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Species Richness and Exotic Species Invasion in Middle Tennessee Cedar Glades in Relation to Abiotic and Biotic Factors 1

Journal of The Torrey Botanical Society, 2008

Species richness and exotic species invasion in middle Tennessee cedar glades in relation to abio... more Species richness and exotic species invasion in middle Tennessee cedar glades in relation to abiotic and biotic factors. J. Torrey Bot. Soc. 135: 540-553. 2008.-Abiotic factors, particularly area, and biotic factors play important roles in determining species richness of continental islands such as cedar glades. We examined the relationship between environmental parameters and species richness on glades and the influence of native species richness on exotic invasion. Field surveys of vascular plants on 40 cedar glades in Rutherford County, Tennessee were conducted during the 2001-2003 growing seasons. Glades were geo-referenced to obtain area, perimeter, distance from autotour road, and degree of isolation. Amount of disturbance also was recorded. Two-hundred thirty two taxa were found with Andropogon virginicus, Croton monanthogynus, Juniperus virginiana, Panicum flexile, and Ulmus alata present on all glades. The exotics Ligustrum sinense, Leucanthemum vulgare, and Taraxacum officinale occurred on the majority of glades. Lobelia appendiculata var. gattingeri, Leavenworthia stylosa, and Pediomelum subacaule were the most frequent endemics. Richness of native, exotic and endemic species increased with increasing area and perimeter and decreased with increasing isolation (P # 0.03); richness was unrelated to distance to road (P $ 0.20). Perimeter explained a greater amount of variation than area for native and exotic species, whereas area accounted for greater variation for endemic species. Slope of the relationship between area and total richness (0.17) was within the range reported for continental islands. Disturbed glades contained a higher number of exotic and native species than nondisturbed ones, but they were larger (P # 0.03). Invasion of exotic species was unrelated to native species richness when glade size was statistically controlled (P 5 0.88). Absence of a relationship is probably due to a lack of substantial competitive interactions. Most endemics occurred over a broad range of glade sizes emphasizing the point that glades of all sizes are worthy of protection.

Contrasting seed germination patterns for intracontinental disjuncts of Heuchera (Saxifragaceae) in North America: the eastern temperate H. parviflora and western montane H. cylindrica

Canadian Journal of Botany-revue Canadienne De Botanique, 2002

Heuchera parviflora var. parviflora grows primarily in southeastern North America and Heuchera cy... more Heuchera parviflora var. parviflora grows primarily in southeastern North America and Heuchera cylindrica var. cylindrica in northwestern North America. Seeds of H. parviflora were collected in Kentucky in November 1995 and 1996 during the dispersal stage of the life cycle, and those of H. cylindrica were collected in Washington in August 1996. The purpose of the study was to compare the germination patterns of these two intracontinental disjunct species of Heuchera. During 2-12 weeks of incubation over a range of thermoperiods (15:6, 20:10, 25:15, 30:15, 35:20°C (12 h : 12 h)) that simulated habitat temperatures, fresh H. parviflora seeds germinated to 62-87% at 20:10 -30:15°C in light. Cold stratification at 5°C effectively broke conditional dormancy in H. parviflora seeds: 76-96% germination took place during 2 weeks of incubation at 15:6 -35:20°C in light following 12 weeks of cold stratification in light. In contrast, fresh H. cylindrica seeds germinated to 69-94% at 15:6 -25:15°C in light during 2-12 weeks of incubation in light, but cold stratification at 5°C did not improve germination. Peak germination of H. parviflora seeds sown in November 1996 in an ambient-temperature greenhouse occurred in early March 1997, whereas that of H. cylindrica seeds sown in September 1996 occurred in late October 1996. Adaptive divergence of these species apparently has occurred with respect to their seed germination ecology. Their dormancy and germination characteristics are similar to the many other species growing in the same vegetation types.

Microhabitat Requirements of the Federally Endangered Dalea foliosa, with Recommendations on Establishment of New Populations

Castanea, 2006

The microhabitat of the federally endangered Dalea foliosa was compared to that of its cedar glad... more The microhabitat of the federally endangered Dalea foliosa was compared to that of its cedar glade congener D. gattingeri, as well as to adjoining habitat absent of both species but appearing suitable for D. foliosa (control site). Compared to D. gattingeri sites, D. foliosa sites had lower coverage of gravel, higher coverage of herbaceous vegetation, and deeper soils. Both species were present on sites with similar leaf litter and moss coverages. Nostoc commune was absent from D. foliosa populations, but present in most D. gattingeri populations. In terms of soil depth and coverage variables, control sites differed little from D. foliosa sites.

