scholarly journals Environmental Controls of Diurnal and Seasonal Variations in the Stem Radius of Platycladus orientalis in Northern China

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 784 ◽  
Author(s):  
Manyu Dong ◽  
Bingqin Wang ◽  
Yuan Jiang ◽  
Xinyuan Ding
Keyword(s):  
Environmental Factors ◽  
Air Temperature ◽  
Water Status ◽  
Growing Season ◽  
Northern China ◽  
Climate Impacts ◽  
Radial Variation ◽  
Critical Threshold ◽  
Platycladus Orientalis ◽  
Environmental Controls

Fine-resolution studies of stem radial variation over short timescales throughout the year can provide insight into intra-annual stem dynamics and improve our understanding of climate impacts on tree physiology and growth processes. Using data from high-resolution point dendrometers collected from Platycladus orientalis (Linn.) trees between September 2013 and December 2014, this study investigated the daily and seasonal patterns of stem radial variation in addition to the relationships between daily stem radial variation and environmental factors over the growing season. Two contrasting daily cycle patterns were observed for warm and cold seasons. A daily mean air temperature of 0 °C was a critical threshold that was related to seasonal shifts in stem diurnal cycle patterns, indicating that air temperature critically influences diurnal stem cycles. The annual variation in P. orientalis stem radius variation can be divided into four distinct periods including (1) spring rehydration, (2) the summer growing season, (3) autumn stagnation, and (4) winter contraction. These periods reflect seasonal changes in tree water status that are especially pronounced in spring and winter. During the growing season, the maximum daily shrinkage (MDS) of P. orientalis was positively correlated with air temperature (Ta) and negatively correlated with soil water content (SWC) and precipitation (P). The vapor pressure deficit (VPD) also exhibited a threshold-based control on MDS at values below or above 0.8 kPa. Daily radial changes (DRC) were negatively correlated with Ta and VPD but positively correlated with relative air humidity (RH) and P. These results suggest that the above environmental factors are associated with tree water status via their influence on moisture availability to trees, which in turn affects the metrics of daily stem variation including MDS and DRC.

The relative importance of environmental factors on the interannual variability of carbon fluxes in the boreal forest

2020 ◽  
Author(s):  
Mariam El-Amine ◽  
Alexandre Roy ◽  
Pierre Legendre ◽  
Oliver Sonnentag
Keyword(s):  
Environmental Factors ◽  
Boreal Forest ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Carbon Sink ◽  
Growing Season ◽  
Carbon Uptake ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity ◽  
Environmental Controls

<p>As climate change will cause a more pronounced rise of air temperature in northern high latitudes than in other parts of the world, it is expected that the strength of the boreal forest carbon sink will be altered. To better understand and quantify these changes, we studied the influence of different environmental controls (e.g., air and soil temperatures, soil water content, photosynthetically active radiation, normalized difference vegetation index) on the timing of the start and end of the boreal forest growing season and the net carbon uptake period in Canada. The influence of these factors on the growing season carbon exchanges between the atmosphere and the boreal forest were also evaluated. There is a need to improve the understanding of the role of the length of the growing season and the net carbon uptake period on the strength of the boreal forest carbon sink, as an extension of these periods might not necessarily result in a stronger carbon sink if other environmental factors are not optimal for carbon sequestration or enhance respiration.</p><p>Here, we used 31 site-years of observation over three Canadian boreal forest stands: Eastern, Northern and Southern Old Black Spruce in Québec, Manitoba and Saskatchewan, respectively. Redundancy analyses were used to highlight the environmental controls that correlate the most with the annual net ecosystem productivity and the start and end of the growing season and the net carbon uptake period. Preliminary results show that the timing at which the air temperature becomes positive correlates the most strongly with the start of the net carbon uptake period (r = 0.70, p < 0.001) and the start of the growing season (r = 0.55, p < 0.01). Although the increase of the normalized difference vegetation index also correlates with the start of these periods, a thorough examination of this result shows that the latter happens well before the former. No dependency between any environmental control and the end of the net carbon uptake period was identified. Also, the annual net ecosystem productivity is highly correlated with the length of the net carbon uptake period (r = 0.54, p < 0.01). Other environmental controls such as annual precipitations, the mean annual soil temperature or the maximum yearly normalized difference vegetation index have a smaller impact on the annual net ecosystem productivity. By extending the dataset to include forest stands that represent a wider climate and permafrost variability, we will examine the generalizability of these results.</p>

Land-sea interactions of tidal and sea breeze activity regulate mangrove carbon sink

