Soil respiration in the seasonally dry tropics near Townsville, North-Queensland

Soil Research ◽  
1990 ◽  
Vol 28 (5) ◽  
pp. 737 ◽  
Author(s):  
JA Holt ◽  
MJ Hodgen ◽  
D Lamb
Keyword(s):  
Soil Respiration ◽  
Root Respiration ◽  
Respiratory Activity ◽  
Major Effect ◽  
Wet Season ◽  
Untreated Soil ◽  
Seasonally Dry ◽  
Respiration Rates ◽  
Dry Tropics ◽  
Total Soil Respiration

The contribution of root respiration to total soil respiration has been examined in an Australian tropical semi-arid woodland. Respiration rates were estimated by measuring CO2 released from untreated soil and from soil where roots had been severed and were extensively decomposed. The amount of C released as CO2 by soil respiration was estimated to be 3800 kg ha-1 year-1, and by root respiration to be 1500 kg C ha-l year-1. Soil moisture was found to have a major effect on soil respiration, with temperature being less significant. Consequently, most respiratory activity in the soil was confined to the relatively short wet season, with respiration rates being much lower during the dry season.

Diet selection by cattle grazing Stylosanthes-grass pastures in the seasonally dry tropics: effect of year, season, stylo species and botanical composition

1996 ◽  
Vol 36 (7) ◽  
pp. 781 ◽  
Author(s):  
DB Coates
Keyword(s):  
Cattle Grazing ◽  
Diet Selection ◽  
Dry Season ◽  
Major Influence ◽  
Botanical Composition ◽  
Wet Season ◽  
Seasonally Dry ◽  
Dietary Preference ◽  
Dry Tropics ◽  
Opportunity For Selection

The dietary preference of cattle grazing Stylosanthes-based pastures in the seasonally dry tropics of North Queensland was studied using faecal carbon ratios (S13C) to determine grass-legume proportions. Estimates were made at monthly intervals for several years in 1 experiment to determine the effect of year, season and botanical composition on dietary stylo proportions. In another experiment, the effect of stylo cultivars (Verano and Seca) on dietary preference was monitored for 17 months. Where pastures provided ample opportunity for selection, cattle showed a strong preference for grass in the early wet season and in the late dry season. The proportion of stylo in the diet increased during the wet season and reached peak proportions (as high as 80%) in the late wet season or early dry season. Dietary stylo proportions decreased as pastures dried off and as the stylo shed leaf or became more stemmy. The length of the wet season and the amount and distribution of rainfall had a major influence on the seasonal pattern of diet selection. Stylo rarely fell below 20% in the diet. On an annual basis, stylo accounted for about 45% of the diet which was appreciably higher than the proportion of stylo in the pasture. Dietary stylo proportions were higher on Seca-based pasture than on Verano-based pasture. The avoidance of stylo in the early wet season was less pronounced with Seca compared with Verano. Later in the season Seca was the dominant dietary component for a much longer period than Verano. The effect of botanical composition on dietary grass-legume proportions varied between and within years. Correlations between grass-legume proportions in the pasture and in the diet were highest in the late dry season and early wet season when preference for grass was strongest. At the end of the wet season when cattle preferred stylo, dietary stylo was not related to pasture stylo content except in a drought year. Averaged over the full year, dietary stylo content was significantly correlated with pasture stylo content in all years and the correlation was highest in a drought year when there was a high level of utilisation and less opportunity for selection. A simple model relating dietary stylo to pasture stylo was developed and is discussed.

scholarly journals Soil respiration at mean annual temperature predicts annual total across vegetation types and biomes

2009 ◽  
Vol 6 (6) ◽  
pp. 11501-11520
Author(s):  
M. Bahn ◽  
M. Reichstein ◽  
E. A. Davidson ◽  
J. Grünzweig ◽  
M. Jung ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Potential Evapotranspiration ◽  
Terrestrial Ecosystems ◽  
Mean Annual Temperature ◽  
Wet Season ◽  
Seasonally Dry ◽  
Soil Co2 Emissions ◽  
Annual Total ◽  
Spatio Temporal ◽  
Tropical Climates

Abstract. Soil respiration (SR) constitutes the largest flux of CO2 from terrestrial ecosystems to the atmosphere. There still exist considerable uncertainties as to its actual magnitude, as well as its spatial and interannual variability. Based on a reanalysis and synthesis of 72 site-years for 58 forests, plantations, savannas, shrublands and grasslands from boreal to tropical climates we present evidence that total annual SR is closely related to SR at mean annual soil temperature (SR MAT), irrespective of the type of ecosystem and biome. This convergence is to be theoretically expected for non water-limited ecosystems within most of the globally occurring range of annual temperature variability and sensitivity (Q10). We further show that for seasonally dry sites where annual precipitation (P) is lower than potential evapotranspiration (PET), annual SR can be predicted from wet season SR MAT corrected for a factor related to P/PET. Our finding indicates that it is sufficient to measure SR MAT for obtaining a highly constrained estimate of its annual total. This should substantially increase our capacity for assessing the spatial distribution and interannual variation of soil CO2 emissions across ecosystems, landscapes and regions, and thereby contribute to improving the spatio-temporal resolution of a major component of the global carbon cycle.

