Should we use the float test to quantify acorn viability?

Morina, Daniel L.; Lashley, Marcus A.; Chitwood, M. Colter; Moorman, Christopher E.; Perno, Carlo Federico

doi:10.1002/wsb.826

Cited by 14 publications

(8 citation statements)

References 14 publications

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“…Immediately before planting, acorns were randomly selected from the collection and assessed for viability using the float test (Morina et al. ): Floating, cracked, or soft acorns were discarded. We further tested acorn viability under controlled conditions by randomly selecting 60 acorns, planting them in separate pots in our greenhouse on 6 November 2013, and recording emergence (40%) in May 2014.…”

Section: Methodsmentioning

confidence: 99%

“…Between 1 and 14 November 2013, we sowed 200 acorns per plot on their sides at 2.5-5 cm depth and spaced them as uniformly as possible in a grid fashion (~15-20 cm apart), for a total of 1200 acorns per treatment (3600 acorns across the 18 plots). Immediately before planting, acorns were randomly selected from the collection and assessed for viability using the float test (Morina et al 2017): Floating, cracked, or soft acorns were discarded. We further tested acorn viability under controlled conditions by randomly selecting 60 acorns, planting them in separate pots in our greenhouse on 6 November 2013, and recording emergence (40%) in May 2014.…”

Section: Experimental Designmentioning

confidence: 99%

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Native tree and shrub canopy facilitates oak seedling regeneration in semiarid woodland

et al. 2020

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Oaks (Quercus spp.) are currently declining worldwide due to a multitude of threats. Woodland management is often heavily focused on thinning and burning nontarget species to reduce competition and promote oak dominance in the overstory. These techniques have typically been developed in temperate regions, such as eastern U.S. forests, but whether they are the most effective strategy for promoting oak regeneration in semiarid woodlands has not been sufficiently examined. We conducted our study on the eastern Edwards Plateau in central Texas, where several oak species are codominant with Ashe juniper (Juniperus ashei) over karst limestone terrane. These juniper‐oak woodlands provide habitat for many endemic species and play an essential role in the maintenance of key aquifers. A history of canopy clearing and a severe drought in 2011 generated patches of living and dead juniper‐oak canopy interspersed with canopy gaps in our study area. In November 2013, we planted 200 shin oak (Quercus sinuata var. breviloba) acorns in each of three habitat treatments, replicated six times: (1) live canopy, (2) dead canopy, and (3) open invasive grassland. We monitored emergence and survival each year, harvesting five seedlings from each replicate in October 2017 to assess shoot height, rooting depth, biomass, ectomycorrhizal colonization, and foliar nutrients. Canopy trees, living or dead, significantly enhanced seedling emergence and survival. Survival was positively associated with increasing Ashe juniper and oak basal area, shrub cover, and soil organic matter, and negatively associated with increasing canopy gap size (complete mortality in gaps >220 m2). Seedling biomass increased significantly in dead and open treatments along with foliar nutrients N, P, and S (dead treatments) or S and Fe (open treatments), whereas ectomycorrhizal colonization and foliar nutrients Ca, Mg, and Mn increased under living canopy. Our findings suggest that oak regeneration in these juniper‐oak woodlands closely resembles that of Mediterranean regions, where canopy facilitates seedling survival. Both living and dead trees and shrubs enhanced oak regeneration, with seedling survival depending on proximity to larger trees, living roots, shrubs, and juniper‐oak canopy. Planting acorns under canopy is an inexpensive, sustainable, and effective restoration practice in drought‐prone ecosystems.

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Section: Methodsmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

Native tree and shrub canopy facilitates oak seedling regeneration in semiarid woodland

et al. 2020

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“…The acorns were collected haphazardly from a 4‐ha area that contained >700 live Q. rubra trees greater than 5 cm diameter at breast height (DBH); therefore, the acorns were from a variety of maternal trees (although we are unable to determine which acorns originated from which trees). We checked acorns for viability by testing whether they sank in water because acorns that float are typically rotten or damaged (Morina et al, 2017). The viable acorns were then cold stratified for 4.5 months at 4°C and retested for viability.…”

Section: Methodsmentioning

confidence: 99%

Limited evidence that larger acorns bufferQuercus rubraseedlings from density‐dependent biotic stressors

