Decomposition of Eucalyptus leaf litter: influence of seasonal variation in temperature and moisture conditions

1988 ◽  
Vol 20 (3) ◽  
pp. 369-375 ◽  
Author(s):  
Jacqueline L. Orsborne ◽  
Barry J. Macauley
Keyword(s):  
Seasonal Variation ◽  
Leaf Litter ◽  
Moisture Conditions

scholarly journals Seasonal variation in the leaf-litter frog community (Amphibia: Anura) from an Atlantic Forest Area in the Salto Morato Natural Reserve, southern Brazil

2011 ◽  
Vol 28 (6) ◽  
pp. 755-761 ◽  
Author(s):  
Manuela Santos-Pereira ◽  
Adriane Candaten ◽  
Douglas Milani ◽  
Frederico B. Oliveira ◽  
Joana Gardelin ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Leaf Litter ◽  
Atlantic Forest ◽  
Forest Area ◽  
Southern Brazil ◽  
Natural Reserve

Seasonal Variation of Backcalculated Subgrade Moduli

1997 ◽  
Vol 1577 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Bing Long ◽  
Mustaque Hossain ◽  
Andrew J. Gisi
Keyword(s):  
Seasonal Variation ◽  
Moisture Content ◽  
Temperature Effect ◽  
Resilient Modulus ◽  
Natural Soil ◽  
Temperature Regimes ◽  
Almost All ◽  
Moisture Conditions ◽  
Falling Weight ◽  
And Behavior

Seasonal variations in pavement material properties and behavior due to variations in temperature and moisture conditions are known to affect the structural performance of pavement. Temperature, subgrade moisture content, and falling weight deflectometer (FWD) deflection data were collected monthly on four asphalt pavement test sections for a year. Subgrade moduli were backcalculated using the elastic layer theory with two calculation schemes and pavement models. Backcalculation of subgrade moduli by subdividing the subgrade into a compacted subgrade layer and a natural soil subgrade layer resulted in compacted subgrade moduli that are more sensitive to the seasonal variation for all sites. It was found that for almost all sites, the patterns of subgrade response, in terms of subgrade moduli versus subgrade moisture content, simulated sine-shaped forms signifying a temperature effect. The temperature effect was confirmed by the strong correlation between backcalculated subgrade moduli and pavement surface temperature during FWD tests. The lowest backcalculated subgrade moduli were obtained for two sections during months when asphalt surface temperatures were excessively high (greater than 40°C). Both backcalculation schemes showed similar trends in variation of subgrade moduli over seasons. When the AASHTO relative damage concept was used to compute the effective roadbed soil resilient modulus for design, similar values were found for both schemes for most of the sites. The minimum frequency of FWD testing to capture the seasonal variation of subgrade was found to be three tests per year, or testing every fourth month, assuming that unusually high temperature regimes could be avoided.

scholarly journals SEASONAL VARIATION IN LEAF LITTER NUTRIENT CONCENTRATIONS OF VALDIVIAN RAINFOREST TREES

2003 ◽  
Vol 60 (1) ◽  
Author(s):  
Christopher H. Lusk ◽  
Francisco Matus ◽  
María Moreno-Chacón ◽  
Alfredo Saldaña ◽  
Mylthon Jiménez-Castillo
Keyword(s):  
Seasonal Variation ◽  
Leaf Litter ◽  
Nutrient Concentrations

Aspen and pine leaf litter decomposition in laboratory microcosms. I. Linear versus exponential models of decay

1988 ◽  
Vol 66 (10) ◽  
pp. 1960-1965 ◽  
Author(s):  
Barry R. Taylor ◽  
Dennis Parkinson
Keyword(s):  
Mass Loss ◽  
Leaf Litter ◽  
Populus Tremuloides ◽  
Pinus Contorta ◽  
Exponential Model ◽  
Plant Litter ◽  
Adverse Conditions ◽  
Negative Exponential Model ◽  
Negative Exponential ◽  
Moisture Conditions

Leaf litter of trembling aspen (Populus tremuloides Michx.) and lodgepole–jack pine (Pinus contorta Loud, × P. banksiana Lamb.) was decomposed in laboratory microcosms at 2, 10, 18, or 26 °C and three watering rates (15, 30, or 60 mL∙week−1) for 16 weeks. Aspen litter lost 5.0–37.3% of original mass, and pine litter lost 7.8–14.9%. Decay curves fit a sample linear model equally as well as the negative exponential model regardless of temperature or moisture conditions or species of litter. A general explanation of circumstances promoting apparently linear mass loss from decaying plant litter is derived from these data, a survey of the literature, and the assumption that all decay curves are ultimately curvilinear. Mass loss rates are expected to appear linear from slowly decaying substrates such as bole wood or when decay of rapidly decomposing substrates is not followed past the inflection point of the curve. Climatic variables that favour decomposer activity are hypothesized to increase the concavity of decay curves, while adverse conditions do the opposite.

scholarly journals ¿Qué ocurre con el banco de semillas del suelo 17 años después del corte de la vegetación?

2015 ◽  
Vol 63 (2) ◽  
pp. 321 ◽  
Author(s):  
Leonardo Brasil Mendes ◽  
Kleber Andrade da Silva ◽  
Danielle Melo dos Santos ◽  
Josiene Maria Falcão Fraga dos Santos ◽  
Ulysses Paulino De Albuquerque ◽  
...  
Keyword(s):  
Species Richness ◽  
Seasonal Variation ◽  
Leaf Litter ◽  
Seed Bank ◽  
Soil Depth ◽  
Dry Forest ◽  
Annual Rainfall ◽  
Seed Density ◽  
Mature Forest ◽  
Young Forest

Seed banks play an important role in the resilience of potential anthropogenic areas and are influenced by seasonal variation. The spatial and temporal heterogeneity of the forests influences the richness and density of the soil seed bank, but there is a hypothesis that such influence can be changed in anthropogenic areas, where we expect to find lower richness and seed density in relation to the seed bank of mature forests. The richness and seasonal density of seeds in the soil depth of a young caatinga forest, 17 years after an agricultural activity was abandoned, were evaluated and compared with those of a mature forest. The study was conducted at the Instituto Agronômico de Pernambuco - IPA (Estação Experimental José Nilson de Melo), located in Caruaru, Pernambuco, Brazil, in an area of tropical dry forest, known locally as “caatinga”. The local climate is seasonal, the dry season occurring from September to February and the rainy season concentrated in the remaining months. The average annual rainfall over time (time series of 30 years) is 692mm. In each climatic season (rainy and dry), the seed bank was sampled in 210 20x20cm plots (105 in the leaf litter and 105 at 5cm soil depth). The richness and seed density of the soil samples were evaluated by the method of seedling emergence. The seed bank had 47 species, with a predominance of herbaceous plants. Seasonal variation in richness and seed density in the soil (leaf litter + soil) was not significant, but 42 species of the mature forest were absent from the seed bank of the young forest, despite 17 years of natural regeneration and its proximity to the mature forest. On its own, the soil has greater richness and density of seeds than the leaf litter. The depth of seed deposition in the soil bank of the young forest significantly explained 36% of the species richness and 16% of the seed density, with a significant interaction effect with the climatic season only on species richness, explaining 4% of the variation recorded. The seed density of the young forest (1 277seeds/m<sup>2</sup>) was greater than that the mature forest indicating that the time abandoned had not yet been sufficient for complete recovery of plant diversity and there is no longer any seed limitation of pioneer species for regeneration of the young forest.

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