scholarly journals Patterns and controls of soil respiration and its temperature sensitivity in grassland ecosystems across China

2018 ◽  
Author(s):  
Jiguang Feng ◽  
Jingsheng Wang ◽  
Yanjun Song ◽  
Biao Zhu

Abstract. Soil respiration (Rs), a key process in the terrestrial carbon cycle, is very sensitive to climate change. In this study, we synthesized 54 measurements of annual Rs and 171 estimates of Q10 value (the temperature sensitivity of soil respiration) in grasslands across China. We quantitatively analyzed their spatial patterns and controlling factors in five grassland types, including temperate typical steppe, temperate meadow steppe, temperate desert steppe, alpine grassland, and warm-tropical grassland. Results showed that the mean (± SE) annual Rs was 582.0 ± 57.9 g C m−2 yr−1 across Chinese grasslands. Annual Rs significantly differed among grassland types, and positively correlated with mean annual temperature, mean annual precipitation, soil organic carbon content and aboveground biomass, but negatively correlated with latitude and soil pH (P < 0.05). Among these factors, mean annual precipitation was the primary factor controlling the spatial variation of annual Rs in Chinese grasslands. The mean contributions of growing season Rs and heterotrophic respiration to annual Rs were 78.7 % and 72.8 %, respectively. Moreover, the mean (± SE) of Q10 across Chinese grasslands was 2.60 ± 0.08, ranging from 1.03 to 8.13, and varied largely within and among grassland types, and among soil temperature measurement depths. Generally, the seasonal variation of soil respiration in Chinese grasslands cannot be well explained by soil temperature using the van't Hoff equation. Longitude and altitude were the dominant driving factors and accounted for 26.0 % of the variation in Q10 derived by soil temperature at the depth of 5 cm. Overall, our findings advance our understanding of the spatial variation and environmental control of soil respiration and Q10 across Chinese grasslands, and also improve our ability to predict soil carbon efflux under climate change on the regional scale.

2018 ◽  
Vol 15 (17) ◽  
pp. 5329-5341 ◽  
Author(s):  
Jiguang Feng ◽  
Jingsheng Wang ◽  
Yanjun Song ◽  
Biao Zhu

Abstract. Soil respiration (Rs), a key process in the terrestrial carbon cycle, is very sensitive to climate change. In this study, we synthesized 54 measurements of annual Rs and 171 estimates of Q10 value (the temperature sensitivity of soil respiration) in grasslands across China. We quantitatively analyzed their spatial patterns and controlling factors in five grassland types, including temperate typical steppe, temperate meadow steppe, temperate desert steppe, alpine grassland, and warm, tropical grassland. Results showed that the mean (±SE) annual Rs was 582.0±57.9 g C m−2 yr−1 across Chinese grasslands. Annual Rs significantly differed among grassland types, and was positively correlated with mean annual temperature, mean annual precipitation, soil temperature, soil moisture, soil organic carbon content, and aboveground biomass, but negatively correlated with soil pH (p<0.05). Among these factors, mean annual precipitation was the primary factor controlling the variation of annual Rs among grassland types. Based on the overall data across Chinese grasslands, the Q10 values ranged from 1.03 to 8.13, with a mean (±SE) of 2.60±0.08. Moreover, the Q10 values varied largely within and among grassland types and soil temperature measurement depths. Among grassland types, the highest Q10 derived by soil temperature at a depth of 5 cm occurred in alpine grasslands. In addition, the seasonal variation of soil respiration in Chinese grasslands generally cannot be explained well by soil temperature using the van't Hoff equation. Overall, our findings suggest that the combined factors of soil temperature and moisture would better predict soil respiration in arid and semi-arid regions, highlight the importance of precipitation in controlling soil respiration in grasslands, and imply that alpine grasslands in China might release more carbon dioxide to the atmosphere under climate warming.


