Density Effect on the Fruit-set, Seed Crop Viability and Seedling Vigour ofAbies pinsapo

Arista, Montserrat; Lozano, Salvador Talavera

doi:10.1006/anbo.1996.0021

Cited by 44 publications

(34 citation statements)

References 23 publications

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“…In our study, the sub-humid areas produced substantially heavier cones with better seed fills in comparison to the lower semiarid zones. Other previous studies showed that stand density also affects the cone production per tree, reducing the production due to the higher tree densities within the stand (Ayari et al, 2010;2011a), that is associated with an increased tree competition (Arista and Talavera, 1996;Karlsson and Orlander, 2002). In the present study, stand density affected negatively the crown dimension of the average tree, especially CrS and CrV.…”

Section: Discussionsupporting

confidence: 46%

Stand, tree and crown variables affecting cone crop and seed yield of Aleppo pine forests in different bioclimatic regions of Tunisia

Ayari

Zubizarreta-Gerendiain

Tomé³

et al. 2012

For. syst.

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In Tunisia, the Aleppo pine seed has a great importance, since in the last decades human consumption has risen considerable. Thus its regeneration and seed production capacities are important factors to take into account to reach the necessities of the country. To study the production of cones and seeds of Aleppo pine, Tunisia's native Aleppo pine forests were surveyed in summer 2006, using 79 plots (40 × 25 m: 1,000 m²) spread over four bioclimatic zones. Stand and tree characteristics, crown dimensions and cone/seed variables were measured from an average tree of each plot (i.e. a total of 79 trees). Recorded data were submitted to simple and multiple regression analyses for explaining the variability in crown volume and crown surface, cone number and seed yield per average tree. Results showed a negative correlation between the stand density, crown characteristics and number of cones and seeds harvested from the average tree. For crown volume and surface, age, stand density, tree height, diameter at breast height, crown diameter and crown height were important explanatory variables under multiple regression analyses. For cone number per tree, only the age, stand density and total height were the most determinant variables. Matures cone number per tree and cone mass per tree were the most informative parameters for the total seed yields per tree. Finally, forest managers should know that crown size affects cone and seed crop of the Aleppo pine individual tree grown in Tunisia, but has no effects on seed number per cone and seed mass per cone.Key words: Aleppo pine; crown dimensions; cone number; seed yields; bioclimatic zones; Tunisia. ResumenVariables de parcela, árbol y copa que afectan la producción de piñas y piñones en bosques de pino carrasco de Túnez En Túnez, la producción de piñones del pino carrasco tiene una gran importancia, ya que en las últimas décadas su consumo ha aumentado de forma considerable. Por ello, su regeneración y capacidad de producción de piñas/piñones en un factor a tener en cuenta en Túnez. En verano del 2006 se eligieron 79 parcelas de 1.000 m² (40 × 25 m) situadas en cuatro zonas bioclimáticas representativas de Túnez para el estudio de la capacidad de producción de piñas/piñones del pino carrasco. Teniendo en cuenta todos los árboles de las parcelas, se identificó el árbol promedio, del que posteriormente se medirían variables de árbol, dimensión de copa y producción de piñas/piñones. Los resultados demuestran una correlación negativa entre la densidad de la parcela, características de la copa y el número de piñas/piñones recolectados por cada árbol promedio. Para la descripción del volumen y superficie de copa, las variables más importantes fueron edad, densidad de parcela, altura y diámetro del árbol, y altura y diámetro de la copa. Las variables edad, densidad de parcela y altura del árbol fueron las más significativas para la determinación de nú-mero de piñas por árbol. Para el cálculo del total de piñones por árbol, las variables más informativas fueron el nú-mero ...

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Section: Discussionsupporting

confidence: 46%

Stand, tree and crown variables affecting cone crop and seed yield of Aleppo pine forests in different bioclimatic regions of Tunisia

Ayari

Zubizarreta-Gerendiain

Tomé³

et al. 2012

For. syst.

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“…Second, young trees in revegetated areas are unlikely to provide the large fruit crops that older trees in unmined forest can. Additionally, high tree stem densities -typically much higher in revegetation than in unmined forest -can limit tree growth rates (Stoneman et al 1997;Grigg and Grant 2009) and may also constrain flowering and fruit crops (Arista 1996;Williams et al 2006). Glossy black cockatoos (Calyptorhynchus lathami) preferentially feed in trees with large fruit crops, probably because it is more energy efficient (Chapman and Paton 2005); so, the same may hold true for our study species in the jarrah forest.…”

