Interactions among Overstory Structure, Seedling Life-history Traits, and Fire in Frequently Burned Neotropical Pine Forests

O’Brien, Joseph J.; Hiers, J. Kevin; Callaham, Mac A.; Mitchell, Robert J.; Jack, Steve B.

doi:10.1579/0044-7447-37.7.542

Cited by 75 publications

(56 citation statements)

References 8 publications

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“…Large and sudden increases in rates of sedimentation, charcoal concentration, and pine pollen (pine woodland is a pyrogenic vegetation community; O'Brien et al ., ) took place 1.2–0.8 ka in the Bahamas (Kjellmark, ; Slayton, ). This is when people arrived in the northern Bahamas (Steadman et al ., ) and strongly suggests an increase in fire from human burning of the landscape.…”

Section: Discussionmentioning

confidence: 96%

Changes in a West Indian bird community since the late Pleistocene

Steadman

Franklin

2014

Journal of Biogeography

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Aim To establish a chronology for late Quaternary avian extinction, extirpation and persistence in the Bahamas, thereby testing the relative roles of climate change and human impact as causes of extinction. Location Great Abaco Island (Abaco), Bahamas, West Indies. Methods We analysed the resident bird community as sampled by Pleistocene (> 11.7 ka) and Holocene (< 11.7 ka) fossils. Each species was classified as extinct (lost globally), extirpated (gone from Abaco but persists elsewhere), or extant (still resident on Abaco). We compared patterns of extinction, extirpation and persistence to independent estimates of climate and sea level for glacial (late Pleistocene) and interglacial (Holocene) times. Results Of 45 bird species identified in Pleistocene fossils, 25 (56%) no longer occur on Abaco (21 extirpated, 4 extinct). Of 37 species recorded in Holocene deposits, 15 (14 extirpated, 1 extinct; total 41%) no longer exist on Abaco. Of the 30 extant species, 12 were recovered as both Pleistocene and Holocene fossils, as were 9 of the 30 extirpated or extinct species. Most of the extinct or extirpated species that were only recorded from Pleistocene contexts are characteristic of open habitats (pine woodlands or grasslands); several of the extirpated species are currently found only where winters are cooler than in the modern or Pleistocene Bahamas. In contrast, most of the extinct or extirpated species recorded from Holocene contexts are habitat generalists. Main conclusions The fossil evidence suggests two main times of late Quaternary avian extirpation and extinction in the Bahamas. The first was during the PleistoceneHolocene transition (PHT; 15-9 ka) and was fuelled by climate change and associated changes in sea level and island area. The second took place during the late Holocene (< 4 ka, perhaps primarily < 1 ka) and can be attributed to human impact. Although some species lost during the PHT are currently found where climates are cooler and drier than in the Bahamas today, a taxonomically and ecologically diverse set of species persisted through that major climate change but did not survive the past millennium of human presence.

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Section: Discussionmentioning

confidence: 96%

Changes in a West Indian bird community since the late Pleistocene

Steadman

Franklin

2014

Journal of Biogeography

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“…Indeed, all of the species exhibiting small soil CO 2 efflux responses to girdling (Edwards & Ross‐Todd, ; Binkley et al ., ) share the life‐history characteristic of resprouting from the root system after disturbance, which is associated with a large below‐ground carbohydrate storage pool (Bowen & Pate, ; Clarke & Knox, ; Schutz et al ., ). Although not a resprouter, longleaf pine has an evolutionary history of chronic disturbance from fire and exhibits the propensity to store NSCs to escape fire as a juvenile through bolting (Wahlenberg, ; O'Brien et al ., ) and to refoliate the canopy after scorching throughout its life history (Guo et al ., ; Aubrey et al ., ).…”

Section: Discussionmentioning

confidence: 99%

“…Longleaf pine ( Pinus palustris ) is a tree species from the southeastern US that exhibits different adaptations to frequent fire. Juvenile longleaf pine persists in a ‘grass stage’ for 3–15 yr where the terminal bud is protected from fire damage as taproot development and allocation towards NSCs are favored over above‐ground growth—a strategy which facilitates bolting and escape from surface fires when seedlings are released (Wahlenberg, ; O'Brien et al ., ). Following two successive annual foliar scorching events of a longleaf pine stand, there was no reduction in soil CO 2 efflux despite an immediate 80% reduction in canopy leaf area and sap flow (Aubrey et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Stored root carbohydrates can maintain root respiration for extended periods

