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Parent Trees (parent + tree)
Selected AbstractsSeedling survival in Manilkara butugi Chiov. along a dispersal gradient in Kakamega forest, KenyaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2010Geoffery M. Wahungu Abstract The spatial patterns of seedling distribution in Manilkara butugi were studied between December 2004 and April 2005 at Kakamega forest, Kenya. Our objectives were to determine the spatial variation in seedling density in relation to distance from the parent tree and the survivorship patterns of M. butugi seedlings. We hypothesized that seedling density and mortality would be highest beneath the parent tree and would reduce with increasing distance from the parent tree. Line transects, radiating along the four compass directions from mature female M. butugi trees were established, and quadrats marked out at intervals of 5 m in which seedlings were counted. To determine establishment and survivorship, belt transects 5 m × 40 m running along the northerly compass direction were laid and data collected on seedling variables. Seedling density reduced with increasing distance from the parent plant (F = 25.72, df = 3; P < 0.001). Whereas seedling height (F = 14.806, df = 1; P < 0.05) and the number of leaves (F = 12.45, df = 1; P < 0.05) increased with increasing distance from the parent tree, damage to seedlings reduced with increasing distance (F = 27.59, P < 0.05). Our results were consistent with the Janzen,Cornell escape hypothesis and have implications for natural regeneration of M. butugi and to maintenance of species diversity. Résumé Entre décembre 2004 et avril 2005, on a étudié le schéma spatial de la distribution de jeunes plants de Manilkara butugi dans la forêt de Kakamega, au Kenya. Notre objectif était de déterminer la variation spatiale de la distribution de la densité des jeunes plants en fonction de la distance par rapport à l'arbre parent et le schéma de la survie des jeunes plants de M. butugi. Nous avions émis l'hypothèse que la densité et la mortalité des jeunes plants seraient maximales sous l'arbre parent et qu'elles iraient en diminuant quand la distance augmenterait par rapport à lui. Nous avons défini des transects en ligne, rayonnant dans les quatre directions de la boussole à partir de M. butugi femelles adultes, et délimité tous les cinq mètres des quadrats où les jeunes plants furent comptés. Pour déterminer l'établissement et la survie, des transects en bandes de 5m x 40m ont été définis le long de la direction nord et nous avons récolté des données sur des variables concernant les jeunes plants. La densité des jeunes plants diminuait avec l'éloignement par rapport à l'arbre parent (F = 25.72; ddl = 3; P < 0.001). Alors que la hauteur des jeunes plants (F = 14.806; ddl = 1; P < 0.05) et le nombre de feuilles (F = 12.45, ddl = 1; P < 0.05) augmentaient avec la distance les séparant de l'arbre parent, les dommages causés aux jeunes plants diminuaient (F = 27.59; P < 0.05). Nos résultats concordent avec l'hypothèse d'évitement de Janzen-Connell et ils ont des implications pour la régénération naturelle de M. butugi et pour la préservation de la diversité des espèces. [source] Patterns of Seed Dispersal and Dispersal Failure in a Hawaiian Dry Forest Having Only Introduced BirdsBIOTROPICA, Issue 4 2010Charles G. Chimera ABSTRACT Dry forests are among the most endangered natural communities in the Hawaiian Islands. Most have been reduced to isolated trees and small forest fragments in which native tree species reproduce poorly. The replacement of native birds by introduced generalists may be contributing to dry forest decline through modification of seed dispersal patterns. To document seed dispersal by introduced birds, we conducted foraging observations on fleshy-fruited trees and measured seed rain under trees and in adjacent open areas for 1 year in a dry forest dominated by native trees. Although trees covered only 15.2 percent of the study area, 96.9 percent of the bird-dispersed seeds were deposited beneath them. The Japanese white-eye (Zosterops japonicus) was the principal dispersal agent. Among bird-dispersed seeds, those of the invasive tree Bocconia frutescens accounted for 75 percent of all seeds collected beneath trees (14.8 seeds/m2/yr) and the invasive shrub Lantana camara accounted for 17 percent. Although nearly 60 percent of the reserve's native woody species possess fleshy fruits, introduced birds rarely disperse their seeds. Native trees accounted for <8 percent of all bird-dispersed seeds and are consequently experiencing dispersal failure by falling directly under parent trees. Smaller-seeded non-native plants, in contrast, may be benefiting from dispersal by introduced birds. Current dispersal patterns suggest that these readily disseminated non-native plants may eventually replace the remaining native flora. [source] Seed Dispersal of the Palm Syagrus romanzoffiana by Tapirs in the Semi-deciduous Atlantic Forest of ArgentinaBIOTROPICA, Issue 4 2009Mariano I. Giombini ABSTRACT Vertebrates play a fundamental role in the dispersal of Neotropical trees, generating different seed shadows according to their physical and behavioral features. Tapirs are capable of consuming great quantities