scholarly journals Seasonal coordination of leaf hydraulics and gas exchange in a wintergreen fern

AoB Plants ◽  
2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Kyra A Prats ◽  
Craig R Brodersen
Keyword(s):  
Seasonal Changes ◽  
Light Availability ◽  
Leaf Temperature ◽  
Carbon Gain ◽  
Hydraulic Systems ◽  
Leaf Hydraulics ◽  
Maximum Photosynthetic Rate ◽  
Polystichum Acrostichoides ◽  
Annual Carbon ◽  
Hinge Zone

Abstract Wintergreen fern Polystichum acrostichoides has fronds that are photosynthetically active year-round, despite diurnal and seasonal changes in soil moisture, air temperature and light availability. This species can fix much of its annual carbon during periods when the deciduous canopy is open. Yet, remaining photosynthetically active year-round requires the maintenance of photosynthetic and hydraulic systems that are vulnerable to freeze–thaw cycles. We aimed to determine the anatomical and physiological strategies P. acrostichoides uses to maintain positive carbon gain, and the coordination between the hydraulic and photosynthetic systems. We found that the first night below 0 °C led to 25 % loss of conductivity (PLC) in stipes, suggesting that winter-induced embolism occurred. Maximum photosynthetic rate and chlorophyll fluorescence declined during winter but recovered by spring, despite PLC remaining high; the remaining hydraulic capacity was sufficient to supply the leaves with water. The onset of colder temperatures coincided with the development of a necrotic hinge zone at the stipe base, allowing fronds to overwinter lying prostrate and maintain a favourable leaf temperature. Our conductivity data show that the hinge zone did not affect leaf hydraulics because of the flexibility of the vasculature. Collectively, these strategies help P. acrostichoides to survive in northeastern forests.

scholarly journals Phenology as a strategy for carbon optimality: a global model

2014 ◽  
Vol 11 (3) ◽  
pp. 763-778 ◽  
Author(s):  
S. Caldararu ◽  
D. W. Purves ◽  
P. I. Palmer
Keyword(s):  
Leaf Growth ◽  
Mechanistic Model ◽  
Leaf Age ◽  
Light Availability ◽  
Carbon Assimilation ◽  
Carbon Gain ◽  
Area Index ◽  
Growing Season Length ◽  
Tropical Areas ◽  
Gains And Losses

Abstract. Phenology is essential to our understanding of biogeochemical cycles and the climate system. We develop a global mechanistic model of leaf phenology based on the hypothesis that phenology is a strategy for optimal carbon gain at the canopy level so that trees adjust leaf gains and losses in response to environmental factors such as light, temperature and soil moisture, to achieve maximum carbon assimilation. We fit this model to five years of satellite observations of leaf area index (LAI) using a Bayesian fitting algorithm. We show that our model is able to reproduce phenological patterns for all vegetation types and use it to explore variations in growing season length and the climate factors that limit leaf growth for different biomes. Phenology in wet tropical areas is limited by leaf age physiological constraints while at higher latitude leaf seasonality is limited by low temperature and light availability. Leaf growth in grassland regions is limited by water availability but often in combination with other factors. This model will advance the current understanding of phenology for ecosystem carbon models and our ability to predict future phenological behaviour.

Photosynthesis and physiological traits of evergreen broadleafed saplings during winter under different light environments in a temperate forest

2006 ◽  
Vol 84 (1) ◽  
pp. 60-69 ◽  
Author(s):  
Yoshiyuki Miyazawa ◽  
Kihachiro Kikuzawa
Keyword(s):  
Temperate Forest ◽  
Light Availability ◽  
Net Photosynthesis ◽  
Carbon Gain ◽  
Leaf Mass Per Area ◽  
Camellia Japonica ◽  
Leaf Mass ◽  
Unit Leaf ◽  
Canopy Trees ◽  
Photosynthetic Traits

Photosynthetic traits of the evergreen broadleafed species Camellia japonica L. and Quercus glauca Thunb. were continuously investigated during autumn and winter using saplings that grew in different light environments (gap, deciduous canopy understory, and evergreen canopy understory) in a temperate forest. Light-saturated rates of net photosynthesis in midwinter and spring were lower than those in autumn. Photosynthetic capacity, scaled to a common leaf temperature of 25 °C, increased or remained stable after autumn and then decreased in spring in most leaves. Photosynthetic traits per unit leaf area were different among leaves in different light environments of both Camellia and Quercus during most periods. However, photosynthetic traits per unit leaf mass did not differ among leaves in different light environments, suggesting that differences in photosynthetic traits were mainly due to different leaf mass per area among leaves. Photosynthetic rates under light availability typical in the environment were lower in winter than in autumn in leaves in the sun in a gap but were not different in leaves in the shade under evergreen canopy trees. Thus, the importance of winter carbon gain for annual carbon gain is small in leaves in a gap but is large in leaves under evergreen canopy trees.

