Boreal Forest Wildfire and Climate Linked Drivers of Carbon and Nitrogen Loss

Abstract. The boreal landscape covers large portions of the earth's land area and stores a significant percentage of its terrestrial carbon (C). Increased emissions due to climate change amplified fire frequency, size and intensity threaten to remove elements such as C and nitrogen (N) from forest soil and vegetation at rates faster than they accumulate. This may result in large areas within the region becoming a net source of greenhouse gases creating a positive feedback loop with a changing climate. Estimates of per area fire emissions are regionally limited and knowledge of their relation to climate and ecosystem properties is sparse. This study sampled 50 separate Swedish wildfires from 2018 providing quantitative estimates of C and N loss due to fire along a climate gradient. Mean annual precipitation had strong positive effects on total fuel, which was the strongest driver for increasing C and N losses, while mean annual temperature (MAT) had greater influence on both pre- and postfire fuel bulk and chemical properties which had mixed effects on C and N losses. Significant fire induced loss of C occurred in the 50 plots comparable to estimates in similar Eurasian forests but approximately a quarter of those found in typical North American boreal wildfires. N loss was insignificant though large proportions were collected from lower soil layers to a surface layer of char in proportion to increased MAT. These results reveal the variability of C and N losses between global regions and across local climate conditions and a need to better incorporate these factors into models to improve estimates of global emissions of C and N due to fire in future climate scenarios. Additionally, this study demonstrated the linkage between climate and the chemical transformation of residual soil fuel and discusses its potential for altering C and N dynamics in postfire recovery.

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Variability of soil carbon and nitrogen stocks after conversion of natural forest to plantations in Eastern China

PeerJ ◽

10.7717/peerj.8377 ◽

2020 ◽

Vol 8 ◽

pp. e8377

Author(s):

Mbezele Junior Yannick Ngaba ◽

Xiang-Qing Ma ◽

Ya-Lin Hu

Keyword(s):

Eastern China ◽

Horizontal Distribution ◽

Natural Forest ◽

Mean Annual Precipitation ◽

Mean Annual Temperature ◽

Plantation Forest ◽

Soil C ◽

Factors Affecting ◽

Soil C And N ◽

C And N

Forest plantation, either through afforestation or reforestation, has been suggested to reverse and mitigate the process of deforestation. However, uncertainties remain in the potential of plantation forest (PF) to sequestrate carbon (C) and nitrogen (N) compared to natural forest (NF). Soil C and N stocks require a critical and updated look at what is happening especially in the context of increasing rate of land use change and climate change. The current study was conducted in China’s Eastern forest to estimate soil C and N stocks in six depth layers (0–10, 10–20, 20–40, 40–60, 60–80 and 80–100 cm) and two forest types (NF and PF) at four sites along climate factors gradient. The results showed that the overall mean soil C and N amounts to a depth of 20 cm ranged from 2.6 ± 1.1 Mg ha−1 to 38.6 ± 23.1 Mg ha−1, and soil nitrogen stock ranged from 0.2 ± 0.1 Mg ha−1 to 3.3 ± 1.5 Mg ha−1. Moreover, a loss of C stock was observed at Qingyuan (QY) by −7%, Dinghushan (DH) by −26%, Jianfengling (JF) by −13% while that of N stock was observed at QY (−8%), DH (−19%) and JF (−12%) at both depth layers. These results indicate that NFs have a better capacity to accumulate soil C and N. The soil C and N decreased from the southeast to the northeast and increased from tropical to temperate mixed forests zone in the eastern part of the study area. The C and N stock mainly occurred in the topsoil and decreased significantly with depth. Moreover, soil C and N stocks increased with age of plantation. This study provides an overview of the current spatial distribution and soil stocks of C and N, as well as the effects of environmental factors on soil C and N stocks. It also indicated that, although mean annual temperature and mean annual precipitation are the key factors affecting the variations in soil C and N, their vertical and horizontal distribution differed in various aspects.

