Water

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15 pages, 3997 KiB

Open AccessArticle

Xylem Formation in Populus euphratica and Its Response to Environmental Factors in the Lower Reaches of Tarim River, China

by Miaomiao Li, Qingzhi He, Mao Ye, Weilong Chen, Guoyan Zeng, Xiaoting Pan and Xi Zhang

Water 2024, 16(14), 1974; https://doi.org/10.3390/w16141974 - 12 Jul 2024

Viewed by 602

Abstract

In order to gain a deeper understanding of the effects of environmental factors on the formation of Populus euphratica xylem, this study analysed the anatomical characteristics of Populus euphratica xylem and its response to environmental factors using wood anatomy as an example of [...] Read more.

In order to gain a deeper understanding of the effects of environmental factors on the formation of Populus euphratica xylem, this study analysed the anatomical characteristics of Populus euphratica xylem and its response to environmental factors using wood anatomy as an example of Populus euphratica in the Yingsu section of the lower Tarim River. The results showed the following: (1) Throughout the growing season, the number of conduits of Populus euphratica in the two sample sites showed a slow increasing trend with the increase in groundwater burial depth, and the total conduit area showed an increasing and then decreasing trend with the increase in groundwater burial depth. The four indices of total, minimum, average, and maximum conduit areas in Populus euphratica xylem increased significantly with increasing temperatures during the growing season. (2) From the principal component analysis, the anatomical parameters of Populus euphratica xylem were found to be positively correlated with the depth of groundwater, average air temperature, maximum air temperature, minimum air temperature, surface temperature, relative humidity, and saturated water and air pressure deficit in the two sampling sites The most significant effects were found in the air temperature and depth of the groundwater. (3) The contribution of groundwater level and air temperature to different growth stages of Populus euphratica xylem was different. During the early part of the growing season of Populus euphratica, the air temperature was the main factor influencing the number of xylem conduits and total conduit area. As the growing season entered the middle stage, the air temperature and groundwater together affected the conduit parameters. In the later part of the growing season, groundwater became the most important factor affecting the number of conduits and the total conduit area. (4) The sensitivity analyses yielded a sensitive groundwater burial depth of 5.2 m for changes in the number of conduits in the xylem of the Populus euphratica and 5.9 m for changes in the total conduit area; the sensitive air temperature for the total conduit area in the xylem of the Populus euphratica was 22.0 °C, and the sensitive air temperature for the average conduit area was 18.5 °C. The results of this study can have important theoretical significance for understanding the Populus euphratica forests, as well as ecological water resource management in the lower Tarim River. They also provide scientific basis for the restoration and protection of Populus euphratica forests in the lower Tarim River. Full article

(This article belongs to the Special Issue Implications of Climate Change on the Sustainable Management of the Water–Forest Nexus)

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9 pages, 1237 KiB

Open AccessArticle

ENSO Signals Recorded by Ash Tree Rings in Iberian Riparian Forests

by Jesús Julio Camarero

Water 2022, 14(19), 3027; https://doi.org/10.3390/w14193027 - 26 Sep 2022

Cited by 1 | Viewed by 1561

Abstract

Climate–atmospheric patterns affect ecological processes. The El Niño Southern Oscillation (ENSO) represents the strongest global source of climate variability at annual scales, but its impacts on Mediterranean forests are still understudied. Here, ENSO signals recorded by river flow and radial growth series of [...] Read more.

Climate–atmospheric patterns affect ecological processes. The El Niño Southern Oscillation (ENSO) represents the strongest global source of climate variability at annual scales, but its impacts on Mediterranean forests are still understudied. Here, ENSO signals recorded by river flow and radial growth series of Mediterranean riparian forests are uncovered in the middle Ebro basin, northeastern Spain. A chronology or mean series of tree ring widths (period 1970–2018, 27 trees) was built for narrow-leaved ash (Fraxinus angustifolia). Growth indices increased as the river flow did during the prior winter and from May to September. Ash growth indices and river flow of the hydrological year were positively related (r = 0.54, p < 0.001), suggesting that a higher soil moisture enhances growth. This correlation remained significant after taking out the influence of precipitation. Ash growth indices (r = −0.46, p = 0.001) and river flow during the hydrological year (r = −0.30, p = 0.03) were negatively associated with the January Southern Oscillation Index (SOI). These relationships suggest that high SOI values corresponding to La Niña events lead to reduced river flow, thus decreasing ash radial growth. Further approaches could be used to better understand how the ENSO impacts drought-prone riparian forests subjected to increasing aridity. Full article

