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Adaptive strategy to drought conditions: diurnal variation in water use of a Central Asian desert shrub

Wang S-S., Chen X., Zhou K.-F., Wang Q.

Polish Journal of Ecology

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2015

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Vol. 63, nr 1

63--76

EN

Water availability is one of the most important factors limiting photosynthetic assimilation of carbon dioxide and growth of individual plants in terrestrial ecosystems. It is especially important for desert shrubs because the diurnal water availability is particularly sensitive to climate change in arid ecosystems. Water use efficiency (WUE) is an indicator of water availability and is frequently used to assess plant performance in various ecosystems, particularly in arid ecosystems. The WUE of plants has been widely assessed using ecological methods and field measurements; however, these approaches are impractical to obtain numerous near-simultaneous estimates of plant water status at the landscape-scale. Consequently, landscape-scale assessments of plant water status are practically pursued through modeling. In this study, measurement and modeling of the diurnal variations of WUE were conducted for a native dominant desert shrub, Tamarix ramosissima, in its original habitat on the periphery of the Gurbantunggut Desert, China. The diurnal net photosynthesis (An), stomatal conductance (gs), and transpiration (Tr) were measured for each individual using a portable photosynthesis system. A coupled model of stomatal conductance, photosynthesis, and transpiration was applied to simulate the diurnal dynamics of An, gs, Tr, and WUE. The model explained 83, 47, 83, and 55% of the variance in the measured An, gs, Tr, and WUE values, respectively, for this desert ecosystem in which T. ramosissima is sparsely distributed. The results demonstrated that the coupled photosynthesis-stomatal conductance-transpiration model strategy is a promising approach to estimate water availability in desert ecosystems in Central Asia.

2

Effects of different irrigation strategies on soil water, salt, and nitrate nitrogen transport

Xu C., Zeng W. Z., Wu J. W., Huang J. S.

Ecological Chemistry and Engineering. S

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2015

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Vol. 22, nr 4

589--609

EN

Intermittent irrigation has attracted much attention as a water-saving technology in arid and semi-arid regions. For understanding the effect of intermittent irrigation on water and solute storage varied from irrigation amount per time (IRA), irrigation application frequency (IRAF), irrigation intervals (IRI) and even soil texture (ST), intermittent irrigation experiment was carried out in 33 micro-plots in Inner Mongolia, China. The experiment results were used for the calibration and validation of HYDRUS-1D software. Then 3 ST (silty clay loam, silty loam, and silty clay), 5 IRA (2, 4, 6, 8, and 10 cm), 4 IRAF (2, 3, 4, and 5 times) and 4 IRI (1, 2, 3, and 4 days) were combined and total 240 scenarios were simulated by HYDRUS-1D. Analysis of variance (ANVOA) of simulated results indicated that ST, IRA, and IRAF had significant effect on salt and nitrate nitrogen (NO3−-N) storage of 0-40 cm depth soil in intermittent irrigation while only ST affected soil water storage obviously. Furthermore, salt leaching percentage (SLP) and water use efficiency (WUE) of 0-40 cm depth were calculated and statistical prediction models for SLP were established based on the ANOVA using multiple regression analysis in each soil texture. Then constraint conditions of soil water storage (around field capacity), salt storage (smaller than 168 mg·cm−2), WUE (as large as possible) in 0-40 cm depth and total irrigation water amount (less than 25 cm) were proposed to find out the optimal intermittent irrigation strategies. Before sowing, the optimal irrigation strategy for silty clay loam soil was 6 cm IRA, 3 times IRAF, and 2 days IRI respectively. For silty loam and silty clay soils, IRA, IRAF, and IRI were 8 cm, 3 times, and 2 days respectively.

