scholarly journals Plant water resource partitioning and xylem-to-leaf deuterium enrichment in Lanzhou, northwest China

2020 ◽  
Vol 20 (3) ◽  
pp. 1127-1140
Author(s):  
Qinqin Du ◽  
Mingjun Zhang ◽  
Shengjie Wang ◽  
Athanassios A. Argiriou ◽  
Cunwei Che ◽  
...  
Keyword(s):  
Soil Water ◽  
River Water ◽  
Plant Species ◽  
Water Resource ◽  
Resource Partitioning ◽  
Growing Season ◽  
Dry Season ◽  
Leaf Water ◽  
Leaf Phenology ◽  
Deuterium Enrichment

Abstract Lanzhou lies at the western Loess Plateau, China, and has a typical semi-arid temperate continental climate. Plants in this area are exposed to a prolonged dry season. In this study, we measured the stable isotopes of hydrogen (δD) and oxygen (δ18O) of the local precipitation, river water, soil water, plant xylem water, and leaf water at four sampling sites during the 2016 growing season. Our results showed that plants relied mostly on wet season precipitation at sites N1, N2, and N3 because this recharged the soil after the long dry season. Leaf phenology had a significant effect on evaporation distance (ED) value, and evergreen plants have adapted to water tapping from deep soil water sources during the dry season. The ED values of trees and shrubs were quite different in the dry season, indicating water competition among different plant species was mitigated due to water resource partitioning. Moreover, plants at site N4 relied on a water source admixed with river water throughout the whole growing season. The mean value of xylem-to-leaf water deuterium enrichment (ɛl/x) was −0.91 ± 0.36‰ over all plant species, seasons, and sampling sites. Plant species, leaf phenology, and seasons were found to be the primary factors influencing the ɛl/x, while growth form and elevation had negligible effects.

scholarly journals Plant water resource partitioning and xylem-leaf deuterium enrichment in a seasonally dry tropical climate

2016 ◽  
Author(s):  
Lien De Wispelaere ◽  
Samuel Bodé ◽  
Pedro Hervé-Fernández ◽  
Andreas Hemp ◽  
Dirk Verschuren ◽  
...  
Keyword(s):  
Plant Species ◽  
Lake Water ◽  
Growth Form ◽  
Water Source ◽  
Dry Season ◽  
Leaf Water ◽  
Leaf Phenology ◽  
Water Pool ◽  
Lake Shore ◽  
Deuterium Enrichment

Abstract. Lake Challa (3°19' S, 37°42' E) is a steep-sided crater lake situated in equatorial East Africa, a tropical semi-arid area with bimodal rainfall pattern. Plants in this region are exposed to a prolonged dry season and we investigated if (1) these plants show spatial variability and temporal shifts in their water source use; (2) seasonal differences in the isotopic composition of precipitation are reflected in xylem water; and (3) plant family, growth form, leaf phenology, habitat and season influence the xylem-to-leaf water deuterium enrichment. In this study, the δ2H and δ18O of precipitation, lake water, groundwater, plant xylem water and plant leaf water were measured across different plant species, seasons and plant habitats in the vicinity of Lake Challa. We found that plants rely mostly on water from the "short" rains falling from October to December (northeastern monsoon), as these recharge the soil after the long dry season. This plant-available water pool is only slightly replenished by the "long" rains falling from February to May (southeastern monsoon), in agreement with the "two water world" hypothesis according to which plants rely on a static water pool while a mobile water pool recharges the groundwater. Trees at the lake shore and on the crater rim use more evaporated water than shrubs in the same habitats, suggesting that trees tap water from the topsoil where the nutrient content is highest. Plants at the lake shore rely on a water source admixed with lake water. The enrichment in deuterium from xylem water to leaf water averages 24 ± 28 ‰. According to our results, plant species and their associated leaf phenology are the primary factors influencing this enrichment factor, while growth form and season have negligible effects.

scholarly journals Plant water resource partitioning and isotopic fractionation during transpiration in a seasonally dry tropical climate

2017 ◽  
Vol 14 (1) ◽  
pp. 73-88 ◽  
Author(s):  
Lien De Wispelaere ◽  
Samuel Bodé ◽  
Pedro Hervé-Fernández ◽  
Andreas Hemp ◽  
Dirk Verschuren ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Water Resource ◽  
Resource Use ◽  
Growth Form ◽  
Water Source ◽  
Leaf Water ◽  
Leaf Phenology ◽  
Water Pool ◽  
Static Water ◽  
Deuterium Enrichment

