Increased Post-Drought Growth after Thinning in Pinus nigra Plantations

In Mediterranean seasonally dry regions, the rise in dieback and mortality episodes observed in pine afforestations has been related to higher drought intensity and lack of appropriate management, which enhance competition between trees for water and light. However, there is little understanding of the benefits of silviculture for plantations under seasonal drought stress. A combination of dendrochronology and wood C and O isotope analyses was used in three Black pine (Pinus nigra) plantations to work out the responses of radial growth (BAI, basal area increment) and water-use efficiency (WUEi) to thinning treatments (removal of 40% of the stand basal area). Thinning had a positive effect on BAI and WUEi, reduced drought sensitivity, and reduced the temporal dependence on the previous year’s growth. These results were significant even 13–14 years after thinning and coherent for the three study sites. Differences were found between the sites regarding the physiological mechanisms of adaptation. In two sites, we inferred the enhanced WUEi was due to increased photosynthetic rates (A) at constant stomatal conductance (gs). In the third site, which had higher tree density and therefore competition, we inferred increases in both A and gs, with the former being proportionally larger than the latter.

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Localized basal area affects soil respiration temperature sensitivity in a coastal deciduous forest

Biogeosciences ◽

10.5194/bg-17-771-2020 ◽

2020 ◽

Vol 17 (3) ◽

pp. 771-780 ◽

Cited By ~ 1

Author(s):

Stephanie C. Pennington ◽

Nate G. McDowell ◽

J. Patrick Megonigal ◽

James C. Stegen ◽

Ben Bond-Lamberty

Keyword(s):

Soil Moisture ◽

Soil Respiration ◽

Spatial Variability ◽

Temperature Sensitivity ◽

Large Scale ◽

Deciduous Forest ◽

Basal Area ◽

Soil Surface ◽

Study Sites ◽

Positive Effect

Abstract. Soil respiration (Rs), the flow of CO2 from the soil surface to the atmosphere, is one of the largest carbon fluxes in the terrestrial biosphere. The spatial variability of Rs is both large and poorly understood, limiting our ability to robustly scale it in space. One factor in Rs spatial variability is the autotrophic contribution from plant roots, but it is uncertain how the presence of plants affects the magnitude and temperature sensitivity of Rs. This study used 1 year of Rs measurements to examine the effect of localized basal area on Rs in the growing and dormant seasons, as well as during moisture-limited times, in a temperate, coastal, deciduous forest in eastern Maryland, USA. In a linear mixed-effects model, tree basal area within a 5 m radius (BA5) exerted a significant positive effect on the temperature sensitivity of soil respiration. Soil moisture was the dominant control on Rs during the dry portions of the year, while soil moisture, temperature, and BA5 all exerted significant effects on Rs in wetter periods. Our results suggest that autotrophic respiration is more sensitive to temperature than heterotrophic respiration at these sites, although we did not measure these source fluxes directly, and that soil respiration is highly moisture sensitive, even in a record-rainfall year. The Rs flux magnitudes (0.46–15.0 µmol m−2 s−1) and variability (coefficient of variability 10 %–23 % across plots) observed in this study were comparable to values observed in similar forests. Six Rs observations would be required in order to estimate the mean across all study sites to within 50 %, and 518 would be required in order to estimate it to within 5 %, with 95 % confidence. A better understanding of the spatial interactions between plants and microbes, as well as the strength and speed of above- and belowground coupling, is necessary to link these processes with large-scale soil-to-atmosphere C fluxes.

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Disentangling the role of photosynthesis and stomatal conductance on rising forest water-use efficiency

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1905912116 ◽

2019 ◽

Vol 116 (34) ◽

pp. 16909-16914 ◽

Cited By ~ 31

Author(s):

Rossella Guerrieri ◽

Soumaya Belmecheri ◽

Scott V. Ollinger ◽

Heidi Asbjornsen ◽

Katie Jennings ◽

...

