Patterns of frugivory, seed dispersal and predation of blue fan palms (Brahea armata) in oases of northern Baja California

Wehncke, Elisabet V.; Medellín, Xavier López; Ezcurra, Exequiel

doi:10.1016/j.jaridenv.2009.03.007

Cited by 22 publications

(32 citation statements)

References 61 publications

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“…Patchiness in bird abundance was hierarchically nested, as larger patches themselves contained smaller ones (see similar patterns in Fauchald et al 2000, Wehnke et al 2009). Comparing systems, average patch sizes of bird abundance at the broad and intermediate scales were very similar in the Cantabrian forest and the Mediterranean shrubland, but comparatively narrower in the Patagonian forest (Fig.…”

Section: Spatial Scale and Environmental Correlates Of Frugivory By Bmentioning

confidence: 79%

“…In all studied ecosystems, and independently of the effect of habitat structure, large-scale bird clumps occurred in fruit-rich patches, suggesting a pervasive and generalized process of fruit resource tracking across the whole landscape. Large-scale fruit tracking by birds has been evidenced for other temperate and non-temperate ecosystems (e.g., Whitney and Smith 1998, Tellerı´a and Pe´rez-Tris 2003, Guitia´n and Munilla 2008, Wehnke et al 2009). Strong vagility, flocking behavior, and an almost exclusively fruit-based diet of temperate migrant passerines during autumn and winter (e.g., Turdus spp.…”

Section: Spatial Scale and Environmental Correlates Of Frugivory By Bmentioning

confidence: 99%

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The spatial scale of plant–animal interactions: effects of resource availability and habitat structure

García

Zamora

Amico

2011

Ecological Monographs

122

117

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Abstract. Plant-animal interactions are crucial nodes in the structure of communities and pivotal drivers of ecosystem functioning. Much of this relevance may depend on how animals cope with plant resources at different spatial scales. However, little is known about how and why different interactions perform at different scales in the same environmental setting. In this study we assess the spatial scales at which two plant-animal interactions operate and disentangle the environmental factors (plant resource availability vs. habitat structure) underpinning these operational scales. We studied two interactions with opposite (mutualistic vs. antagonistic) ecological effects on fleshy-fruited trees, frugivory and seed dispersal by birds, and the later predation by rodents on bird-dispersed seeds. Employing a standardized sampling, we covered three temperate ecosystems hosting structurally similar plant-frugivoreseed predator systems: Cantabrian forest, Mediterranean shrubland, and Patagonian forest. We sampled habitat structure (tree and understory covers), fleshy-fruit abundance, birddispersed seed occurrence, frugivorous bird abundance, and seed predation rate, along 1500-2500 m transects. Using a spatially explicit approach, we broke down the predictable spatial patterns of bird abundance and seed predation rate into patchiness at three consecutive spatial scales (broad, intermediate, and fine). The degree of patchiness and the allocation of spatial variability at different scales suggested a hierarchically nested structure in frugivory and seed predation, but a larger operational scale in seed predation than in frugivory. Scale-specific spatial distributions were explained by the response of animals to plant resource availability and habitat structure. Birds tracked fruits at large spatial scales in all systems and, within some systems, even across consecutive scales. Seed predation distribution was more responsive to habitat features than to resource availability. The reinforcement of resource tracking patterns across scales sometimes occurred simultaneously with the dilution of habitat effects, suggesting that scale dependence may emerge from trade-offs between resource acquisition and the effects of other factors, such as predation risk, on interacting animals. Our findings suggest that scale dependence in frugivory and seed predation may affect the balance of demographic effects of these interactions in plant populations. Moreover, the consistency of frugivory patterns within and across spatial scales may condition the redundancy of seed dispersal as an ecosystem function.

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Section: Spatial Scale and Environmental Correlates Of Frugivory By Bmentioning

confidence: 79%

Section: Spatial Scale and Environmental Correlates Of Frugivory By Bmentioning

confidence: 99%

The spatial scale of plant–animal interactions: effects of resource availability and habitat structure

García

Zamora

Amico

2011

Ecological Monographs

122

117

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“…In the northern desert of the Baja California peninsula, remnant vegetation patches from an ancient paratropical forest have remained as isolated oases on mountaintops and along canyons where wetter conditions are preserved [30][31][32]. Dominated by the endemic blue fan palm (Brahea armata, Arecaceae), these oases seem to keep a certain degree of connectedness, although their effectiveness as corridors for the fauna and flora remains unknown.…”

Section: Introductionmentioning

confidence: 99%

Revealing an Endemic Herbivore-Palm Interaction in Remote Desert Oases of Baja California