Germination ecophysiology of the western North American species Osmorhiza depauperata ( Apiaceae ): implications of preadaptation and phylogenetic niche conservatism in seed dormancy evolution

Seed Science Research, 2004

Requirements for dormancy break and embryo growth were determined for seeds of the western North ... more Requirements for dormancy break and embryo growth were determined for seeds of the western North American species, Osmorhiza depauperata. Seeds were collected in August 2001 from Sandia Crest (3200 m elevation) and Las Huertas (2300 m), New Mexico (USA). Embryos in fresh seeds were c. 0.6 mm long, and they had to grow to c. 9-10 mm before the radicle emerged from the mericarp. Embryo growth occurred at low temperatures (1 and 5°C), and seeds germinated to high percentages at 1°C during 32 weeks of incubation in the light. No seeds germinated at 5, 15/6, 20/10, 25/15 or 30/15°C during 32 weeks of incubation. Although a 4-18 week warm-temperature (25/15°C) pretreatment increased germination rates at 1°C, it was unnecessary for a high percentage of seeds to germinate. Gibberellic acid (GA 3 , 10-1000 mg l ‫1מ‬ ) did not substitute for cold stratification. Seeds from the lowelevation population contained larger embryos and required less time to germinate than those from the highelevation population. O. depauperata seeds have deep complex morphophysiological dormancy (MPD), which is similar to two other western North American congeners and an Asian congener, but different from two eastern North American congeners. Results from this study suggest that: (1) phylogenetic niche conservatism has played a role in the persistence of deep complex MPD in the three western North American species of Osmorhiza; and (2) the stimulatory effect from a warm pretreatment in species needing only cold stratification for dormancy break is a preadaptation that initiated the development of an absolute warm requirement in species needing both warm and cold stratification.

Germinability of seeds stored in capsules on plants of two myrtaceous shrubs: differences among age cohorts and between species

Australian Journal of Botany, 2009

Canopy-stored seed banks are a common trait among members of several plant families in sclerophyl... more Canopy-stored seed banks are a common trait among members of several plant families in sclerophyllous woodlands of Australia and South Africa, with their fruits usually opening in response to damage or fire. Unknown is whether the degree of dormancy and of germination differs among age cohorts in seeds stored on the mother plant. We examined the extent and speed of germination from two intensely serotinous myrtaceous species, Callistemon glaucus and Calothamnus quadrifidus, for seed held in capsules for up to 9 years. Germination of both species differed significantly among age cohorts (P < 0.0001). However, no consistent increase in germination over a range of temperatures with storage was found, suggesting that no after-ripening occurred and that seeds were non-dormant at maturity. Differences among cohorts may be due to pre-conditioning. Significant (P 0.0214) differences occurred between the small-seeded Callistemon and the large-seeded Calothamnus. Germination was (1) optimum at !20 C for Callistemon but at <20 C for Calothamnus, (2) 9-12 days earlier for Callistemon than for Calothamnus, and (3) higher in light than in darkness for Callistemon but equal in both light conditions for Calothamnus. While germination of the species differed in important features, we would expect synchronous germination of all age cohorts to occur following fire and the onset of regular rainfall.

Growth and Reproduction of the Invasive Ligustrum sinense and Native Forestiera ligustrina (Oleaceae): Implications for the Invasion and Persistence of a Nonnative Shrub

International Journal of Plant Sciences, 2002

and †Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Bengkulu, Bengkulu 38371, Indonesia

Comparison of the seed germination of native and non-native winter annual Apiaceae in North America, with particular focus on Cyclospermum leptophyllum naturalized from South America