Section: Successional Changes In Feeding Activitymentioning

confidence: 75%

Successional changes in feeding activity by threatened cockatoos in revegetated mine sites

et al. 2016

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Context: Provision of key habitat resources is essential for effectively managing species that have specific ecological requirements and occur in production landscapes. Threatened black cockatoos in the jarrah (Eucalyptus marginata) forest of Western Australia have a wide range, so their conservation requires support from all land tenures, not just reserves. Mining in the jarrah forest temporarily removes cockatoo feeding habitat, so it is important to understand how cockatoos exploit revegetated areas for food resources. Aims:We aimed to determine whether there were successional patterns in cockatoo feeding activity in revegetation aged from 4 to 23 years at three mine sites in the jarrah forest in south-western Australia. Methods:We surveyed 232 plots in revegetation to document (1) structural and floristic variation in vegetation across mine sites and revegetation ages, (2) differences in cockatoo feeding activity across mine sites and revegetation ages on the basis of feeding residues and (3) any edge effect reflecting preferential use of vegetation at the interior or exterior of mine pits. We also documented the frequency of occurrence of cockatoo food plants and feeding residues in 480 plots in unmined forest to compare with revegetated areas.Key results: Marri (Corymbia calophylla) and jarrah were commonly consumed in unmined forest and Banksia and Hakea species were also fed on to a lesser extent. Revegetated mine pits provided food within 4 years and continued to do so up until the oldest plots studied (23 years). The relative importance of food plants shifted from proteaceous species in young revegetation to myrtaceous species in intermediate to older revegetation. However, extent of feeding on myrtaceous species in older revegetation did not equate to feeding rates in unmined forest, with lower frequencies recorded in revegetation.Conclusions: Black cockatoos fed in revegetation at all three mine sites, despite variations in vegetation age, structure and floristics. Feeding on proteaceous and myrtaceous food plants occurred within 4 and 7 years of revegetation being established, respectively, indicating that some food resources are restored quickly after mining disturbance of the jarrah forest. Implications:Our results emphasise the importance of monitoring fauna recolonisation over appropriate time scales, to understand how successional processes in revegetation influence fauna population persistence in production landscapes.

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“…Two lines of evidence support this conclusion. Firstly, in wind-pollinated plants, the efficiency of wind pollination increases as density increases (Whitehead 1983;Allison 1990;Arista and Talavera 1996;Friedman and Barrett 2009). Density, however, depends on the spatial scale of measurement, and inter-plant distance is a more direct and meaningful measure to evaluate the effects of proximity (Harper 1977).…”

Section: Discussionmentioning

confidence: 99%

The role of pollen limitation on the coexistence of two dioecious, wind-pollinated, closely related shrubs in a fluctuating environment

2010

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Elucidating the mechanisms of species coexistence is a crucial goal in ecology. Theory suggests that, when resource abundance fluctuates, coexistence can be achieved if each species in a competing pair is better at exploiting resources at opposite extremes of a fluctuating resource spectrum. Nonetheless, the proximal mechanisms allowing coexistence remain largely unexplored. In a previous paper, we showed that the coexistence of two Atriplex species was facilitated by their varying demographic response (in survival, growth and recruitment) to fluctuation in water availability. Here we explore the effect of spatial distribution, and pollen and resource limitation on the reproductive success (production of viable seeds) of the same two species. An analysis of their spatial distribution showed that Atriplex acanthocarpa had a clumped distribution, which is thought to increase the effectiveness of pollination in wind-pollinated plants, while Atriplex canescens had a random distribution, a pattern expected to restrict wind-pollination success. A pollen and resource (water and nutrients) addition experiment implemented through a repeated-measures design demonstrated that seed viability of A. canescens was both pollen and resource limited, but that these effects were negligible in A. acanthocarpa. Under natural conditions, pollen limitation restricted seed number in A. canescens to only one-third of that recorded when manual pollination was performed. By decreasing its fecundity (and consequent potential seedling recruitment), pollen limitation reverses the competitive advantage of A. canescens over A. acanthocarpa when the limiting resource (water) is abundant and seedling recruitment takes place. To our knowledge, our study of this congeneric pair in the Chihuahuan Desert is the first to document a link between pollen limitation and species coexistence.

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Density Effect on the Fruit-set, Seed Crop Viability and Seedling Vigour ofAbies pinsapo

Cited by 44 publications

References 23 publications

Stand, tree and crown variables affecting cone crop and seed yield of Aleppo pine forests in different bioclimatic regions of Tunisia

Stand, tree and crown variables affecting cone crop and seed yield of Aleppo pine forests in different bioclimatic regions of Tunisia

Successional changes in feeding activity by threatened cockatoos in revegetated mine sites

The role of pollen limitation on the coexistence of two dioecious, wind-pollinated, closely related shrubs in a fluctuating environment

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