Leaf and Ecosystem Gas Exchange Responses of Buffel Grass-Dominated Grassland to Summer Precipitation

doi:10.1016/S1002-0160(14)60081-3

Pedosphere

Volume 25, Issue 1, February 2015, Pages 112-123

https://doi.org/10.1016/S1002-0160(14)60081-3 Get rights and content

ABSTRACT

Sporadic rain events that occur during summer play an important role in the initiation of biological activity of semi-arid grasslands. To understand how ecosystem processes of a buffel grass (Cenchrus ciliaris L.)-dominated grassland respond to summer rain events, an LI 6 400 gas exchange system was used to measure the leaf gas exchange and plant canopy chambers were used to measure net ecosystem CO₂ exchange (NEE) and ecosystem respiration (R_eco), which were made sequentially during periods before rain (dry) and after rain (wet). Gross ecosystem photosynthesis (GEP) was estimated from NEE and R_eco fluxes, and light use efficiency parameters were estimated using a rectangular hyperbola model. Prior to the monsoon rain, grassland biomass was non-green and dry exhibiting positive NEE (carbon source) and low GEP values during which the soil water became increasingly scarce. An initial rain pulse (60 mm) increased the NEE from pre-monsoon levels to negative NEE (carbon gain) with markedly higher GEP and increased green biomass. The leaf photosynthesis and leaf stomatal conductance were also improved substantially. The maximum net CO₂ uptake (i.e., negative NEE) was sustained in the subsequent period due to multiple rain events. As a result, the grassland acted as a net carbon sink for 20 d after first rain. With cessation of rain (drying cycle), net CO₂ uptake was reduced to lower values. High sensitivity of this grassland to rain suggests that any decrease in precipitation in summer may likely affect the carbon sequestration of the semiarid ecosystem.

REFERENCES (44)

J.E. Bowers
Seedling emergence on Sonoran Desert dunes
J. Arid Environ
(1996)
Y.L. Fu et al.
Depression of net ecosystem CO₂ exchange in semi-arid Leymus chinensis steppe and alpine shrub
Agr. Forest Meteorol
(2006)
M.Z. Hussain et al.
CO₂ exchange and biomass development of the herbaceous vegetation in the Portuguese montado ecosystem during spring
Agr. Ecosyst. Environ
(2009)
J.F. Kjelgaard et al.
Carbon dioxide exchange in a subtropical, mixed C₃/C₄ grassland on the Edwards Plateau, Texas
Agr. Forest Meteorol
(2008)
T.P. Meyers
A comparison of summertime water and CO₂ fluxes over rangeland for well watered and drought conditions
Agr. Forest Meteorol
(2001)
P. Mielnick et al.
Long-term measurements of CO₂ flux and evapotranspiration in a Chihuahuan desert grassland
J. Arid Environ
(2005)
P.S. Nobel
Root-soil responses to water pulses in dry environments
O.E. Sala et al.
Plant recovery following prolonged drought in a shortgrass steppe
Agr. Meteorol
(1982)
L.A. Wever et al.
Seasonal and interannual variation in evapotranspiration, energy balance and surface conductance in a northern temperate grassland
Agr. Forest Meteorol
(2002)
G.P. Asner et al.
Net changes in regional woody vegetation cover and carbon storage in Texas Drylands, 1937–1999
Glob. Change Biol
(2003)

A.T. Austin et al.

Water pulses and biogeochemical cycles in arid and semiarid ecosystems

Oecologia

(2004)

S. Batra et al.

In vitro high frequency plant regeneration in buffel grass (Cenchrus ciliaris L.)

J. Plant Biol

(2002)

A. Buldgen et al.

Physiological reactions to imposed water deficit by Andropogon gayanus cv. Bisquamulatus and Cenchrus ciliaris cv. Biloela in a mixed fodder crop

J. Agr. Sci

(1998)

J.M. Cable et al.

Soil texture drives responses of soil respiration to precipitation pulses in the Sonoran Desert: Implications for climate change

Ecosystems

(2008)

M. Chaieb et al.

Impact of clipping on root systems of 3 grasses species in Tunisia

J. Range Manage

(1996)

R.A. Chimner et al.

Ecosystem respiration responses to experimental manipulations of winter and summer precipitation in a Mixedgrass Prairie, WY, USA

Biogeochemistry

(2005)

B.G. Cook et al.

