Testing the Dispersion of Juveniles Relative to Adults: A New Analytic Method

Hamill, David; Wright, S. Joseph

doi:10.2307/1939817

Cited by 70 publications

(58 citation statements)

References 4 publications

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“…En un muestreo relativamente similar en dos sitios cercanos, el cual abarcó un área de 28 ha por sitio (490 vs 484 parcelas) se encontraron diferencias importantes tanto en la densidad como en la distribución espacial de plántulas y semillas del roble. Por un lado, respecto a las plántulas, que son el relejo de la dispersión de semillas una vez han ocurrido los eventos de reorganización (dispersión primaria y secundaria), germinación y establecimiento (Hamill & Wright 1986, Bleher & Böhning-Gaese 2001, se encontró una mayor abundancia y agregación en el sitio de mayor intervención (vereda Canadá) en general y para cada una de las categorías de edad (A, B y C). Además, aunque en los dos sitios se encontró una marcada disminución en la densidad de plántulas entre categorías de edad, el patrón de distribución permaneció constante.…”

Section: Discusión De Resultadosunclassified

Efecto de la intervención antrópica en la distribución de las semillas y plántulas del roble (Quercus Humboldtii Bonpl., Fagaceae) en la cordillera Oriental Colombiana

2004

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Section: Discusión De Resultadosunclassified

Efecto de la intervención antrópica en la distribución de las semillas y plántulas del roble (Quercus Humboldtii Bonpl., Fagaceae) en la cordillera Oriental Colombiana

2004

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“…The more diffuse dispersion pattern in seedlings may be the result of primary (and secondary) dispersal (cf. Hamill & Wright 1986, Peres & Baider 1997, a higher removal rate of cached seeds close to adult trees (cf. Howe & Smallwood 1982, more cotyledon predation of recently emerged seedlings at high density or close to adult trees (as cotyledons become part of the stem, cotyledon predation kills the individual; cf.…”

Section: Regeneration In Exploited Populationsmentioning

confidence: 99%

Demography of the Brazil nut tree (Bertholletia excelsa) in the Bolivian Amazon: impact of seed extraction on recruitment and population dynamics

2002

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ABSTRACT. A demographic study was carried out on Bertholletia excelsa, the Brazil nut tree, in two primary forest sites in Northern Bolivia where Brazil nuts have been harvested for several decades. In spite of the large proportion (93%) of seeds that are harvested, reasonable densities of recently emerged seedlings were found. Seeds of Bertholletia are contained in woody fruits that are primarily opened by agoutis. Most fruits are left untouched on the forest floor for 1-2 y before they are opened, possibly due to high energetic costs of fruit opening just after fruit fall. However, the proportion of viable seeds is strongly reduced in older fruits.Growth in diameter at breast height (dbh) was low for pole-sized trees (< 15 cm dbh) and adult trees (> 100 cm dbh) and peaked for intermediate-sized trees (30-60 cm). These trees often attained a growth rate of > 1.5 cm y −1 , which is high compared with other non-pioneer tropical trees. This, and the strong growth response to increased light availability found for seedlings and saplings, suggest that Bertholletia excelsa can be classified as a gap-dependent species. Matrix population models were constructed for both study populations. Population growth rates (λ) were close to one, and were most sensitive to persistence in one size category. Age estimates revealed that age at first reproduction (at dbh > 60 cm) amounts to over 120 y, and age in the last category (dbh > 160 cm) to almost 300 y. Given the continuous rejuvenation of the population, the stable population size, the high age at maturity and the long reproductive period, it is concluded that current levels of Brazil nut extraction may be sustained at least for several decades and perhaps for even longer periods.

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“…The test of relative dispersion of young and old trees compares observed and expected nearest neighbour distances (procedure of Hamill & Wright 1986). …”

Section: Spatial and Age Distributionsmentioning

confidence: 99%

Aspects of the population biology of the gregarious tree Cordia elaeagnoides in Mexican tropical deciduous forest

Groenendael¹,

Bullock²,

Perez-Jimenez

1996

J. Trop. Ecol.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Cambridge University Press is collaborating with JSTOR to digitize, preserve and extend access to Journal of Tropical Ecology.http://www.jstor.org Journal of Tropical Ecology (1996) ABSTRACT. Cordia elaeagnoides is locally important within a large area of southern Mexico as a highly gregarious canopy tree of dry forest and as a timber species. Its recruitment is problematic so studies of its reproduction and population dynamics were undertaken. The distylous flowers are apparently self-compatible, and pollination and seed dispersal are by wind. Pre-dispersal mortality is largely from embryo abortion, and post-dispersal predation is mostly by generalist rodents. Some seeds may survive in enforced dormancy for two or more years. Recruitment was apparently absent for more than a decade, but had previously occurred within established stands, where size classes were interspersed at random. Population size structure suggests that recruitment over the last century occurred in several pulses. Growth rates determined from ring counts and remeasurement of marked trees support a size-age relationship. The youngest reproductive trees are estimated to be about 18 years old, and about 5% of the present population is over 95 years old.RESUMEN. Cordia elaeagnoides es una especie gregaria del dosel muy importante localmente en la selva tropical caducifolia del sur de Mexico; ademas es maderable. Ya que su reclutamiento no es regular se llevaron a cabo estudios sobre su reproducci6n y dinamica poblacional. Las flores diestilicas aparentemente son autocompatibles y la polinizaci6n y dispersi6n de semillas son por el viento. La mortalidad predispersi6n es principalmente por aborci6n de embriones y la posterior a la dispersi6n por roedores generalistas. Aparentemente no hubo reclutamiento durante mas de una decada, pero sucedi6 anteriormente dentro de los parajes, donde arboles de diferentes clases de tamanio se encuentran entremezclados al azar. La estructura poblacional por tamanios sugiere que el reclutamiento durante el uiltimo siglo occuri6 en varios pulsos. Tasas de crecimiento determinados por conteo de anillos y por remedici6n de arboles marcados sostienen una relaci6n tamanioedad. La edad de los arboles reproductivos mas jovenes se estima en 18 afios y un 5% de la poblaci6n actual tiene mas de 95 afios.

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Testing the Dispersion of Juveniles Relative to Adults: A New Analytic Method

Cited by 70 publications

References 4 publications

Efecto de la intervención antrópica en la distribución de las semillas y plántulas del roble (Quercus Humboldtii Bonpl., Fagaceae) en la cordillera Oriental Colombiana

Efecto de la intervención antrópica en la distribución de las semillas y plántulas del roble (Quercus Humboldtii Bonpl., Fagaceae) en la cordillera Oriental Colombiana

Demography of the Brazil nut tree (Bertholletia excelsa) in the Bolivian Amazon: impact of seed extraction on recruitment and population dynamics

Aspects of the population biology of the gregarious tree Cordia elaeagnoides in Mexican tropical deciduous forest

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