(This article belongs to the Special Issue Implications of Climate Change on the Sustainable Management of the Water–Forest Nexus)

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14 pages, 643 KiB

Open AccessFeature PaperArticle

Effects of Spring Warming and Drought Events on the Autumn Growth of Larix kaempferi Seedlings

by Hyeonji Kim, Heejae Jo, Gwang-Jung Kim, Hyung-Sub Kim and Yowhan Son

Water 2022, 14(12), 1962; https://doi.org/10.3390/w14121962 - 19 Jun 2022

Cited by 1 | Viewed by 2180

Abstract

High temperatures and droughts following winter dormancy can negatively affect seedling growth and mortality. An open-field experiment was conducted to study the growth and mortality of Larix kaempferi seedlings in response to spring warming and drought treatments and to determine whether seedlings could [...] Read more.

High temperatures and droughts following winter dormancy can negatively affect seedling growth and mortality. An open-field experiment was conducted to study the growth and mortality of Larix kaempferi seedlings in response to spring warming and drought treatments and to determine whether seedlings could regain their growth capability once the treatments were discontinued. In May 2020, 1-year-old seedlings were exposed to four treatments: control, warming-only, drought-only, and the combined warming and drought. Drought treatment reduced the seedling height and root collar diameter and increased the mortality rate. The combined warming and drought treatments had the highest mortality rates, followed by the drought, control, and warming treatments. However, after the cessation of the treatments, the combined warming and drought treatments increased seedling height, root collar diameter, and individual seedling biomass because the high mortality rate relaxed competition among seedlings. This suggests that the effects of low competition on the surviving seedlings may mitigate the negative effects of warming and drought on seedling growth. Our study demonstrates that despite the high mortality and decreased growth during the treatment period, seedlings subjected to combined high temperature and drought stress showed short-term high levels of growth compared to seedlings subjected to a single stress. Full article

(This article belongs to the Special Issue Implications of Climate Change on the Sustainable Management of the Water–Forest Nexus)

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12 pages, 6360 KiB

Open AccessFeature PaperArticle

Effects of Forest and Agriculture Land Covers on Organic Carbon Flux Mediated through Precipitation

by Gang-Sun Kim, Sle-gee Lee, Jongyeol Lee, Eunbeen Park, Cholho Song, Mina Hong, Young-Jin Ko and Woo-Kyun Lee

Water 2022, 14(4), 623; https://doi.org/10.3390/w14040623 - 17 Feb 2022

Cited by 1 | Viewed by 2407

Abstract

Carbon stored on land is discharged into rivers through water flow, which is an important mechanism for energy transfer from land to river ecosystems. The goal of this study was to identify the relationship between land cover and carbon flux mediated through precipitation. [...] Read more.

Carbon stored on land is discharged into rivers through water flow, which is an important mechanism for energy transfer from land to river ecosystems. The goal of this study was to identify the relationship between land cover and carbon flux mediated through precipitation. In order to clarify the general relationship, research was conducted on a range of national scales. Eighty-two watershed samples from an area where the urban land cover area was less than 10% and with a water-quality measurement point at an outlet were delineated. Carbon flux and soil organic carbon of the watershed was estimated using the Soil and Water Assessment Tool model, Forest Biomass and Dead Organic Matter Carbon model, and other data. Finally, the data were analyzed to determine the relationship between soil organic carbon and carbon flux. As a result, it was concluded that the carbon flux of the watershed increased with increasing area of the watershed. Under the same area condition, it was revealed that the greater the forest soil organic carbon, the less the carbon flux released from the watershed. Through this study, it was observed that as the above-ground biomass of forest increased, the carbon flux from watershed to river outlet decreased logarithmically. Full article

