Mangrove microclimates alter seedling dynamics at the range edge

Devaney, John L.; Lehmann, Michael; Feller, Ilka C.; Parker, John D.

doi:10.1002/ecy.1979

Cited by 52 publications

(40 citation statements)

References 46 publications

(87 reference statements)

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“…This amount of temperature buffering during frost can have large impacts for tropical plants because most tropical plants are vulnerable to temperatures of just a few degrees below freezing (Sakai & Larcher, 1987). Thus protective effect of trees against extreme cold has been recognized to be important for maintaining mangrove forests (Devaney et al, 2017;Osland et al, 2015), subtropical thicket (Duker, Cowling, Preez, & Potts, 2015), and tropical alpine forest (Rehm & Feeley, 2015) near the limit of their cold tolerance. In all these systems, damage to trees is greatest where tree cover is lowest, thereby reinforcing existing patterns of tree density.…”

Section: Discussionmentioning

confidence: 99%

Rare frost events reinforce tropical savanna–forest boundaries

et al. 2018

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The ability of vegetation to ameliorate or exacerbate environmental extremes can generate feedbacks that mediate the distribution of biomes. It has been suggested that feedbacks between vegetation and frost damage may be important for maintaining savanna, particularly at the edge of the tropics. We quantified frost damage and air temperature across a network of 30 permanent plots distributed across tropical savanna–forest boundaries in Brazil during an uncommonly hard frost. Tree cover strongly buffered temperatures during frost events, such that forest sites were up to 5°C warmer than nearby sites occupied by open shrub savanna. Consequently, in forest, woody plants were not damaged, but in savanna, there was extensive dieback of trees and shrubs. Within savanna, frost had disproportionately large effects on small individuals, likely due to colder temperatures near the ground and the lower thermal mass of thin stems. Across species, frost tolerance was strongly correlated with latitudinal range limit, revealing the importance of minimum temperature as a species filter at the regional scale. Counterintuitively, savanna species, which are adapted to open habitats where frost is more likely, were more vulnerable to cold than were forest species and experienced more than twice the amount of leaf damage as co‐occurring forest species. Synthesis. Frost reinforces the effects of fire on vegetation structure by preferentially damaging trees in open environments and generating high loads of dead, flammable fuels. However, frost does not currently occur with sufficient frequency in the region to maintain open savanna by itself. Nevertheless, it occurs with sufficient frequency and severity that it likely acts as an environmental filter and evolutionary selective factor for some of the most frost‐sensitive species.

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Section: Discussionmentioning

confidence: 99%

Rare frost events reinforce tropical savanna–forest boundaries

et al. 2018

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“…The magnitude of the impact that salt marsh plants have on the survival and establishment of mangrove seedlings can vary depending on environmental conditions and stressors, such as salinity and the frequency and duration of freezing events (Coldren and Proffitt ), as well as mangrove species identity (Devaney et al. ). In our experiment, S. alterniflora had negative effects on A. germinans seedlings in the absence of oil, consistent with prior field experiments examining S. alterniflora interactions with A. germinans seedlings (Patterson et al.…”

Section: Discussionmentioning

confidence: 99%

Effects of oil exposure, plant species composition, and plant genotypic diversity on salt marsh and mangrove assemblages

et al. 2018

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2018. Effects of oil exposure, plant species composition, and plant genotypic diversity on salt marsh and mangrove assemblages. Ecosphere 9(4):Abstract. Climate change is causing shifts in the distribution and abundance of many species.Because species vary in the rate and degree of these shifts, novel transition zones have developed where new combinations of species overlap. If climate-mediated range shifts result in greater diversity, transition communities could have enhanced resistance and/or resilience, particularly if the resident and colonizing species differ in their response to environmental change. The range expansion of the tropical black mangrove, Avicennia germinans, into salt marshes dominated by the temperate cordgrass, Spartina alterniflora, provides an opportunity to examine the responses of climate-mediated transition zones to disturbance. We conducted a yearlong mesocosm experiment testing the effects of plant species identity and composition (A. germinans, S. alterniflora), as well as plant genotypic diversity (S. alterniflora only), on the response of coastal wetlands to oiling disturbance. Oil negatively impacted S. alterniflora and A. germinans both above-and belowground, though the timing of these effects varied, with S. alterniflora showing more immediate declines than A. germinans. As hypothesized, the magnitude of the oil effect was reduced in the mixed plant species treatment compared to the single species treatment for A. germinans survival (12% vs. 21% reduction) and belowground biomass (19% vs. 71% reduction). In addition, when exposed to oil, A. germinans crown area and volume were greater in the mixed species treatment compared to the single species treatment at the end of the experiment. However, we did not detect any benefit of mixed species communities or S. alterniflora genotypic diversity for the S. alterniflora response to oil. Our results suggest that transition habitats in the northern Gulf of Mexico where A. germinans and S. alterniflora co-occur will be negatively impacted by future oiling events, but that they are no more susceptible, and perhaps slightly less so, than habitats dominated by either individual species.