Tropical Forages: An Interactive Selection Tool

(2005)

E.A. Davidson et al.

Soil water content and temperature as independent or confounded factors controlling soil respiration in a temperate mixed hardwood forest

Glob. Change Biol

(1998)

E. De la Barrera et al.

High temperature effects on gas exchange for the invasive buffel grass (Pennisetum ciliare [L.] link)

Weed Biol. Manage

(2007)

I.R. Dixon et al.

Eradication of buffel grass (Cenchrus ciliaris) on Airlie Island, Pilbara Coast, Western Australia

H. Eswaran et al.

Global carbon sinks

E.P. Hamerlynck et al.

Consequences of cool-season drought-induced plant mortality to Chihuahuan Desert grassland ecosystem and soil respiration dynamics

Ecosystems

(2013)

Cited by (9)

Soil water leaf gas exchange and biomass production of Buffelgrass (Cenchrus ciliaris L.) with two ploidy levels under arid zone
2023, Acta Ecologica Sinica
Citation Excerpt :
Therefore, in response to water stress, the total biomass productivity of C. cilaris significantly decreased, and was affected more in T1 than in T3. The results recorded in our research those highlighted by Hussain et al. [49], who revealed a decrease in SN, TN, and a drop in shoot and root biomass under water stress. Siddiqui et al. [50] clarified that under water stress, M. mucronatum (L.) and C. ciliaris biomass production decreased.
Cenchrus ciliaris corresponds to a perennial grass that is widespread in arid environments. This study aimed to assess growth and leaf exchange under water deficit stress of tetraploid (P1) and hexaploid (P2) individuals of C. ciliaris. The experiment was conducted under four treatments (Tc, T1, T2, and T3). Growth phenology, photosynthesis (A), stomatal conductance (Gs), CO₂ concentration, and transpiration (Tr) were observed during the stress cycle. The obtained results revealed that the highest growth potentialities were recorded for P2 population in both treatments. Both populations responded differently to water deficit stress displaying various values for tiller and the number of spikes. A significant effect of soil moisture treatments on C. ciliaris plant biomass was recorded (P < 0.05). Moreover, there were different responses to drought stress between both contrasting populations. The results also demonstrated that polyploidy level affected only the phenological parameters. Photosynthetic parameters, such as (A) and (Gs) significantly decreased under severe stress between populations and treatments. It could be inferred that C. ciliaris accessions respond to drought through showing significant changes in their physiological and phenological behavior.
Net ecosystem carbon exchange for Bermuda grass growing in mesocosms as affected by irrigation frequency
2022, Pedosphere
Citation Excerpt :
Recognition of the need to increase soil C stocks to improve soil quality and offset greenhouse gas emissions (Rumpel et al., 2018) means that it has become urgent to investigate the processes regulating inputs and losses of C in irrigated grasslands to inform managers about the most effective practices to minimise C losses. Irrigation increases water content in root zone, which alters the rates of photosynthesis and respiration in grasslands (Scott et al., 2009; Hussain et al., 2015). Irrigation also modifies the microbial processes that regulate C cycling (Entry et al., 2008; Trost et al., 2013; Karlowsky et al., 2018) and thus changes the components of C balance (Moinet et al., 2017; Whitehead et al., 2018).
Intensification of grazed grasslands following conversion from dryland to irrigated farming has the potential to alter ecosystem carbon (C) cycling and affect components of carbon dioxide (CO₂) exchange that could lead to either net accumulation or loss of soil C. While there are many studies on the effect of water availability on biomass production and soil C stocks, much less is known about the effect of the frequency of water inputs on the components of CO₂ exchange. We grew Bermuda grass (Cynodon dactylon L.) in mesocosms under irrigation frequencies of every day (I₁ treatment, 30 d), every two days (I₂ treatment, 12 d), every three days (I₃ treatment, 30 d), and every six days (I₆ treatment, 18 d, after I₂ treatment). Rates of CO₂ exchange for estimating net ecosystem CO₂ exchange (F_N), ecosystem respiration (R_E), and soil respiration (R_S) were measured, and gross C uptake by plants (F_G) and respiration from leaves (R_L) were calculated during two periods, 1–12 and 13–30 d, of the 30-d experiment. During the first 12 d, there were no significant differences in cumulative F_N (mean ± standard deviation, 61 ± 30 g C m^-2, n = 4). During the subsequent 18 d, cumulative F_N decreased with decreasing irrigation frequency and increasing cumulative soil water deficit (W), with values of 70 ± 22, 60 ± 16, and 18 ± 12 g C m^-2 for the I₁, I₃, and I₆ treatments, respectively. There were similar decreases in F_G, R_E and R_L with increasing W, but differences in R_S were not significant. Use of the C₄ grass growing in a C₃-derived soil enabled partitioning of R_S into its autotrophic (R_A) and heterotrophic (R_H) components using a ¹³C natural abundance isotopic technique at the end of the experiment when differences in cumulative W between the treatments were the greatest. The values of R_H and its percentage contributions to R_S (43% ± 8%, 42% ± 8%, and 8% ± 5% for the I₁, I₃, and I₆ treatments, respectively) suggested that R_H remained unaffected across a wide range of W and then decreased under extreme W. There were no significant differences in aboveground biomass between the treatments. Nitrous oxide (N₂O) emission was measured to determine if there was a trade-off effect between irrigation frequency and increasing W on net greenhouse gas emission, but no significant differences were found between the treatments. These findings suggest that over short periods in well-drained soil, irrigation frequency could be managed to manipulate soil water deficit in order to reduce net belowground respiratory C losses, particularly those from the microbial decomposition of soil organic matter, with no significant effect on biomass production and N₂O emission.