Keyword(s):

Stomatal Conductance ◽

Water Use Efficiency ◽

Water Use ◽

Tree Ring ◽

Carbon Assimilation ◽

Basal Area ◽

Atmospheric Measurements ◽

Physiological Mechanisms ◽

Carbon And Oxygen Isotope ◽

Use Efficiency

Multiple lines of evidence suggest that plant water-use efficiency (WUE)—the ratio of carbon assimilation to water loss—has increased in recent decades. Although rising atmospheric CO2 has been proposed as the principal cause, the underlying physiological mechanisms are still being debated, and implications for the global water cycle remain uncertain. Here, we addressed this gap using 30-y tree ring records of carbon and oxygen isotope measurements and basal area increment from 12 species in 8 North American mature temperate forests. Our goal was to separate the contributions of enhanced photosynthesis and reduced stomatal conductance to WUE trends and to assess consistency between multiple commonly used methods for estimating WUE. Our results show that tree ring-derived estimates of increases in WUE are consistent with estimates from atmospheric measurements and predictions based on an optimal balancing of carbon gains and water costs, but are lower than those based on ecosystem-scale flux observations. Although both physiological mechanisms contributed to rising WUE, enhanced photosynthesis was widespread, while reductions in stomatal conductance were modest and restricted to species that experienced moisture limitations. This finding challenges the hypothesis that rising WUE in forests is primarily the result of widespread, CO2-induced reductions in stomatal conductance.

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PHYSIOLOGICAL MECHANISMS OF ADAPTATION TO COLD

Aerospace and Environmental Medicine ◽

10.21687/0233-528x-2016-50-4-5-13 ◽

2016 ◽

Vol 50 (4) ◽

pp. 5-13 ◽

Cited By ~ 1

Author(s):

M.M. Saltykova ◽

Keyword(s):

Physiological Mechanisms ◽

Adaptation To Cold ◽

Mechanisms Of Adaptation

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Silicon dioxide nanofertilizers improve photosynthetic capacity of two Criollo cocoa clones (Theobroma cacao L.)

Experimental Agriculture ◽

10.1017/s0014479721000065 ◽

2021 ◽

pp. 1-18

Author(s):

Pedro Gómez-Vera ◽

Héctor Blanco-Flores ◽

Ana Marta Francisco ◽

Jimmy Castillo ◽

Wilmer Tezara

Keyword(s):

Silicon Dioxide ◽

Physiological Response ◽

Photosynthetic Capacity ◽

Foliar Application ◽

Photosynthetic Pigment ◽

Photochemical Activity ◽

Total Soluble Protein ◽

Nutrient Contents ◽

Use Efficiency ◽

Positive Effect

Summary Studies on the effect of nanofertilizers (NF) in physiological performance of plants is scarce, especially that related to substances encapsulated into silicon dioxide (SiO2) nanoparticles in cocoa plants. The effect of foliar application of SiO2-NF on nutrient contents, gas exchange, photochemical activity, photosynthetic pigments, total soluble protein (TSP), photosynthetic nitrogen use efficiency (PNUE), and growth in seedlings of two cocoa clones (OC-61 and BR-05) in a greenhouse was assessed. Spraying with SiO2-NF increased net photosynthetic rate (A) by 16 and 60% and electron transport rate (J) by 52 and 162% in clones OC-61 and BR-05, respectively, without changes in photosynthetic pigment concentration in either clone. The SiO2-NF caused a decrease of 37 and 22% in stomatal conductance in OC-61 and BR-05, respectively; a similar trend was observed in transpiration rate, causing an increase of 42 and 100% in water use efficiency in OC-61 and BR-05, respectively. In both clones, diameter of graft increased on average 28% with SiO2-NF. Higher photosynthetic capacity was related to an increase in leaf N, P, and TSP. A significant reduction in PNUE (A/N ratio) was found in OC-61, whereas in BR-05 PNUE increased after spraying with SiO2-NF. Overall, spraying with SiO2-NF had a positive effect on photosynthetic processes in both cocoa clones, associated with an increase in nutrients content, which translated into improved growth. A differential physiological response to spraying with SiO2-NF between clones was also found, with BR-05 being the clone with a better physiological response during the establishment and development stages.

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The role of forest deadwood in rockfall protection

10.5194/egusphere-egu21-10791 ◽

2021 ◽

Author(s):

Adrian Ringenbach ◽

Peter Bebi ◽

Perry Bartelt ◽

Andrin Caviezel

Keyword(s):