(This article belongs to the Special Issue Implications of Climate Change on the Sustainable Management of the Water–Forest Nexus)

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16 pages, 1413 KiB

Open AccessArticle

Physiological and Shoot Growth Responses of Abies holophylla and Abies koreana Seedlings to Open-Field Experimental Warming and Increased Precipitation

by Heejae Jo, Florent Noulèkoun, Asia Khamzina, Hanna Chang and Yowhan Son

Water 2022, 14(3), 356; https://doi.org/10.3390/w14030356 - 26 Jan 2022

Cited by 4 | Viewed by 2469

Abstract

Projected changes in temperature and precipitation in mid-latitude wet regions are expected to significantly affect forest ecosystems. We studied the physiological and shoot growth responses of Abies holophylla and Abies koreana seedlings to warming (3 °C above ambient temperature) and increased precipitation (irrigation [...] Read more.

Projected changes in temperature and precipitation in mid-latitude wet regions are expected to significantly affect forest ecosystems. We studied the physiological and shoot growth responses of Abies holophylla and Abies koreana seedlings to warming (3 °C above ambient temperature) and increased precipitation (irrigation with 40% of rainfall) treatments under open-field conditions. The physiological parameters, quantified by the net photosynthetic rate, transpiration rate, stomatal conductance, and total chlorophyll content, were monitored from July to October 2018. Shoot growth (i.e., root collar diameter and height) was assessed in August and December 2018. Irrespective of the treatments, the physiological parameters of both species decreased from July to August under warming treatment due to heat stress before recovering in September and October. Warming alone (W) and warming along with increased precipitation (W*P) decreased the physiological activities of both species in July, August, and September, with more pronounced effects on A. koreana compared with A. holophylla. Increased precipitation resulted in the increased chlorophyll content of both species in October. Shoot growth was not generally affected by the treatments, except for a subtle reduction in height under W*P for A. koreana. A. holophylla had consistently higher values for the physiological parameters and shoot growth than A. koreana. Our results indicate that the physiological activities of the Abies species could be seriously reduced under climate change, with a more severe impact on A. koreana. Among the two species, A. holophylla appears to be a more robust candidate for future forest planting. Full article

(This article belongs to the Special Issue Implications of Climate Change on the Sustainable Management of the Water–Forest Nexus)

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18 pages, 4242 KiB

Open AccessArticle

Afforestation of Degraded Croplands as a Water-Saving Option in Irrigated Region of the Aral Sea Basin

by Navneet Kumar, Asia Khamzina, Patrick Knöfel, John P. A. Lamers and Bernhard Tischbein

Water 2021, 13(10), 1433; https://doi.org/10.3390/w13101433 - 20 May 2021

Cited by 10 | Viewed by 4312

Abstract

Climate change is likely to decrease surface water availability in Central Asia, thereby necessitating land use adaptations in irrigated regions. The introduction of trees to marginally productive croplands with shallow groundwater was suggested for irrigation water-saving and improving the land’s productivity. Considering the [...] Read more.

Climate change is likely to decrease surface water availability in Central Asia, thereby necessitating land use adaptations in irrigated regions. The introduction of trees to marginally productive croplands with shallow groundwater was suggested for irrigation water-saving and improving the land’s productivity. Considering the possible trade-offs with water availability in large-scale afforestation, our study predicted the impacts on water balance components in the lower reaches of the Amudarya River to facilitate afforestation planning using the Soil and Water Assessment Tool (SWAT). The land-use scenarios used for modeling analysis considered the afforestation of 62% and 100% of marginally productive croplands under average and low irrigation water supply identified from historical land-use maps. The results indicate a dramatic decrease in the examined water balance components in all afforestation scenarios based largely on the reduced irrigation demand of trees compared to the main crops. Specifically, replacing current crops (mostly cotton) with trees on all marginal land (approximately 663 km²) in the study region with an average water availability would save 1037 mln m³ of gross irrigation input within the study region and lower the annual drainage discharge by 504 mln m³. These effects have a considerable potential to support irrigation water management and enhance drainage functions in adapting to future water supply limitations. Full article