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Tracking the Deposition and Sources of Soil Carbon and Nitrogen in Highly Eroded Hilly-Gully Watershed in Northeastern China

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18062971 ◽

2021 ◽

Vol 18 (6) ◽

pp. 2971

Author(s):

Na Li ◽

Yanqing Zhang ◽

Zhanxiang Sun ◽

John Yang ◽

Enke Liu ◽

...

Keyword(s):

Organic Carbon ◽

Best Management Practices ◽

Management Practices ◽

Northeastern China ◽

Nutrient Loss ◽

N Loss ◽

N Losses ◽

Soil C ◽

Soil C And N ◽

C And N

Understanding the deposition and tracking the source of soil organic carbon (C) and nitrogen (N) within agricultural watersheds are critical for assessing soil C and N budgets and developing watershed-specific best management practices. Few studies have been conducted and reported on highly eroded hilly-gully watersheds. In this field study, a constructed dam-controlled hilly-gully watershed in northeastern China was selected to identify the sources of soil C and N losses. Soils at various land uses and landscape positions, and sediments near the constructed dam, were collected and analyzed for selected physiochemical properties, total organic carbon (TOC), total nitrogen (TN), and stable isotopes (13C and 15N). Soil C and N loss and deposition in the watershed were assessed and the relative contributions of each source quantified by a stable isotope mixing model (SIAR). Results indicated that soil C loss was primarily from cropland, accounting for 58.75%, followed by gully (25.49%), forest (9.2%), and grassland (6.49%). Soil N loss was similar to soil C, with cropland contribution of 80.58%, gully of 10.30%, grassland of 7.54%, and forest of 1.59%. The C and N deposition gradually decreased along the direction of the runoff pathway near the constructed dam, and the deposited C and N from cropland and gullies showed an order: middle-dam > bottom-dam > upper-dam and upper-dam > bottom-dam > middle-dam, respectively. A high correlation between soil TOC or TN and the sediment properties suggested that the deposition conditions could be the major factors affecting the C and N pools in the sedimentary zones. This study would provide a scientific insight to develop effective management practices for soil erosion and nutrient loss control in highly eroded agriculture watersheds.

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A Process-Based Model for Cattle Manure Compost Windrows: Part 2. Model Performance and Application

Transactions of the ASABE ◽

10.13031/trans.12058 ◽

2017 ◽

Vol 60 (3) ◽

pp. 893-913 ◽

Cited By ~ 1

Author(s):

Henry F. Bonifacio ◽

C. Alan Rotz ◽

Tom L. Richard

Keyword(s):

Management Practices ◽

Model Performance ◽

Organic Soil ◽

Cattle Manure ◽

Published Data ◽

Gaseous Emissions ◽

N Loss ◽

N Losses ◽

Percentage Points ◽

C And N

Abstract. A model was developed and incorporated into the Integrated Farm System Model (IFSM, v.4.3) that simulates important processes occurring during windrow composting of manure. The model, documented in an accompanying article, predicts changes in windrow properties and conditions and the resulting emissions of C and N. Our objective in this article was to evaluate the performance of the compost windrow model. Model predictions were compared to published data from an independent cattle manure composting study that characterized static (no turning) and turned windrows composted over a 188-day period. The model did very well in simulating C and N losses for the turned windrow treatment, with predicted and measured cumulative C losses of 78% and 77%, respectively, and cumulative N losses of 55% and 57%, respectively, by day 99 of composting. By day 188 of composting, predicted cumulative N loss (56%) differed from measured (58%) by 2 percentage points only, whereas predicted cumulative C loss matched the corresponding measured value (80%). For the static windrow treatment, the model also did well in simulating cumulative C loss by day 99, with a difference of 5 percentage points between predicted (50%) and measured (45%) values. On the other hand, there was a difference of 12 percentage points between predicted (31%) and measured (19%) cumulative N losses for the static windrow by day 99. This discrepancy in simulating N loss for the static windrow treatment was not surprising, as the NH3 biofiltration effect of the finished compost cover on the actual static windrow was not modeled. After simulating the turning of the static windrow treatment on day 99, predicted and measured cumulative N losses by day 188 were equal at 44%. With the compost windrow model as a component, IFSM can be used to evaluate gaseous emissions from composted manure as influenced by windrow management practices and environmental conditions, along with other aspects of performance, environmental impact, and economics of cattle feeding operations. Simulating different composting strategies showed that addition of dry material to the cattle manure at the start of composting and turning of the manure windrow during composting produced a more stable organic soil amendment but caused greater carbon and nitrogen losses. Keywords: Cattle manure, Composting, Emissions, IFSM, Process-based modeling.

