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Thicket Density [article]

Siddharth Bhaskar
2020 arXiv   pre-print
We identify the rate of growth of this shatter function, the quantity analogous to VC density, with Shelah's ω-rank.  ...  In this context, we call these two quantities thicket dimension and thicket density to emphasize the analogy.  ...  As an immediate corollary, we deduce that thicket density is integer-valued, in contrast to VC density.  ... 
arXiv:1702.03956v4 fatcat:tzuhbj5sanff3nkjopr5oa4ysu

Relations between density of rhododendron thickets and diversity of riparian forests

T.T Baker, D.H Van Lear
1998 Forest Ecology and Management  
Species richness and percent cover in the regeneration layer were inversely related to R. maximum thicket density in both Spring and Fall samplings.  ...  This study characterized the density and biomass attributes of R. maximum thickets and examined their effects on plant species richness, percent cover, and regeneration patterns within a southern Appalachian  ...  Species richness was about four times greater in plots where thicket-density was scarce than in plots where thicket-density was high.  ... 
doi:10.1016/s0378-1127(98)00259-x fatcat:5v6a747x2jghxk7iet5pnfjnby

Clonal diversity impacts coral cover in Acropora cervicornis thickets: Potential relationships between density, growth, and polymorphisms

Crawford Drury, Justin B. Greer, Iliana Baums, Brooke Gintert, Diego Lirman
2019 Ecology and Evolution  
We find that high-density aggregations called thickets are composed of up to 30 genotypes at a single site, but 47% of genotypes are also found as isolated, discrete colonies outside these aggregations  ...  These results highlight intraspecific diversity as a density-dependent factor that may impact traits important for the structure and function of coral reefs.  ...  (b) Representative photographs of thicket from Sunny Isles composed of continuous interlocking skeleton at high densities.  ... 
doi:10.1002/ece3.5035 pmid:31031924 pmcid:PMC6476746 fatcat:qbqpnnk6fbfablbjfc54gk7glu

Breeding bird communities of second‐rotation plantations at different stages of the forest cycle

Oisín F. McD. Sweeney, Mark W. Wilson, Sandra Irwin, Thomas C. Kelly, John O'Halloran
2010 Bird Study  
Bird density was significantly higher in the second rotation in all age classes except for Pre-thicket, but migrant density was significantly higher in Pre-thicket in the second rotation.  ...  Pre-thicket held significantly lower total bird density, but significantly higher migrant bird density, than this Closed canopy age class.  ...  higher migrant bird density than first-rotation Pre-thicket.  ... 
doi:10.1080/00063651003801713 fatcat:sxfviyvpjjdshh6fani5jhkriq

Mediating effects of sea urchins on interactions among corals, algae and herbivorous fish in the Moorea lagoon, French Polynesia

BD Mapstone, NL Andrew, Y Chancerelle, B Salvat
2007 Marine Ecology Progress Series  
Reducing sea urchin densities to very low levels also resulted in collapse of the coral thickets and reduced densities of the fish, although algal biomass was apparently unaffected.  ...  After 2 yr of this treatment, the coral thickets began to collapse.  ...  The interactions between sea urchin densities and thicket structure may explain some of the changes in thickets during other periods.  ... 
doi:10.3354/meps332143 fatcat:ihfbuz357vgwbehwm7gvim44lu

Pre-logging Treatment of Invasive Glossy Buckthorn (Frangula alnus Mill.) Promotes Regeneration of Eastern White Pine (Pinus strobus L.)

Thomas Lee, Stephen Eisenhaure, Ian Gaudreau
2016 Forests  
than in thickets of recovering buckthorn.  ...  Buckthorn reduction increased density and height of pine seedlings, and seedling height also increased with logging.  ...  Logging Treatment Replicate Buckthorn Treatment (Subplot) Percent of Subplot Area in Thicket Buckthorn Density (m −2 ) in Thicket Buckthorn Density (m −2 ) in Non-Thicket Buckthorn  ... 
doi:10.3390/f8010016 fatcat:pc3finaaivbhfh6irddr62fsfe

How to Measure Patent Thickets: A Novel Approach

Georg von Graevenitz, Stefan Wagner, Dietmar Harhoff
2009 Social Science Research Network  
The existing literature identifies patent thickets indirectly. In this paper we propose a novel measure based on patent citations which allows us to measure the density of patent thickets directly.  ...  Moreover, we identify technology areas which are particularly impacted by patent thickets. JEL: L13, L20, O34.  ...  The number of triples measures the density of patent thickets in a technology area.  ... 
doi:10.2139/ssrn.1434056 fatcat:3nwxbkz3bvcuhg6twjhd7zum2m

How to measure patent thickets—A novel approach

Georg von Graevenitz, Stefan Wagner, Dietmar Harhoff
2011 Economics Letters  
The existing literature identifies patent thickets indirectly. In this paper we propose a novel measure based on patent citations which allows us to measure the density of patent thickets directly.  ...  Moreover, we identify technology areas which are particularly impacted by patent thickets. JEL: L13, L20, O34.  ...  The number of triples measures the density of patent thickets in a technology area.  ... 
doi:10.1016/j.econlet.2010.12.005 fatcat:7hmyusfn5fa3zdik3hkl3expky