Flowering and fruiting phenologies of seasonal and aseasonal neotropical forests: the role of annual changes in irradiance

2007 ◽  
Vol 23 (2) ◽  
pp. 231-251 ◽  
Author(s):  
Jess K. Zimmerman ◽  
S. Joseph Wright ◽  
O. Calderón ◽  
M. Aponte Pagan ◽  
S. Paton
Keyword(s):  
Soil Moisture ◽  
Seasonal Variation ◽  
Solar Irradiance ◽  
Seasonal Changes ◽  
Light Availability ◽  
Barro Colorado Island ◽  
Wet Season ◽  
Neotropical Forests ◽  
Seasonally Dry ◽  
Solar Declination

The seasonality of both rainfall and solar irradiance might influence the evolution of flowering and fruiting in tropical forests. In seasonally dry forests, to the degree that soil moisture limits plant productivity, community-wide peaks in reproduction are expected during the rainy season, with seedfall and germination timed to allow seedlings to become well established while soil moisture is available. Where soil moisture is never seasonally limiting, seasonal changes in light availability caused by periods of cloudiness or seasonally low zenithal sun angles should favour reproduction during seasons when irradiance levels are high. To evaluate these predictions, we documented the timing of flower and fruit fall for 10 and 15 y at El Verde, Puerto Rico, and Barro Colorado Island (BCI), Panama. At El Verde, rainfall is abundant year-round and solar declination largely determines seasonal variation in irradiance. At BCI, rainfall is abundant throughout the 8-mo wet season while drought develops and average solar irradiance increases by 40–50% over the 4-mo dry season. Seasonal variation in the number of species flowering and fruiting at both sites was generally consistent with the hypothesis that seasonal variation in irradiance limits the evolution of reproductive phenologies. Community-level metrics provided no evidence for a similar role for moisture availability at BCI. Seasonal variation in irradiance also strongly influenced seed development times at both sites. Thus, community-wide phenologies reveal a strong signature of seasonal changes in irradiance, even in those forests that exhibit some degree of seasonality in rainfall.

Leaf- and plant-level carbon gain in yellow birch, sugar maple, and beech seedlings from contrasting forest light environments

2000 ◽  
Vol 30 (3) ◽  
pp. 390-404 ◽  
Author(s):  
Marilou Beaudet ◽  
Christian Messier ◽  
David W Hilbert ◽  
Ernest Lo ◽  
Zhang M Wang ◽  
...  
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Light Availability ◽  
Fagus Grandifolia ◽  
Carbon Gain ◽  
Betula Alleghaniensis ◽  
Yellow Birch ◽  
Significant Difference ◽  
Leaf Level ◽  
Plant Level

Leaf-level photosynthetic-light response and plant-level daily carbon gain were estimated for seedlings of moderately shade-tolerant yellow birch (Betula alleghaniensis Britton) and shade-tolerant sugar maple (Acer saccharum Marsh.) and beech (Fagus grandifolia Ehrh.) growing in gaps and under a closed canopy in a sugar maple stand at Duchesnay, Que. All three species had a higher photosynthetic capacity (Amax) in the gaps than in shade, but yellow birch and beech responded more markedly than sugar maple to the increase in light availability. The high degree of plasticity observed in beech suggests that the prediction that photosynthetic plasticity should decrease with increasing shade tolerance may not hold when comparisons are made among a few late-successional species. Unit-area daily carbon gain (CA) was significantly higher in the gaps than in shade for all three species, but no significant difference was observed between light environments for plant-level carbon gain (CW). In shade, we found no difference of CA and CW among species. In gaps, beech had a significantly higher CA than sugar maple but similar to that of birch, and birch had a significantly higher CW than maple but similar to that of beech. Sugar maple consistently had lower carbon gains than yellow birch and beech but is nevertheless the dominant species at our study site. These results indicate that although plant-level carbon gain is presumably more closely related to growth and survival of a species than leaf-level photosynthesis, it is still many steps removed from the ecological success of a species.