Plant Species Biology, 2008

To increase our knowledge of the seed dormancy breaking and germination requirements of native an... more To increase our knowledge of the seed dormancy breaking and germination requirements of native and non-native winter annual Apiaceae in temperate eastern North America, a study was conducted on seeds of Cyclospermum (Apium) leptophyllum, which is native to South America, but naturalized in North America and elsewhere. A high percentage of fresh seeds germinated over a narrow range of temperatures, but the range increased when seeds were incubated continuously in light or buried in soil at high summer temperatures, indicating the presence of conditional physiological dormancy (PD). Embryos grew from approximately 0.3 to 1.25 mm (316% increase in length) inside the seeds before the radicle emerged; thus, seeds had morphological dormancy (MD) as well as PD, that is, morphophysiological dormancy (MPD). Embryo growth did not occur during summer in seeds exposed to natural temperatures, but embryos did grow in autumn. For seeds sown in the field in June, both embryo growth and germination occurred in autumn. Thus, seeds have non-deep simple MPD, with PD being broken in summer and MD in autumn. A comparison of C. leptophyllum with native and non-native winter annual Apiaceae in the region reveals that all species have MD, but the proportion of fresh seeds that also has PD (thus, MPD) varies between species. A combination of factors, including PD, an inability to germinate at high summer temperatures, a relatively low temperature requirement for embryo growth and a lack of dispersal until autumn (in two non-natives), delays germination of both natives and non-natives until autumn, when conditions are favorable for both germination and seedling establishment.

Agroecosystem management for rare species of Paysonia (Brassicaceae): integrating their seed ecology and life cycle with cropping regimens in a changing climate

American Journal of Botany, 2007

Dormancy break and germination of seeds are governed by climatic cues, and predicted changes in c... more Dormancy break and germination of seeds are governed by climatic cues, and predicted changes in climate may impact the ecology and conservation of species. Paysonia perforata and P. stonensis are rare brassicaceous winter annuals occurring primarily in fields on floodplains, where corn or soybeans are recommended for habitat maintenance. We tested the effects of precipitation, based on two predictions of changes in climate, on seed germination in these two species and placed the results into a management framework. Seeds of both species, collected during peak dispersal in late April/early May, were given various periods of light (or darkness) followed by darkness (or light) at summer temperatures before placement in darkness during late summer/early autumn in both laboratory and field. The light requirement was met earliest at 10 wk (mid-July) on alternating wet/ dry substrate (simulating current climatic conditions). However, seeds of P. perforata and P. stonensis were photostimulated earliest at 2 wk (mid-May) and 6 wk (mid-June), respectively, on a continuously moist substrate (simulating predicted future conditions). The soil seed bank could be depleted if plowing coincides with photostimulation of seeds. Fields should be prepared after dispersal but before seeds are photostimulated and harvesting completed before seed germination in early September. Because seeds are highly photostimulated in late summer, disturbance from harvesting must be low to prevent burial. Cultivation of soybean, particularly for forage, is better matched to the seed biology and life cycle of Paysonia than that of corn under current and predicted climates.

Differences in light and temperature responses determine autumn versus spring germination for seeds of Schoenolirion croceum

Canadian Journal of Botany-revue Canadienne De Botanique, 2004

Seeds of the southeastern North American Schoenolirion croceum (Michx.) Wood are dormant when dis... more Seeds of the southeastern North American Schoenolirion croceum (Michx.) Wood are dormant when dispersed in late spring to early summer. Fresh seeds buried in soil after dispersal germinate in autumn, whereas those sown on the soil surface do so the following late winter -early spring. To understand this difference in germination phenology, we examined the light and temperature requirements for dormancy break and germination. Seeds germinated to high percentages in darkness over 12:12 h thermoperiods ranging from 15:6 to 35:20°C following warm stratification (25:15°C) in darkness, whereas no seeds germinated in light following stratification in light. On the other hand, seeds germinated to high percentages in light and in darkness following cold stratification (5°C) in light or darkness. Seeds exposed to light during autumn germinated in winter-spring regardless of the light regime in summer or winterspring, whereas those in darkness during autumn germinated in autumn regardless of the light regime in summer. Thus, light conditions during autumn are critical for determining whether seeds will germinate in autumn versus early spring. In contrast with many other species in which germination phenology is mostly temperature controlled, timing of germination for S. croceum depends on the light conditions in relation to temperatures experienced during dormancy release.

MORPHOPHYSIOLOGICAL DORMANCY IN SEEDS OF TWO NORTH AMERICAN AND ONE EURASIAN SPECIES OF SAMBUCUS (CAPRIFOLIACEAE) WITH UNDERDEVELOPED SPATULATE EMBRYOS1