Abstract. Lake Chala (3°19′ S, 37°42′ E) is a steep-sided crater lake situated in equatorial East Africa, a tropical semiarid area with a bimodal rainfall pattern. Plants in this region are exposed to a prolonged dry season, and we investigated if (1) these plants show spatial variability and temporal shifts in their water source use; (2) seasonal differences in the isotopic composition of precipitation are reflected in xylem water; and (3) plant family, growth form, leaf phenology, habitat and season influence the xylem-to-leaf water deuterium enrichment. In this study, the δ2H and δ18O of precipitation, lake water, groundwater, plant xylem water and plant leaf water were measured across different plant species, seasons and plant habitats in the vicinity of Lake Chala. We found that plants rely mostly on water from the short rains falling from October to December (northeastern monsoon), as these recharge the soil after the long dry season. This plant-available, static water pool is only slightly replenished by the long rains falling from February to May (southeastern monsoon), in agreement with the two water worlds hypothesis, according to which plants rely on a static water pool while a mobile water pool recharges the groundwater. Spatial variability in water resource use exists in the study region, with plants at the lakeshore relying on a water source admixed with lake water. Leaf phenology does not affect water resource use. According to our results, plant species and their associated leaf phenology are the primary factors influencing the enrichment in deuterium from xylem water to leaf water (εl/x), with deciduous species giving the highest enrichment, while growth form and season have negligible effects. Our observations have important implications for the interpretation of δ2H of plant leaf wax n-alkanes (δ2Hwax) from paleohydrological records in tropical East Africa, given that the temporal variability in the isotopic composition of precipitation is not reflected in xylem water and that leaf water deuterium enrichment is a key factor in shaping δ2Hwax. The large interspecies variability in xylem–leaf enrichment (24 ± 28 ‰) is potentially troublesome, taking into account the likelihood of changes in species assemblage with climate shifts.

scholarly journals Liana and tree below-ground water competition—evidence for water resource partitioning during the dry season

2018 ◽  
Vol 38 (7) ◽  
pp. 1071-1083 ◽  
Author(s):  
Hannes De Deurwaerder ◽  
Pedro Hervé-Fernández ◽  
Clément Stahl ◽  
Benoit Burban ◽  
Pascal Petronelli ◽  
...  
Keyword(s):  
Ground Water ◽  
Water Resource ◽  
Resource Partitioning ◽  
Dry Season ◽  
Water Competition ◽  
Below Ground

Resource partitioning within a browsing guild in a key habitat, the Chobe Riverfront, Botswana

2005 ◽  
Vol 21 (6) ◽  
pp. 641-649 ◽  
Author(s):  
Shimane W. Makhabu
Keyword(s):  
Plant Species ◽  
Resource Use ◽  
Resource Partitioning ◽  
Woody Species ◽  
Food Resources ◽  
Dry Season ◽  
Population Increase ◽  
Species Identity ◽  
Plant Parts ◽  
Elephant Population

Resource partitioning between elephant, giraffe, kudu and impala was assessed. This was to address concerns that elephant population increase adversely affects other species through depleting their food in key areas close to permanent water. Resources considered were woody species browsed, height browsed and plant parts browsed. Animals were observed as they browsed and the plant species, browsing heights and plant parts browsed were recorded. Observations were made over 1 y and the data were divided between wet and dry season. Schoener's index of resource use overlap was calculated for plant species, browsing heights and plant parts eaten and differences in overlap between wet and dry season were tested. Levin's measure of niche breadth in plant species utilized by the different browsers was calculated. Woody species identity was the main separator between food resources that elephant used and those giraffe, impala and kudu used. Giraffe, kudu and impala mainly browsed the same species and plant parts but browsed at different heights. There was no difference in resource use overlap between seasons with different resource availability. Since elephant browsed different woody species from those browsed by the others, it is unlikely that the increasing elephant population will deplete food resources for the other browsers.

scholarly journals IS DEEP SOWING BENEFICIAL FOR DRY SEASON CROPPING WITHOUT IRRIGATION ON SANDY SOIL WITH SHALLOW WATER TABLE?