Jevon

Lang

Ayres

et al. 2021

American J of Botany

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Plant performance and functional traits vary considerably within species, particularly in response to environmental variation. Plant responses may reflect lifehistory trade-offs, such as between resource acquisition and resource conservation. Larger seeds may buffer young plants from the negative effects of environmental variation, such as limitations in nutrients or water. However, whether seed size plays a similar role in how plants respond to variation in their biotic environment, including competition and soil microbial communities, remains poorly understood. Methods: We used a greenhouse experiment to test the interactive effects of intraspecific competition, the origin of the soil microbial community, and seed size on performance and functional traits in Quercus rubra L. seedlings. Results: Intraspecific variation in seedling traits weakly aligned with a resource acquisition-conservation trade-off. Across the wide range of initial acorn mass, competition decreased seedling biomass by about 35%. Competition directly decreased the root mass ratio and indirectly increased specific leaf area and specific root length, via the negative effects on total biomass. In contrast, soil microbial communities had minor effects on seedlings, and we found no differences between plants receiving soil originating from a conspecific adult and plants receiving soil originating from a heterospecific adult. Conclusions: Competition is a more important driver of intraspecific variation in young Quercus rubra seedling performance and traits, both directly and by delaying ontogenetic development, than soil microbial communities. Seed size is an important predictor of seedling biomass, but a larger seed does not necessarily buffer seedlings from the effects of competition.

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“…Floating seeds were presumed to lack an endosperm or embryo, while seeds that sunk were presumed filled. Seeds were dropped into water for approximately 15 seconds to differentiate presumed non-viable, floating seeds from presumed viable, sinking seeds (Gribko and Jones 1995; Morina et al . 2017).…”

Section: Methodsmentioning

confidence: 99%

“…Floating seeds were presumed to lack an endosperm or embryo, while seeds that sunk were presumed filled. Seeds were dropped into water for a period of approximately 15 seconds to differentiate presumed non-viable, floating seed from presumed viable, sinking seeds (Gribko and Jones, 1995;Morina et al, 2017). Those seeds classed as likely viable were organized by maternal tree using paper bags, and then placed in a Blue M drying oven (Thermal Product Solutions, White Deer, Pennsylvania, USA) maintained at 37°C for 24 hours to remove potential surface moisture.…”

Section: Seed Viability Tests -mentioning

confidence: 99%

Seed morphological traits as a tool to quantify variation maintained inex situcollections: a case study inPinus torreyana(Parry)

Santo

Polgar

Nies

et al. 2020

Preprint

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PREMISEOptimizing the amount of genetic diversity captured in seed collections is a long-standing objective of ex situ conservation. Particularly for rare species where limited genetic information is available, it poses a significant challenge. However, understanding the within and among population distribution of trait variation within seed collections may provide a means to approximate standing genetic variation and inform conservation efforts.METHODSWe quantified seed morphological variation and seedling emergence both within and among populations for existing seed collections of Torrey pine (Pinus torreyana), a critically endangered pine endemic to California. Using a simulation-based approach, we used estimates of within-population variance to estimate the number of maternal families required to captured 95% of trait variation within each existing seed collection.KEY RESULTSOn average, 21% and 22% of seed morphological variation in Torrey pine was explained by population origin and maternal family within populations respectively. Despite significant morphological differences, seedling emergence was similar across populations. Simulations revealed that 80% and 68% of all maternal families within island and mainland seed collection respectively needed to be resampled to ensure 95% of seed trait variation within existing collections was captured.CONCLUSIONSOverall, these results suggest that substantial structure exists for seed morphological traits both within and between populations. From a conservation perspective, this indicates that to optimize genetic diversity captured in Torrey pine ex situ conservation collections, maximizing the number of maternal families sampled within each population will be necessary.

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Should we use the float test to quantify acorn viability?

Cited by 14 publications

References 14 publications

Native tree and shrub canopy facilitates oak seedling regeneration in semiarid woodland

Native tree and shrub canopy facilitates oak seedling regeneration in semiarid woodland

Limited evidence that larger acorns bufferQuercus rubraseedlings from density‐dependent biotic stressors

Seed morphological traits as a tool to quantify variation maintained inex situcollections: a case study inPinus torreyana(Parry)

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