The impact of rain events on CO<inf>2</inf> emissions from contrasting land use systems in semi-arid West African savannas
2019, Science of the Total Environment
Citation Excerpt :
Thus, it is crucial to predict the ecological performance and productivity of savannas under present and future climate conditions. It is well known that rain in general stimulates plant growth and biomass development, which in turn leads to increased CO2 uptake of savannas (e.g. Scholes and Walker, 1993; Ardö et al., 2008; Otieno et al., 2010; Hussain et al., 2015). However, rain also triggers CO2 emission pulses through increasing respiration (Xu et al., 2004).
In the future the Sudanian savanna – one of West Africa's high-potential “bread baskets” – will likely face shorter rainy seasons with more extreme rains and droughts. That could have serious impacts on the vegetation and its carbon dioxide (CO₂) exchange with potentially increasing CO₂ emissions accelerating climate warming. Understanding how the CO₂ fluxes in this area respond to environmental variables, in particular rain events, is essential, but available data are scarce. In this study, we monitored net ecosystem exchange (NEE) of CO₂, rainfall and other environmental parameters during four years at three savannas. Savannas were characterized by different vegetation due to different land use: i) woody and nearly pristine, ii) mixture of cropland and grassland and iii) intensive grazing. The impact of rain events on CO₂ exchange for these contrasting ecosystems were analyzed for single rain events (short-term) and on a yearly time scale (long-term) using three eddy covariance towers. We found that the woody pristine savanna site was a prominent sink of CO₂ (−864 to −1299 g CO₂ m⁻² y⁻¹) while the degraded sites were net CO₂ sources (118 to 605 g CO₂ m⁻² y⁻¹) with a complicated relation with annual rainfall amounts. The NEE responses to single rain events revealed that daytime rain systematically decreased the sink strengths at all sites, which might be associated with decreased light availability. At the degraded sites, additional factors increasing CO₂ losses were rain duration and dry spell length. The observed patterns of immediate CO₂ flux responses to rainfall at differently used savannas indicate strong internal feedbacks between vegetation and land use changes and raise the question whether the CO₂ sink strengths might be overestimated with possible implications for global CO₂ budgets. Sustainable adaptation strategies need to be developed for West Africa.
Controls of carbon flux in a semi-arid grassland ecosystem experiencing wetland loss: Vegetation patterns and environmental variables
2018, Agricultural and Forest Meteorology
Citation Excerpt :
Moreover, since it is difficult to estimate accurately the location of a wetland in a large, rural area (He et al., 2009) and field investigation is time-consuming, we proposed a new, rapid and simple method to estimate the location of a wetland. Although several literatures have found a relationship between NEE and environmental parameters in grasslands (Suyker and Verma, 2001; Li et al., 2005; Nakano et al., 2008; Hussain et al., 2015), few of them focus on a grassland ecosystem experiencing wetland loss. The main objectives of this study were: (1) to extract the location of wetland in the grassland ecosystem; (2) to evaluate the CO2 flux that is modified by GPP and ecosystem respiration (Reco), and to estimate the contribution of wetland loss to CO2 flux in the semi-arid grassland ecosystem; and (3) to quantify the influence of atmospheric constraints and vegetation patterns on CO2 flux in both wetland and grassland.
Inner Mongolia, China, contains the world’s largest grassland ecosystem. This has many areas of wetland, which provide important ecological services, especially carbon sequestration in the semi-arid terrestrial ecosystems. However, the area of wetland has decreased sharply in the past two decades. This study examined ways to recognize and extract wetland from grassland to determine the difference among net ecosystem exchange (NEE), gross primary production (GPP) and ecosystem respiration (R_eco) between wetland and grassland and to evaluate the influence of wetland loss on carbon sequestration in the grassland. The eddy covariance (EC) flux technique was coupled with the Vegetation Photosynthesis and Respiration Model (VPRM) to upscale the spatial patterns of carbon flux. The results showed that the region was a carbon source in 2016, probably caused by overharvesting and degradation of forests. The value of the NEE (average: 6.63 ± 3.50 g C m⁻² d⁻¹) in grassland was apparently higher than that in wetland (average: 0.86 ± 1.69 g C m⁻² d⁻¹), which suggested that the capability of carbon sequestration in wetland was still stronger than that in grassland even in carbon loss condition. The results showed a positive relationship between aboveground biomass (AGB) and ground-based daily GPP or R_eco for both wetland and grassland and a negative relationship between AGB and NEE. The ground-based daily NEE was also significantly related to soil water content (SWC) but showed no relationship with daily precipitation (PRE), which suggested that SWC was a more important impact factor than precipitation on CO₂ flux exchange in the study area. The change between wetland and grassland did not influence the positive relationship between AGB or SWC and CO₂ flux. Our study provides a new way to determine the spatial CO₂ flux exchange and its controlling factors (environmental variables and vegetation patterns) and to successfully analyze its differences in wetland and grassland.