2013 ◽  
Vol 49 (3) ◽  
pp. 366-381
Author(s):  
B. BUAKUM ◽  
V. LIMPINUNTANA ◽  
N. VORASOOT ◽  
K. PANNANGPETCH ◽  
R. W. BELL
Keyword(s):  
Shallow Water ◽  
Water Content ◽  
Soil Water ◽  
Water Table ◽  
Growing Season ◽  
Dry Season ◽  
Shallow Water Table ◽  
Water Tables ◽  
Permanent Wilting Point ◽  
Wilting Point

SUMMARYDeep sowing (15 cm) on sands in the dry season is a practice used in post-rice sowing of legumes without irrigation, designed to increase moisture access for germination, growth and crops yield. However, with such deep sowing there can be a penalty for emergence and growth if there is abundant water stored in the upper soil profile during the growing season. Hence, there is a need to define the soil water regimes under which deep sowing is advantageous for different legumes. To investigate the adaptation of legume crop species to deep sowing, we studied their emergence, growth and yield on three deep soils (3–16% clay) with shallow water tables during two years in northeast Thailand. At site 1 and 2, peanut, cowpea, mungbean and soybean were sown shallow (~5 cm) or deep (~15 cm). At site 3, only cowpea and peanut were shallow or deep sown. Shallow water tables maintained soil water content (0–15 cm) above permanent wilting point throughout the growing season. Deep sowing of all legumes delayed emergence by 3–7 days at all locations. Shoot dry weight of legumes after deep sowing was mostly similar or lower than weight after shallow sowing. Yield and harvest index of legumes did not differ meaningfully among sowing depths. Therefore, deep sowing was not beneficial for dry season cropping without irrigation when there was a shallow water table and sufficient water for crop growth throughout soil profiles in the growing season. Taken together with previous studies, we conclude that shallow rather than deep sowing of legumes was preferred when the soil water content at 0–15-cm depth remained higher than permanent wilting point throughout the growing season due to shallow water table.

scholarly journals The Stable Isotopic Composition of Different Water Bodies at the Soil–Plant–Atmosphere Continuum (SPAC) of the Western Loess Plateau, China

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1742
Author(s):  
Che ◽  
Zhang ◽  
Argiriou ◽  
Wang ◽  
Du ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Soil Water ◽  
River Water ◽  
Soil Layer ◽  
Growing Season ◽  
Water Bodies ◽  
Lanzhou City ◽  
Shallow Soil ◽  
Water Plant ◽  
Stable Isotopic

Understanding the isotopic composition and interrelations of different water bodies at the soil–plant–atmosphere continuum (SPAC) is crucial to reveal the processes and mechanisms of regional water cycles. Rainfall, river water, plant, and soil samples from Lanzhou City, China, were collected from April to October 2016. The hydrogen (δ2H) and oxygen (δ18O) of the local precipitation, river water, soil water, plant xylem water, and leaf water were determined. We found that trees mainly uptake the middle (30–60 cm) and deep (60–100 cm) layer soil water during the growing season, and the shrubs mainly uptake the middle soil water. All herbs uptake the shallow soil water (0–30 cm) during the growing season. The δ18O of shallow soil water was found to be isotopic-enriched because of evaporation and exhibited a decline from the shallow soil layer towards the deeper layer. The variation of δ18O and soil water content (SWC) was remarkable in shallow soil, which was mainly due to evaporation and precipitation infiltration, while water in the middle and deep layer was less affected by these phenomena.

scholarly journals Effects of groundwater abstraction on two keystone tree species in an arid savanna national park

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e2923 ◽  
Author(s):  
Eleanor Shadwell ◽  
Edmund February
Keyword(s):  
Soil Water ◽  
Water Use ◽  
Water Table ◽  
Tree Species ◽  
Dry Season ◽  
Leaf Water ◽  
Groundwater Abstraction ◽  
Stomatal Regulation ◽  
Water Potentials ◽  
Large Trees

BackgroundIn arid systems with no surface water, deep boreholes in ephemeral river beds provide for humans and animals. With continually increasing infrastructure development for tourism in arid wildlife parks such as the Kgalagadi Transfrontier Park in southern Africa, we ask what effects increased abstraction may have on large trees. Large trees in arid savannas perform essential ecosystem services by providing food, shade, nesting sites and increased nutrients for many other plant and animal species and for this are regarded as keystone species.MethodsWe determine seasonal fluctuations in the water table while also determining the water source for the dominant large tree species in the Auob and Nossob rivers in the Park. We also determine the extent to which these trees are physiologically stressed using leafδ13C, xylem pressure potentials, specific leaf area and an estimate of canopy death. We do this both upstream and downstream of a low water use borehole in the Auob River and a high water use borehole in the Nossob River.ResultsOur results show that the trees are indeed using deep groundwater in the wet season and that this is the same water used by people. In the dry season, trees in the Auob downstream of the active borehole become detached from the aquifer and use more isotopically enriched soil water. In the Nossob in the dry season, all trees use isotopically enriched soil water, and downstream of the active borehole use stomatal regulation to maintain leaf water potentials. These results suggest that trees in the more heavily utilised Nossob are under more water stress than those trees in the Auob but that trees in both rivers demonstrate physiological adaptation to the changes in available water with smaller heavier leaves, no significant canopy dieback and in the dry season in the Nossob stomatal regulation of leaf water potentials.DiscussionAn increase in abstraction of groundwater particularly at the Nossob borehole may cause an additional draw down of the water table adding to the physiological stress demonstrated in our study. The managers of the Kgalagadi Transfrontier Park have a mandate that includes biodiversity conservation. To fulfil this mandate, upper and lower thresholds for groundwater abstraction that allow for an adequate ecological reserve have to be determined.

