A spatially explicit model of leaf litter fall in hemlock–hardwood forests

1996 ◽  
Vol 26 (11) ◽  
pp. 1905-1913 ◽  
Author(s):  
James B. Ferrari ◽  
Shinya Sugita
Keyword(s):  
Leaf Litter ◽  
Hardwood Forests ◽  
Likelihood Method ◽  
Spatially Explicit ◽  
Model Parameters ◽  
Leaf Fall ◽  
Litter Fall ◽  
Explicit Model ◽  
Spatially Explicit Model ◽  
Isolated Trees

A spatially explicit model of leaf litter fall was developed for hemlock–hardwood forests using litter-trap data from mapped forest plots and from isolated trees. The model assumes that litter declines exponentially with distance, as shown by the litter traps from isolated trees, and that a variable allometric equation describes the relationship of DBH to foliage biomass. Model parameters were estimated by a maximum likelihood method using field data from one mapped plot and then tested on a second plot. Predicted leaf fall of sugar maple (Acersaccharum Marsh.), yellow birch (Betulaalleghaniensis Britton), basswood (Tiliaamericana L.), and eastern hemlock (Tsugacanadensis (L.) Carrière) was consistent with the leaf fall measured in 20 traps (r = 0.86, 0.77, 0.95, 0.92, respectively). Data from 100 paired litter traps show the similarity of litter fall at sites 2.7 m apart; trap contents in two successive autumns were also comparable. The model results show that hemlock has the narrowest leaf-fall shadow, while basswood has the broadest. The average radius within which 90% of the leaf litter fall to a trap originates is 17.1 m. A litter fall model can be used to predict nutrient inputs to the forest floor based on a stem map, and strengthens links between population and ecosystem ecology.

scholarly journals Comparing Phylogeographic Hypotheses by Simulating DNA Sequences under a Spatially Explicit Model of Coalescence

2014 ◽  
Vol 31 (12) ◽  
pp. 3359-3372 ◽  
Author(s):  
Simon Dellicour ◽  
Chedly Kastally ◽  
Olivier J. Hardy ◽  
Patrick Mardulyn
Keyword(s):  
Dna Sequences ◽  
Spatially Explicit ◽  
Explicit Model ◽  
Spatially Explicit Model

scholarly journals Spatiotemporal dynamics of soil phosphorus and crop uptake in global cropland during the 20th century

2017 ◽  
Vol 14 (8) ◽  
pp. 2055-2068 ◽  
Author(s):  
Jie Zhang ◽  
Arthur H. W. Beusen ◽  
Dirk F. Van Apeldoorn ◽  
José M. Mogollón ◽  
Chaoqing Yu ◽  
...  
Keyword(s):  
Crop Production ◽  
Soil Phosphorus ◽  
Fertilizer Application ◽  
P Uptake ◽  
Vital Role ◽  
Spatially Explicit ◽  
Explicit Model ◽  
Spatially Explicit Model ◽  
Soil P ◽  
Crop Uptake

Abstract. Phosphorus (P) plays a vital role in global crop production and food security. In this study, we investigate the changes in soil P pool inventories calibrated from historical countrywide crop P uptake, using a 0.5-by-0.5° spatially explicit model for the period 1900–2010. Globally, the total P pool per hectare increased rapidly between 1900 and 2010 in soils of Europe (+31 %), South America (+2 %), North America (+15 %), Asia (+17 %), and Oceania (+17 %), while it has been stable in Africa. Simulated crop P uptake is influenced by both soil properties (available P and the P retention potential) and crop characteristics (maximum uptake). Until 1950, P fertilizer application had a negligible influence on crop uptake, but recently it has become a driving factor for food production in industrialized countries and a number of transition countries like Brazil, Korea, and China. This comprehensive and spatially explicit model can be used to assess how long surplus P fertilization is needed or how long depletions of built-up surplus P can continue without affecting crop yield.

scholarly journals Resource-Driven Encounters and the Induction of Disease Among Consumers

2016 ◽  
Author(s):  
Rebecca K. Borchering ◽  
Steve E. Bellan ◽  
Jason M. Flynn ◽  
Juliet R.C. Pulliam ◽  
Scott A. McKinley
Keyword(s):  
National Park ◽  
Interaction Model ◽  
Spatially Explicit ◽  
Encounter Rate ◽  
Model Parameters ◽  
Expected Number ◽  
Spatially Explicit Model ◽  
Consumer Population ◽  
Using Data ◽  
The Relationship

