Ecosystem Function and Dynamics

Ecosystem Respiration ◽

Ecosystem Dynamics ◽

Ecosystem Production

This chapter focuses on the distinction between ecosystem function and ecosystem dynamics. Ecosystem function refers to the manner in which the ecosystem of interest works, and interactions among its component parts and fluxes, including biotic and abiotic compartments. Meanwhile, ecosystem dynamics refers to variation in ecosystem function through time in response to perturbations that are continuous or stochastic in nature, or in relation to changes in ecosystem components. Therefore, the study of ecosystem dynamics derives from an understanding of ecosystem function, and this, in turn, depends critically on successful identification of the important drivers within the ecosystem. Inevitably, a discussion of ecosystem function and dynamics boils down to the factors that influence and contribute to variation in net ecosystem production—the result of net primary productivity and ecosystem respiration.

Carbon dioxide fluxes over an ancient broadleaved deciduous woodland in southern England

Biogeosciences ◽

10.5194/bg-8-1595-2011 ◽

2011 ◽

Vol 8 (6) ◽

pp. 1595-1613 ◽

Cited By ~ 36

Author(s):

M. V. Thomas ◽

Y. Malhi ◽

K. M. Fenn ◽

J. B. Fisher ◽

M. D. Morecroft ◽

...

Keyword(s):

Carbon Dioxide ◽

Primary Productivity ◽

Management Practices ◽

Deciduous Forest ◽

Carbon Sink ◽

Ecosystem Respiration ◽

Flux Chamber ◽

Southern England ◽

Temperate Deciduous

Abstract. We present results from a study of canopy-atmosphere fluxes of carbon dioxide from 2007 to 2009 above a site in Wytham Woods, an ancient temperate broadleaved deciduous forest in southern England. Gap-filled net ecosystem exchange (NEE) data were partitioned into gross primary productivity (GPP) and ecosystem respiration (Re) and analysed on daily, monthly and annual timescales. Over the continuous 24 month study period annual GPP was estimated to be 21.1 Mg C ha−1 yr−1 and Re to be 19.8 Mg C ha−1 yr−1; net ecosystem productivity (NEP) was 1.2 Mg C ha−1 yr−1. These estimates were compared with independent bottom-up estimates derived from net primary productivity (NPP) and flux chamber measurements recorded at a plot within the flux footprint in 2008 (GPP = 26.5 ± 6.8 Mg C ha−1 yr−1, Re = 24.8 ± 6.8 Mg C ha−1 yr−1, biomass increment = ~1.7 Mg C ha−1 yr−1). Over the two years the difference in seasonal NEP was predominantly caused by changes in ecosystem respiration, whereas GPP remained similar for equivalent months in different years. Although solar radiation was the largest influence on daily values of CO2 fluxes (R2 = 0.53 for the summer months for a linear regression), variation in Re appeared to be driven by temperature. Our findings suggest that this ancient woodland site is currently a substantial sink for carbon, resulting from continued growth that is probably a legacy of past management practices abandoned over 40 years ago. Our GPP and Re values are generally higher than other broadleaved temperate deciduous woodlands and may represent the influence of the UK's maritime climate, or the particular species composition of this site. The carbon sink value of Wytham Woods supports the protection and management of temperate deciduous woodlands (including those managed for conservation rather than silvicultural objectives) as a strategy to mitigate atmospheric carbon dioxide increases.

Precipitation legacy effects on dryland ecosystem carbon fluxes: direction, magnitude and biogeochemical carryovers

Biogeosciences ◽

10.5194/bg-13-425-2016 ◽

2016 ◽

Vol 13 (2) ◽

pp. 425-439 ◽

Cited By ~ 27

Author(s):

W. Shen ◽

G. D. Jenerette ◽

D. Hui ◽

R. L. Scott

Keyword(s):

