Post-dispersive losses of acorns from Mediterranean savannah-like forests and shrublands

Leiva, María José; Fernández-Alés, Rocı́o

doi:10.1016/s0378-1127(02)00294-3

Cited by 47 publications

(31 citation statements)

References 18 publications

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“…It is known that Cistus shrubs have allelopathic effects, inhibiting seedling germination and survival (Chaves and Escudero 2001;Lobón et al 2002). There could be also limitations in acorn dispersal, increased acorn predation (Herrera 1995;Leiva and Fernández-Alés 2003), or limitations in seedling germination and or survival under the dense and dry shrub cover (Retana et al 1999).…”

Section: Mechanisms Limiting Forest Recoverymentioning

confidence: 99%

Are drought and wildfires turning Mediterranean cork oak forests into persistent shrublands?

Acácio

Holmgren

Rego³

et al. 2008

Agroforest Syst

146

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In the Iberian Peninsula Mediterranean oak forests have been transformed into a mosaic landscape of four main patch-types: forests, savannas, shrublands and grasslands. We used aerial photographs over a period of 45 years to quantify the persistence and rates of transitions between vegetation patch-types in southern Portugal, where cork oak is the dominant tree species. We used logistic regression to relate vegetation changes with topographical features and wildfire history. Over the 45 years, shrublands have been the most persistent patch-type (59%), and have been expanding; forests are also persistent (55%) but have been decreasing since 1985; savannas and grasslands were less persistent (33% and 15%, respectively). Shrublands persistence was significantly correlated with wildfire occurrence, particularly on southern exposures after 1995. In contrast, forest persistence decreased with wildfire occurrence, and forests were more likely to change into shrublands where wildfire had occurred after 1995.

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Section: Mechanisms Limiting Forest Recoverymentioning

confidence: 99%

Are drought and wildfires turning Mediterranean cork oak forests into persistent shrublands?

Acácio

Holmgren

Rego³

et al. 2008

Agroforest Syst

146

View full text Add to dashboard Cite

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“…Coppice originated from firewood exploitation is common in the steepest slopes and shallowest soils, and now plays and essential role for wildlife and game species. The ecosystem is in great danger as a result of the changing social and economic structure (Pinto-Correia, 1993;San Miguel, 1994;Gómez-Limón and de Lucío, 1999) and the almost absolute lack of tree regeneration in most stands (Pulido et al, 2001;Leiva and Fernández-Alés, 2003;Pulido et al, 2005). Lack of regeneration is one of the greatest problems of the ecosystem and is likely to become more problematic in the climate change scenarios expected for Mediterranean regions.…”

Section: The Holm Oak and Iberian Dehesas: A Mediterranean Anthropic mentioning

confidence: 99%

“…The role of acorn size is controversial: bigger acorns are preferably consumed by predators (Gómez, 2004) including pigs (García et al, 2003), which might hamper regeneration (Leiva and Fernández-Alés, 2003). Seedlings from bigger acorns average higher number of leaves and higher leaf area (Díaz et al, 2003), which might be an advantage for young seedlings.…”

Section: Acorn Size and Morphologymentioning

confidence: 99%

Acorn production in Spanish holm oak woodlands

2006

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We present a review on the state-of-the-art of fruit prodution in Western Iberia woodlands («dehesas»), and particularly in Q. ilex (holm oak) «dehesas». This threatened ecosystem is of very high ecological and economical importance. Quercus sp. fruits (acorns) are essential for wildlife, and for pig fattening in «dehesas». In the first part of this review we briefly describe the phenology of the holm oak and the factors affecting acorn morphology and chemical composition.In the second half we analyze the main known factors reported in the literature that determine acorn production: pruning, stand characteristics, and site (weather and soil). We make several suggestions to improve future research and detect the existing gaps in the undertanding of acorn production.Fruit production is highly variable, both between and within years and individuals. The mean production in «dehesas» (mean density circa 50 trees/ha) is around 250-600 kg/ha (≈100 g/canopy-m 2 , CV > 100%). Acorn morphology is also very variable, with mean sound acorn size around 3.5 × 1.6 cm, CV ≈ 10% (3.5 g/acorn, CV > 50%). Silviculture plays an essential role in acorn production. Acorn production per tree seems to be negatively related to density. The effect of pruning is less clear: production seems to be reduced in the first and second years after pruning. After the third year it is not possible to discern from the literature whether there is any response to pruning or not. Weather and soil (site) also impact production and their effects should be explored in future management. The influence of genetics is unknown and should also be addressed. Longer data series are necessary. The dasometric features of the stands need to be characterized, in order to better understand production and compare results from different locations. Much research is still required to understand the functioning of fruiting in these woodlands.Key words: Quercus ilex, holm oak, acorn, fruit production, dehesa, agrosilvopastoral systems. Resumen Producción de bellota en las dehesas españolas de encinaEl alto interés ecológico y económico de la producción de fruto en las dehesas ibéricas, concretamente las de encina (Quercus ilex), nos ha movido a realizar una revisión del estado actual de conocimientos. Los frutos (bellotas) de Quercus sp. resultan esenciales para la fauna salvaje y el engorde de ganado porcino en las dehesas. En la primera parte de este trabajo se describen brevemente las características fenológicas de la especie, así como los factores que influyen en la variabilidad morfológica y la composición bromatológica del fruto. En la segunda parte se analizan los factores fundamentales estudiados en la bibliografía que determinan la producción: la poda, las características dasométricas (densidad y distribución diamétrica) y la influencia del sitio (suelo y clima). Se realizan sugerencias para mejorar futuras líneas de trabajo, así como se subrayan áreas de conocimiento deficitarias.La producción es muy variable tanto intra-como interanualmente. La producció...