AbstractSubmitted Manuscript 2016. Territorial animals share a variety of common resources, which can be a major driver of conspecific encounter rates. We examine how changes in resource availability influence the rate of encounters among individuals in a consumer population by implementing a spatially explicit model for resource visitation behavior by consumers. Using data from 2009 and 2010 in Etosha National Park, we verify our model's prediction that there is a saturation effect in the expected number of jackals that visit a given carcass site as carcasses become abundant. However, this does not directly imply that the overall resource-driven encounter rate among jackals decreases. This is because the increase in available carcasses is accompanied by an increase in the number of jackals that detect and potentially visit carcasses. Using simulations and mathematical analysis of our consumer-resource interaction model, we characterize key features of the relationship between resource-driven encounter rate and model parameters. These results are used to investigate a standing hypothesis that the outbreak of a fatal disease among zebras can potentially lead to an outbreak of an entirely different disease in the jackal population, a process we refer to as indirect induction of disease.

scholarly journals A Spatially Explicit Model to Predict the Relative Risk of Golden Eagle Electrocutions in the Northwestern Plains, USA

2020 ◽  
Vol 54 (2) ◽  
pp. 110 ◽  
Author(s):  
Geoffrey Bedrosian ◽  
Jason D. Carlisle ◽  
Brian Woodbridge ◽  
Jeffrey R. Dunk ◽  
Zach P. Wallace ◽  
...  
Keyword(s):  
Relative Risk ◽  
Spatially Explicit ◽  
Explicit Model ◽  
Golden Eagle ◽  
Spatially Explicit Model ◽  
Northwestern Plains

Foliar sulfur and nitrogen along an 800-km pollution gradient

1992 ◽  
Vol 22 (11) ◽  
pp. 1761-1769 ◽  
Author(s):  
Kurt S. Pregitzer ◽  
Andrew J. Burton ◽  
Glenn D. Mroz ◽  
Hal O. Liechty ◽  
Neil W. MacDonald
Keyword(s):  
Leaf Litter ◽  
Acidic Deposition ◽  
N Deposition ◽  
Hardwood Forests ◽  
Litter Fall ◽  
Pollution Gradient ◽  
Northern Hardwood Forests ◽  
Northern Hardwood ◽  
Molar Ratios ◽  
Foliar S

Emissions of sulfur (S) and nitrogen (N) oxides in the midwestern and northeastern United States result in pronounced regional gradients of acidic deposition. The objective of this study was to determine the extent to which atmospheric deposition alters the uptake and cycling of S and N in five analogous northern hardwood forests located along one of the most pronounced regional gradients of SO42−-S and NO3−-N deposition in the United States. We tested the hypothesis that acidic deposition would alter foliar S and N ratios and nutrient cycling in aboveground litter fall. Sulfate in both wet deposition and throughfall increased by a factor of two across the 800-km deposition gradient. The July concentration of S in sugar maple (Acersaccharum Marsh.) leaves increased from about 1600 μg•g−1 at the northern research sites to 1800–1900 μg•g−1 at the southern sites. Differences in leaf litter S concentration were even more pronounced (872–1356 μg•g−1), and a clear geographic trend was always apparent in litter S concentration. The 3-year average S content of leaf litter was 63% greater at the southern end of the pollution gradient. Nitrate and total N deposition were also significantly greater at the southern end of the gradient. The concentration of N in both summer foliage and leaf litter was not correlated with N deposition, but the content of N in leaf litter was significantly correlated with N deposition. The molar ratios of S:N in mid-July foliage and leaf litter increased as atmospheric deposition of SO42−-S increased. Ratios of S:N were always much greater in leaf litter than in mid-July foliage. The molar ratios of S:N retranslocated from the canopies of these northern hardwood forests were less than those in mid-July foliage or litter fall and showed no geographic trend related to deposition, suggesting that S and N are retranslocated in a relatively fixed proportion. Significant correlations between SO42−-S deposition and foliar S concentration, S cycling, and the molar ratio of S:N in foliage suggest that sulfate deposition has altered the uptake and cycling of S in northern hardwood forests of the Great Lakes region.

scholarly journals A spatially explicit model of postdisaster housing recovery

2019 ◽  
Vol 35 (2) ◽  
pp. 150-161 ◽  
Author(s):  
Ali Nejat ◽  
Roxana J. Javid ◽  
Souparno Ghosh ◽  
Saeed Moradi
Keyword(s):  
Spatially Explicit ◽  
Explicit Model ◽  
Spatially Explicit Model ◽  
Housing Recovery
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