(This article belongs to the Special Issue Implications of Climate Change on the Sustainable Management of the Water–Forest Nexus)

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18 pages, 9983 KiB

Open AccessEditor’s ChoiceArticle

2019–2020 Australia Fire and Its Relationship to Hydroclimatological and Vegetation Variabilities

by Mohammad Reza Ehsani, Jorge Arevalo, Christoforus Bayu Risanto, Mostafa Javadian, Charles John Devine, Alireza Arabzadeh, Hector L. Venegas-Quiñones, Ambria Paige Dell’Oro and Ali Behrangi

Water 2020, 12(11), 3067; https://doi.org/10.3390/w12113067 - 2 Nov 2020

Cited by 30 | Viewed by 6995

Abstract

Wildfire is a major concern worldwide and particularly in Australia. The 2019–2020 wildfires in Australia became historically significant as they were widespread and extremely severe. Linking climate and vegetation settings to wildfires can provide insightful information for wildfire prediction, and help better understand [...] Read more.

Wildfire is a major concern worldwide and particularly in Australia. The 2019–2020 wildfires in Australia became historically significant as they were widespread and extremely severe. Linking climate and vegetation settings to wildfires can provide insightful information for wildfire prediction, and help better understand wildfires behavior in the future. The goal of this research was to examine the relationship between the recent wildfires, various hydroclimatological variables, and satellite-retrieved vegetation indices. The analyses performed here show the uniqueness of the 2019–2020 wildfires. The near-surface air temperature from December 2019 to February 2020 was about 1 °C higher than the 20-year mean, which increased the evaporative demand. The lack of precipitation before the wildfires, due to an enhanced high-pressure system over southeast Australia, prevented the soil from having enough moisture to supply the demand, and set the stage for a large amount of dry fuel that highly favored the spread of the fires. Full article

(This article belongs to the Special Issue Implications of Climate Change on the Sustainable Management of the Water–Forest Nexus)

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7 pages, 1111 KiB

Open AccessCommunication

Isotopic Signatures as an Indicator of Long-Term Water-Use Efficiency of Haloxylon Plantations on the Dried Aral Sea Bed

by Asia Khamzina, Jiae An, Hanna Chang and Yowhan Son

Water 2020, 12(1), 99; https://doi.org/10.3390/w12010099 - 27 Dec 2019

Cited by 2 | Viewed by 2451

Abstract

The desiccation of the Aral Sea due to water withdrawal from contributing rivers has resulted in an unprecedented change in the region’s climate, from maritime to hot dry desert. Afforestation has been implemented on the desiccated seafloor—the Aralkum Desert—for stabilizing the exposed substrate. [...] Read more.

The desiccation of the Aral Sea due to water withdrawal from contributing rivers has resulted in an unprecedented change in the region’s climate, from maritime to hot dry desert. Afforestation has been implemented on the desiccated seafloor—the Aralkum Desert—for stabilizing the exposed substrate. However, studies on the long-term status of the afforested sites are limited. Here, we examined C and N isotopic signatures in Haloxylon aphyllum plantations, as indicators of time-integrated plant response to the prevalent water and salinity constraints, in northern Aralkum, Kazakhstan. Foliar ¹³C composition analysis in a chronosequence of H. aphyllum plantation sites (aged 1–27 years) on the sandy substrate revealed a significant trend towards higher water-use efficiency in older plantations, possibly in response to declining water availability. A lack of correlation between plant ¹³C signature and soil electrical conductivity suggests no history of salt stress despite the saline environment. Furthermore, ¹⁵N enrichment in plant tissue in the water-limited Aralkum ecosystem indicates the relative openness of N cycling. There was an increase in species richness and self-propagation at the plot scale, indicating successful afforestation effort. Coupled with other approaches, isotope discrimination might elucidate mechanisms underlying stress tolerance in H. aphyllum, which could support the afforestation efforts. Full article

(This article belongs to the Special Issue Implications of Climate Change on the Sustainable Management of the Water–Forest Nexus)

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