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“…Key constraints on the speed of regeneration include (1) dispersal limitation because seed sources are remote and dispersal vectors may be rare (Rey Benayas et al 2008a;Pons and Pausas 2007a;Zamora et al 2010;Ramos-Palacios et al 2014); (2) seed predation Pérez-Ramos and Marañón 2008;Gómez and Hódar 2008;Leiva and Fernández 2003); (3) biotic limitation such as competition from established woody vegetation and herbaceous vegetation (Rey Benayas et al 2005;Cuesta et al 2010a), and herbivory Puerta et al 2012); and (4) abiotic limitation such as low water availability, extreme temperatures, poor soil structure and low nutrient availability (Rey Benayas 1998;Cuesta et al 2010b). Intensification of land use has brought remnant areas of natural or semi-natural vegetation into mainstream agriculture and as a result many of such areas have been lost or severely degraded.…”

Section: Introductionmentioning

confidence: 99%

“…Rodents and magpies are both predators and dispersers of acorns (Waite 1985), but rabbits and hares, which are abundant in our field site, are only predators (Zamora et al 1985;Díaz et al 1996;Leiva and Fernández 2003;Guzmán et al 2008). We have clear evidence of acorn predation in situ for a small fraction of the unprotected acorns but suspect that most of the unfound acorns were either entirely consumed immediately after removal or re-cached and consumed later in other sites (Perea et al 2011), as the farmland environment where our woodland islets are embedded may exacerbate predation.…”

mentioning

confidence: 98%

Predation and aridity slow down the spread of 21-year-old planted woodland islets in restored Mediterranean farmland

et al. 2015

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Planted woodland islets act as sources of seed that may accelerate woodland development in extensive agricultural landscapes. We assessed a 1-ha plot that was planted with 16 100-m 2 islets of holm oak Quercus ilex subsp. ballota seedlings near Toledo (Spain) in 1993. In spring 2014 we measured (1) acorn predation and (2) seedling emergence from seeded acorns at different distances from and orientations around the islets with half of the acorns protected to prevent predation, (3) survival of emerged seedlings, and (4) natural tree establishment outside of the planted islets. Most (96.9 %) unprotected acorns were removed or predated. Seedling emergence from protected acorns ranged from 42.9 % on the northern side of the islets to 13.2 % on the southern side, suggesting a less stressful microclimate on the northern side. Survival of naturally established seedlings was 28.6 % by the end of first summer; seedling mortality was chiefly due to drought (45.0 %) and herbivory (35.0 %). Density of emerged seedlings, surviving seedlings after first dry season, and established oaks [1-year old was similar at different distances from the islets. Over the 21 year time period, 58 new oak individuals [1-year old have established (an average of 3.3 established individuals per ha per year) at an average distance of 6.3 ± 5.4 m away from the closest islet. We conclude that initial oak regeneration triggered by small planted islets in Mediterranean abandoned farmland is slowed down by high acorn predation, seedling herbivory, and stressful microclimatic conditions. Regardless, these islets are a viable tool for regeneration of Mediterranean oak woodland.

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Post-dispersive losses of acorns from Mediterranean savannah-like forests and shrublands

Cited by 47 publications

References 18 publications

Are drought and wildfires turning Mediterranean cork oak forests into persistent shrublands?

Are drought and wildfires turning Mediterranean cork oak forests into persistent shrublands?

Acorn production in Spanish holm oak woodlands

Predation and aridity slow down the spread of 21-year-old planted woodland islets in restored Mediterranean farmland

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