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Climatic Controls on Stable Carbon and Nitrogen Isotope Compositions of Temperate Grasslands in Northern China

10.21203/rs.3.rs-1126749/v1 ◽

2022 ◽

Author(s):

Yuntao Wu ◽

Xiaodong Zhang ◽

Zhaoliang Song ◽

Changxun Yu ◽

Man Liu ◽

...

Keyword(s):

Plant Community ◽

Spatial Scales ◽

Northern China ◽

Biogeochemical Cycles ◽

Mean Annual Precipitation ◽

Future Research ◽

Mean Annual Temperature ◽

Stable Carbon ◽

Soil System ◽

C And N

Abstract Aims The natural abundances of stable carbon (C) and nitrogen (N) isotopes (δ13C and δ15N) are extensively used to indicate the C and N biogeochemical cycles at large spatial scales. However, the spatial patterns of δ13C and δ15N in plant-soil system of grasslands in northern China and their main driving factors are still not well understood.Methods We conducted sampling campaigns during 2016-2018 in grasslands of northern China and measured plant and soil δ13C and δ15N compositions to determine effects soil physicochemical properties and climatic factors on spatial distribution of δ13C and δ15N.Results Generally, plant and soil δ13C values increased with the decrease of mean annual precipitation (MAP). The interactions between mean annual temperature (MAT) and soil organic carbon have significant impact on soil δ13C. However, plant and soil δ15N decreased with the increase of MAT. Within all factors, the interactions between MAT and MAP on soil δ15N were significant.Conclusions Our results suggest that C cycling in grasslands of northern China is strongly mediated by plant community and MAT, because C4 species were more prevalent in arid regions. Meanwhile, N cycling is mainly directly regulated by MAT and plant community composition via its effect on the plant δ15N. All of these will provide scientific references for future research on the C and N biogeochemical cycles of temperate grassland ecosystems in northern China.

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Foliar Urea with N-(n-butyl) Thiophosphoric Triamide for Sustainable Yield and Quality of Pineapple in a Controlled Environment

Sustainability ◽

10.3390/su13126880 ◽

2021 ◽

Vol 13 (12) ◽

pp. 6880

Author(s):

Mohammad Amdadul Haque ◽

Siti Zaharah Sakimin ◽

Phebe Ding ◽

Noraini Md. Jaafar ◽

Mohd Khanif Yusop ◽

...

Keyword(s):

Nitrogen Loss ◽

Growth Yield ◽

Fruit Weight ◽

Soluble Solids ◽

Urea Solution ◽

Urease Inhibitor ◽

N Losses ◽

N Accumulation ◽

Yield And Quality

In agricultural production, nitrogen loss leads to economic loss and is a high environmental risk affecting plant growth, yield, and quality. Use of the N fertilizer with a urease inhibitor is thus necessary to minimize N losses and increase the efficiency of N. This study aimed to evaluate the effects of N-(n-butyl) Thiophosphoric Triamide (NBPT) on the growth, yield, and quality of pineapple. The experiment involved two foliar fertilizer treatments: 1% (w/v) urea solution with NBPT (2.25 mL kg−1 urea) was treated as NLU (NBPT Liquid Urea), and the same concentration of urea without NBPT served as the control. Both were applied 12 times, starting 1 month after planting (MAP) and continuing once a month for 12 months. The application of urea with NBPT notably increased the above-ground dry biomass per plant (20% and 10% at 8 and 12 MAP, respectively), leaf area per plant (23% and 15% at 8 and 12 MAP, respectively), N accumulation per plant (10%), PFPN (Partial Factor Productivity) (13%), and average fruit weight (15%) compared to the treatment with urea alone (control). The analysis of quality parameters indicated that urea with NBPT improves TSS (Total Soluble Solids) (19%), ascorbic acid (10%), and sucrose (14%) but reduces the total organic acid content (21%) in pineapple. When using urea with a urease inhibitor (NBPT), there was a significant improvement in growth, yield, quality, and nitrogen use efficiency, with the additional benefit of reduced nitrogen losses, in combination with easy handling. Hence, urea with a urease inhibitor can be used as a viable alternative for increasing pineapple yield by boosting growth with better fruit quality.