of large fruits, and they defecate seeds far from parent trees. For instance, intact seeds of the palm Syagrus romanzoffiana have been found in tapir dung piles in the Atlantic Forest of southeastern Brazil, suggesting that tapirs effectively disperse this species. However, recruitment was not examined therein. We studied tapir endozoochory of large and medium seeds in the semi-deciduous Atlantic Forest of Argentina by examining dung piles found within Iguazu National Park. We recorded dung-pile positions to evaluate the spatial distribution. We also counted the number of juveniles in 2 × 2 m quadrats placed on old dung piles in latrines, beneath adults and in random sites to estimate recruitment levels. Syagrus romanzoffiana seeds were present in 98 percent of dung piles, averaging >200 seeds/dung pile, indicating that this species constitutes the main fruit component in the tapir's diet. Dung piles showed a clumped deposition pattern reflecting the use of latrines. Juvenile recruitment in latrines was 21 times higher than that of under-adult sites and 500 times greater than in random sites, and correlated with the frequency of use of the areas. We concluded that the lowland tapir is a major disperser of S. romanzoffiana. Given that this palm can be considered a keystone species, a disruption of this interaction might affect the entire community of frugivores in the long term. [source] Seed Dispersal of a High Quality Fruit by Specialized Frugivores: High Quality Dispersal?,BIOTROPICA, Issue 2 2000Daniel G. Wenny ABSTRACT Dispersal quality, as estimated by the cumulative effects of dispersal, germination, seed predation, and seedling survival, was examined for Beilschmiedia pendula (Lauraceae) in Monteverde, Costa Rica. I determined the pattern of dispersal by finding seeds deposited by birds, protected the seeds from seed predators with cages to assess germination and seedling survival, and examined seed predation rates with marked seeds. Seed predation, germination, and seedling survival were compared between seeds naturally dispersed by birds and seeds placed at randomly located sites. Approximately 70 percent of seeds dispersed by birds (N= 244) were deposited <10 m from crown edges of fruiting B. pendula trees, although some seeds were dispersed at least 70 m away. Larger seeds were more likely to be dispersed under or close to the parent trees, and larger seeds produced larger seedlings. Seed size was not correlated directly with seedling survival, but larger seedlings at three months were most likely to survive one year. Seed predation by mammals and insects and seedling mortality due to fungal pathogens were concentrated beneath the crowns of parent trees. Seedlings and saplings were more abundant beneath fruiting B. pendula trees, but individuals farther away were taller on average. Thus, dispersal is beneficial for B. pendula, but such benefits appear most pronounced at a small spatial scale; seeds dispersed >30 m from the crown edges actually had a lower probability of survival than those dispersed 10,20 m. Only 10 percent of B. pendula. seeds received high-quality dispersal in terms of landing in the zone with the highest per seed probability of seedling survival 10,20 m from parental crowns. RESUMEN La calidad de dispersión, estimado del efecto acurnulativo de dispersión, germinación, predación de semillas, y sobrevivencia de plantulas fue examinada por Beikcbmiedia pendula (Lauracea) en Monteverde, Costa Rica. Determinté el partén de disperstón, encontrando semillas defecadas o regurgitadas por aves, protegi semillas de predatores con jaulas para determinar germinación y sobrevivencia de plantulas, y examiné la proporción de predación de semillas con semillas marcadas. Predación de semillas, germinación y sobrevivencia de plantulas fueron comparadas con semillas dispersadas naturalmente por aves y con semillas localizadas en lugares al azar. Aproximadamente 70 porcento de las semillas dispersadas por aves (N = 244) fueron depositadas cerca de 10 mdel horde de la corona de árboles en fruto de B. pendula, aunque algunas semillas fueron dispersadas hasta 70 m mas lejos. Semillas grandes tuvieron la tendencia de ser dispersadas debajo o cerca del Brbol parental, y semillas grandes produjeron plantulas grandes. El tamaño de la semilla no estaba correlacionada directamente con sobrevivencia de plantulas, pero plantulas grandes a 3 mesa tuvieron la tendencia de sobrevivir. Predación de semillas por los roedores y insectos, y mortalitad de plantulas por hongos patogtnicos fueron lo mas comun debajo de la corona de los árboles parentales. Plantulas y arbolillos fueron mós abundantes debajo de drboles en fruto de B. pendula, pero individuos distantes fueron en promedio más altos. Dispersión es favorable para B. pendula, pero estos beneficios aparentan ser más ptonunciados a una escala espacial menot; semillas dispersadas más de 30 m del horde de la corona en realidad tienen una probabilidad menor de sobrevivencia que las que son dispersadas entre 10,20 m. Solamente 10 porcento de las seniillas de B. pendula recibieron despersión de calidad alta en terminos de aterrizar en una zona con la más alta probabilidad de sobrevivencia de plantulas entre 10,20 m de la corona parental. [source] | ||||||||||