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“…absolute minimum temperatures), the duration of freezing temperatures also influences plant physiological responses to winter temperature extremes (Attaway, 1997;Larcher, 2003). Microclimatic factors and life stage effects also add complexity to the identification of temperature thresholds for mangrove freeze damage and mortality (Devaney, Lehmann, Feller, & Parker, 2017;Osland, Hartmann, et al, 2019;Ross et al, 2009). Due in part to the influence of microclimatic gradients, freeze effects on A. germinans individuals are life stage dependent, where taller trees are more resistant to freezing temperature than shorter trees (Osland et al, 2015).…”

Section: Temperature Thresholdsmentioning

confidence: 99%

Temperature thresholds for black mangrove (Avicennia germinans) freeze damage, mortality and recovery in North America: Refining tipping points for range expansion in a warming climate

et al. 2019

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Near the tropical‐temperate transition zone, warming winter temperatures are expected to facilitate the poleward range expansion of freeze‐sensitive tropical organisms. In coastal wetlands of eastern and central North America, freeze‐sensitive woody plants (mangroves) are expected to expand northward into regions currently dominated by freeze‐tolerant herbaceous salt marsh plants. To advance understanding of mangrove range expansion, there is a need to refine temperature thresholds for mangrove freeze damage, mortality and recovery. We integrated data from 38 sites spread across the mangrove range edge in the Gulf of Mexico and Atlantic coasts of North America, including data from a regional collaborative network – the Mangrove Migration Network. In 2018, an extreme freeze event affected 60% of these sites, with minimum temperatures ranging from 0 to −7°C. We used temperature and vegetation data from before and after the freeze to quantify temperature thresholds for leaf damage, mortality and biomass recovery of the black mangrove (Avicennia germinans) – the most freeze‐tolerant mangrove species in North America. For A. germinans individuals near their northern range limit, our results indicate that temperature thresholds for leaf damage are close to −4°C, but temperature thresholds for mortality are closer to −7°C. Thresholds are expected to be warmer for more southern A. germinans individuals and for the other two common mangrove species in the region (Laguncularia racemosa and Rhizophora mangle). Regenerative buds allowed A. germinans to resprout and recover quickly from above‐ground freeze damage. Hence, biomass recovery levels during the first post‐freeze growing season were 90%, 78%, 62% and 45% for temperatures of −4, −5, −6 and −7°C, respectively. Due to a combination of vigorous resprouting and new recruitment from propagules, we expect full recovery at most sites within 1–3 years, assuming no further freeze events. Synthesis. To improve predictions of tropical range expansion in response to climate change, there is a need to better understand tropical species’ responses to winter temperature extremes. Collectively, our results refine temperature thresholds for A. germinans freeze damage, mortality and recovery, which can improve predictions of mangrove range expansion and coastal wetland ecological transformations in a warming climate.

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Mangrove microclimates alter seedling dynamics at the range edge

Cited by 52 publications

References 46 publications

Rare frost events reinforce tropical savanna–forest boundaries

Rare frost events reinforce tropical savanna–forest boundaries

Effects of oil exposure, plant species composition, and plant genotypic diversity on salt marsh and mangrove assemblages

Temperature thresholds for black mangrove (Avicennia germinans) freeze damage, mortality and recovery in North America: Refining tipping points for range expansion in a warming climate

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