Field evidence for the optimality hypothesis of gas exchange in plants

1999 ◽  
Vol 26 (3) ◽  
pp. 239 ◽  
Author(s):  
Pertti Hari ◽  
Annikki Mäkelä ◽  
Frank Berninger ◽  
Toivo Pohja

The ‘optimality hypothesis’ of gas exchange in plants has been studied since the 1970s, but testing it in the field has proven difficult. A recent reformulation of the hypothesis with detailing assumptions on leaf structure makes it possible to solve the optimisation problem explicitly, such that the predictions of gas exchange are readily testable against field data. This form of the model was tested against field measurements of photosynthesis, transpiration and stomatal conductance in Scots pine (Pinus sylvestris) shoots during three clear summer days. Model parameters were estimated independently from photosynthesis measurements on preceding days. The measurements were carried out at a new field measurement station with a very low level of noise. The predictions of photosynthesis, transpiration andstomatal conductance explained 84–98% of the variance in the data.

1982 ◽  
Vol 5 (1) ◽  
pp. 75-83
Author(s):  
J-E. HALLGREN ◽  
S. LINDER ◽  
A. RICHTER ◽  
E. TROENG ◽  
L. GRANAT

1982 ◽  
Vol 5 (1) ◽  
pp. 75-83
Author(s):  
J-E. Hallgren ◽  
S. Lindert ◽  
A. Richter ◽  
E. Troeng ◽  
L. Granat

2019 ◽  
Vol 26 (01) ◽  
pp. 85-93
Author(s):  
Batsaikhan G ◽  
Battulga P ◽  
Baterdene J ◽  
Gerelbaatar S ◽  
Tsogtbaatar J

This study was conducted in planted forests located in the Tujyin Nars National Park territory of Selenge province, Mongolia. We aimed at studying the effect of climate factors on seedling survival and tree growth at the Scots pine plantations. A total of five 50 x 20 m (0.1 ha) sized square sample plots were established at the plantations, planted between 2003 and 2007. All field measurements and data collection were carried out annually in September and October between 2003 and 2017. Annual field measurements of seedlings included: tree health status, diameter at stem basis, total height and annual height increments. We used climate data taken from the closest meteorological station (8-15 km to the north-west), “Sukhbaatar” located in Sukhbaatar Soum of Selenge province. To calculate the statistical analysis of the survival rate and seedling growth, we used the one-way analysis of variance (ANOVA) method to determine statistically significant differences in means among variables between the sites. An F-test and Pearson's correlation coefficient were used to assess the relationships between climate variables and survival and tree growth. Our findings showed a significant difference (F=28.4, p<0.001) between seedling survival among plantations planted in different years of plantation establishment. The study revealed that there is a strong negative correlation (r=-0.76) between seedling survival and number of critical dry days, and contrary, strong positive correlation (r =0.71) with the precipitation for May. The increment of planted trees was more sensitive to air temperature (r = 0.47), annual rainfall (r = 0.72), air relative humidity and number of dry days during the first three years than in subsequent years. Таримал өсвөр нарсан (pinus sylvestris l.) ойн амьдралт, өсөлтөнд уур амьсгалын үзүүлэх нөлөө Хураангуй  Тус судалгааг Сэлэнгэ аймгийн Алтанбулаг, Шаамар сумын нутагт ойжуулалтаар тарьж  ургуулсан таримал нарсан ойд гүйцэтгэв. Судалгааны ажлын зорилго нь таримал ойн моддын  амьдралт, өсөлтөнд уур амьсгалын үзүүлэх нөлөөг судлахад оршино. Судалгаанд 2003-2007  онуудад ойжуулсан таримал ойн мониторинг судалгааг 2003 -2017 онуудад жил бүр  тасралтгүй гүйцэтгэлээ. Ойжуулсан талбай бүрд 50 х 20 м (1000 м2) хэмжээтэй дээж  талбайг байгуулан, түүнд таримал модны эрүүл байдал, ишний өндөр, диаметрийн өсөлт  болон титмийн өндрийг хэмжив. Ишний шинжилгээний дээжид модны өндрийн болон  диаметрийн өсөлтийн хэмжилтийг хийсэн ба уур амьсгалын үзүүлэлтэд судалгааны талбайд  хамгийн ойр (10 км) орших Сэлэнгэ аймгийн цаг уурын ажиглалтын “Сүхбаатар” станцын  2003-2017 оны хугацаанд дахь цаг уурын мэдээг ашиглав. Хэмжилтийн статистик  үзүүлэлтүүдийг боловсруулахад нэг хүчин зүйлт вариансийн шинжилгээ (ANOVA), модны  өндөр, диаметрийн өсөлтийн явц болон уур амьсгалын үзүүлэлтүүд хоорондын хамаарлыг  Персоны корреляцын коэффициеитээр илэрхийлэв. Судалгааны үр дүнгээс үзвэл, ялгаатай цаг  хугацаанд ойжуулсан талбайн моддын амьдралт статистикийн хувьд ялгаатай (F=28.4,  p<0.001), ялангуяа 5-р сарын хэт хуурайшилттай өдрийн үргэлжлэх хугацаа (r=-0.76),  ургамал ургалтын хугацааны агаарын температур, хур тунадасны нийлбэр (5-р сар r =0.71,  6- сар r=0.41, 7- сар r= 0.46) - тэй хүчтэй, эерэг хамааралтай байна. Ойжуулалтанд  шилжүүлсний дараах тарьцын хоёр болон гурав дахь жилийн нийлбэр өндрийн өсөлт, жилийн  дундаж агаарын температур (r = 0.47), диаметрийн өсөлт нь жилийн нийлбэр хур  тунадастай (r = 0.72) эерэг, хүчтэй хамааралтай байна.  Түлхүүр үг: Ойжуулалт,өндөр, диаметр, цаг уур, хамаарал 