Feeding of Galaxias olidus (Guenther) (Pisces: Galaxiidae) in an intermittent Australian stream

1994 ◽  
Vol 45 (2) ◽  
pp. 227 ◽  
Author(s):  
GP Closs
Keyword(s):  
Seasonal Changes ◽  
Stream Flow ◽  
Light Availability ◽  
High Flow ◽  
High Rate ◽  
Low Flow ◽  
Intermittent Streams ◽  
Feeding Rates ◽  
Seasonal Basis ◽  
Predatory Impact

Patterns of feeding in the mountain galaxiid (Galaxias olidus) were examined at dawn and dusk during low flow in April and high flow in September in an intermittent stream. During April (low flow), feeding rates were relatively low and aperiodic, whereas in September (high flow), the fish were clearly feeding diurnally at a relatively high rate. These results suggest that feeding in G. olidus in intermittent streams may vary on a daily and seasonal basis, possibly as a consequence of changes in light availability and stream flow. Light determines the ability of fish to find their prey, and seasonal changes in flow may determine the availability of prey (i.e. drifting invertebrates). This pattern suggests that the predatory impact of drift-feeding fish, such as G. olidus, is likely to be considerably less during low-flow periods when drifting invertebrates are not available than during high-flow periods when such prey may be abundant.

The ecology of Ramalina menziesii. V. Estimation of gross carbon gain and thallus hydration source from diurnal measurements and climatic data

1986 ◽  
Vol 64 (8) ◽  
pp. 1698-1702 ◽  
Author(s):  
U. Matthes-Sears ◽  
T. H. Nash III
Keyword(s):  
Carbon Fixation ◽  
Daily Precipitation ◽  
Dry Weight ◽  
Predictor Variables ◽  
Carbon Gain ◽  
Climatic Data ◽  
Atmospheric Water ◽  
Annual Carbon ◽  
Total Gain ◽  
Calculated Average

All subsets regression analysis was used to determine the set of meteorological variables that best predicted daily gross carbon fixation of the lichen Ramalina menziesii Tayl. measured on 23 days at Hastings Reservation in central coastal California. The regression equation containing the two best predictor variables, the duration of diurnal atmospheric humidities equal to or above 90% and daily precipitation, was then used in conjunction with weather records to estimate daily, seasonal, and annual gross CO2 gain of R. menziesii at Hastings for the years 1981 – 1983. Calculated average annual gross CO2 fixation for these 3 years was 2756 mg CO2∙g dry weight−1. For 66% of this total gain, the most likely source of thallus hydration was rainfall. Dewfall was responsible for 15%, atmospheric water vapor uptake for 11%, and for the remaining 8% the source was uncertain. Three-fourths of the annual carbon fixation took place during the 6 months of the rainy season.

Simultaneous Effects of Foliar Nitrogen, Temperature, and Humidity on Gas Exchange in Pinus radiata

1995 ◽  
Vol 22 (4) ◽  
pp. 615 ◽  
Author(s):  
DW Sheriff ◽  
JP Mattay
Keyword(s):  
Gas Exchange ◽  
Pinus Radiata ◽  
Vapour Pressure ◽  
Measurement Data ◽  
Carbon Assimilation ◽  
Vapour Pressure Deficit ◽  
Leaf Temperature ◽  
Carbon Gain ◽  
Foliar Nitrogen ◽  
Foliar N

Seedlings of Pinus radiata were grown in a glasshouse in large pots with sand as the potting mix. They were kept well-watered and frequently supplied with nutrient solutions which contained different amounts of nitrogen for different treatments. Carbon assimilation and diffusive conductance of the foliage were measured under steady-state conditions at saturating light in all treatments. Experimental variables were leaf-air vapour pressure difference and leaf temperature at time of measurement. Data were fitted to a non-linear regression equation to examine responses of carbon assimilation, diffusive conductance, transpiration, assimilatory nitrogen-use efficiency, and assimilatory transpiration efficiency to foliar nitrogen concentration expressed on a leaf area basis ([N]), to leaf temperature, and to leaf-air vapour pressure (D). Parameters from the regression have been used to plot three-dimensional surfaces, so that simultaneous effects of experimental variables can be easily visualised. Carbon assimilation increased linearly with foliar [N], declined exponentially as D increased, and had a broad temperature optimum between c. 14 and 38�C. Diffusive conductance increased linearly with foliar [N], was related to the reciprocal of D, and declined as temperature increased. Using climatic vapour pressure deficit and air temperature data for Canberra, ACT, and for Mount Gambier, SA, and with the functions that had been fitted to experimental data, it was found that these regional climatic differences have potential for appreciably affecting carbon gain and water loss in the regions, which have P. radiata plantations. Predicted differences in carbon gain are of the order of reported differences in stem growth in the regions. This shows the need to take into account regional variation in climatic variables that strongly affect gas exchange when investigating regional differences in productivity.

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