2020 ◽  
Author(s):  
Xudong Zhu ◽  
Zhangcai Qin ◽  
Lulu Song
Keyword(s):  
Environmental Factors ◽  
Eddy Covariance ◽  
Air Temperature ◽  
Indirect Effects ◽  
Carbon Sink ◽  
Sea Breeze ◽  
Temporal Variations ◽  
Tidal Inundation ◽  
Environmental Controls ◽  
Mangrove Wetland

<p>Coastal mangrove wetlands experience unique land-sea interactions including periodical tidal activity and land/sea breeze cycle. However, the influence of tidal and sea breeze activity on net ecosystem exchange of carbon dioxide (NEE) between mangrove and the atmosphere has not yet been investigated. In this study, temporal variations in mangrove-atmospheric NEE and its direct and indirect environmental controls were examined based on a three-year dataset of continuous eddy covariance and auxiliary measurements in a subtropical estuarine mangrove wetland of southeastern China. The results showed this mangrove wetland acted as a consistent carbon sink over the three-year period (mean NEE of -1233 g C m<sup>-2</sup> year<sup>-1</sup>) with the strongest carbon sink capacity in spring, and the impacts of environmental factors on mangrove NEE varied across time scales: (1) half-hourly daytime carbon influx was regulated by photosynthetically active radiation (PAR) with down-regulation effects from high temperature and vapor pressure deficit (VPD), while half-hourly nighttime carbon efflux was dominated by air temperature with additional suppression effects from tidal inundation and rain; (2) the importance of environmental factors in controlling daily NEE decreased in the order of PAR, air temperature, sea breeze, VPD, tidal salinity, and tidal inundation; (3) the seasonality of monthly NEE was strongly regulated by tidal inundation and rain. This was the first study to examine both direct and indirect effects of tidal and sea breeze activity on mangrove NEE using long-term continuous eddy covariance measurements, and to confirm the importance of previously neglected indirect effects of tidal and sea breeze on mangrove carbon sink. Strong negative correlations between mangrove carbon sink and air temperature/tidal inundation implied that mangrove wetland could become a weaker blue carbon sink in response to global warming and sea level rise in the future.</p>

scholarly journals A Comparison of Thermal Growing Season Indices for the Northern China during 1961–2015

2017 ◽  
Vol 2017 ◽  
pp. 1-14
Author(s):  
Linli Cui ◽  
Jun Shi ◽  
Yue Ma
Keyword(s):  
Climate Change ◽  
Air Temperature ◽  
Terrestrial Ecosystem ◽  
Growing Season ◽  
Northern China ◽  
Important Influence ◽  
Vegetation Phenology ◽  
Selection Of

Vegetation phenology is one of the most direct and sensitive indicators of terrestrial ecosystem in response to climate change. Based on daily mean air temperature at 877 meteorological stations over northern China from 1961 to 2015, the correlations and differences for different definitions of the growing season parameters (start, end, and length of the growing season) were investigated, and results show that higher correlations of 0.81–0.93 are found when indices which do not consider frost are compared with those of the same length which include the frost criteria, and lower correlations of 0.63–0.79 are observed when the length of indices is different and one of the indices includes the frost criteria or EI 3 (10 d < 5°C) is included. Lower correlations and larger differences are generally observed in the eastern and northwestern parts while higher correlation and smaller difference appeared in the northeastern and southwestern parts of northern China; thus the applicability comparison and selection of different definitions have important influence on the identifying and counting of the timing and length of the growing season in the eastern and northwestern regions of northern China.

scholarly journals Quantitative accuracy assessment of the revised sparse Gash model using distinct time-step climatic parameters

2021 ◽  
Author(s):  
Yiran Li ◽  
Chuanjie Zhang ◽  
Yong Niu
Keyword(s):  
Accuracy Assessment ◽  
Growing Season ◽  
Northern China ◽  
Climatic Parameters ◽  
Time Step ◽  
Platycladus Orientalis ◽  
Climate Parameters ◽  
Quantitative Accuracy ◽  
Modeling Accuracy ◽  
Event Basis

Abstract Rainfall interception (I) can considerably influence the transport process of water. The revised sparse Gash model (RSGM) is a tool for determining the I, which assumes that the two climate parameters in the model are equal for all storms. However, few studies have provided additional cases to reexamine the correctness of this assumption and investigated the response of I of single storms to the time-step variability in climatic parameters. Hence, running the RSGM separately on an event basis during the growing season in 2017 and using three time-step climatic parameters (storm-based, monthly, and fixed) to estimate I for the forest stands of Pinus tabuliformis, Platycladus orientalis, and Acer truncatum in Northern China. In summary, the modeling accuracy of both cumulative I and individual I was enhanced by increasing the time step of the climatic parameters in this study. These positively support the assumption in the RSGM. These results suggest that it is more appropriate to run the RSGM using fixed climate parameters to estimate I for these tree species during the growing season in northern China. Additionally, the assumption in the RSGM should be appealed to be further confirmed across the widest possible range of species, regions, and time scales.