2020 ◽  
Vol 1 (2) ◽  
pp. 171-179

Soil respiration is a major component of global carbon cycle. Therefore, it is crucial to understand the environmental controls on soil respiration for evaluating potential response of ecosystems to climate change. In a temperate deciduous forest (located in Northern-Hungary) we added or removed aboveground and belowground litter to determine total soil respiration. We investigated the relationship between total soil CO2 efflux, soil moisture, and soil temperature. Soil CO2 efflux was measured at each plot using soda-lime method. Temperature sensitivity of soil respiration (Q10) was monitored via measuring soil temperature on an hourly basis, while soil moisture was determined monthly. Soil respiration increased in control plots from the second year after implementing the treatment, but results showed fluctuations from one year to another. The effect of doubled litter was less significant than the effect of removal. Removed litter and root inputs caused substantial decrease in soil respiration. We found that temperature was more influential in the control of soil respiration than soil moisture. In plots with no litter Q10 varied in the largest interval. For treatment with doubled litter layer, temperature sensitivity of CO2 efflux did not change considerably. The effect of increasing soil temperature is more conspicuous to soil respiration in litter removal treatments since lack of litter causes greater irradiation. When exclusively leaf litter was considered, the effect of temperature on soil respiration was lower in treatments with added litter than with removed litter. Our results reveal that soil life is impacted by the absence of organic matter, rather than by an excess of organic matter. Results of CO2 emission from soils with different organic matter content can contribute to sustainable land use, considering the changed climatic factors caused by global climate change.


2020 ◽  
Author(s):  
Haoming Yu ◽  
Yunting Fang ◽  
Ronghua Kang

&lt;p&gt;N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt; Emissions from soil in terrestrial ecosystems is a crucial component of the global nitrogen (N) cycle. The response of these two gases emissions from forest soil to temperature change and its underlying mechanisms are essential for predicting N cycle to global warming. Despite the warming-induced effects on soil N cycle is considered to be positive in general, our understanding of temperature sensitivity (Q&lt;sub&gt;10&lt;/sub&gt;) of N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt; emissions is rather limited. We quantified the Q&lt;sub&gt;10&lt;/sub&gt; of N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt; emissions in forest soils and explored their major driving factors by conducting an incubation experiment using &lt;sup&gt;15&lt;/sup&gt;N tracer (Na&lt;sup&gt;15&lt;/sup&gt;NO&lt;sub&gt;3&lt;/sub&gt;) with soil samples from nineteen forest sites from temperate to tropical zones. The environmental conditions largely varied: mean annual temperature (MAT) ranging from -5.4 to 21.5&lt;sup&gt;o&lt;/sup&gt;C and mean annual precipitation (MAP) ranging from 300 to 2449 mm. The soil pH varied between 3.62 to 6.38. We incubated soil samples under an anaerobic condition with temperature from 5 to 35&lt;sup&gt;o&lt;/sup&gt;C with an interval of 5&lt;sup&gt;o&lt;/sup&gt;C for 12 or 24 hours, respectively. Soil temperature strongly affected the production of N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt;.&amp;#160;N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt; production rates showed a positive exponential relation with incubate time and temperature for all forest soils. Our results showed that the Q&lt;sub&gt;10&lt;/sub&gt; values ranged from 1.31 to 2.98 for N&lt;sub&gt;2&lt;/sub&gt;O emission and 1.69 to 3.83 for N&lt;sub&gt;2&lt;/sub&gt; emission, indicating a generally positive feedback of N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt; production to warming. Higher Q&lt;sub&gt;10&lt;/sub&gt; values for N&lt;sub&gt;2&lt;/sub&gt; than N&lt;sub&gt;2&lt;/sub&gt;O implies that N&lt;sub&gt;2&lt;/sub&gt; emission is more sensitive to temperature increase. The N&lt;sub&gt;2&lt;/sub&gt;O/(N&lt;sub&gt;2&lt;/sub&gt;O+N&lt;sub&gt;2&lt;/sub&gt;) decreased with increasing temperature in fifteen of nineteen forest soils, suggesting that warming accelerates N&lt;sub&gt;2&lt;/sub&gt; emission. Strong spatial variation in Q&lt;sub&gt;10&lt;/sub&gt; were also observed, with tropical forest soils exhibiting high Q&lt;sub&gt;10&lt;/sub&gt; values and relatively low Q&lt;sub&gt;10&lt;/sub&gt; in temperate forest soils. This variation is attributed to the inherent differences in N biogeochemical cycling behavior between the microbial communities among sites. Despite soil temperature primarily controls the N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt; emissions,&amp;#160;we &amp;#160;explored the effects of other factors such as pH, C/N, DOC and related functional genes. In addition, we partitioned N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt; emissions to different microbial processes (e.g., denitrification, co-denitrification and anammox).&amp;#160;The results indicated that denitrification was the main pathway of N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sub&gt;2&lt;/sub&gt; production under anaerobic environment and the contribution increased as temperature rise.&lt;/p&gt;&lt;p&gt;Key words: Temperature sensitivity, N&lt;sub&gt;2&lt;/sub&gt;O, N&lt;sub&gt;2&lt;/sub&gt;, Forest soil, Nitrogen cycle, Global warming, Denitrification&lt;/p&gt;