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Biological and extrinsic correlates of extinction risk in Chinese lizards

Current Zoology ◽

10.1093/cz/zoab040 ◽

2021 ◽

Author(s):

Yuxi Zhong ◽

Chuanwu Chen ◽

Yanping Wang

Keyword(s):

Body Size ◽

Extinction Risk ◽

Species Traits ◽

Geographic Range ◽

Range Size ◽

Habitat Specialization ◽

Mean Annual Precipitation ◽

Mean Annual Temperature ◽

Small Range ◽

Extrinsic Factors

Abstract China is a country with one of the most species rich reptile faunas in the world. However, nearly a quarter of Chinese lizard species assessed by the China Biodiversity Red List are threatened. Nevertheless, to date, no study has explicitly examined the pattern and processes of extinction and threat in Chinese lizards. In this study, we conducted the first comparative phylogenetic analysis of extinction risk in Chinese lizards. We addressed the following three questions: 1) What is the pattern of extinction and threat in Chinese lizards? 2) Which species traits and extrinsic factors are related to their extinction risk? 3) How can we protect Chinese lizards based on our results? We collected data on ten species traits (body size, clutch size, geographic range size, activity time, reproductive mode, habitat specialization, habitat use, leg development, maximum elevation, and elevation range) and seven extrinsic factors (mean annual precipitation, mean annual temperature, mean annual solar insolation, normalized difference vegetation index (NDVI), human footprint, human population density, and human exploitation). After phylogenetic correction, these variables were used separately and in combination to assess their associations with extinction risk. We found that Chinese lizards with small geographic range, large body size, high habitat specialization, and living in high precipitation areas were vulnerable to extinction. Conservation priority should thus be given to species with the above extinction-prone traits so as to effectively protect Chinese lizards. Preventing future habitat destruction should also be a primary focus of management efforts because species with small range size and high habitat specialization are particularly vulnerable to habitat loss.

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The interaction of seasonal rainfall and nitrogen fertiliser rate on soil N2O emission, total N loss and crop yield of dryland sorghum and sunflower grown on sub-tropical Vertosols

Soil Research ◽

10.1071/sr15286 ◽

2016 ◽

Vol 54 (5) ◽

pp. 604 ◽

Cited By ~ 23

Author(s):

G. D. Schwenke ◽

B. M. Haigh

Keyword(s):

