Comparative water balance profiles of Orchidaceae seeds for epiphytic and terrestrial taxa endemic to North America

Yoder, Jay A.; Imfeld, Samantha M.; Heydinger, Derrick J.; Hart, Chloé; Collier, Matthew H.; Gribbins, Kevin M.; Zettler, Lawrence W.

doi:10.1007/s11258-010-9765-2

Cited by 23 publications

(14 citation statements)

References 27 publications

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“…Yoder et al . (2010) studied ten North American endemics, Tsutsumi et al . (2007) compared seeds of six epiphytic and terrestrial Liparis species and Zhang et al .…”

Section: Discussionmentioning

confidence: 99%

“…A few other studies have directly compared seed characteristics of epiphytic and terrestrial orchids. Yoder et al (2010) studied ten North American endemics, Tsutsumi et al (2007) compared seeds of six epiphytic and terrestrial Liparis species and Zhang et al (2015) compared epiphytic and terrestrial Paphiopedilum species. The results of these studies are inconsistent: while epiphytic orchids in the first study had smaller, lighter and more porous seeds, which agrees with our findings, the opposite observation was made in the comparison of congeneric Liparis: epiphytes had larger seeds with smaller air volume.…”

Section: Discussionmentioning

confidence: 99%

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Measuring the terminal velocity of tiny diaspores

et al. 2016

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Although it has long been acknowledged that seed characteristics are of major importance to the conquest of tree crowns by vascular epiphytes, there is surprisingly little quantitative evidence on the aerodynamic properties of their diaspores. We used a custom-built device to determine the terminal velocity (Vterm) of falling seeds, a parameter that has been shown to have high predictive power for the wind dispersal potential of diaspores under natural conditions. We determined Vterm of 45 species of epiphytic and terrestrial Orchidaceae, which almost doubles the currently available database for this family. Although varying by a factor of five with values of 0.09–0.4 m s−1, Vterm was invariably very slow compared to plants in general. For each species, we also took morphological data and determined seed mass. None of these parameters was linearly correlated with Vterm and neither did the average Vterm differ between species found in the two habitats, although seeds of terrestrial taxa were significantly larger and heavier. Finally, we demonstrate the potential of our device to measure Vterm of even smaller diaspores by successfully quantifying Vterm of fern spores. This tool has much potential for the quantitative study of dispersal of plants with tiny diaspores, particularly in a conservation context in fragmented landscapes.

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“…Yoder et al . (2010) studied ten North American endemics, Tsutsumi et al . (2007) compared seeds of six epiphytic and terrestrial Liparis species and Zhang et al .…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Measuring the terminal velocity of tiny diaspores

et al. 2016

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“…Finally, the relatively rapid rate with which epiphytic orchid seeds absorb water, germinate and begin photosynthesis suggests that they may not experience the extended period of physiological dependence on mycorrhizal fungi that terrestrial orchids do (Yoder et al . ; Rasmussen ). Nevertheless, some seedlings detectably associated with fungi that form orchid mycorrhizas, suggesting that seedlings can benefit from mycorrhizal symbioses but that these symbioses are not spatially aggregated around conspecific adults.…”

Section: Discussionmentioning

confidence: 99%

Critical importance of large native trees for conservation of a rare Neotropical epiphyte

2013

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Summary1. The distribution of rare plants may be limited by environmental or density-dependent factors that reduce population growth and persistence. The relative importance of environmental limitations vs. the degree to which conspecifics influence recruitment may determine optimal management strategies for plants of conservation concern. 2. We sowed seeds of a rare epiphytic orchid in trees from agricultural Costa Rican landscapes to ask how recruitment is influenced by established conspecific plants and the environment. We hypothesized that recruitment is positively influenced by conspecific plants. Conspecific adults were expected to be associated with favourable microhabitats and mycorrhizal fungi for germinating seeds, without creating unfavourably competitive conditions. Alternatively, we hypothesized that recruitment varies due to environmental differences among study sites or host trees, irrespective of adult proximity. 3. We experimentally added 240 packets of seeds from 2 source populations into four naturally established populations. Germination was evaluated after five months. We used mixed models and conditional inference trees to evaluate results. 4. Proximity to conspecific adults neither increased nor decreased germination. Instead, large native trees and microsites with more closed canopies supported significantly greater germination than smaller cultivated trees and microsites with more open canopies. 5. Synthesis. Landscape changes that replace large native trees with a more homogenous array of cultivated species may not only reduce rare epiphyte populations directly, but also limit their ability to colonize disturbed secondary habitats. Because the habitat is the prime determinant of recruitment, large and often isolated native trees that act as refuges for rare epiphytes in disturbed landscapes should be a top priority for local conservation efforts.

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“…Further, epiphytes lack the enhanced water retention capacity associated with the terrestrials ( Yoder et al. 2000 ) and their seeds are smaller, lighter, and are more porous ( Yoder et al. 2010 ), implying that epiphytic orchids are capable of germinating quickly under adequate substrate moisture.…”

Section: Introductionmentioning

confidence: 99%

Regeneration responses to water and temperature stress drive recruitment success in hemiepiphytic fig species

et al. 2020

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Mechanisms for surviving water and temperature stress in epiphytes are essential adaptations for successful regeneration in forest canopies. Hemiepiphytes start their life cycle as epiphytes, eventually establishing areal root connections to the ground. This strategy allows for greater light capture, while benefitting from minimized risk of fire, flooding, and damage by terrestrial herbivores, but exposes the vulnerable seedling stage to heat and drought stress. However, the response to temperature and water stress during early regeneration in hemiepiphytes is not known. In this study, we tested the effect of temperature (15/5°C, 25/15°C, 35/25°C; day/night diurnal variation) and water availability, as substrate moisture (0.00 MPa, −0.20 MPa, −0.35 MPa) and water vapor (18.5% to 99.5% relative humidity), on seed germination, seedling emergence, and survival in six hemiepiphytic and nine non-hemiepiphytic Ficus species. Under high temperature conditions (35/25°C), hemiepiphytes had higher gemination and seedling survival, achieved peak germination slower and extended germination. Greater water stress (−0.35 MPa) in the growth substrate resulted in higher germination of non-hemiepiphytes; hemiepiphytes, in contrast, took a shorter time to complete germination, but had higher seedling emergence and survival. Hemiepiphytes germinated at 99.5% relative humidity more readily compared to non-hemiepiphytes. These findings provide the first comprehensive evidence that hemiepiphytic Ficus species are better adapted to drier and warmer conditions during the critical transition from seed to seedling. Through greater flexibility in achieving peak germination and duration of regeneration activity, hemiepiphytes modulate their recruitment process to be more resilient under abiotic stressors. This may allow them to be more successful in regenerating in forest canopies under ambient conditions that are transient. These results support previous work showing greater drought tolerance of hemiepiphytic Ficus species in larger size classes, and extend this finding to show that physiological adaptations for drought and heat tolerance start from the early seedling emergence stage.

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Comparative water balance profiles of Orchidaceae seeds for epiphytic and terrestrial taxa endemic to North America

Cited by 23 publications

References 27 publications

Measuring the terminal velocity of tiny diaspores

Measuring the terminal velocity of tiny diaspores

Critical importance of large native trees for conservation of a rare Neotropical epiphyte

Regeneration responses to water and temperature stress drive recruitment success in hemiepiphytic fig species

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