Plant Biomass ◽

Net Primary Production ◽

Ecosystem Respiration ◽

Ecosystem Dynamics ◽

Legacy Effects ◽

Previous Period ◽

Legacy Effect ◽

Ecosystem Production ◽

Legacy Impacts ◽

Abstract. The precipitation legacy effect, defined as the impact of historical precipitation (PPT) on extant ecosystem dynamics, has been recognized as an important driver in shaping the temporal variability of dryland aboveground net primary production (ANPP) and soil respiration. How the PPT legacy influences whole ecosystem-level carbon (C) fluxes has rarely been quantitatively assessed, particularly at longer temporal scales. We parameterized a process-based ecosystem model to a semiarid savanna ecosystem in the southwestern USA, calibrated and evaluated the model performance based on 7 years of eddy-covariance measurements, and conducted two sets of simulation experiments to assess interdecadal and interannual PPT legacy effects over a 30-year simulation period. The results showed that decreasing the previous period/year PPT (dry legacy) always increased subsequent net ecosystem production (NEP) whereas increasing the previous period/year PPT (wet legacy) decreased NEP. The simulated dry-legacy impacts mostly increased subsequent gross ecosystem production (GEP) and reduced ecosystem respiration (Re), but the wet legacy mostly reduced GEP and increased Re. Although the direction and magnitude of GEP and Re responses to the simulated dry and wet legacies were influenced by both the previous and current PPT conditions, the NEP responses were predominantly determined by the previous PPT characteristics including rainfall amount, seasonality and event size distribution. Larger PPT difference between periods/years resulted in larger legacy impacts, with dry legacies fostering more C sequestration and wet legacies more C release. The carryover of soil N between periods/years was mainly responsible for the GEP responses, while the carryovers of plant biomass, litter and soil organic matter were mainly responsible for the Re responses. These simulation results suggest that previous PPT conditions can exert substantial legacy impacts on current ecosystem C balance, which should be taken into account while assessing the response of dryland ecosystem C dynamics to future PPT regime changes.

Assessment on 2000-2010 Ecosystem Function Changes of Yiwulvshan National Nature Scenic Area

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1051.489 ◽

2014 ◽

Vol 1051 ◽

pp. 489-494

Author(s):

Xiao Chen Wang ◽

Jing Hai Zhu ◽

Yuan Man Hu ◽

Wei Ling Liu

Keyword(s):

Remote Sensing ◽

Ecosystem Function ◽

Primary Productivity ◽

Water Conservation ◽

Remote Sensing Data ◽

Vegetation Coverage ◽

The Past ◽

Remote Sensing Technology ◽

Sensing Technology

Based on the remote-sensing data and ground data, this study is conducted on the ecosystem function of Yiwulvshan National Nature Scenic Area (hereinafter as “Yiwulvshan Scenic Area”) from 2000 to 2010 with the GIS (geographic information system) and RS (remote sensing) technology, so as to provide reference for better environmental protection of the scenic area. It is shown from the results that there is no obvious change of land use in Yiwulvshan Scenic Area; while the capacity for soil and water conservation is slightly improved mainly due to increase of vegetation coverage; the vegetation net primary productivity declines somewhat about 5.27% in past 10 years; and biodiversity is slightly increased. As a whole, the ecosystem function of Yiwulvshan Scenic Area basically kept stable in the past 10 years, which indicated that the existing regulations can effectively protect the ecological function of the Scenic Area.

North American boreal forests are a large carbon source due to wildfires from 1986 to 2016

10.21203/rs.3.rs-73841/v1 ◽

2020 ◽

Author(s):

Bailu Zhao ◽

Qianlai Zhuang ◽

Narasinha Shurpali ◽

Kajar Köster ◽

Frank Berninger ◽

...

Keyword(s):

Net Primary Production ◽

Ecosystem Dynamics ◽

Fire Disturbance ◽

Burn Severity ◽

Fire Emissions ◽

Terrestrial Ecosystem Model ◽

C Balance ◽

Ecosystem Production ◽

Abstract Wildfires are a major disturbance to forest carbon (C) balance through both immediate combustion emissions and post-fire ecosystem dynamics. Here we use a process-based biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to simulate C budget in Alaska and Canada during 1986-2016, as impacted by fire disturbances. We extracted the data of difference Normalized Burn Ratio (dNBR) for fires from Landsat TM/ETM imagery and estimated the proportion of vegetation and soil C combustion. We observed that the region is a C source of 2.74 Pg C during the 31-year period. The observed C loss, 57.1 Tg C yr-1, was attributed to fire emissions, overwhelming the net ecosystem production (1.9 Tg C yr-1) in the region. Our simulated during-fire emissions for Alaska and Canada are within the range of field measurements and other model estimates. As burn severity increases, combustion emission tended to switch from vegetation origin towards soil origin. Burn severity regulates post-fire C dynamics. Low severity fires increase soil temperature and decrease soil moisture and thus, enhance soil respiration. However, the opposite trend was found under moderate or high burn severity. The proportion of post-fire soil emission in total emissions increased with burn severity. Net nitrogen mineralization gradually recovered after fire, enhancing net primary production. Net ecosystem production recovered fast under higher burn severities. The impact of fire disturbance on the C balance of northern ecosystems and the associated uncertainties can be better characterized with long-term, prior, during- and post-disturbance data across the geospatial spectrum. Our findings suggest that the regional source of carbon to the atmosphere will persist if the observed forest wildfire occurrence and severity continues into the future.

