Seed and seedling ecology of piñon and juniper species in the pygmy woodlands of western North America

Chambers, Jeanne C.; Wall, Stephen B. Vander; Schupp, Eugene W.

doi:10.1007/bf02856556

Cited by 155 publications

(180 citation statements)

References 87 publications

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“…El establecimiento de los nuevos reclutas, o individuos que entran a la población, es un proceso crítico en la vida de las plantas debido a que depende en gran parte de micrositios óptimos que brinden nutrientes y protección necesaria para la germinación, el crecimiento y la supervivencia de las semillas y las plántulas (Eriksson y Ehrlen, 1992;Chambers y MacMahon, 1994;Begon et al, 1995;Schupp, 1995, Chambers et al, 1999Fenner y Thompson 2005). En ambientes con condiciones ambientales drásticas como los páramos, el reclutamiento de las plántulas es un factor limitante en la dinámica de las poblaciones, sin embargo, son poco los estudios sobre las estrategias que les permiten a las semillas y las plántulas persistir en estos ambientes (Vargas y Pérez-Martínez, 2014).…”

Section: Discussionunclassified

CARACTERIZACIÓN DE MICROSITIOS PARA EL ESTABLECIMIENTO DE PLÁNTULAS DE Espeletia uribei (Asteraceae)

Maya¹,

Gómez²

2016

Acta biol. Colomb.

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RESUMENCon el fin de determinar si los micrositios de establecimiento están limitando el reclutamiento de las plántulas y la regeneración de Espeletia uribei, un frailejón endémico y valor objeto de conservación del Parque Nacional Natural Chingaza, se evaluaron diez variables bióticas y abióticas dentro de micrositios con plántulas y micrositios vacíos. Las variables que más se relacionaron con el establecimiento fueron: la distancia al adulto reproductivo más cercano, el tipo de zona de luz "abierta" y la estructura de vegetación "herbácea" asociada. La distancia al adulto reproductivo más cercano dificulta que las semillas alcancen micrositios más alejados debido al tipo de dispersión primaria barócora de la especie. Zonas de luz "abiertas" y vegetación asociada herbácea condicionaron la capacidad de germinación y establecimiento de la especie. Los resultados mostraron que el reclutamiento de E. uribei está limitado por la disponibilidad de micrositios que reúnan estas condiciones, un factor que es importante considerar para el planteamiento de futuros proyectos de manejo para la conservación y restauración de las poblaciones de la especie.Palabras clave: distancia al adulto, frailejón, luz, microhábitat, páramo, reclutamiento, vegetación asociada. ABSTRACTIn order to determine whether microsites are limiting seedling recruitment and regeneration of Espeletica uribei (an endemic frailejon, a valuable species subject to conservation in the Parque Nacional Natural Chingaza) ten biotic and abiotic variables were evaluated from E. uribei seedling microsites as well as from sites without seedlings. The variables associated with seedling establishment were distance from the nearest reproductive adult, the quality of exposure to light, and associated herbaceous structure. Reduced distances from the nearest reproductive adult made it difficult for the seeds to reach distant microsites due to the principle wind dispersal type (anemochory). Open gaps and associated herbaceous structure positively affect the germination capacity and establishment of the species. The results suggest that E. uribei recruitment is limited by the availability of microsites that meet these conditions. These are important factors to consider when planning future projects for the conservation and restoration of this species.

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Section: Discussionunclassified

CARACTERIZACIÓN DE MICROSITIOS PARA EL ESTABLECIMIENTO DE PLÁNTULAS DE Espeletia uribei (Asteraceae)

Maya¹,

Gómez²

2016

Acta biol. Colomb.