scholarly journals Characterizing Growing Season Length of Subtropical Coniferous Forests with a Phenological Model

Forests ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 95
Author(s):  
Yuan Gong ◽  
Christina L. Staudhammer ◽  
Susanne Wiesner ◽  
Gregory Starr ◽  
Yinlong Zhang
Keyword(s):  
Climate Change ◽  
Soil Water ◽  
Prescribed Fire ◽  
Water Availability ◽  
Longleaf Pine ◽  
Growing Season ◽  
Soil Water Availability ◽  
Future Climate Change ◽  
Short Term ◽  
Phenological Model

Understanding plant phenological change is of great concern in the context of global climate change. Phenological models can aid in understanding and predicting growing season changes and can be parameterized with gross primary production (GPP) estimated using the eddy covariance (EC) technique. This study used nine years of EC-derived GPP data from three mature subtropical longleaf pine forests in the southeastern United States with differing soil water holding capacity in combination with site-specific micrometeorological data to parameterize a photosynthesis-based phenological model. We evaluated how weather conditions and prescribed fire led to variation in the ecosystem phenological processes. The results suggest that soil water availability had an effect on phenology, and greater soil water availability was associated with a longer growing season (LOS). We also observed that prescribed fire, a common forest management activity in the region, had a limited impact on phenological processes. Dormant season fire had no significant effect on phenological processes by site, but we observed differences in the start of the growing season (SOS) between fire and non-fire years. Fire delayed SOS by 10 d ± 5 d (SE), and this effect was greater with higher soil water availability, extending SOS by 18 d on average. Fire was also associated with increased sensitivity of spring phenology to radiation and air temperature. We found that interannual climate change and periodic weather anomalies (flood, short-term drought, and long-term drought), controlled annual ecosystem phenological processes more than prescribed fire. When water availability increased following short-term summer drought, the growing season was extended. With future climate change, subtropical areas of the Southeastern US are expected to experience more frequent short-term droughts, which could shorten the region’s growing season and lead to a reduction in the longleaf pine ecosystem’s carbon sequestration capacity.

Effects of moisture supply in the dry season and subsequent defoliation on persistence of the savanna grasses Themeda triandra, Heteropogon contortus and Panicum maximum

1992 ◽  
Vol 43 (2) ◽  
pp. 241 ◽  
Author(s):  
JJ Mott ◽  
MM Ludlow ◽  
JH Richards ◽  
AD Parsons
Keyword(s):  
Growing Season ◽  
Close Correlation ◽  
Dry Season ◽  
Carbon Gain ◽  
Panicum Maximum ◽  
Wet Season ◽  
Themeda Triandra ◽  
Heteropogon Contortus ◽  
Moisture Conditions ◽  
Sheath Material

The close correlation between grazing-induced mortality and major climatic patterns in Australian savannas, led us to the hypothesis that moisture conditions during the dry, non-growing season could affect sensitivity to grazing in the subsequent growing season. Using three widespread savanna species (Themeda triandra, Heteropogon contortus and Panicum maximum), this hypothesis was tested experimentally and the mechanisms controlling this response examined and quantified. In T. triandra drought during the dry season led to major mortality in defoliated plants in the next growing season. This mortality was caused by a synchrony of tillering at the commencement of the wet season, leaving few buds for replacement once parent tillers were killed by defoliation. T. triandra was also the most sensitive species to defoliation. This sensitivity was due to the poor ability of the plant to maintain positive carbon gain after defoliation. Several factors contributed to this poor ability, including: low total photosynthetic rate, low specific leaf area, and a large proportion of sheath material with poor photosynthetic capacity remaining after cutting. Both H. contortus and P. maximum growing under irrigated and fertilized conditions did not display any effects of previous moisture treatments when defoliated during the next wet season and were much less sensitive to defoliation than T. triandra.

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