2020 ◽  
Vol 47 (2) ◽  
pp. 418
Author(s):  
Juan M. Robledo ◽  
Maricel Y. Horn ◽  
Claudia I. Galli ◽  
Luisa M. Anzótegui

The continental sedimentary rocks that constitute the Palo Pintado Formation of the late Miocene from Salta province, presents a great paleoclimatic interest due to the environmental conditions prevailing during this geochronologic interval. The geological and paleobotanical data suggest that during the sedimentary rocks accumulation of the Palo Pintado Formation (Angastaco Basin), wetter conditions would have existed comparing with other nearby and contemporary Formations, for example the Playa del Zorro Aloformation (late Miocene of Catamarca) and the Chiquimil (late Miocene of Tucumán), Salicas and the Toro Negro Formations (both from the late Miocene of La Rioja). In this study, the margin and the foliar area of the leaves contained on rocks from the Palo Pintado Formation are analyzed, in order to obtain the mean annual temperature (MAT) and the mean annual precipitation (MAP). The resulting values were: 23.98 °C and 330.8 mm. These results are coincident by the interpretation of different authors, who consider that the Palo Pintado Formation would have been deposited under a relatively humid environment, possibly as a consequence of the rains that affected locally the Angastaco basin región.


2018 ◽  
Author(s):  
Kashif Jamal ◽  
Shakil Ahmad ◽  
Xin Li ◽  
Muhammad Rizwan ◽  
Hongyi Li ◽  
...  

Abstract. Climate change has significant impacts on hydrology in high altitude snow and glacier covered mountainous regions. These regions are highly sensitive to changes in climate variables, such as temperature and precipitation and producing high runoffs. Runoff produced from different altitude ranges and their sensitivity to current and changing climate is also unknown. This study was carried out in high altitude mountainous cryosphere Hunza River Catchment (HRC) which is located in Hindukush and Karakoram ranges and is the major tributary of the Indus River Basin. Snowmelt-Runoff Model (SRM) was used to analyse the current and projected hydrological regimes and the sensitivity of Snow Cover Area (SCA) at different altitude levels under current and changing climate. Under the current condition (i.e., 2001–2010 except 2006), the results showed that about half of the mean annual streamflows at the outlet of the HRC is contributed by the altitude ranges of 4500–5500 m a.s.l. Climatic projections under the RCP8.5 and RCP4.5 scenarios were used for the climate change impact assessment. Compared to the baseline climate, the mean annual temperature would increase by 0.7 (0.6), 2.4 (1.3) and 4.6 (1.9) ℃, respectively during 2030s, 2060s and 2090s; and the mean annual precipitation would increase by 63.3 (33.6) mm during 2090s under the RCP8.5 (RCP4.5) projections. Moreover, two SCA scenarios were developed, i.e., the baseline unchanged SCA and the hypothetical change in SCA scenarios. In the first SCA scenario, the results showed that additional streamflows of 43 (34), 153 (83.4) and 304 (115.7) m3 s−1 under RCP8.5 (RCP4.5) will be added into baseline annual streamflows of 269 m3 s−1 during 2030s, 2060s and 2090s, respectively. In the second scenario, we found that 10 % and 15 % decrease in SCA would result in increases (or decrease) in streamflows approximately by 18 (2) % and 42 (7) % under the RCP8.5 (RCP4.5) scenario during 2060s and 2090s, respectively. Whereas altitude range 4500–5500 m a.s.l showed increasing trend during pre-monsoon (April–June) and monsoon (July–August) season under changed SCA scenario for both RCPs scenarios. Current and near future climate pattern is favourable for Indus River regarding high water flows. However, future water flow pattern is declining because of disappearance or decrease in snow and glaciers melt area which correspondingly means that mid/downstream water allocation will be effected or reduced at some extent. Proper adaptations or managements strategies should be executed for upcoming harsh conditions.


