the interior estuary is limited. It could be visually interpreted in Figure 8(a) that dieback starts along Mud Bay (the northern Winyah Bay) and expands toward the estuary. Dieback in 2003 is concentrated in the south tip while the 2004–2005 dieback sites are isolated in the northwest end of the study area. As shown in the high-resolution land cover map in Figure 1, the NIWB estuary is dominated with S. alterniflora in low marsh. Reasonably, most dieback occurred on this marsh species. The 2nd most dominant marsh species in the estuary, J. roemerianus, grows in high marsh in southern estuary and is often mixed with scrub-shrub. Figure 8(a) reveals that J. roemerianus suffered from dieback in 2002–2003 (also evidenced in Figure 6(b)). Similarly, most dieback patches of J. roemerianus were quickly recovered within one year (Figure 8(b)). Given its limited spatial extent and mixed growing condition, we did not expand our research on J. roemerianus.
Urban forest restoration ecology: a review from Hamilton, New Zealand
Published in Journal of the Royal Society of New Zealand, 2019
Kiri Joy Wallace, Bruce D. Clarkson
Canopy closure in newly-planted forests is the first, most important threshold in forest development (Doroski et al. 2017). Wallace et al. (2017) studied the dynamics of a chronosequence of New Zealand planted urban forests aged 3–70 years, looking for thresholds of ecosystem properties most important for native tree regeneration. Using breakpoint analyses, they found that distinct thresholds existed in urban forests about twenty years after initial plantings (Figure 3). At twenty years canopy openness dropped to less than 5%, causing senescence of competitive non-native herbaceous ground weeds, and stabilisation of the microclimate (humidity and soil temperatures in particular). These conditions were significant drivers causing native tree seedling regeneration only after the canopy closure threshold was crossed. The forest will then develop naturally through other successional stages, including canopy gap formation through eventual dieback of the planted early-successional tree species. These gaps provide light levels required by some important late-successional saplings to fully recruit into the canopy (Knowles and Beveridge 1982; Lusk and Ogden 1992). This later stage is appropriate for enrichment plantings if low seed dispersal into the site is limiting spontaneous recruitment, and may require ‘managing the gap’ actions if light-demanding weeds take advantage of the newly available light resource (Whaley et al. 1997).