Seasonal Pattern of Stem Diameter Growth of Qinghai Spruce in the Qilian Mountains, Northwestern China

Wan, Yunfan; Yu, Pengtao; Li, Xiaoqing; Wang, Yanhui; Wang, Bin; Yu, Yipeng; Zhang, Lei; Liu, Xiande; Wang, Shunli

doi:10.3390/f11050494

Cited by 17 publications

(24 citation statements)

References 45 publications

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“…Elevation, as a natural simulant of future climates [11], has a strong impact on local climate conditions, and seasonal patterns of stem growth and climate-growth relationships may vary with elevation, such as variations in temperature and precipitation [12][13][14]. Many studies have reported that intra-annual stem growth for the same tree species had divergent across elevations; i.e., the growth initiation was linearly delayed and nearly synchronous with increasing elevations, which was primarily controlled by temperature [14][15][16][17]; however, the growth cessation was no consensus across elevations, which was predominately controlled by photoperiod and an earlier cell differentiation [15,18,19], while was influenced by soil moisture deficit in arid and semi-arid regions [17,[20][21][22]. Although there is still much uncertainty about intra-annual stem growth at different elevations, how seasonal patterns of stem growth is controlled by climatic and soil conditions at different elevations has rarely been studied in dryland montane forests of northwestern China.…”

Section: Introductionmentioning

confidence: 99%

Divergent Seasonal Patterns of Qinghai Spruce Growth with Elevation in Northwestern China

Wan

et al. 2022

Forests

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Dryland montane forests are important agents for soil and water resource conservation. The growth of these forests under climate warming is strongly affected by local environmental factors. However, how environmental factors impact intra-annual stem growth dynamics across environmental gradients in these regions remains unclear. This work focused on assessing seasonal patterns of stem growth across different elevations and how environmental factors impact stem growth in the Qilian Mountains, northwestern China. The stem growth of 50 Qinghai spruce trees was monitored for two years across an elevation gradient from 2500 m to 3300 m above sea level (a.s.l.). We found that growth initiation occurred later as the elevation increased, and growth commenced when elevation-specific temperature thresholds were reached. However, growth cessation presented large elevational differences: cessation occurred much earlier at low elevations (2500 m and 2700 m a.s.l.). Exceptionally early growth cessation occurred predominantly at 2700 m a.s.l., which was correlated with seasonal drought/insufficient rainfall and low soil moisture occurring since mid-July 2015. Temperature and soil moisture were the key factors governing the daily rate of stem growth in the beginning, rapid growth, and end stages. Overall, due to effects of seasonal drought and low temperature on growth cessation and growth rate, the annual growth of Qinghai spruce was rather low at both low (2500–2700 m a.s.l.) and high (3100–3300 m a.s.l.) elevations; middle elevations (approximately 2900 m a.s.l.) might be the most favorable Qinghai spruce growth. Our results implied that tree growth will likely decline at low elevations and that the optimal elevation for Qinghai spruce growth in northwestern China is expected to shift upward under future climate warming.

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Section: Introductionmentioning

confidence: 99%

Divergent Seasonal Patterns of Qinghai Spruce Growth with Elevation in Northwestern China

Wan

et al. 2022

Forests

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“…The mean annual sunshine duration was 1892.6 h•a −1 . The mean annual relative humidity was 60% [26,28].…”

Section: Study Areamentioning

confidence: 99%

“…The soil in the plot was thick and highly permeable, with an average soil thickness of 70 cm. The soil type was mountainous grey cinnamon soil and its texture was loam, with sand content of 34%, a total soil porosity of 71.2%, and a bulk density of 0.83 g•cm −3 in the root zone (0 to 60 cm soil layer) [28,34]. Within the 0 to 60 cm root zone, the saturation moisture content was approximately 0.69 m 3 •m −3 and the field capacity was approximately 0.58 m 3 •m −3 [28,34].…”

Section: Research Plotmentioning

confidence: 99%

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The Variation in Water Consumption by Transpiration of Qinghai Spruce among Canopy Layers in the Qilian Mountains, Northwestern China