Population dynamics of tundra voles in relation to configuration of willow thickets in southern arctic tundra

John-André Henden, Rolf Anker Ims, Nigel Gilles Yoccoz, Raymond Sørensen, Siw Turid Killengreen
2010 Polar Biology  
Within regions, the occupancy pattern during the increase phase was positively related to willow thicket conWguration (in particular edge density and willow height) only in the region attaining the highest  ...  The lack of consistency in the response of tundra vole populations to willow thicket con-Wguration, as well as the positive relation between the degree of thicket shredding and tundra vole habitat occupancy  ...  Acknowledgments We are grateful to Knut Langeland for assistance on classiWcation of willow thickets from aerial photographs, Phillip D.  ... 
doi:10.1007/s00300-010-0908-7 fatcat:s5ktrdkn3vb2xdue5oyjwkr77a

Natural regeneration of subtropical montane forest after clearing fern thickets in the Dominican Republic

Matthew G. Slocum, T. Mitchell Aide, Jess K. Zimmerman, Luis Navarro
2004 Journal of Tropical Ecology  
Also included are densities of woody plants > 125 cm tall in the clearings and in the thickets. Densities are sorted by the total of all columns.  ...  Included are densities of woody plants > 20 cm tall in artificial clearings in the fern thickets, including densities found under trees and in the open (i.e. not under trees).  ... 
doi:10.1017/s0266467404001646 fatcat:ksqoj3nfxnhehmjocksvpjka4i

Recoupling fire and aspen recruitment after wolf reintroduction in Yellowstone National Park, USA

Joshua S. Halofsky, William J. Ripple, Robert L. Beschta
2008 Forest Ecology and Management  
to thicket edges were shorter than stems further from thicket edges.  ...  For elliptical thickets, we randomly placed our belt transect in the middle third of the thicket, perpendicular to the major axis. Each thicket was >15 m from any other thicket.  ... 
doi:10.1016/j.foreco.2008.06.002 fatcat:dht2xg6gb5hxpdhwkab7zgb6ye

Ecology of a corallivorous gastropod, Coralliophila abbreviata, on two scleractinian hosts. I: Population structure of snails and corals

Iliana B. Baums, Margaret W. Miller, Alina M. Szmant
2003 Marine Biology  
In contrast, sites with high density A. palmata stands (thickets) retained colony densities of about $1 colony m -2 among years, while snail infestation increased only from 9% to 14% of colonies surveyed  ...  When resurveyed in 1999, density of colonies in low-density stands had decreased by 75% to 0.1 colonies m -2 .  ...  decrease in colony density in low-density stands compared with thickets (Fig. 2) .  ... 
doi:10.1007/s00227-003-1024-9 fatcat:ky3a76ijlzdyrb5o65twz2ohui

Declining willow ptarmigan populations: The role of habitat structure and community dynamics

John-André Henden, Rolf Anker Ims, Nigel Gilles Yoccoz, Siw Turid Killengreen
2011 Basic and Applied Ecology  
Accordingly, we mea-285 sured the height and density of the thickets in the field at four 286 points along the side of the small quadrat lining the thicket.  ...  Furthermore, the simultaneous strong negative effect of edge density indicates that even at a high percent cover of thickets, increased shredding or fragmentation of willow thickets reduce ptarmigan patch  ... 
doi:10.1016/j.baae.2011.05.006 fatcat:wt7qoorhjbcdjnqp7sdyxfnieq

Observations on the Endemic Pygmy Three-Toed Sloth, Bradypus pygmaeus of Isla Escudo de Veraguas, Panamá

Sam Kaviar, Jakob Shockey, Peter Sundberg, Alistair Robert Evans
2012 PLoS ONE  
The population survey found low numbers of B. pygmaeus in the mangrove thickets and far lower numbers outside of them.  ...  The connectivity of subpopulations between these thickets on the island is not established, as B. pygmaeus movement data is still lacking.  ...  Thicket Area (m 2 ) Population (individual) Density (ind./100 m 2 ) Thicket 1 35094 16 0.046 Thicket 10 23095 11 0.048 Thicket 3 18533 15 0.081 Thicket 6 14224 14 0.098 Thicket  ... 
doi:10.1371/journal.pone.0049854 pmid:23185461 pmcid:PMC3504081 fatcat:tfwj4725fvd2pdw27sdytjpbuq

How Spatial Variation in Areal Extent and Configuration of Labile Vegetation States Affect the Riparian Bird Community in Arctic Tundra

John-André Henden, Nigel G. Yoccoz, Rolf A. Ims, Knut Langeland, Han YH. Chen
2013 PLoS ONE  
Thickets are however labile, as tall shrubs respond rapidly to both abiotic and biotic environmental drivers.  ...  Thickets of tall shrubs represent a conspicuous vegetation state in northern and temperate ecosystems, where it serves important ecological functions, including habitat for wildlife.  ...  Exploratory analyses of the willow thicket configuration variables showed that the fragmentation variables patch density and edge density were strongly correlated (Pearson correlation .0.7), whereas the  ... 
doi:10.1371/journal.pone.0063312 pmid:23691020 pmcid:PMC3653927 fatcat:h7ekc5v2i5eanpkry6fsdi2nbi
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