scholarly journals Contribution of root respiration to total soil respiration during non-growing season in mine reclaimed soil with different covering soil thicknesses

2020 ◽  
Author(s):  
Min Chen ◽  
Xiaoyang Chen ◽  
Zhiyong Hu ◽  
Tingyu Fan ◽  
Shiwen Zhang ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Root Respiration ◽  
Growing Season ◽  
Growth Season ◽  
Soil Thickness ◽  
Total Soil ◽  
Reclaimed Soil ◽  
Total Soil Respiration ◽  
Monthly Variations

Abstract An accurate assessment of root respiration in mine reclaimed soil is important for effectively evaluating mining area ecosystem. This study investigated dynamic changes in root respiration and contribution of root respiration to total soil respiration (Rr/Rt ratio) during the non-growth season in mine reclaimed soil with different covering soil thicknesses. According to covering soil thicknesses, the study area was divided into four sites: 10-25 cm (site A), 25-45 cm (site B), 45-55 cm (site C) and 55-65 cm (site D). From November 2017 to April 2018 (except February in 2018), the soil respiration, root respiration, temperature at 5 cm, water content and root biomass were measured. The results showed that soil temperature and root respiration exhibited similar diurnal and monthly variations. The root respiration was strongly influenced by soil temperature during the non-growing season, which showed an exponential and positive relationship with soil temperature (P<0.001). The root respiration varied with the covering soil thickness and was the greatest with the covering soil thickness at 25–45 cm. The Rr/Rt ratio also exhibited monthly variations. During the non-growth season, the mean value of the Rr/Rt ratio were 51.15% in mine reclaimed soil. The study indicated that root respiration was the primary source of soil respiration and important to estimate the potential of emission of soil CO 2 at regional scale in mine reclaimed soil.

scholarly journals Contribution of root respiration to total soil respiration during non-growing season in mine reclaimed soil with different covering soil thicknesses

2020 ◽  
Author(s):  
Min Chen ◽  
Xiaoyang Chen ◽  
Zhiyong Hu ◽  
Tingyu Fan ◽  
Shiwen Zhang ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Root Respiration ◽  
Regional Scale ◽  
Growing Season ◽  
Soil Thickness ◽  
Total Soil ◽  
Reclaimed Soil ◽  
Total Soil Respiration ◽  
Monthly Variations

Abstract An accurate assessment of root respiration in mine reclaimed soil is important for effectively evaluating mining area ecosystem. This study investigated dynamic changes in root respiration and contribution of root respiration to total soil respiration (Rr/Rt ratio) during the non-growing season in mine reclaimed soil with different covering soil thicknesses. According to covering soil thicknesses, the study area was divided into four sites: 10-25 cm (site A), 25-45 cm (site B), 45-55 cm (site C) and 55-65 cm (site D). From November 2017 to April 2018 (except February in 2018), the soil respiration, root respiration, temperature at 5 cm, water content and root biomass were measured. The results showed that soil temperature and root respiration exhibited similar diurnal and monthly variations. The root respiration was strongly influenced by soil temperature during the non-growing season, which showed an exponential and positive relationship with soil temperature (P<0.001). The root respiration varied with the covering soil thickness and was the greatest with the covering soil thickness at 25–45 cm. The Rr/Rt ratio also exhibited monthly variations. During the non-growing season, the mean value of the Rr/Rt ratio was 51.15% in mine reclaimed soil. The study indicated that root respiration was the primary source of soil respiration and important to estimate the potential emission of soil CO2 at regional scale in mine reclaimed soil.

Partitioning of total soil respiration into root, rhizosphere and basal-soil CO2 fluxes in contrasting rice production systems

Soil Research ◽  
2020 ◽  
Vol 58 (6) ◽  
pp. 592
Author(s):  
S. Neogi ◽  
P. K. Dash ◽  
P. Bhattacharyya ◽  
S. R. Padhy ◽  
K. S. Roy ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Dehydrogenase Activity ◽  
Root Respiration ◽  
Production Systems ◽  
Rice Production ◽  
Carbon Pools ◽  
Labile Carbon ◽  
Basal Soil Respiration ◽  
Total Soil ◽  
Total Soil Respiration