scholarly journals Growth features of Arbutus andrachne L. under the conditions of field vegetation experiment on the Southern Coast of the Crimea

2021 ◽  
Vol 1 (157) ◽  
pp. 135-143
Author(s):  
O. A. Ilnitsky ◽  
A. T. Gil ◽  
A. V. Pashtetsky
Keyword(s):  
Environmental Factors ◽  
Air Temperature ◽  
Growing Season ◽  
Climatic Conditions ◽  
Southern Coast ◽  
Trunk Diameter ◽  
Second Stage ◽  
The Crimea ◽  
Growth Features ◽  
Intensive Growth

The dependence of the growth rate of Arbutus andrachne L. on some environmental factors was studied under the conditions of the Southern Coast vegetation experiment in different periods of the species vegetation, which made it possible to find the optimal and limiting conditions for its growth. In March, vegetation began at an average daily air temperature of 3.5 – 7.50 °C and the increase in stem diameter was approximately 0.42 % (0.09 mm), at the second stage (April-May) – 3.7 % (0.58 mm) with a further exit to plateau. In July - August, two sections of the d % change are observed: the first section is from July 27 till August 19 - intensive growth of d % by 12.58 % (1.961 mm), the second section after August 19 – access to the growth plateau, which is associated with an increase in air temperature to 30-35 °C. In September-October, two sections of the d % change are observed: the first section lasted from September 01 till September 15 - intensive growth of d % by 3.55 % (0.582 mm), the second section after September 15 – exit to a plateau of growth, lowering the air temperature to 8-10 °C and the end of the growing season. In November, an increase in trunk diameter was not observed. The optimal environmental factors were: in March-May, Ta = 20-2 °C, Da = 0.4-1.2 kPa, I = 300-900 mmol / m2s; July-August, Ta = 22-28 °C, Da = 1.4-2.5 kPa, I = 500-1000 μmol / m2s; in September-October, Ta = 16-25 °C, Da = 0.3-1.5 kPa, I = 400-800 μmol / m2s, respectively. The results of our experiments allow us to compare the ecological and physiological characteristics we obtained with the climatic conditions of a particular region and evaluate the possibilities of introducing it into other regions.

scholarly journals Seasonal Climate Impacts on Vocal Activity in Two Neotropical Nonpasserines

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 319
Author(s):  
Cristian Pérez-Granados ◽  
Karl-L. Schuchmann
Keyword(s):  
Air Temperature ◽  
Daily Rainfall ◽  
Climatic Conditions ◽  
Dry Season ◽  
Climate Impacts ◽  
Calling Behavior ◽  
Wet Season ◽  
Focal Species ◽  
Calling Activity ◽  
Vocal Activity

Climatic conditions represent one of the main constraints that influence avian calling behavior. Here, we monitored the daily calling activity of the Undulated Tinamou (Crypturellus undulatus) and the Chaco Chachalaca (Ortalis canicollis) during the dry and wet seasons in the Brazilian Pantanal. We aimed to assess the effects of climate predictors on the vocal activity of these focal species and evaluate whether these effects may vary among seasons. Air temperature was positively associated with the daily calling activity of both species during the dry season. However, the vocal activity of both species was unrelated to air temperature during the wet season, when higher temperatures occur. Daily rainfall was positively related to the daily calling activity of both species during the dry season, when rainfall events are scarce and seem to act as a trigger for breeding phenology of the focal species. Nonetheless, air temperature was negatively associated with the daily calling activity of the Undulated Tinamou during the wet season, when rainfall was abundant. This study improves our understanding of the vocal behavior of tropical birds and their relationships with climate, but further research is needed to elucidate the mechanisms behind the associations found in our study.

scholarly journals Indirect drivers of plant diversity-productivity relationship in semiarid sandy grasslands

2012 ◽  
Vol 9 (4) ◽  
pp. 1277-1289 ◽  
Author(s):  
X. A. Zuo ◽  
J. M. H. Knops ◽  
X. Y. Zhao ◽  
H. L. Zhao ◽  
T. H. Zhang ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Plant Diversity ◽  
Structural Equation ◽  
Environmental Gradients ◽  
Northern China ◽  
Equation Modeling ◽  
Vegetation Composition ◽  
Wet Meadow ◽  
Positive Correlation ◽  
Sandy Grasslands