Variable decomposition of two plant litters and their effects on the carbon sequestration ability of wetland soil in the Yangtze River estuary
2018, Geoderma
Citation Excerpt :
Wetlands contain about 12–15% of the global carbon pool, and they have been studied as sources or sinks of carbon to discover the relationship with global climate change (Sabine et al., 2004; Erwin, 2009; Means et al., 2016; Cao et al., 2017). The carbon sequestration ability of a wetland is often evaluated by the quantity of plant biomass, which indicates the amount of CO2 that has been fixed through photosynthesis (Saunders et al., 2012; Hansen and Nestlerode, 2014; Hussain et al., 2015). Mitsch et al. (2014) theorized that carbon sequestration is consistently higher in naturally colonized wetlands than in planted wetlands due to their much greater productivity.
Highly efficient sequestration of carbon into soil by plants is crucial to wetland ecosystems under rising atmospheric CO₂. The carbon sequestration ability of wetland can be roughly evaluated from the amount of carbon fixed through plant's photosynthesis, but the decomposition properties of plant litter returning to soil are also essential to its evaluation. We examined litter decomposition of Phragmites australis (P. australis) and Spartina alterniflora (S. alterniflora), two dominant plants from Jiuduansha wetland in the Yangtze River estuary, returned to soil in-situ and ex-situ, to clarify their effect on soil respiration and carbon sequestration efficiency. Both mass and carbon content of S. alterniflora were lost faster than P. australis when their plant litters were returned to soil. Soil type exerted a significant effect on litter decomposition but not on plant ranking for decomposition rate (k). High moisture and low nitrogen content in the wetland soils resulted in the lower decomposition rates of litter, compared with inland soils. Litter properties were determining factors in ranking of decomposition rate, in which the k was negatively correlated with the lignin/N and C/N ratios, and positively correlated with the initial nitrogen content. P. australis had low nitrogen content, high lignin/N and C/N ratios, so it had the lower decomposition rate and soil respiration. Combine the plant biomass, litter decomposition and soil respiration, P. australis wetland possesses the higher carbon sequestration ability in the Yangtze River estuary than S. alterniflora wetland.
Carbon and water fluxes in an exotic buffelgrass savanna
2016, Rangeland Ecology and Management
Citation Excerpt :
In this paper we document the nature of biosphere/atmosphere CO2 and water exchanges in an arid ecosystem that has been transformed into an exotic buffelgrass (C. ciliaris) savanna for cattle grazing management. While studies have previously documented carbon fluxes over buffelgrass-dominated ecosystems near the native range of this species (Lalrammawia and Paliwal, 2010; Hussain et al., 2015), here we document seasonality and interannual variation on ecosystem fluxes for a site where this species was introduced within the aridlands of North America. Given the increasing extent of human-influenced and degraded lands, documenting and understanding the nature ecosystem exchange dynamics within these novel ecosystems is of growing concern.
Buffelgrass savanna is becoming widespread in aridland ecosystems around the world following invasion or deliberate land conversion for cattle forage. There is still a gap of information regarding functional and ecohydrological aspects such as carbon, water, and greenhouse gas exchanges in these highly productive novel ecosystems where buffelgrass is an exotic species. We measured net ecosystem CO₂ exchange (NEE), ecosystem respiration (R_eco), gross primary production (GPP), and evapotranspiration (ET) with eddy covariance techniques over a buffelgrass savanna established for cattle grazing, approximately 30 yr ago within the Sonoran Desert. The savanna was a net carbon sink (NEE − 230 g C/m²/yr) during both a year with above average and one with below-average precipitation (NEE − 84 g C/m²/yr). Water loss through evapotranspiration (ET) was similar to total annual rainfall input. Up to 62% of the annual fixed carbon and 75% of ET occurred during the summer monsoon season, when 72 − 86% of annual rainfall occurred and buffelgrass was active. ET from summer months explained 73% of variation in NEE, with an average ET of 50 mm H₂O/month needed to turn the ecosystem into a net carbon sink during this season. Other seasons in the year, when buffelgrass was dormant, contributed with up to 48% of annual fixed carbon but with higher water use efficiency (− NEE/ET). We discuss the importance of the seasonal variability in R_eco, GPP, and ET processes and the phenology of native plant species for the net carbon uptake through the year for this managed novel ecosystem.