In contrast to previous reports, the endocarps (''seed coats'') of Sambucus species are not imper... more In contrast to previous reports, the endocarps (''seed coats'') of Sambucus species are not impermeable to water; thus, the seeds do not have physical dormancy. Seeds of the North American species Sambucus canadensis and S. pubens and of the European species S. racemosa have spatulate shaped embryos that are ϳ60% fully developed (elongated) at seed maturity. The embryo has to extend to the full length of the seed to germinate. Embryos in freshly matured seeds of S. canadensis and in those of S. pubens grew better at 25Њ/15ЊC than at 5ЊC, whereas the rate of embryo growth in S. racemosa was higher at 5ЊC than at 25Њ/15ЊC. Seeds of all three species germinated to significantly higher percentages in light (14-h photoperiod) than in darkness. Fresh seeds of neither species germinated during 2 wk of incubation over a range of thermoperiods. Warm followed by cold stratification broke dormancy in seeds of S. canadensis and in those of S. pubens. Thus, seeds of these two North American species have deep simple morphophysiological dormancy (MPD). In comparison, seeds of the European species S. racemosa required a cold stratification period only for dormancy break, and thus they have intermediate complex MPD. GA 3 was much more effective in breaking dormancy in seeds of S. racemosa than it was in those of S. canadensis or S. pubens.

Defining transient and persistent seed banks in species with pronounced seasonal dormancy and germination patterns

Seed Science Research, 2005

The most often used time-line for distinguishing a transient seed bank from a persistent seed ban... more The most often used time-line for distinguishing a transient seed bank from a persistent seed bank is one calendar year. Thus, species whose seeds live in or on the soil for , 1 year have a transient seed bank, whereas those whose seeds live for $ 1 year have a persistent seed bank. However, dormancy cycling of seeds buried in soil has not been given due consideration in these models. When dormancy cycling is considered, it is shown that seeds of both autumn-germinators and spring-germinators are in the dormant state when they are 1 year old. Thus, unless the seeds live until at least the second germination season (i.e. usually 16 -18 months following dispersal), they are, in effect, part of a transient seed bank, having lived through only one germination season. We propose that for seeds of such species to be considered part of a short-term persistent seed bank, they should remain viable and germinable until at least the second germination season, and to be part of a long-term persistent seed bank, until at least the sixth germination season. Our definitions are applicable to seeds with physiological, physical or morphophysiological dormancy, which often require . 1 year after maturity to come out of dormancy in nature. We discuss modifications of the seedling emergence method for detection of a soil seed bank, so that they correspond to our definitions of seed-bank strategies.

AGROECOSYSTEM MANAGEMENT FOR RARE SPECIES OF PAYSONIA (BRASSICACEAE): INTEGRATING THEIR SEED ECOLOGY AND LIFE CYCLE WITH CROPPING REGIMENS IN A CHANGING CLIMATE1

Dormancy break and germination of seeds are governed by climatic cues, and predicted changes in c... more Dormancy break and germination of seeds are governed by climatic cues, and predicted changes in climate may impact the ecology and conservation of species. Paysonia perforata and P. stonensis are rare brassicaceous winter annuals occurring primarily in fields on floodplains, where corn or soybeans are recommended for habitat maintenance. We tested the effects of precipitation, based on two predictions of changes in climate, on seed germination in these two species and placed the results into a management framework. Seeds of both species, collected during peak dispersal in late April/early May, were given various periods of light (or darkness) followed by darkness (or light) at summer temperatures before placement in darkness during late summer/early autumn in both laboratory and field. The light requirement was met earliest at 10 wk (mid-July) on alternating wet/ dry substrate (simulating current climatic conditions). However, seeds of P. perforata and P. stonensis were photostimulated earliest at 2 wk (mid-May) and 6 wk (mid-June), respectively, on a continuously moist substrate (simulating predicted future conditions). The soil seed bank could be depleted if plowing coincides with photostimulation of seeds. Fields should be prepared after dispersal but before seeds are photostimulated and harvesting completed before seed germination in early September. Because seeds are highly photostimulated in late summer, disturbance from harvesting must be low to prevent burial. Cultivation of soybean, particularly for forage, is better matched to the seed biology and life cycle of Paysonia than that of corn under current and predicted climates.

A Contribution to the Life History of the Rare Indonesian Holoparasite Rafflesia patma (Rafflesiaceae)1