Crop Yield ◽

Crop Production ◽

Field Experiments ◽

N2o Emission ◽

N2o Emissions ◽

N Loss ◽

N Losses ◽

Total N ◽

Tropical Regions ◽

The Impact

Summer crop production on slow-draining Vertosols in a sub-tropical climate has the potential for large emissions of soil nitrous oxide (N2O) from denitrification of applied nitrogen (N) fertiliser. While it is well established that applying N fertiliser will increase N2O emissions above background levels, previous research in temperate climates has shown that increasing N fertiliser rates can increase N2O emissions linearly, exponentially or not at all. Little such data exists for summer cropping in sub-tropical regions. In four field experiments at two locations across two summers, we assessed the impact of increasing N fertiliser rate on both soil N2O emissions and crop yield of grain sorghum (Sorghum bicolor L.) or sunflower (Helianthus annuus L.) in Vertosols of sub-tropical Australia. Rates of N fertiliser, applied as urea at sowing, included a nil application, an optimum N rate and a double-optimum rate. Daily N2O fluxes ranged from –3.8 to 2734g N2O-Nha–1day–1 and cumulative N2O emissions ranged from 96 to 6659g N2O-Nha–1 during crop growth. Emissions of N2O increased with increased N fertiliser rates at all experimental sites, but the rate of N loss was five times greater in wetter-than-average seasons than in drier conditions. For two of the four experiments, periods of intense rainfall resulted in N2O emission factors (EF, percent of applied N emitted) in the range of 1.2–3.2%. In contrast, the EFs for the two drier experiments were 0.41–0.56% with no effect of N fertiliser rate. Additional 15N mini-plots aimed to determine whether N fertiliser rate affected total N lost from the soil–plant system between sowing and harvest. Total 15N unaccounted was in the range of 28–45% of applied N and was presumed to be emitted as N2O+N2. At the drier site, the ratio of N2 (estimated by difference)to N2O (measured) lost was a constant 43%, whereas the ratio declined from 29% to 12% with increased N fertiliser rate for the wetter experiment. Choosing an N fertiliser rate aimed at optimum crop production mitigates potentially high environmental (N2O) and agronomic (N2+N2O) gaseous N losses from over-application, particularly in seasons with high intensity rainfall occurring soon after fertiliser application.

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Spatial Patterns and Drivers of Soil Chemical Properties in a Typical Hickory Plantation

10.21203/rs.3.rs-845777/v1 ◽

2021 ◽

Author(s):

Mengjiao Sun ◽

Enqing Hou ◽

Jiasen Wu ◽

Jianqin Huang ◽

Xingzhao Huang

Keyword(s):

Random Forest ◽

Soil Nutrients ◽

Spatial Patterns ◽

Abiotic Factors ◽

Soil Nutrient ◽

Parent Material ◽

Mean Annual Precipitation ◽

Nutrient Concentrations ◽

Available Phosphorus ◽

Mean Annual Temperature

Abstract Background: Soil nutrients play critical roles in regulating and improving the sustainable development of economic forests. Consequently, an elucidation of the spatial patterns and drivers of soil nutrients in these forests is fundamental to their management. For this study, we collected 314 composite soils at a 0-30 cm depth from a typical hickory plantation in Lin 'an, Zhejiang Province, China. We determined the concentrations of macronutrients (i.e., soil organic carbon, hydrolyzed nitrogen, available phosphorus, and available potassium) and micronutrients (i.e., iron, manganese, zinc, and copper.) of the soils. We employed random forest analysis to quantify the relative importance of soil-forming factors to predict the soil nutrient concentrations, which could then be extrapolated to the entire hickory region. Results: Random forest models explained 61%–88% of the variations in soil nutrient concentrations. The mean annual temperature and mean annual precipitation were the most important predictor of soil macronutrient and micronutrient concentrations. Moreover, parent material was another key predictor of soil available phosphorus and micronutrient concentrations. Mapping results demonstrated the importance of climate in controlling the spatial distribution of soil nutrient concentrations at finer scales, as well as the effect of parent material, topography, stand structure, and management measures of hickory plantations. Conclusions: Our study highlights the biotic factors, abiotic factors, and management factors control over soil macronutrient and micronutrient concentrations, which have significant implications for the sustainability of soil nutrients in forest plantations.

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Upside-down fluxes Down Under: CO<sub>2</sub> net sink in winter and net source in summer in a temperate evergreen broadleaf forest

Biogeosciences ◽

10.5194/bg-15-3703-2018 ◽

2018 ◽

Vol 15 (12) ◽

pp. 3703-3716 ◽

Cited By ~ 12

Author(s):

Alexandre A. Renchon ◽

Anne Griebel ◽

Daniel Metzen ◽

Christopher A. Williams ◽

Belinda Medlyn ◽

...