Measurement of net ecosystem production and ecosystem respiration in a Zoysia japonica grassland, central Japan, by the chamber method

Ecological Research ◽

10.1007/s11284-009-0678-2 ◽

2010 ◽

Vol 25 (2) ◽

pp. 483-493 ◽

Cited By ~ 10

Author(s):

Deepa Dhital ◽

Hiroyuki Muraoka ◽

Yuichiro Yashiro ◽

Yoko Shizu ◽

Hiroshi Koizumi

Keyword(s):

Ecosystem Respiration ◽

Zoysia Japonica ◽

Central Japan ◽

Chamber Method ◽

Ecosystem Production

Quantifying the UK’s Carbon Dioxide Flux: An atmospheric inverse modelling approach using a regional measurement network

10.5194/acp-2018-839 ◽

2018 ◽

Author(s):

Emily D. White ◽

Matthew Rigby ◽

Mark F. Lunt ◽

Anita L. Ganesan ◽

Alistair J. Manning ◽

...

Keyword(s):

Carbon Dioxide ◽

Primary Productivity ◽

Transport Model ◽

Ecosystem Respiration ◽

Carbon Dioxide Flux ◽

Inverse Modelling ◽

Chemical Transport Model ◽

The Uk ◽

Abstract. We present a method to derive atmospheric-observation-based estimates of carbon dioxide (CO2) fluxes at the national scale, demonstrated using data from a network of surface tall tower sites across the UK and Ireland over the period 2013–2014. The inversion is carried out using simulations from a Lagrangian chemical transport model and an innovative hierarchical Bayesian Markov chain Monte Carlo (MCMC) framework, which addresses some of the traditional problems faced by inverse modelling studies, such as subjectivity in the specification of model and prior uncertainties. Biospheric fluxes related to gross primary productivity and terrestrial ecosystem respiration are solved separately in the inversion and then combined a posteriori to determine net primary productivity. Two different models, CARDAMOM and JULES, provide prior estimates for these fluxes. We carry out separate inversions to assess the impact of these different priors on the posterior flux estimates and evaluate the differences between the prior and posterior estimates in terms of missing model components. The Numerical Atmospheric dispersion Modelling Environment (NAME) is used to relate fluxes to the measurements taken across the regional network. Posterior CO2 estimates from the two inversions agree within estimated uncertainties, despite large differences in the prior fluxes from the different models. With our method, averaging results from 2013 and 2014, we find a total annual net biospheric flux for the UK of −8 ± 79 Tg CO2 yr−1 (CARDAMOM prior) and −64 ± 85 Tg CO2 yr−1 (JULES prior), where -ve values represent an uptake of CO2. These biospheric CO2 estimates show that annual UK biospheric sources and sinks are roughly in balance. These annual mean estimates are consistently higher than the prior estimates, which show much more pronounced uptake in the summer months.

Partitioning of canopy and soil CO<sub>2</sub> fluxes in a pine forests at the dry timberline

10.5194/bg-2019-291 ◽

2019 ◽

Author(s):

Rafat Qubaja ◽

Feyodor Tatarinov ◽

Eyal Rotenberg ◽

Dan Yakir

Keyword(s):

Soil Respiration ◽

Primary Productivity ◽

Carbon Allocation ◽

Ecosystem Respiration ◽

Pine Forest ◽

Carbon Accumulation ◽

Dry Forest ◽

Co2 Uptake ◽

The Mean

Abstract. Partitioning carbon fluxes is key to understanding the process underlying ecosystem response to change. This study used soil and canopy fluxes with stable isotopes (13C) and radiocarbon (14C) measurements of a 50-year-old dry (i.e., 287 mm of annual precipitation) pine forest to partition the ecosystem’s CO2 flux into gross primary productivity (GPP) and ecosystem respiration (Re) and soil respiration flux into autotrophic (Rsa), heterotrophic (Rh), and inorganic (Ri) components. On an annual scale, GPP and Re were 655 and 488 g C m−2, respectively, with a net primary productivity (NPP) of 276 g C m−2 and carbon-use efficiency (CUE = NPP / GPP) of 0.42. Soil respiration (Rs) made up 60 % of the total ecosystem respiration and was comprised of 24 ± 4 %, 23 ± 4 %, and 13 ± 1 % Rsa, Rh, and Ri, respectively. The contribution of root and microbial respiration to Re increased during high productivity periods, and inorganic sources were more significant components when soil water content was low. Compared to the mean values for 2001–2006 at the same site; (Grünzweig et al., 2009), annual Rs decreased by 27 % to the mean 2016 rates of 0.8 ± 0.1 µmol m−2 s−1). This was associated with decrease in the respiration Q10 values across the same observation by 36 % and 9 % in the wet and dry periods, respectively. Low rates of soil carbon loss combined with relatively high below ground carbon allocation (i.e., 40 % of canopy CO2 uptake) help explain the high soil organic carbon accumulation and the relatively high ecosystem CUE of the dry forest. This was indicative of the higher resilience of the pine forest to climate change and the significant potential for carbon sequestration in these regions.