Wehncke¹,

López-Medellín²,

Wall³

et al. 2013

AJPS

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In the Central Desert of northern Baja California, blue fan palm populations (Brahea armata) are found as isolated oases on mountaintops and along canyons with ephemeral flow conditions. Here, the effect of the interaction between the larva of an endemic moth, Litoprosopus bajaensis, and this endemic blue fan palm was documented for the first time. We registered the phenology of palms by counting the number of shoots with flowers or fruits, assessing their damage and calculating the reproductive success per individual palm within three populations: San Pedro Martir, Cataviña, and La Libertad. Palm populations were severely impacted by this larva, causing high damage to the inflorescences. No differences were found in the number of inflorescence stems produced and damaged among study sites; but the reproductive success of palms was significantly higher in Cataviña than in the other sites during the entire sampling period, and consequently an important proportion of stems escaped from the herbivore predation. We suggest that differences among sites may be explained by the fact that Cataviña is the only alluvial canyon and can be considered an area of high nutrient uptake, resource availability, and rooting depths. In contrast the other two are bedrock canyons, where water runs intensely, sweeping away great portions of the nearby vegetation. Cataviña received the highest precipitation during the winter season of 2010 allowing a continuous production of inflorescence stems and fruits. This preliminary study reveals a new endemic interaction, it occurrence at population and regional levels, and highlights the role of desert oases as resource patches and connectivity pathways for mobile insects. Finally, it also highlights the effects of different water flow dynamics and water pulses in providing an opportunity window of escape from predation for host plant species living in desert environments.

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“…In particular, palm oases are distributed as distinct patches in space and time and, therefore, seed dispersal and post-dispersal seed predation processes both within and between oases are of great demographic importance (Wehncke et al 2009). For example, spatial variation in seed predation may arise because some habitats, irrespective of seed availability, are more suitable for certain granivores than others (Hulme and Benkman 2002).…”

Section: Introductionmentioning

confidence: 99%

“…Within each oasis, we explored the distribution patterns of the palms, with the expectation that these patterns may offer some preliminary clues for the identification and scaling of critical underlying mechanisms driving palm establishment and distribution in these highly fluctuating ecosystems. Since such riparian ecosystems provide vital ecological services for human and nonhuman life (Wehncke et al 2009), the identification of these processes is cruciala for sustaining biodiversity and water availability in desert regions in the face of ongoing environmental change.…”

Section: Introductionmentioning

confidence: 99%

Blue fan palm distribution and seed removal patterns in three desert oases of northern Baja California, Mexico

2009

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Information on the current processes controlling the distribution patterns of relict palm populations at the limit of their northwestern distribution in America are poorly known. We explored the importance of post-dispersal seed removal by vertebrates, recruitment, and distribution patterns of the blue fan palm, Brahea armata, in the Northern Baja California peninsula, by evaluating (i) the levels of blue fan palm seed removal by vertebrates at two spatial scales and the initial fate of dispersed seeds, (ii) the spatial distribution and association of seedlings and adults at two spatial scales, (iii) seed removal levels and seedling densities based on density and distance to adult palm trees, and (iv) the population age structure. Overall, seed removal levels were low at all sites, varied at regional but not at local scales, with small rodents apparently being responsible of most removals. Adult density and distribution differed among oases, but seedling densities did differ locally. Whereas seed removal did not vary with distance from seed sources or parent trees, a weak positive association between seedlings and adults at the whole patch level indicated that establishment tended to occur in or near those grid cells where adults had established successfully. However, the analysis showed a negative association between seedling and adult densities within the patches, indicating that within the grid cells where growth was most successful, seedlings established preferentially in relatively open spaces. All life-history categories were adequately represented within each site and populations seemed to be in a fairly good conservation state. We did not find evidence to establish that post-dispersal seed removal by rodents is a main factor defining the recruitment patterns in these oases. In contrast, the effect of flood pulses seems to be significant and may have strong and conclusive effects on palm seedling distributions. We suggest that local biotic (nurse plants) and/or abiotic (canyon physiography, nurse objects) factors at each particular canyon have the potential to affect post-dispersal seed removal activity patterns by rodents, as well as to provide vital protection for palm seedling establishment from the extreme floods. This baseline information will help in further investigations on the possible mechanisms that sustain Electronic supplementary material The online version of this article (

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Patterns of frugivory, seed dispersal and predation of blue fan palms (Brahea armata) in oases of northern Baja California

Cited by 22 publications

References 61 publications

The spatial scale of plant–animal interactions: effects of resource availability and habitat structure

The spatial scale of plant–animal interactions: effects of resource availability and habitat structure

Revealing an Endemic Herbivore-Palm Interaction in Remote Desert Oases of Baja California

Blue fan palm distribution and seed removal patterns in three desert oases of northern Baja California, Mexico

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