2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Zhiyong Wu ◽  
Heng Xiao ◽  
Guihua Lu ◽  
Jinming Chen

The water resources in the Yellow River basin (YRB) are vital to social and economic development in North and Northwest China. The basin has a marked continental monsoon climate and its water resources are especially vulnerable to climate change. Projected runoff in the basin for the period from 2001 to 2030 was simulated using the variable infiltration capacity (VIC) macroscale hydrology model. VIC was first calibrated using observations and then was driven by the precipitation and temperature projected by the RegCM3 high-resolution regional climate model under the IPCC scenario A2. Results show that, under the scenario A2, the mean annual temperature of the basin could increase by 1.6°C, while mean annual precipitation could decrease by 2.6%. There could be an 11.6% reduction in annual runoff in the basin according to the VIC projection. However, there are marked regional variations in these climate change impacts. Reductions of 13.6%, 25.7%, and 24.6% could be expected in the regions of Hekouzhen to Longmen, Longmen to Sanmenxia, and Sanmenxia to Huayuankou, respectively. Our study suggests that the condition of water resources in the YRB could become more severe in the period from 2001 to 2030 under the scenario A2.


2019 ◽  
Vol 156 (3) ◽  
pp. 299-314 ◽  
Author(s):  
Gabriel Rondeau-Genesse ◽  
Marco Braun

Abstract The pace of climate change can have a direct impact on the efforts required to adapt. For short timescales, however, this pace can be masked by internal variability (IV). Over a few decades, this can cause climate change effects to exceed what would be expected from the greenhouse gas (GHG) emissions alone or, to the contrary, cause slowdowns or even hiatuses. This phenomenon is difficult to explore using ensembles such as CMIP5, which are composed of multiple climate models and thus combine both IV and inter-model differences. This study instead uses CanESM2-LE and CESM-LE, two state-of-the-art large ensembles (LE) that comprise multiple realizations from a single climate model and a single GHG emission scenario, to quantify the relationship between IV and climate change over the next decades in Canada and the USA. The mean annual temperature and the 3-day maximum and minimum temperatures are assessed. Results indicate that under the RCP8.5, temperatures within most of the individual large ensemble members will increase in a roughly linear manner between 2021 and 2060. However, members of the large ensembles in which a slowdown of warming is found during the 2021–2040 period are two to five times more likely to experience a period of very fast warming in the following decades. The opposite scenario, where the changes expected by 2050 would occur early because of IV, remains fairly uncommon for the mean annual temperature, but occurs in 5 to 15% of the large ensemble members for the temperature extremes.


2017 ◽  
Vol 30 (17) ◽  
pp. 6683-6700 ◽  
Author(s):  
Qingyu Guan ◽  
Xiazhong Sun ◽  
Jing Yang ◽  
Baotian Pan ◽  
Shilei Zhao ◽  
...  