Keyword(s):

Large Scale ◽

Vegetation Index ◽

Ecosystem Respiration ◽

Vapour Pressure Deficit ◽

Summer Rainfall ◽

Mean Annual Precipitation ◽

Surface Conductance ◽

Mean Annual Temperature ◽

Eddy Covariance Method ◽

Area Index

Abstract. Predicting the seasonal dynamics of ecosystem carbon fluxes is challenging in broadleaved evergreen forests because of their moderate climates and subtle changes in canopy phenology. We assessed the climatic and biotic drivers of the seasonality of net ecosystem–atmosphere CO2 exchange (NEE) of a eucalyptus-dominated forest near Sydney, Australia, using the eddy covariance method. The climate is characterised by a mean annual precipitation of 800 mm and a mean annual temperature of 18 ∘C, hot summers and mild winters, with highly variable precipitation. In the 4-year study, the ecosystem was a sink each year (−225 g C m−2 yr−1 on average, with a standard deviation of 108 g C m−2 yr−1); inter-annual variations were not related to meteorological conditions. Daily net C uptake was always detected during the cooler, drier winter months (June through August), while net C loss occurred during the warmer, wetter summer months (December through February). Gross primary productivity (GPP) seasonality was low, despite longer days with higher light intensity in summer, because vapour pressure deficit (D) and air temperature (Ta) restricted surface conductance during summer while winter temperatures were still high enough to support photosynthesis. Maximum GPP during ideal environmental conditions was significantly correlated with remotely sensed enhanced vegetation index (EVI; r2 = 0.46) and with canopy leaf area index (LAI; r2 = 0.29), which increased rapidly after mid-summer rainfall events. Ecosystem respiration (ER) was highest during summer in wet soils and lowest during winter months. ER had larger seasonal amplitude compared to GPP, and therefore drove the seasonal variation of NEE. Because summer carbon uptake may become increasingly limited by atmospheric demand and high temperature, and because ecosystem respiration could be enhanced by rising temperatures, our results suggest the potential for large-scale seasonal shifts in NEE in sclerophyll vegetation under climate change.

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Extent and Variation of Nitrogen Losses from Non-legume Field Crops of Conterminous United States

Nitrogen ◽

10.3390/nitrogen1010005 ◽

2020 ◽

Vol 1 (1) ◽

pp. 34-51

Author(s):

Amitava Chatterjee

Keyword(s):

United States ◽

Management Strategies ◽

Application Rate ◽

Fertilizer N ◽

N Loss ◽

N Losses ◽

Field Crops ◽

N Application Rate ◽

Spatio Temporal ◽

N Management

Nitrogen (N) losses from field crops have raised environmental concerns. This manuscript accompanies a database of N loss studies from non-legume field crops conducted across the conterminous United States. Cumulative N losses through nitrous oxide-denitrification (CN2O), ammonia volatilization (CNH3), and nitrate leaching (CNO3−) during the growing season and associated crop, soil, and water management information were gathered to determine the extent and controls of these losses. This database consisted of 404, 26, and 358 observations of CN2O, CNH3, and CNO3− losses, respectively, from sixty-two peer-reviewed manuscripts. Corn (Zea mays) dominated the N loss studies. Losses ranged between −0.04 to 16.9, 2.50 to 50.9, and 0 to 257 kg N ha−1 for CN2O, CNH3 and CNO3−, respectively. Most CN2O and CNO3− observations were reported from Colorado (n = 100) and Iowa (n = 176), respectively. The highest values of CN2O, and CNO3− were reported from Illinois and Minnesota states, and corn and potato (Solanum tuberosum), respectively. The application of anhydrous NH3 had the highest value of CN2O loss, and ammonium nitrate had the highest CNO3− loss. Among the different placement methods, the injection of fertilizer-N had the highest CN2O loss, whereas the banding of fertilizer-N had the highest CNO3− loss. The maximum CNO3− loss was higher for chisel than no-tillage practice. Both CN2O and CNO3− were positively correlated with fertilizer N application rate and the amount of water input (irrigation and rainfall). Fertilizer-N management strategies to control N loss should consider the spatio-temporal variability of interactions among climate, crop-and soil types.

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