Abstract. Although patterns between plant diversity and ecosystem productivity have been much studied, a consistent relationship has not yet emerged. Differing patterns between plant diversity and productivity have been observed in response to spatial variability of environmental factors and vegetation composition. In this study, we measured vegetation cover, plant diversity, productivity, soil properties and site characteristics along an environmental gradient (mobile dune, semi-fixed dune, fixed dune, dry meadow, wet meadow and flood plain grasslands) of natural sandy grasslands in semiarid areas of northern China. We used multivariate analysis to examine the relationships between environmental factors, vegetation composition, plant diversity and productivity. We found a positive correlation between plant diversity and productivity. Vegetation composition aggregated by the ordination technique of non-metric multidimensional scaling had also a significantly positive correlation with plant diversity and productivity. Environmental gradients in relation to soil and topography affected the distribution patterns of vegetation composition, species diversity and productivity. However, environmental gradients were a better determinant of vegetation composition and productivity than of plant diversity. Structural equation modeling suggested that environmental factors determine vegetation composition, which in turn independently drives both plant diversity and productivity. Thus, the positive correlation between plant diversity and productivity is indirectly driven by vegetation composition, which is determined by environmental gradients in soil and topography.

Evaluation of the influence of ambient air temperature and air velocity on mortar cement durability using a forced convection solar dryer

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Younes Bahammou ◽  
Mounir Kouhila ◽  
Haytem Moussaoui ◽  
Hamza Lamsyehe ◽  
Zakaria Tagnamas ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Forced Convection ◽  
Air Temperature ◽  
Building Materials ◽  
Ambient Air ◽  
Physical Significance ◽  
Drying Process ◽  
Air Velocity ◽  
Content Type ◽  
Ambient Air Temperature

PurposeThis work aims to study the hydrothermal behavior of mortar cement toward certain environmental factors (ambient air temperature and air velocity) based on its drying kinetics data. The objective is to provide a better understanding and controlling the stability of mortar structures, which integrate the sorption phenomenon, drying process, air pressure and intrinsic characteristics. This leads to predict the comportment of mortar structures in relation with main environmental factors and minimize the risk of cracking mortar structures at an early age.Design/methodology/approachThermokinetic study was carried out in natural and forced convection solar drying at three temperatures 20, 30 and 40°C and three air velocities (1, 3 and 5 m.s-1). The empirical and semiempirical models tested successfully describe the drying kinetics of mortar. These models simulate the drying process of water absorbed by capillarity, which is the most common humidity transfer mechanism in building materials and contain parameters with physical significance, which integrate the effect of several environmental factors and intrinsic characteristics of mortar structures.FindingsThe models simulate the drying process of water absorbed by capillarity, which is the most common humidity transfer mechanism in building materials and contain parameters with physical significance, which integrate the effect of several environmental factors and intrinsic characteristics of mortar structures. The average activation energy obtained expressed the temperature effect on the mortar diffusivity. The drying constant and the diffusion coefficient can be used to predict the influence of these environmental factors on the drying behavior of various building materials and therefore on their durability.Originality/valueEvaluation of the effect of several environmental factors and intrinsic characteristics of mortar structures on their durability.

scholarly journals Seasonal dynamics of methane emissions from a subarctic fen in the Hudson Bay Lowlands

2013 ◽  
Vol 10 (7) ◽  
pp. 4465-4479 ◽  
Author(s):  
K. L. Hanis ◽  
M. Tenuta ◽  
B. D. Amiro ◽  
T. N. Papakyriakou
Keyword(s):  
Soil Temperature ◽  
Air Temperature ◽  
Growing Season ◽  
Near Surface ◽  
Growing Seasons ◽  
Air Temperatures ◽  
Soil Temperatures ◽  
Surface Soil Temperature ◽  
Filling Method ◽  
Highly Correlated

Abstract. Ecosystem-scale methane (CH4) flux (FCH4) over a subarctic fen at Churchill, Manitoba, Canada was measured to understand the magnitude of emissions during spring and fall shoulder seasons, and the growing season in relation to physical and biological conditions. FCH4 was measured using eddy covariance with a closed-path analyser in four years (2008–2011). Cumulative measured annual FCH4 (shoulder plus growing seasons) ranged from 3.0 to 9.6 g CH4 m−2 yr−1 among the four study years, with a mean of 6.5 to 7.1 g CH4 m−2 yr−1 depending upon gap-filling method. Soil temperatures to depths of 50 cm and air temperature were highly correlated with FCH4, with near-surface soil temperature at 5 cm most correlated across spring, fall, and the shoulder and growing seasons. The response of FCH4 to soil temperature at the 5 cm depth and air temperature was more than double in spring to that of fall. Emission episodes were generally not observed during spring thaw. Growing season emissions also depended upon soil and air temperatures but the water table also exerted influence, with FCH4 highest when water was 2–13 cm below and lowest when it was at or above the mean peat surface.

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