Net ecosystem production in a Spanish black pine forest after a low burn-severity fire: Significance of different modelling approaches for estimating gross primary production

2017 ◽  
Vol 246 ◽  
pp. 178-193 ◽  
Author(s):  
E. Martínez-García ◽  
E. Rubio ◽  
F.A. García-Morote ◽  
M. Andrés-Abellán ◽  
H. Miettinen ◽  
...  
2006 ◽  
Vol 63 (5) ◽  
pp. 1130-1141 ◽  
Author(s):  
George H Lauster ◽  
Paul C Hanson ◽  
Timothy K Kratz

Net ecosystem production (NEP) trends among lakes have been ascribed to differences in nutrient and allochthonous carbon inputs, but little is known on how different habitats within lakes contribute to these trends. We sampled pelagic and littoral surface waters using sonde (i.e., free-water) and bottle methods concurrently in lakes spanning a range of trophic conditions. We considered whether the typically higher metabolism estimates found with sonde methods are due to contributions from littoral habitats not reflected by bottle estimates. We sought the source of littoral contributions by selecting sites with maximum differences in macrophyte abundance. Sonde estimates for pelagic primary production and respiration were two–three times greater than bottle estimates. Sonde/bottle ratios were higher in productive lakes and lakes with more littoral area. Bottle estimates were similar among all sites, and sonde estimates in macrophyte-poor sites were similar to pelagic sondes. However, sonde estimates in macrophyte-rich areas were four–nine times greater than bottle estimates. Results suggest littoral zones increase whole-lake NEP in eutrophic systems, whereas the Sphagnum mat surrounding dystrophic lakes decreases NEP. Non-planktonic organisms associated with macrophytes provide important littoral contributions to whole-lake metabolism and to understanding NEP trends among lakes.


Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1587
Author(s):  
Imam Basuki ◽  
J. Boone Kauffman ◽  
James T. Peterson ◽  
Gusti Z. Anshari ◽  
Daniel Murdiyarso

Deforested and converted tropical peat swamp forests are susceptible to fires and are a major source of greenhouse gas (GHG) emissions. However, information on the influence of land-use change (LUC) on the carbon dynamics in these disturbed peat forests is limited. This study aimed to quantify soil respiration (heterotrophic and autotrophic), net primary production (NPP), and net ecosystem production (NEP) in peat swamp forests, partially logged forests, early seral grasslands (deforested peat), and smallholder-oil palm estates (converted peat). Peat swamp forests (PSF) showed similar soil respiration with logged forests (LPSF) and oil palm (OP) estates (37.7 Mg CO2 ha−1 yr−1, 40.7 Mg CO2 ha−1 yr−1, and 38.7 Mg CO2 ha−1 yr−1, respectively), but higher than early seral (ES) grassland sites (30.7 Mg CO2 ha−1 yr−1). NPP of intact peat forests (13.2 Mg C ha−1 yr−1) was significantly greater than LPSF (11.1 Mg C ha−1 yr−1), ES (10.8 Mg C ha−1 yr−1), and OP (3.7 Mg C ha−1 yr−1). Peat swamp forests and seral grasslands were net carbon sinks (10.8 Mg CO2 ha−1 yr−1 and 9.1 CO2 ha−1 yr−1, respectively). In contrast, logged forests and oil palm estates were net carbon sources; they had negative mean Net Ecosystem Production (NEP) values (−0.1 Mg CO2 ha−1 yr−1 and −25.1 Mg CO2 ha−1 yr−1, respectively). The shift from carbon sinks to sources associated with land-use change was principally due to a decreased Net Primary Production (NPP) rather than increased soil respiration. Conservation of the remaining peat swamp forests and rehabilitation of deforested peatlands are crucial in GHG emission reduction programs.


2020 ◽  
Author(s):  
Bailu Zhao ◽  
Qianlai Zhuang ◽  
Narasinha Shurpali ◽  
Kajar Köster ◽  
Frank Berninger ◽  
...  

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.


2021 ◽  
Vol 301-302 ◽  
pp. 108337
Author(s):  
Xianglin Tian ◽  
Francesco Minunno ◽  
Pauliina Schiestl-Aalto ◽  
Jinshu Chi ◽  
Peng Zhao ◽  
...  

2020 ◽  
Author(s):  
Bailu Zhao ◽  
Qianlai Zhuang ◽  
Narasinha Shurpali ◽  
Kajar Köster ◽  
Frank Berninger ◽  
...  

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.


2003 ◽  
Vol 33 (12) ◽  
pp. 2340-2351 ◽  
Author(s):  
Zhong Li ◽  
Michael J Apps ◽  
Werner A Kurz ◽  
Ed Banfield

Temporal variations of net primary production (NPP) and net ecosystem production (NEP) in west central Canadian forests over the period of 1920–1995 and their responses to natural and anthropogenic disturbances were simulated using the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS2). The results show that forest NPP in the region was 215 g C·year–1·m–2 in 1920, varied between 105 and 317 g·C year–1·m–2 depending on ecoclimatic province, but gradually increased to 330 (158 to 395) g C·year–1·m–2 in the early 1980s before declining to 290 (148 to 395) g C·year–1·m–2 by 1995. Forest NEP was estimated to be 53 (–13 to 88) g C·year–1·m–2 in 1920–1924, increased to 75 (5 to 98) g C·year–1·m–2 in 1960, and then declined to 26 (–14 to 53) g C·year–1·m–2 in 1991–1995. Natural disturbances played a greater role than harvest in determining the temporal pattern of forest NPP and NEP during the period because of the larger area affected by natural disturbances. This study also indicated that ignoring disturbances would lead to an overestimation of forest NPP and NEP in ecosystem modeling.


2018 ◽  
Vol 64 (No. 8) ◽  
pp. 353-360 ◽  
Author(s):  
Lamptey Shirley ◽  
Li Lingling ◽  
Xie Junhong

Agriculture in the semi-arid is often challenged by overuse of nitrogen (N), inadequate soil water and heavy carbon emissions thereby threatening sustainability. Field experiments were conducted to investigate the effect of nitrogen fertilization levels (N<sub>0</sub> – 0, N<sub>100</sub> – 100, N<sub>200</sub> – 200, N<sub>300</sub> – 300 kg N/ha) on soil water dynamics, soil respiration (Rs), net ecosystem production (NEP), and biomass yields. Zero nitrogen soils decreased Rs by 23% and 16% compared to N<sub>300</sub> and N<sub>200</sub> soils, respectively. However, biomass yield was greatest under N<sub>300</sub> compared with N<sub>0</sub>, which therefore translated into increased net primary production by 89% and NEP by 101% compared to N<sub>0</sub>. To a lesser extent, N<sub>200</sub> increased net primary production by 69% and net ecosystem production by 79% compared to N<sub>0</sub>. Grain yields were greatest under N<sub>300</sub> compared with N<sub>100</sub> and N<sub>0</sub>, which therefore translated into increased carbon emission efficiency (CEE) by 53, 39 and 3% under N<sub>300</sub> compared to N<sub>0</sub>, N<sub>100</sub> and N<sub>200</sub> treatments, respectively. There appears potential for 200 kg N/ha to be used to improve yield and increase CEE.


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