2020 ◽  
Vol 78 (4) ◽  
pp. 777-784 ◽  
Author(s):  
Gerhard Sinn ◽  
Daniel Chuchała ◽  
Kazimierz A. Orlowski ◽  
Piotr Taube

2003 ◽  
Vol 30 (6) ◽  
pp. 673 ◽  
Author(s):  
Hans R. Schultz

Measurements of gas exchange and stomatal conductance were made on potted and field-grown grapevines (Vitis vinifera L.) on leaves from different light environments (sun and shade) at different phenological stages during the season to parameterise the Farquhar model. The model parameters for Rubisco activity (Vcmax), maximum electron transport rate (Jmax), and triose-phosphate utilisation (TPU) were estimated on the basis of a large data set (n = 105) of CO2 assimilation (A) versus internal CO2 pressure (Ci) curves. Leaf age was described with the leaf plastochron index (LPI). Stomatal coupling to photosynthesis was modelled with the Ball–Woodrow–Berry empirical model of stomatal conductance. Mature shade leaves had 35–40% lower values of Vcmax, Jmax and TPU than sun leaves. The difference between leaf types decreased at the end of the season. The ratio Jmax / Vcmax and values of day respiration (Rd) and CO2 compensation point in the absence of mitochondrial respiration (Γ*) varied little during the season and were independent of LPI. Validation of the model with independent diurnal data sets of measurements of gas exchange and stomatal conductance at ambient CO2 concentrations for three days between June and October, covering a large range of environmental conditions, showed good agreement between measured and simulated values.


2017 ◽  
Vol 47 (4) ◽  
pp. 488-499 ◽  
Author(s):  
Minna Kivimäenpää ◽  
Sirkka Sutinen ◽  
Hanna Valolahti ◽  
Elina Häikiö ◽  
Johanna Riikonen ◽  
...  

Acclimation of conifer needle anatomy to climate change is poorly understood. We studied needle anatomy, shoot gas exchange, current-year shoot length, and stem diameter growth in Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) seedlings exposed to elevated ozone (1.35× to 1.5× ambient concentration) and elevated temperature (0.9–1.3 °C + ambient temperature) alone and in combination for two exposure seasons in two separate open-field experiments in central Finland. Pines grew also at two soil nitrogen levels. In spruce, warming increased mesophyll intercellular space and reduced gas exchange and shoot growth and made needles narrower and the epidermis and hypodermis thinner. In pine, warming made needles bigger, increased shoot and stem growth, stomatal row number, and proportions of vascular cylinder, phloem, and xylem and reduced the proportion of mesophyll. These responses indicate that pine benefited and spruce suffered from moderate warming. Ozone caused a thickening of epi- and hypo-dermis and a lower stomatal conductance in both species, reduced stomatal density in spruce, and increased proportions of phloem, xylem, and sclerenchyma and reduced growth in pine. Ozone responses suggest increased oxidative stress defense. Stomatal responses were affected by interactions of elevated temperature and ozone in both species. Nitrogen availability modified ozone and temperature responses, particularly in the vascular tissues in pine.


Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1143 ◽  
Author(s):  
Hongzhong Dang ◽  
Ping Lu ◽  
Wenbin Yang ◽  
Hui Han ◽  
Jun Zhang

Determining plant–water relationships in response to drought events can provide important information about the adaptation of trees to climate change. The Mongolian Scots pine (Pinus sylvestris var. mongolica Litv), as one of the major tree species to control soil loss and desertification in northern China, has experienced severe degradation in recent decades. Here, we aimed to examine the impacts of a two-year consecutive drought and another year of drought on the radial growth, transpiration, and canopy stomatal conductance of Mongolian Scots pine over a five-year period, especially in terms of its recovery after drought. The study period during 2013–2017 consisted of a ‘normal’ year, a ‘dry year’, a ‘very dry’ year, a ‘wet’ year, and a ‘dry’ year, according to annual precipitation and soil moisture conditions. Based on measurements of the sap flow and diameters at breast height of 11 sample trees as well as the concurrent environmental factors, we quantified the reductions in tree radial growth, transpiration, and canopy stomatal conductance during the drought development as well as their recovery after the drought. The results showed that the tree radial growth, transpiration, and canopy stomatal conductance of Mongolian Scots pines decreased by 33.8%, 51.9%, and 51.5%, respectively, due to the two consecutive years of drought. Moreover, these reductions did not fully recover after the two-year drought was relieved. The minimum difference of these parameters between before and after the two-year consecutive drought period was 8.5% in tree radial growth, 45.1% in transpiration levels, and 42.4% in canopy stomatal conductance. We concluded that the two consecutive years of drought resulted in not only large reductions in tree radial growth and water use, but also their lagged and limited recoveries after drought. The study also highlighted the limited resilience of Mongolian Scots pine trees to prolonged drought in semi-arid sandy environmental conditions.


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