The effect of fire on gas exchange and aboveground biomass production in annually vs biennially burnedSpartina pectinata wetlands

Wetlands ◽  
1993 ◽  
Vol 13 (4) ◽  
pp. 299-303 ◽  
Author(s):  
Stephen R. Johnson ◽  
Alan K. Knapp
Keyword(s):  
Gas Exchange ◽  
Biomass Production ◽  
Aboveground Biomass

scholarly journals Response of water fluxes and biomass production to climate change in permanent grassland soil ecosystems

2021 ◽  
Vol 25 (12) ◽  
pp. 6087-6106
Author(s):  
Veronika Forstner ◽  
Jannis Groh ◽  
Matevz Vremec ◽  
Markus Herndl ◽  
Harry Vereecken ◽  
...  
Keyword(s):  
Climate Change ◽  
Elevated Temperature ◽  
Biomass Production ◽  
Aboveground Biomass ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Actual Evapotranspiration ◽  
Water Fluxes ◽  
Permanent Grassland ◽  
Experimental Approaches

Abstract. Effects of climate change on the ecosystem productivity and water fluxes have been studied in various types of experiments. However, it is still largely unknown whether and how the experimental approach itself affects the results of such studies. We employed two contrasting experimental approaches, using high-precision weighable monolithic lysimeters, over a period of 4 years to identify and compare the responses of water fluxes and aboveground biomass to climate change in permanent grassland. The first, manipulative, approach is based on controlled increases of atmospheric CO2 concentration and surface temperature. The second, observational, approach uses data from a space-for-time substitution along a gradient of climatic conditions. The Budyko framework was used to identify if the soil ecosystem is energy limited or water limited. Elevated temperature reduced the amount of non-rainfall water, particularly during the growing season in both approaches. In energy-limited grassland ecosystems, elevated temperature increased the actual evapotranspiration and decreased aboveground biomass. As a consequence, elevated temperature led to decreasing seepage rates in energy-limited systems. Under water-limited conditions in dry periods, elevated temperature aggravated water stress and, thus, resulted in reduced actual evapotranspiration. The already small seepage rates of the drier soils remained almost unaffected under these conditions compared to soils under wetter conditions. Elevated atmospheric CO2 reduced both actual evapotranspiration and aboveground biomass in the manipulative experiment and, therefore, led to a clear increase and change in seasonality of seepage. As expected, the aboveground biomass productivity and ecosystem efficiency indicators of the water-limited ecosystems were negatively correlated with an increase in aridity, while the trend was unclear for the energy-limited ecosystems. In both experimental approaches, the responses of soil water fluxes and biomass production mainly depend on the ecosystems' status with respect to energy or water limitation. To thoroughly understand the ecosystem response to climate change and be able to identify tipping points, experiments need to embrace sufficiently extreme boundary conditions and explore responses to individual and multiple drivers, such as temperature, CO2 concentration, and precipitation, including non-rainfall water. In this regard, manipulative and observational climate change experiments complement one another and, thus, should be combined in the investigation of climate change effects on grassland.

Aboveground Biomass Production of Cenchrus ciliaris in Tunisian Arid Zone

2007 ◽  
Vol 7 (6) ◽  
pp. 985-988 ◽  
Author(s):  
Idi Abdelkader ◽  
Ali Ferchichi . ◽  
Mohamed Chaieb .
Keyword(s):  
Biomass Production ◽  
Aboveground Biomass ◽  
Arid Zone ◽  
Cenchrus Ciliaris

scholarly journals Biomass production and leaf gas exchange of perennial legumes associated with bananas

2016 ◽  
Vol 11 (6) ◽  
pp. 487-493
Author(s):  
Edineide Lima Barbosa Francisca ◽  
Feitosa De Lacerda Claudivan ◽  
De Oliveira Feitosa Hernandes ◽  
Jardelson Ferreira Francisco ◽  
Vieira Amorim Aiala ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Biomass Production ◽  
Leaf Gas Exchange ◽  
Perennial Legumes

scholarly journals Assimilation of Sentinel-2 Estimated LAI into a Crop Model: Influence of Timing and Frequency of Acquisitions on Simulation of Water Stress and Biomass Production of Winter Wheat

Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1813
Author(s):  
Andreas Tewes ◽  
Carsten Montzka ◽  
Manuel Nolte ◽  
Gunther Krauss ◽  
Holger Hoffmann ◽  
...  
Keyword(s):  
Water Stress ◽  
Winter Wheat ◽  
Biomass Production ◽  
Aboveground Biomass ◽  
Stem Elongation ◽  
Simulation Models ◽  
Development Stage ◽  
Crop Model ◽  
Area Index ◽  
Sentinel 2

The Sentinel-2 (S2) Toolbox permits for the automated retrieval of leaf area index (LAI). LAI assimilation into crop simulation models could aid to improve the prediction accuracy for biomass at field level. We investigated if the combined effects of assimilation date and corresponding growth stage plus observational frequency have an impact on the crop model-based simulation of water stress and biomass production. We simulated winter wheat growth in nine fields in Germany over two years. S2 LAI estimations for each field were categorized into three phases, depending on the development stage of the crop at acquisition date (tillering, stem elongation, booting to flowering). LAI was assimilated in every possible combinational setup using the ensemble Kalman filter (EnKF). We evaluated the performance of the simulations based on the comparison of measured and simulated aboveground biomass at harvest. The results showed that the effects on water stress remained largely limited, because it mostly occurred after we stopped LAI assimilation. With regard to aboveground biomass, we found that the assimilation of only one LAI estimate from either the tillering or the booting to flowering stage resulted in simulated biomass values similar or closer to measured values than in those where more than one LAI estimate from the stem elongation phase were assimilated. LAI assimilation after the tillering phase might therefore be not necessarily required, as it may not lead to the desired improvement effect.

Nutrient cycling in a mixed-species plantation of Eucalyptus globulus and Acacia mearnsii

2005 ◽  
Vol 35 (12) ◽  
pp. 2942-2950 ◽  
Author(s):  
David I Forrester ◽  
Jürgen Bauhus ◽  
Annette L Cowie
Keyword(s):  
Nutrient Cycling ◽  
Biomass Production ◽  
Aboveground Biomass ◽  
Eucalyptus Globulus ◽  
N Availability ◽  
Species Replacement ◽  
Mixed Species ◽  
Acacia Mearnsii ◽  
Replacement Series ◽  
Silvicultural System

A doubling of aboveground biomass production has been observed in mixtures of Eucalyptus globulus Labill. and Acacia mearnsii de Wildeman when compared with monocultures after 11 years of growth. This study examined to what extent increased nitrogen (N) availability and accelerated rates of nutrient cycling may contribute to increased growth in mixtures. Monocultures of E. globulus (E) and A. mearnsii (A) and mixtures of these species were planted in a species replacement series: 100% E, 75% E + 25% A, 50% E + 50% A, 25% E + 75% A, and 100% A. Litterfall mass increased with aboveground biomass production and was highest in 50:50 mixtures and lowest in monocultures. Owing to higher N concentrations of A. mearnsii litter, N contents of annual litterfall were at least twice as high in stands containing A. mearnsii (32-49 kg·ha–1·year–1) as in E. globulus monocultures (14 kg·ha–1·year–1). Stands with A. mearnsii also cycled higher quantities of phosphorus (P) in annual litterfall than E. globulus monocultures. This study demonstrated that mixing A. mearnsii with E. globulus increased the quantity and rates of N and P cycled through aboveground litterfall when compared with E. globulus monocultures. Thus, mixed-species plantations appear to be a useful silvicultural system to improve nutrition of eucalypts without fertilization.

Growth response to thinning and its relation to site resources in Eucalyptusregnans

1995 ◽  
Vol 25 (1) ◽  
pp. 69-80 ◽  
Author(s):  
P.W. West ◽  
G.H.R. Osier
Keyword(s):  
Biomass Production ◽  
Tree Growth ◽  
Aboveground Biomass ◽  
Growth Response ◽  
Radiation Absorption ◽  
Light Use Efficiency ◽  
Individual Tree ◽  
Individual Tree Growth ◽  
Use Efficiency ◽  
Individual Trees