Wan

Wang

et al. 2020

Forests

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It is important for integrated forest-water management to develop a better understanding of the variation of tree transpiration among different canopy layers in the forests and its response to soil moisture and weather conditions. The results will provide insights into water consumption by trees occupying different social positions of the forests. In the present study, an experiment was conducted in the Qilian Mountains, northwest China, and 13 trees, i.e., 4–5 trees from each one of dominant (the relative tree height (HR) > 1.65), subdominant (1.25 < HR ≤ 1.65) and intermediate-suppressed (HR ≤ 1.25) layers) were chosen as sample trees in a pure Qinghai spruce (Picea crassifolia Kom.) forest stand. The sap flux density of sample trees, soil moisture of main root zone (0 to 60 cm) and meteorological conditions in open field were observed simultaneously from July to October of 2015 and 2016. The results showed that (1) The mean daily stand transpiration for the study period in 2015 and 2016 (July–October), was 0.408 and 0.313 mm·day−1, and the cumulative stand transpiration was 54.84 and 40.97 mm, accounting for 24.14% (227.2 mm) and 16.39% (249.9 mm) of the total precipitation over the same periods, respectively. (2) The transpiration varied greatly among canopy layers, and the transpiration of the dominant and codominant layers was the main contributors to the stand transpiration, contributing 86.05% and 81.28% of the stand transpiration, respectively, in 2015 and 2016. (3) The stand transpiration was strongly affected by potential evapotranspiration (PET) and volumetric soil moisture (VSM). However, the transpiration of trees from the dominant and codominant layers was more sensitive to PET changes and that from the intermediate-suppressed layer was more susceptible to soil drought. This implied that in dry period, such as in drought events, the dominant and codominant trees would transpire more water, while the intermediate-suppressed trees almost stopped transpiration. These remind us that the canopy structure was the essential factor affecting single-tree and forest transpiration in the dryland areas.

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“…The vegetation cover was mainly alpine meadow and alpine steppe grasslands, dominated by sedges Kobresia pygmaea , Kobresia tibetica , and Kobresia humilis , and Stipa purpurea grass [ 24 ]. The region is characterized by an alpine semi-arid climate with an annual precipitation of approximately 430 mm, and an annual potential evaporation of about 1080 mm [ 25 – 26 ]. About 90% of precipitation falls as rain from May to September, with snowfall contributing less than 10% [ 25 ].…”

Section: Study Descriptionmentioning

confidence: 99%

Impacts of the active layer on runoff in an upland permafrost basin, northern Tibetan Plateau

et al. 2018

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The paucity of studies on permafrost runoff generation processes, especially in mountain permafrost, constrains the understanding of permafrost hydrology and prediction of hydrological responses to permafrost degradation. This study investigated runoff generation processes, in addition to the contribution of summer thaw depth, soil temperature, soil moisture, and precipitation to streamflow in a small upland permafrost basin in the northern Tibetan Plateau. Results indicated that the thawing period and the duration of the zero-curtain were longer in permafrost of the northern Tibetan Plateau than in the Arctic. Limited snowmelt delayed the initiation of surface runoff in the peat permafrost in the study area. The runoff displayed intermittent generation, with the duration of most runoff events lasting less than 24 h. Precipitation without runoff generation was generally correlated with lower soil moisture conditions. Combined analysis suggested runoff generation in this region was controlled by soil temperature, thaw depth, precipitation frequency and amount, and antecedent soil moisture. This study serves as an important baseline to evaluate future environmental changes on the Tibetan Plateau.

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Seasonal Pattern of Stem Diameter Growth of Qinghai Spruce in the Qilian Mountains, Northwestern China

Cited by 17 publications

References 45 publications

Divergent Seasonal Patterns of Qinghai Spruce Growth with Elevation in Northwestern China

Divergent Seasonal Patterns of Qinghai Spruce Growth with Elevation in Northwestern China

The Variation in Water Consumption by Transpiration of Qinghai Spruce among Canopy Layers in the Qilian Mountains, Northwestern China

Impacts of the active layer on runoff in an upland permafrost basin, northern Tibetan Plateau

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