Effects of Hydrothermal Conditions on the Net Primary Productivity in the Source Region of Yangtze River, China

10.21203/rs.2.24647/v1 ◽

2020 ◽

Author(s):

Zhe Yuan ◽

Yongqiang Wang ◽

Jijun Xu ◽

Jun Yin ◽

Shu Chen

Keyword(s):

Soil Water ◽

Primary Productivity ◽

Yangtze River ◽

Source Region ◽

Recent Decade ◽

Ecosystem Dynamics ◽

Hydrothermal Conditions ◽

Average Value ◽

Accumulated Temperature

Abstract Background: The ecosystems and natural environment of the Source Region of Yangtze River (SRYR) is highly susceptible to the climate change. Quantifying the response of vegetation Net Primary Productivity (NPP) to the changes of hydrothermal conditions is an important way to identify and predict global ecosystem dynamics. Methods: Using MODIS/Terra Yearly NPP data at 1km×1km spatial resolution, the spatial-temporal variation of NPP was analyzed at first. Then, correlations between NPP and hydrothermal conditions were evaluated with soil water content and accumulated temperature. Finally, a response model was built to analyze the sensitivity of the NPP to precipitation and temperature changes. Result: (1) NPP is generally lower in the western SRYR and increases gradually toward the east, with an average value of 85.2 gC/m 2 . The total NPP had increased by 1.42TgC per year from 2000 to 2014. The fastest change rate of NPP is presented in the Downstream region, followed by the middle stream region and Dam River Basin; (2) the NPP of one specific year has obvious relationship with the accumulated temperature of the same year and the soil water deficit of the previous year. The temperature is the dominant climate factor impacting vegetation growth in the SRYR; (3) It is shown an increase of NPP by 0.194 TgC (nearly 30%) with a 1-°C increase in annual mean temperature. While a 10% increase in annual precipitation corresponds to an increase in NPP by 0.517 TgC (nearly 5%). Conclusion: A warming, wetting and greening SRYR was detected in recent decade. The NPP in SRYR is more sensitive to changes in temperature than changes in precipitation.

North American Boreal Forests Are a Large Carbon Source Due to Wildfires From 1986 to 2016

10.21203/rs.3.rs-108154/v1 ◽

2020 ◽

Author(s):

Bailu Zhao ◽

Qianlai Zhuang ◽

Narasinha Shurpali ◽

Kajar Köster ◽

Frank Berninger ◽

...

Keyword(s):

Net Primary Production ◽

Ecosystem Dynamics ◽

Fire Disturbance ◽

Burn Severity ◽

Fire Emissions ◽

Terrestrial Ecosystem Model ◽

C Balance ◽

Ecosystem Production ◽

Abstract Wildfires are a major disturbance to forest carbon (C) balance through both immediate combustion emissions and post-fire ecosystem dynamics. Here we use a process-based biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to simulate C budget in Alaska and Canada during 1986-2016, as impacted by fire disturbances. We extracted the data of difference Normalized Burn Ratio (dNBR) for fires from Landsat TM/ETM imagery and estimated the proportion of vegetation and soil C combustion. We observed that the region is a C source of 2.74 Pg C during the 31-year period. The observed C loss, 57.1 Tg C yr-1, was attributed to fire emissions, overwhelming the net ecosystem production (1.9 Tg C yr-1) in the region. Our simulated during-fire emissions for Alaska and Canada are within the range of field measurements and other model estimates. As burn severity increases, combustion emission tended to switch from vegetation origin towards soil origin. When dNBR is below 300, fires increase soil temperature and decrease soil moisture and thus, enhance soil respiration. However, the opposite trend was found under moderate or high burn severity. The proportion of post-fire soil emission in total emissions increased with burn severity. Net nitrogen mineralization gradually recovered after fire, enhancing net primary production. Net ecosystem production recovered fast under higher burn severities. The impact of fire disturbance on the C balance of northern ecosystems and the associated uncertainties can be better characterized with long-term, prior, during- and post-disturbance data across the geospatial spectrum. Our findings suggest that the regional source of carbon to the atmosphere will persist if the observed forest wildfire occurrence and severity continues into the future.