PL

Nawadnianie przerywane zwraca uwagę jako technologia oszczędnego użycia wody w regionach suchych i półpustynnych. Dla zrozumienia wpływu parametrów nawadniania przerywanego, takich jak czas (IRA), częstotliwości stosowania nawadniania (IRAF), odstępy czasu nawadniania (IRI), a także struktury gleby (ST) na magazynowanie wody i substancji rozpuszczonych, przeprowadzono eksperyment przerywanego nawadniania na 33 mikropoletkach w Mongolii Wewnętrznej, w Chinach. Wyniki doświadczeń użyto do kalibracji i walidacji oprogramowania HYDRUS-1D. Następnie 3 ST (mulisty piasek gliniasty, muliste iły i gliny pylaste), 5 IRA (2, 4, 6, 8 i 10 cm), 4 IRAF (2, 3, 4 i 5 razy) i 4 IRI (1, 2, 3 i 4 dni) połączono ogółem w 240 scenariuszy symulowanych przez HYDRUS-1D. Analiza wariancji (ANVOA) symulowanych wyników wykazała, że ST, IRA i IRAF miały znaczący wpływ na sól i azot azotanowy (NO3–-N), składowane na głębokości 0-40 cm gleby w nawadnianiu przerywanym, podczas gdy ST wpływał tylko na magazynowanie wody w glebie. Ponadto, procentowe ługowanie soli (SLP) i efektywność wykorzystania wody (WUE) zostały obliczone dla głębokości 0-40 cm i statystyczne modele predykcyjne dla SLP zostały ustalone na podstawie analizy wariancji i za pomocą analizy regresji wielokrotnej w każdej strukturze gleby. Aby określić optymalną strategię sporadycznego nawadniania, zaproponowano ograniczenie warunków magazynowania wody w glebie (około pojemności polowej), magazynowania soli (mniejsze niż 168 mg · cm–2), WUE (jak największa) w 0-40 cm głębokości i całkowitej ilości wody do nawadniania (mniej niż 25 cm). Przed siewem optymalna strategia nawadniania gleb mulistych gliniastych zakładała odpowiednio 6 cm IRA, 3 razy IRAF i 2 dni IRI. Dla gliny pylastej i ilastych gleb gliniastych założono IRA, IRAF i IRI odpowiednio 8 cm, 3 razy i 2 dni.

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Peng G., Wu C., Xu X., Yang D.

Polish Journal of Ecology

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2012

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Vol. 60, nr 2

311-321

EN

In woody perennials, leaf structure and biochemistry vary with tree age under changing environments. However, the related eco-physiological mechanisms have not been elucidated yet. In this study, we investigated agerelated responses of juvenile and mature subalpine fir trees (Abies faxoniana Rehder & E.H. Wilson.) growing at altitudes between 2,500 and 3,500 m in the Wanglang Natural Reserve in southwest China, to study the adaptive strategies of different age trees to suit changing environments. We found that there were distinct age- and altituderelated changes in the structural and biochemical characteristics of leaves. At all altitudes, mature trees exhibited higher area- and mass-based leaf nitrogen content (N[area], N[mass]), leaf mass per area (LMA) and stable isotope carbon composition ([delta^13]C), and a lower chlorophyll (Chl) content than those juvenile trees, except for N[mass] at 3,000 m as well as LMA at 2,750 m, where the values of N[mass] and LMA in mature trees were slightly lower than those in juvenile trees. Furthermore, leaf characteristics showed significant differences in the change rates with altitude between different age groups. Our results indicated that assimilative organs in mature trees do not suffering from nutrient deficiency and that juvenile and mature trees possess different adaptive growth strategies under changing environments, as indicated by higher leaf N content in mature trees and the opposite patterns of LMA and Chl content between two age groups. We also concluded that juvenile could be more sensitive to global warming due to a greater altitudinal influence on the leaf traits in juvenile trees than those in mature trees.

4

Evaluation of the physiological activity of Salix viminalis grown in hydroponic cultures with different salinity degree

Wróbel J., Mikiciuk M., Stolarska A., Marska B.

Ecological Chemistry and Engineering. A

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2008

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Vol. 15, nr 4-5

443-449

EN

The physiological activity of three basket willow clones, ie Bjor, Jorr and Tora, grown under different salinity conditions on a Hoagland's nutrient solution-based substrate was measured by their gaseous exchange indicators (ie intensity of CO2 assimilation and transpiration) as well as the efficiency of water use in photosynthesis. The obtained results allow to state that salinity differentiates significantly the aforesaid indicators, first of all the assimilation and water use efficiency. From among examined clones, the highest vulnerability to substrate salinity was a characteristic of the Jorr clone, whereas the lowest one of the Bjor clones. It was also found that in all clones, regardless of substrate salinity, a positive and significant correlation is observed between transpiration intensity and stomata1 conductivity.

PL

Aktywność fizjologiczną klonów wierzby wiciowej: Bjor, Jorr i Tora w warunkach zróżnicowanego zasolenia pożywki Hoaglanda mierzono wskaźnikami wymiany gazowej (tj. intensywnością asymilacji CO2 i transpiracji) oraz efektywnością wykorzystania wody w fotosyntezie. Uzyskane wyniki pozwalają stwierdzić, iż zasolenie istotnie zróżnicowało w/w wskaźniki, przede wszystkim asymilację i efektywność wykorzystania wody. Spośród badanych klonów, największą wrażliwością na zasolenie pożywki charakteryzował się klon Tora, a najmniejszą - Bjor. Stwierdzono również, :te bez względu na poziom zasolenia pożywki, u wszystkich klonów obserwuje się dodatnią i istotną korelację między intensywnością transpiracji a przewodnictwem szparkowym.