Aubrey

Teskey

2017

New Phytologist

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Tight coupling between below-ground autotrophic respiration and the availability of recently assimilated carbon (C) has become a paradigm in the ecophysiological literature. Here, we show that stored carbohydrates can decouple respiration from assimilation for prolonged periods by mobilizing reserves from transport roots to absorptive roots. We permanently disrupted the below-ground transfer of recently assimilated C using stem girdling and root trenching and measured soil CO efflux for over 1 yr in longleaf pine (Pinus palustris), a species that has large reserves of stored carbohydrates in roots. Soil CO efflux was not influenced by girdling or trenching through the 14-month observation period. Stored carbohydrate concentrations in absorptive roots were not affected by the disrupted supply of current photosynthate for over 1 yr; however, carbohydrate concentrations in transport roots decreased. Our results indicate that root respiration can be decoupled from recent canopy assimilation and that stored carbohydrates can be mobilized from transport roots to absorptive roots to maintain respiration for over 1 yr. This refines the current paradigm that canopy assimilation and below-ground respiration are tightly coupled and provides evidence of the mechanism and dynamics responsible for decoupling the above- and below-ground processes.

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“…) and likely have major impact on future stand development (O'Brien et al. ). Often the first 2 yr of life are ignored in seedling studies and are likely the most vulnerable life stage.…”

Section: Discussionmentioning

confidence: 99%

The path back: oaks (Quercusspp.) facilitate longleaf pine (Pinus palustris) seedling establishment in xeric sites

et al. 2016

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Mitchell. 2016. The path back: oaks (Quercus spp.) facilitate longleaf pine (Pinus palustris) seedling establishment in xeric sites. Ecosphere 7(6):e01361. 10.1002/ecs2.1361Abstract. Understanding plant-plant facilitation is critical for predicting how plant community function will respond to changing disturbance and climate. In longleaf pine (Pinus palustris Mill.) ecosystems of the southeastern United States, understanding processes that affect pine reproduction is imperative for conservation efforts that aim to maintain ecosystem resilience across its wide geographic range and edaphic gradients. Variation in wildland fire and plant-plant interactions may be overlooked in "coarse filter" restoration management, where actions are often prescribed over a variety of ecological conditions with an assumed outcome. For example, hardwood reduction techniques are commonly deemed necessary for ecological restoration of longleaf pine ecosystems, as hardwoods are presumed competitors with longleaf pine seedlings. Natural regeneration dynamics are difficult to test experimentally given the infrequent and irregular mast seed events of the longleaf pine. Using a long-term, large-scale restoration experiment and a long-term monitoring data site at Eglin Air Force Base, Florida (USA), this study explores the influence of native fire-intolerant oaks on longleaf regeneration. We test for historical observations of hardwood facilitation against the null hypothesis of competitive exclusion. Our results provide evidence of hardwood facilitation on newly germinated longleaf pine seedlings (<2 yr old) after two mast seeding events (1996, 2011). Using regression-tree and Kaplan-Meier survival analyses, we found that deciduous oak midstory density was the most significant variable associated with longleaf pine seedling survival rates in the first 2 yr after germination. We found that as few as 43 oak midstory stems ha −1 were sufficient to facilitate seedling survival, but as many as 1400 stems ha −1 maintained facilitation without competitive exclusion of seedlings. We found that 1.5-yr-old pine seedlings were more moisture stressed under more open canopy conditions when compared to those immediately adjacent to a midstory oak canopy. Recognition that deciduous oaks are important facilitators of longleaf seedling establishment on xeric sites represents a significant departure from conventional wisdom and current management practices that has largely focused on competitive exclusion. This points to a critical role of a deciduous oak midstory of moderate densities for long-term ecosystem resilience in xeric longleaf pine ecosystems in light of climate uncertainty.

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Interactions among Overstory Structure, Seedling Life-history Traits, and Fire in Frequently Burned Neotropical Pine Forests

Cited by 75 publications

References 8 publications

Changes in a West Indian bird community since the late Pleistocene

Changes in a West Indian bird community since the late Pleistocene

Stored root carbohydrates can maintain root respiration for extended periods

The path back: oaks (Quercusspp.) facilitate longleaf pine (Pinus palustris) seedling establishment in xeric sites

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