View all citing articles on Scopus

View full text

PEDOSPHERELeaf and Ecosystem Gas Exchange Responses of Buffel Grass-Dominated Grassland to Summer Precipitation

ABSTRACT

J. Arid Environ

Agr. Forest Meteorol

Agr. Ecosyst. Environ

Agr. Forest Meteorol

Agr. Forest Meteorol

J. Arid Environ

Agr. Meteorol

Agr. Forest Meteorol

Net changes in regional woody vegetation cover and carbon storage in Texas Drylands, 1937–1999

Glob. Change Biol

Water pulses and biogeochemical cycles in arid and semiarid ecosystems

Oecologia

In vitro high frequency plant regeneration in buffel grass (Cenchrus ciliaris L.)

J. Plant Biol

Physiological reactions to imposed water deficit by Andropogon gayanus cv. Bisquamulatus and Cenchrus ciliaris cv. Biloela in a mixed fodder crop

J. Agr. Sci

Soil texture drives responses of soil respiration to precipitation pulses in the Sonoran Desert: Implications for climate change

Ecosystems

Impact of clipping on root systems of 3 grasses species in Tunisia

J. Range Manage

Ecosystem respiration responses to experimental manipulations of winter and summer precipitation in a Mixedgrass Prairie, WY, USA

Biogeochemistry

Tropical Forages: An Interactive Selection Tool

Soil water content and temperature as independent or confounded factors controlling soil respiration in a temperate mixed hardwood forest

Glob. Change Biol

High temperature effects on gas exchange for the invasive buffel grass (Pennisetum ciliare [L.] link)

Weed Biol. Manage

Eradication of buffel grass (Cenchrus ciliaris) on Airlie Island, Pilbara Coast, Western Australia

Global carbon sinks

Consequences of cool-season drought-induced plant mortality to Chihuahuan Desert grassland ecosystem and soil respiration dynamics

Ecosystems

PEDOSPHERE
Leaf and Ecosystem Gas Exchange Responses of Buffel Grass-Dominated Grassland to Summer Precipitation