How plastic mulching affects net primary productivity, soil C fluxes and organic carbon balance in dry agroecosystems in China

2020 ◽  
Vol 263 ◽  
pp. 121470
Author(s):  
Fei Mo ◽  
Kai-Liang Yu ◽  
Thomas W. Crowther ◽  
Jian-Yong Wang ◽  
Hong Zhao ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Primary Productivity ◽  
Carbon Balance ◽  
Net Primary Productivity ◽  
Soil C ◽  
Plastic Mulching

Relationships between net primary productivity and stand age for several forest types and their influence on China’s carbon balance

2011 ◽  
Vol 92 (6) ◽  
pp. 1651-1662 ◽  
Author(s):  
Shaoqiang Wang ◽  
Lei Zhou ◽  
Jingming Chen ◽  
Weimin Ju ◽  
Xianfeng Feng ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Carbon Balance ◽  
Net Primary Productivity ◽  
Stand Age ◽  
Forest Types

scholarly journals Divergent controls of soil organic carbon between observations and process-based models

2021 ◽  
Author(s):  
Katerina Georgiou ◽  
Avni Malhotra ◽  
William R. Wieder ◽  
Jacqueline H. Ennis ◽  
Melannie D. Hartman ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Global Scale ◽  
Mean Annual Temperature ◽  
Biogeochemical Models ◽  
Soc Stocks ◽  
Process Based Models

AbstractThe storage and cycling of soil organic carbon (SOC) are governed by multiple co-varying factors, including climate, plant productivity, edaphic properties, and disturbance history. Yet, it remains unclear which of these factors are the dominant predictors of observed SOC stocks, globally and within biomes, and how the role of these predictors varies between observations and process-based models. Here we use global observations and an ensemble of soil biogeochemical models to quantify the emergent importance of key state factors – namely, mean annual temperature, net primary productivity, and soil mineralogy – in explaining biome- to global-scale variation in SOC stocks. We use a machine-learning approach to disentangle the role of covariates and elucidate individual relationships with SOC, without imposing expected relationships a priori. While we observe qualitatively similar relationships between SOC and covariates in observations and models, the magnitude and degree of non-linearity vary substantially among the models and observations. Models appear to overemphasize the importance of temperature and primary productivity (especially in forests and herbaceous biomes, respectively), while observations suggest a greater relative importance of soil minerals. This mismatch is also evident globally. However, we observe agreement between observations and model outputs in select individual biomes – namely, temperate deciduous forests and grasslands, which both show stronger relationships of SOC stocks with temperature and productivity, respectively. This approach highlights biomes with the largest uncertainty and mismatch with observations for targeted model improvements. Understanding the role of dominant SOC controls, and the discrepancies between models and observations, globally and across biomes, is essential for improving and validating process representations in soil and ecosystem models for projections under novel future conditions.

scholarly journals Global distribution of soil organic carbon, based on the Harmonized World Soil Database – Part 2: Certainty of changes related to land-use and climate

2014 ◽  
Vol 1 (1) ◽  
pp. 363-400
Author(s):  
M. Köchy ◽  
A. Don ◽  
M. K. van der Molen ◽  
A. Freibauer
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Net Primary Productivity ◽  
Water Saturation ◽  
Soil C ◽  
Climate Effects ◽  
Soil Database ◽  
Global Soil ◽  
Soc Stocks

Abstract. Global biosphere models vary greatly in their projections of future changes of global soil organic carbon (SOC) stocks and aggregated global SOC masses in response to climate change. We estimated the certainty (likelihood) and quantity of increases and decreases on a half-degree grid. We assessed the effect of changes in controlling factors, including net primary productivity (NPP), litter quality, soil acidity, water-saturation, depth of permafrost, land use, temperature, and aridity, in a temporally implicit model that uses categorized driver variables associated by probabilities (Bayesian Network). The probability-weighted results show that, globally, climate effects on NPP had the strongest impact on SOC stocks and the certainty of change after 75 years. Actual land use had the greatest effect locally because the assumed certainty of land use change per unit area was small. The probability-weighted contribution of climate to decomposition was greatest in the humid tropics because of greater absolute effects on decomposition fractions at higher temperatures. In contrast, climate effects on decomposition fractions were small in cold regions. Differences in decomposition rates between contemporary and future climate were greatest in arid subtropical regions because of projected strong increases in precipitation. Warming in boreal and arctic regions increased NPP, balancing or outweighing potential losses from thawing of permafrost. Across contrasting NPP scenarios tropical mountain forests were identified as hotspots of future highly certain C losses. Global soil C mass will increase by 1% with a certainty of 75% if NPP increases due to carbon-dioxide fertilization. At a certainty level of 75%, soil C mass will not change if CO2-induced increase of NPP is limited by nutrients.

scholarly journals Sensitivity of grassland carbon pools to plant diversity, elevated CO2, and soil nitrogen addition over 19 years