Airborne dust derived from desertification in northern China can be transported to East Asia and other regions, impairing human health and affecting the global climate. This study of northern China dust provides an understanding of the mechanism of dust generation and transportation. The authors used dust storm and climatological data from 129 sites and normalized difference vegetation index (NDVI) datasets in northern China to analyze spatiotemporal characteristics and determine the main factors controlling dust storms occurring during 1960–2007. Dust storm–prone areas are consistent with the spatial distribution of northern China deserts where the average wind speed (AWS) is more than 2 m s−1, the mean annual temperature (MAT) ranges from 5° to 10°C, and the mean annual precipitation (MAP) is less than 450 mm. Dust storms commonly occur on spring afternoons in a 3- to 6-h pattern. The three predominant factors that can affect DSF are the maximum wind speed, AWS, and MAT. During 1960–2007, dust storm frequency (DSF) in most regions of northern China fluctuated but had a decreasing trend; this was mainly caused by a gradual reduction in wind speed. The effect of temperature on DSF is complex, as positive and negative correlations exist simultaneously. Temperatures can affect source material (dust, sand, etc.), cyclone activity, and vegetation growth status, which influence the generation of dust storms. NDVI and precipitation are negatively correlated with DSF, but the effect is weak. Vegetation can protect the topsoil environment and prevent dust storm creation but is affected by the primary decisive influence of precipitation.


1999 ◽  
Vol 29 (11) ◽  
pp. 1660-1668 ◽  
Author(s):  
Gerald E Rehfeldt ◽  
Nadja M Tchebakova ◽  
Leonard K Barnhardt

Growth and survival of eight populations of Larix sukaczewii Dylis and one of both Larix sibirica Ledeb. and Larix gmelinii (Rupr.) Rupr. were used to assess the effectiveness of climate transfer functions for predicting the 13-year performance of Eurasian provenances introduced to Alberta. Quadratic regression models showed that transfer distances for five climate variables (mean annual temperature, degree-days <0°C, mean temperature in the coldest month, ratio of the mean annual temperature to mean annual precipitation, and the summer-winter temperature range) were particularly effective in predicting height and survival. Optimal transfer distances did not differ significantly from zero, and as a result, the best growth and survival in Alberta should be obtained by matching the provenance climate to that of the planting site for the five variables. Verification of the climate transfer functions with independent data from Russian provenance tests were strongly supportive. The results demonstrate the effectiveness of climate transfer functions for describing the response of plant populations to the environment and thereby have practical implications in reforestation.


2020 ◽  
Author(s):  
Lisa Zwanzig ◽  
Martin Zwanzig ◽  
Daniela Sauer

&lt;p&gt;Soil formation is controlled by climate, vegetation, organisms, topography, parent material and time. There are various hypotheses on the relative importance of these individual soil-forming factors. The quantitative influence of each soil-forming factor on the expression and rates of soil-forming processes, and in particular the influence of the different factors in combination, have not yet been sufficiently analyzed. The aim of this study was to quantify the influence of the soil-forming factors on the rates of podzolization. For this purpose, we compiled published data from 46 soil chronosequence studies in a database. These studies contained altogether 231 soil profiles of known age, on which we tested existing hypotheses on the influence of different soil-forming factors. The formation of an E horizon and its increase in thickness over time is one of the characteristic features of Podzol formation. As it is one of the few features that was described in all 46 studies, we used it as an indicator of progressive podzolization. Through statistical analysis, we investigated how E horizon thickness is affected by latitude, longitude, mean annual precipitation, mean annual temperature, range between minimum and maximum monthly temperature, annual number of days with frost, vegetation class (pioneer, deciduous and coniferous), sand content, clay content, and soil age.&lt;/p&gt;&lt;p&gt;Since E horizon thickness exhibited a zero-inflated (semi-)continuous distribution, we opted for a zero-altered gamma (ZAG) model, consisting of a Bernoulli and a Gamma part. The Bernoulli part shows, how the probability of the presence of an E horizon changes with soil age and environmental conditions. The Gamma part of the ZAG model allows for capturing the effects of the covariates on E horizon thickness. Our results indicate that vegetation is the most important factor for both (1) the soil age at which podzolization starts (used indicator: first occurrence of an E horizon), and (2) the rates of podzolization thereafter (used measure: increase of E horizon thickness with soil age). Climatic factors such as mean annual precipitation and range of temperature play subordinate roles. They are important for the soil age at which podzolization starts but less important for the rates of podzolization. We did not identify a significant influence of sand content, neither on the start nor the rates of podzolization. Thus, this statistical assessment of global data provides new insights into the relative importance of the individual soil-forming factors on the onset and temporal course of podzolization.&lt;/p&gt;


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