The factors determining individual tree growth response are examined during the 4 years following thinning in experiments in even-aged, 8- or 12-year-old regrowth Eucalyptusregnans F. Muell. forest at two sites in southern Australia. At one site, a vigorous understorey dominated by a sedge developed after the thinning. At that site, light-use efficiency by the trees was unaffected by thinning and the aboveground biomass production by the trees in the thinned stand was substantially less than that in the unthinned stand. At the other site, little understorey developed, light-use efficiency by trees in the thinned stand was greater than that in the unthinned stand, and aboveground biomass production was unaffected by thinning even though the leaf weight of the thinned stand was far below that of the unthinned stand. Where the understorey developed, it was concluded that it competed successfully with the trees for water, thereby reducing production in the thinned stand when compared with the unthinned stand. The individual tree growth response that occurred in the thinned stand at that site appeared to be due soley to the extra light available to individual trees following the canopy opening. Where the understorey did not develop, it was concluded that individual tree growth response was due not only to the extra light available to individual trees but also to the increased availability of belowground resources, most probably soil water. Application of a pre-existing stand growth model suggested that at that site the tendency for increased growth resulting from extra water availability in the thinned stand was just balanced by decreased growth due to lower radiation absorption by the reduced canopy, so that net production was unaffected by thinning.

Gas exchange and growth of bald cypress seedlings from selected U.S. Gulf Coast populations: responses to elevated salinities

1995 ◽  
Vol 25 (9) ◽  
pp. 1409-1415 ◽  
Author(s):  
S.R. Pezeshki ◽  
R.D. Delaune ◽  
H.S. Choi
Keyword(s):  
Gas Exchange ◽  
Biomass Production ◽  
Growth Traits ◽  
Gulf Coast ◽  
Net Photosynthesis ◽  
Salinity Treatment ◽  
Root Porosity ◽  
Bald Cypress ◽  
Freshwater Source ◽  
Freshwater Population

Bald cypress (Taxodiumdistichum (L.) Rich.) seedlings from two sources in Louisiana were tested for a possible difference in salt tolerance. The study was conducted in rhizotrons under controlled environmental-conditions. Seedlings were subjected to a control (no flood or salt) and three combinations of flooding salinity: flooding only, flooding plus 68 mol•m−3 salt (4 ppt), and flooding plus 136 mol•m−3 salt (8 ppt). Both populations survived the flooding and salinity treatments for the duration of the study. However, gas exchange and net biomass production were reduced in both populations as salinity of floodwater increased from 0 to 136 mol•m−3. The gas exchange and biomass data indicated that plants from the freshwater source had higher growth rates than the brackish plants. This superiority was also maintained under all the treatments except the highest salinity treatment. Significantly greater net photosynthetic capacity per unit area of leaf was found for the freshwater population than for the brackish population in 68 mol•m−3 salt. In addition, greater root porosity, height growth, and biomass production (shoot, root) were found for the freshwater population than for the brackish population under different treatments. The data indicate that there is a potential for population differentiation in bald cypress, as shown primarily by differences in growth traits. However, the data do not support the hypothesis that bald cypress plants from the brackish source have a capacity to survive and grow better in saltwater than plants from the freshwater source. In fact, combined flooding and salinity treatments resulted in significant reductions in net photosynthesis as compared with the control in both sources.

The relative competitiveness of atrazine susceptible and resistant populations of Chenopodium album and C. strictum

1981 ◽  
Vol 59 (5) ◽  
pp. 689-693 ◽  
Author(s):  
S. I. Warwick ◽  
L. Black
Keyword(s):  
Biomass Production ◽  
Aboveground Biomass ◽  
Competitive Ability ◽  
Chenopodium Album ◽  
Dry Weight ◽  
Replacement Series ◽  
Susceptible Population ◽  
Resistant Population ◽  
Reproductive Biomass ◽  
Susceptible Populations

The total aboveground biomass and reproductive dry weight of one atrazine resistant and one susceptible population from southern Ontario of each of two species of Chenopodium, C. album and C. strictum, were compared. The comparison was made between plants grown under both noncompetitive and competitive conditions. Results from a spaced noncompetitive trial provided evidence for: (1) greater total and reproductive biomass production and earlier flowering of resistant and susceptible populations of C. album as compared with both populations of C. strictum, (2) greater aboveground total and reproductive biomass production of the susceptible population of C. album as compared with the resistant population, and (3) greater total aboveground biomass production (but similar reproductive biomass) of the susceptible population of C. strictum as compared with the resistant population. Results from the competition trials (i.e., plants grown in a de Wit replacement series), provided evidence for inter- and intra-specific differences in competitive ability: (1) the susceptible population of C. album was found to be more competitive than the susceptible population of C. strictum, (2) the susceptible population of C. album was a superior competitor to the resistant population, and (3) the resistant and susceptible populations of C. strictum appeared to be equally competitive.

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