Soil respiration contributes significantly to ecosystem respiration and is vital in the context of climate change research. In a season-long experiment we studied total soil respiration (TSR) and its partitioning into root respiration, rhizospheric respiration (RhR) and basal-soil respiration in four contrasting rice production systems: irrigated lowland (IL) (cv. Gayatri); organic nutrient managed irrigated lowland (OIL) (cv. Geetanjali); system of rice intensification (SRI) (cv. Swarna); and aerobic rice system (Aerobic) (cv. APO). We considered TSR to be the sum of root respiration, RhR and basal-soil respiration. Irrespective of the rice production system, TSR was higher at panicle initiation stage. Considering all four systems, the RhR contributed the most (59–83%) and basal-soil respiration the least (10–19%) to the TSR. Mean RhR showed the trend of Aerobic &gt; SRI &gt; IL &gt; OIL across the growing seasons and indicated higher rhizosphere activities in the aerobic system. Mean root respiration showed a trend of IL &gt; OIL &gt; SRI &gt; Aerobic and mean basal-soil respiration had SRI &gt; IL &gt; OIL &gt; Aerobic. Soil labile carbon pools and heterotrophic populations were higher in OIL and dehydrogenase activity was higher in SRI. Microbial biomass carbon, readily mineralisable carbon, dehydrogenase activity and the heterotroph population showed positive correlations with RhR. Hence, regulation of RhR is crucial and can be achieved through rhizosphere modifications linked with labile carbon pools and soil enzymatic activities by plant physiological modification or through soil carbon stabilisation.

Limited impact of irrigation on the phenology of Brachychiton megaphyllus: a deciduous shrub that flowers while leafless during the tropical dry season

2015 ◽  
Vol 31 (5) ◽  
pp. 459-467 ◽  
Author(s):  
Patricia J. Bate ◽  
Donald C. Franklin
Keyword(s):  
Soil Moisture ◽  
Reproductive Activity ◽  
Dry Season ◽  
Reproductive Phenology ◽  
Wet Season ◽  
Canopy Development ◽  
Seasonally Dry ◽  
Dry Tropics ◽  
Tap Root ◽  
Leaf Flush

Abstract:A suite of woody plants inhabiting the seasonally dry tropics flower while leafless during the dry season, raising intriguing questions about the role of moisture limitation in shaping their phenology. Brachychiton megaphyllus is one such species, a shrub of open forests and savannas in northern Australia. We documented leaf and reproductive phenology of 14 shrubs, and irrigated a further 15, to determine if soil moisture affected leafiness and reproductive activity. Brachychiton megaphyllus showed first flower buds shortly after the cessation of wet-season rains, and budded and flowered throughout the dry season. In some plants, leaf flush occurred prior to the first rains. Rates of fruit set and maturity were very low. Irrigation did not significantly influence leaf shoot or subsequent canopy development. Contrary to expectation, irrigation decreased the production of buds and flowers though it had no impact on the production of fruit, a response for which we suggest a number of hypotheses. Phenological responses to irrigation may have been limited because B. megaphyllus responds primarily to cues other than soil moisture and is buffered against seasonal drought by a large tap root. This suggests mechanisms by which flowering while leafless may occur in a range of species.

Contributions of aboveground litter, belowground litter, and root respiration to total soil respiration in a temperate mixed hardwood forest

1993 ◽  
Vol 23 (7) ◽  
pp. 1402-1407 ◽  
Author(s):  
Richard D. Bowden ◽  
Knute J. Nadelhoffer ◽  
Richard D. Boone ◽  
Jerry M. Melillo ◽  
Jason B. Garrison
Keyword(s):  
Carbon Dioxide ◽  
Soil Respiration ◽  
Root Respiration ◽  
Root Activity ◽  
Hardwood Forest ◽  
Total Soil ◽  
Root Litter ◽  
Wide Range ◽  
Total Soil Respiration ◽  
Aboveground Litter

Estimating contributions by root respiration and root litter to total soil respiration is difficult owing to problems in measuring each component separately. In a mixed hardwood forest in Massachusetts, we added or removed aboveground litter and terminated live root activity through construction of trenches and root barriers to determine the contribution of aboveground litter, belowground litter, and root respiration to total soil respiration. Annual soil respiration at control plots, measured by the soda-lime technique, was 371 g C•m−2-year−1. We used aboveground litter inputs (138 g C•m−2year−1) and differences in carbon dioxide effluxes among treatment plots to calculate contributions to total soil respiration by live root respiration (33%) and by organic matter derived from aboveground (37%) and belowground (30%) litter. Newly deposited aboveground litter contributed 31% of the carbon dioxide emitted by total aboveground litter. This estimate is consistent with values published in litter decomposition studies. Nearly two thirds of soil respiration in this forest can be attributed to root activity, comparable with a previous study suggesting that live root respiration plus decomposition of root litter contributes 70–80% of total soil respiration across a wide range of forests.

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