2021 ◽  
Vol 118 (17) ◽  
pp. e2016965118
Author(s):  
Melissa A. Pastore ◽  
Sarah E. Hobbie ◽  
Peter B. Reich
Keyword(s):  
Species Richness ◽  
Soil Nitrogen ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Plant Species Richness ◽  
Nitrogen Addition ◽  
N Deposition ◽  
Global Changes ◽  
Soil C ◽  
C Storage

Whether the terrestrial biosphere will continue to act as a net carbon (C) sink in the face of multiple global changes is questionable. A key uncertainty is whether increases in plant C fixation under elevated carbon dioxide (CO2) will translate into decades-long C storage and whether this depends on other concurrently changing factors. We investigated how manipulations of CO2, soil nitrogen (N) supply, and plant species richness influenced total ecosystem (plant + soil to 60 cm) C storage over 19 y in a free-air CO2 enrichment grassland experiment (BioCON) in Minnesota. On average, after 19 y of treatments, increasing species richness from 1 to 4, 9, or 16 enhanced total ecosystem C storage by 22 to 32%, whereas N addition of 4 g N m−2 ⋅ y−1 and elevated CO2 of +180 ppm had only modest effects (increasing C stores by less than 5%). While all treatments increased net primary productivity, only increasing species richness enhanced net primary productivity sufficiently to more than offset enhanced C losses and substantially increase ecosystem C pools. Effects of the three global change treatments were generally additive, and we did not observe any interactions between CO2 and N. Overall, our results call into question whether elevated CO2 will increase the soil C sink in grassland ecosystems, helping to slow climate change, and suggest that losses of biodiversity may influence C storage as much as or more than increasing CO2 or high rates of N deposition in perennial grassland systems.

Net primary productivity following forest fire for Canadian ecoregions

2000 ◽  
Vol 30 (6) ◽  
pp. 939-947 ◽  
Author(s):  
B D Amiro ◽  
J M Chen ◽  
Jinjun Liu
Keyword(s):  
Primary Productivity ◽  
Forest Fires ◽  
Carbon Balance ◽  
Net Primary Productivity ◽  
Forest Carbon ◽  
Data Set ◽  
Area Index ◽  
Boreal Plains ◽  
Boreal Ecosystem ◽  
Boreal Ecosystem Productivity Simulator

Recent modelling results indicate that forest fires and other disturbances determine the magnitude of the Canadian forest carbon balance. The regeneration of post-fire vegetation is key to the recovery of net primary productivity (NPP) following fire. We geographically co-registered pixels classed using the Boreal Ecosystem Productivity Simulator, a process-based model with AVHRR (advanced very-high resolution radiometer) satellite estimates of leaf-area index and land cover type, with polygons from a recent database of large Canadian fires. NPP development with time since fire was derived for the first 15 years following the disturbance in the boreal and taiga ecozones. About 7 × 106 ha were analysed for over 500 fires occurring between 1980 and 1994. NPP increases linearly through this period, at rates that depend on ecoregion. A longer data set for the Boreal Plains ecozone of Alberta shows that NPP levels off at about 20-30 years and remains constant for 60 years. The NPP trajectories can be used as spatial averages to support models of forest carbon balance and succession through the most fire-prone regions of Canada.

scholarly journals Non-Flat Earth Recalibrated for Terrain and Topsoil

Soil Systems ◽  
2018 ◽  
Vol 2 (4) ◽  
pp. 64 ◽  
Author(s):  
Robert Blakemore
Keyword(s):  
Organic Carbon ◽  
Primary Productivity ◽  
Land Surface ◽  
Net Primary Productivity ◽  
Lidar Data ◽  
Vam Fungi ◽  
Empirical Estimates ◽  
Digital Elevation ◽  
Vesicular Arbuscular ◽  
Global Soil

Earth’s land surface is raised from conventionally flat 15 Gha to >64 Gha accounting for hilly slope undulation and topsoil relief detail. Three main aspects are: topography, rugosity/tortuosity, and micro-relief/porosity of ice/vegetation-free ground. Recalibration arises from four approaches: First, direct empirical estimates of compiled satellite/LiDAR data means of +2.5–26% surface progressively overlain by +94% at cm2 scale for soil ruggedness then +108% for mm2 micro-relief; Second, from digital elevation models with thrice 1.6–2.0 times flat areas; Third, by ‘reverse engineering’ global soil bulk densities and carbon reserves requiring ×4–6 land. Finally, a Fermi estimation doubles the Earth’s surface—as exposed to Sun, air and rain—conveniently set at 100 Gha (with 64 Gha land:36 Gha ocean). Soil organic carbon (SOC) thereby grows to 8580 Gt mainly in SOM-humus with its biotic complexity plus roots, Vesicular-Arbuscular Mycorrhiza (VAM-fungi), leaf-litter and earthworms itself totaling 17,810 Gt. Although four to six times IPCC’s or NASA/NOAA’s calculated 1500–2300 Gt SOC, this is likely an underestimation. Global biomass and biodiversity are at least doubled (×2–3.5) and net primary productivity (NPP) increases to >270 Gt C yr−1 due to terrain. Rationale for a ‘Soil Ecology Institute’ gains ground.

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