Basal Area ◽

Spruce Forest ◽

Runout Distance ◽

In Situ Sensors ◽

Efficient Protection ◽

Cost Efficient ◽

Study Sites ◽

Rockfall Protection

<p>Forests with a high density and basal area of living trees are known for their function as natural and cost-efficient protection against rockfall. The role of deadwood, however, is less understood. We address this knowledge gap in this contribution as we present the results of repeated real-scale experiments in a) a montane beech-spruce forest with and without deadwood and b) in a subalpine scrub mountain pine-spruce forest with deadwood. We used artificial rocks with either an equant or platy shape, masses between 45 kg and 800 kg (&#8776; 0.3 m3), and equipped with in-situ sensors to gain insights into rotational velocities and impact-accelerations. Clusters of deadwood and erected root plates reduced the mean runout distance at both study sites. For site a), we found that more rocks were stopped behind lying than living trees and that the stopping effect of deadwood was greater for equant compared to platy rock shapes. Site b) revealed a braking effect of scrub mountain pines for relatively small (45 kg), but also a visible reduction in rotational velocities for the 800 kg rocks sensor stream. We conclude that deadwood must be taken into account in rockfall modeling and the management of rockfall protection forests.</p>

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The Overexpression of Glutamine Synthetase in Transgenic Poplar: A Review

Silvae Genetica ◽

10.1515/sg-2006-0036 ◽

2006 ◽

Vol 55 (1-6) ◽

pp. 278-284 ◽

Cited By ~ 15

Author(s):

E. G. Kirby ◽

F. Gallardo ◽

H. Man ◽

R. El-Khatib

Keyword(s):

Glutamine Synthetase ◽

Woody Plant ◽

Forest Tree ◽

Considerable Effort ◽

Physiological Mechanisms ◽

Enhanced Resistance ◽

Enhanced Expression ◽

Use Efficiency

Abstract In investigating the pivotal role of glutamine synthetase in woody plant development, we have strived to develop an understanding of the biochemical and physiological mechanisms whereby enhanced expression of glutamine synthetase (GS) in poplar contributes to vegetative growth through enhanced nitrogen use efficiency. Considerable effort has also centered on characterization of enhanced resistance of transgenic GS overexpressor lines to abiotic stresses and proposed mechanisms. This summary of our work also focuses on future applications in forest tree improvement.

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ANALISIS VEGETASI DI PULAU BINTAN, KEPULAUAN RIAU

BERITA BIOLOGI ◽

10.14203/beritabiologi.v18i3.3715 ◽

2019 ◽

Vol 18 (3) ◽

Author(s):

Bayu Arief Pratama ◽

Edi Mirmanto

Keyword(s):

Species Diversity ◽

Ecological Study ◽

Similarity Index ◽

Basal Area ◽

Small Islands ◽

Vegetation Analysis ◽

Strong Relation ◽

Study Sites ◽

Riau Archipelago ◽

Common Tree

Ecological study with special attention to vegetation analysis has been done in the Bintan forest area, Riau Archipelago. Based on three sampling plots of 30 × 30 m, there were 73 tree (dbh ≥ 5 cm) species were recorded, belong to 64 genera and 32 families. The density is fairly high (1,485 individuals /ha) with total basal area relatively low (27.71 m2/ha). Its indicates that most of trees are small size. Similarity index among study sites are relatively low (< 25 %), indicates that there is strong relation between habitat and species composition. Out of the 6 most common tree species in the study area, only Dipterocarpus gracillis was dominant in 2 study sites. Overall species diversity is relatively low, which is characteristic of forest vegetation on small islands.

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Changes in the functional state of the vascular endothelium in young athletes of varying skill levels

Российский педиатрический журнал ◽

10.18821/1560-9561-2016-19-1-14-19 ◽

2019 ◽

Vol 19 (1) ◽

pp. 14-19

Author(s):

Tatyana V. Bershova ◽

M. I. Bakanov ◽

I. E. Smirnov ◽

V. M. Sanfirova ◽

I. T. Korneeva ◽

...

Keyword(s):

Growth Factor ◽

Special Importance ◽

Vascular Endothelial ◽

Young Athletes ◽

Physiological Mechanisms ◽

Skill Levels ◽

Mechanisms Of Adaptation ◽

Training Activities ◽

Endothelial Growth Factor ◽

Metalloproteinase 9

Recent studies indicate to the special importance of endothelial function (EF) in processes of the regulation of blood circulation. There are presented data on the influence of physical loads on changes in EF on the basis of analysis of the changes of serum content of angiogenin, vascular endothelial growth factor, fibroblast growth factor, matrix metalloproteinase-9 and tissue inhibitor of MMP, thrombospondin and endothelin in young swimmers of various sports skill levels. During training activities and with gain in sports skill levels in young athletes there was found that a significant increment of the concentration of mentioned regulators may be a response to intense exercises indicating to active participation of endothelial vasculature of the growing body in a physiological mechanisms of adaptation to physical loads in children.

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