کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4759362 1421359 2017 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Differential tree recruitment in California oak savannas: Are evergreen oaks replacing deciduous oaks?
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم کشاورزی و بیولوژیک بوم شناسی، تکامل، رفتار و سامانه شناسی
پیش نمایش صفحه اول مقاله
Differential tree recruitment in California oak savannas: Are evergreen oaks replacing deciduous oaks?
چکیده انگلیسی
We uncovered an overall underrepresentation of young oaks (<7.5 cm DBH) in both deciduous species (Q. lobata and Q. douglasii), compared to the evergreen oak (Q. agrifolia), even in areas where deciduous species were the locally predominant mature trees. Such differential recruitment was accentuated in areas where Q. lobata was predominant, with young evergreen oaks reaching densities 3-times higher than those of the deciduous oak. Recruitment of all three species was significantly associated with shrub cover, suggesting a facilitative effect, via reduction of both occurrence and intensity of herbivory. However, evergreen oaks were much less vulnerable to herbivory (lower occurrence and intensity) than deciduous oaks and, thus, evergreen recruits were able to thrive even in uncovered areas. Overall, our results provide evidence of differential recruitment at the juvenile stage in co-occurring oak species, which may lead to a replacement of deciduous species with evergreen oaks. The disproportionate effect of shrubs as safe microsites for regeneration of both deciduous and evergreen species suggests that herbivory pressure is an important factor reducing the abundance and heterogeneity of favorable regeneration niches, particularly for the most herbivore-sensitive tree species. Further studies should address to what extent the recruitment patterns described here translate into future differences in adult stages, and whether the actual biased regeneration is mostly due to differential herbivory on deciduous vs. evergreen species. We posit that, for the management and conservation of multi-specific oak savannas, regeneration of deciduous oaks should be prioritized over that of live oaks in order to maintain greater levels of biodiversity and reduce biotic homogenization.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Forest Ecology and Management - Volume 399, 1 September 2017, Pages 1-8
نویسندگان
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