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“…Moreover, juniper may have much higher migration potential than our analysis indicates. For the slower juniper we can probably not ignore mammalian dispersers [31] and passive dispersal agents (such as runoff and streams for dispersing juniper berries, see [5]). The two main avian juniper dispersers, American robins and cedar waxwings, both forage and defecate locally and therefore do not seem to make a large contribution to juniper spread.…”

Section: Discussionmentioning

confidence: 99%

“…In both species birds play a major, but different, role. Junipers produce seeds which are available most of the winter, and consequently many birds (particularly American robins, Turdus migratorius, and cedar waxwings, Bombycilla cedrorum) consume juniper berries [5]. The berries are then digested and seeds are deposited some time later by defecation.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Model of Seed Dispersal by Frugivorous Birds and Migration Potential of Pinyon and Juniper in Utah

Neupane¹,

Powell²

2015

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Seed dispersal of juniper and pinyon is a process in which frugivorous birds play an important role. Birds either consume and digest seeds or carry and cache them at some distance from the source tree. These transported and settled seeds can be described by a dispersal kernel, which captures the probability that the seed will move a certain distance by the end of the process. To model active seed dispersal of this nature, we introduce handling time probabilities into the dispersal model to generate a seed digestion kernel. In the limit of no variability in handling time the seed digestion kernel is Gaussian, whereas for uniform variability in handling time the kernel approaches a Laplace distribution. This allows us to standardize spatial movement (diffusion) and handling time (peak settling rate) parameters for all three distributions and compare. Analysis of the tails indicates that the seed digestion kernel decays at a rate intermediate between Gaussian and Laplace seed kernels. Using this seed digestion kernel, we create an invasion model to estimate the speed at which juniper and pinyon forest boundaries move. We find that the speed of seed invasion corresponding to the digestion kernel was faster than seeds resulting from Laplace and Gaussian kernels for more rapidly digested seeds. For longer handling times the speeds are bounded between the Laplace (faster) and Gaussian (slower) speeds. Using parameter values from the literature we evaluate the migration potential of pinyon and juniper, finding that pinyon may be able to migrate up to two orders of magnitude more rapidly, consistent with observations of pine migration during the Holocene.

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“…The P. pinea seeds appeared to be extraordinarily sensitive to favourable conditions for germination, even after long periods of adverse conditions, suggesting an absence of dormant pine nuts. Non-dormancy behaviour has been reported for different pine species Chambers et al 1999), although dormancy is not an uncommon mechanism within the genus (Cooke et al 2002;Krakowski and ElKassaby 2005;Skordilis and Thanos 1995).…”

Section: Ecological and Management Implicationsmentioning

confidence: 99%

A silviculture-oriented spatio-temporal model for germination in Pinus pinea L. in the Spanish Northern Plateau based on a direct seeding experiment

Manso

Calama²,

Madrigal³

et al. 2013

Eur J Forest Res

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Natural regeneration in Pinus pinea stands commonly fails throughout the Spanish Northern Plateau under current intensive regeneration treatments. As a result, extensive direct seeding is commonly conducted to guarantee regeneration occurrence. In a period of rationalization of the resources devoted to forest management, this kind of techniques may become unaffordable. Given that the climatic and stand factors driving germination remain unknown, tools are required to understand the process and temper the use of direct seeding. In this study, the spatio-temporal pattern of germination of P. pinea was modelled with those purposes. The resulting findings will allow us to (1) determine the main ecological variables involved in germination in the species and (2) infer adequate silvicultural alternatives. The modelling approach focuses on covariates which are readily available to forest managers. A two-step nonlinear mixed model was fitted to predict germination occurrence and abundance in P. pinea under varying climatic, environmental and stand conditions, based on a germination data set covering a 5-year period. The results obtained reveal that the process is primarily driven by climate variables. Favourable conditions for germination commonly occur in fall although the optimum window is often narrow and may not occur at all in some years. At spatial level, it would appear that germination is facilitated by high stand densities, suggesting that current felling intensity should be reduced. In accordance with other studies on P. pinea dispersal, it seems that denser stands during the regeneration period will reduce the present dependence on direct seeding.

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Seed and seedling ecology of piñon and juniper species in the pygmy woodlands of western North America

Cited by 155 publications

References 87 publications

CARACTERIZACIÓN DE MICROSITIOS PARA EL ESTABLECIMIENTO DE PLÁNTULAS DE Espeletia uribei (Asteraceae)

CARACTERIZACIÓN DE MICROSITIOS PARA EL ESTABLECIMIENTO DE PLÁNTULAS DE Espeletia uribei (Asteraceae)

Mathematical Model of Seed Dispersal by Frugivorous Birds and Migration Potential of Pinyon and Juniper in Utah

A silviculture-oriented spatio-temporal model for germination in Pinus pinea L. in the Spanish Northern Plateau based on a direct seeding experiment

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