Biotropica, 2000

Fates and growth of Rafflesia patma buds and insect visitation to the flowers were monitored in a... more Fates and growth of Rafflesia patma buds and insect visitation to the flowers were monitored in an evergreen tropical rain forest in the Pangandaran Nature Reserve, Java, Indonesia, Of 59 buds marked in December 1985, 44 percent died before flowering, 7 percent flowered, and 49 percent were still in bud in May 1986. Mammals and birds caused the deaths of buds before they reached maturity. Only four buds flowered between December 1985 and May 1986; all were male. Rate of increase in diameter (cm/d) was much faster in large than in small buds. Once opening began, the flower opened fully in 24 to 48 hours; the flower remained open for three to five days before rotting. Only two genera of insects visited a male flower of R. patma: Lucilia and Sarcophaga (Diptera). Insect visitation was highest in the afternoon (1300–1700 h) and on the second or third day after flower opening. The increased number of flies visiting the flower coincided with the increasing odor emitted from it. Results of the present study were combined with information from the literature to construct a life cycle diagram of R. patma.Telah dilakukan penelitian tentang pertumbuhan dan perkembangan kuncup dan jenis-jenis serangga yang mengunjungi bunga Rafflesia patma di hutan hujan tropik Taman Wisata Pangandaran, Jawa, Indonesia. Dari 59 kuncup yang dijumpai di bulan Desember 1985, 44 persen mati sebelum mekar, 7 persen mekar, dan 49 persen masih berupa kuncup pada akhir penelitian bulan Mei 1986. Mamalia dan burung, adalah penyebab kematian kuncup sebelum mekar. Empat bunga jantan mekar selama penelitian tetapi tidak ditemukan bunga betina yang mekar. Laju pertambahan garis tengah kuncup (cm/d) lebih cepat pada kuncup bergaris tengah besar daripada kuncup yang kecil. Bunga mekar dalam waktu 24–48 jam dan bunga mekar penuh selama 3–5 hari sebelum akhirnya layu. Dua jenis lalat, Lucilia dan Sarcophaga (Diptera) mengunjungi bunga R. patma yang mekar. Frekwensi kunjungan tertingggi adalah pada sore hari (jam 1300–1700), dan puncak kunjungan terjadi pada hari kedua atau ketiga setelah bunga mekar. Jumlah seranggga pengunjung meningkat seiring dengan meningkatnya intensitas bau yang dikeluarkan oleh bunga. Hasil penelitian ini ditambah dengan informasi dari pustaka yang ada digunakan untuk membentuk diagram siklus hidup R. patina.

Seed germination ecophysiology of two western North American species of Sambucus (Caprifoliaceae sensu lato), and comparisons with eastern North American and European congeners: SEED GERMINATION IN SAMBUCUS

Plant Species Biology, 2010

Seeds of the western North American (wNA) species Sambucus caerulea in the Sambucus nigra species... more Seeds of the western North American (wNA) species Sambucus caerulea in the Sambucus nigra species complex and Sambucus callicarpa in the Sambucus racemosa complex contain embryos that are 70–75% fully developed when freshly matured. These embryos must elongate approximately 15–25% before radicle emergence occurs. Embryos in seeds of both species grew better at 5°C than at 25/15°C. Dormancy was broken by cold stratification at 5°C, which was also the optimal temperature for germination. Gibberellic acid substituted for cold stratification in both species. Thus, seeds of both species have intermediate complex morphophysiological dormancy (MPD). The seed dormancy characteristics of both species differ from those of congeners in eastern North America (eNA). In contrast, dormancy break in S. callicarpa is similar to its European congeners, but is unclear in S. caerulea. Our study represents the first to compare seed dormancy among wNA, eNA and European congeners. In North America, the geographic pattern of dormancy break for Sambucus is similar to that of Osmorhiza (Apiaceae) and Erythronium (Liliaceae): cold stratification is required in wNA taxa and warm + cold stratification is required in eNA taxa. Moreover, the pattern in S. callicarpa is similar to that in some species of Sanicula (Apiaceae): cold stratification in Europe and warm + cold stratification in eNA. The evolution of seed dormancy in these groups might have occurred under similar environmental circumstances, resulting in the sharing of dormancy-breaking mechanisms within geographical regions.

Dormancy-Breaking and Germination Requirements for Seeds of Symphoricarpos orbiculatus (Caprifoliaceae

American Journal of Botany, 2001

Fruits (drupes) of Symphoricarpos orbiculatus ripen in autumn and are dispersed from autumn to sp... more Fruits (drupes) of Symphoricarpos orbiculatus ripen in autumn and are dispersed from autumn to spring. Seeds (true seed plus fibrous endocarp) are dormant at maturity, and they have a small, linear embryo that is underdeveloped. In contrast to previous reports, the endocarp and seed coat of S. orbiculatus are permeable to water; thus, seeds do not have physical dormancy. No fresh seeds germinated during 2 wk of incubation over a 15Њ/6Њ-35Њ/20ЊC range of thermoperiods in light (14-h photoperiod); gibberellic acid and warm or cold stratification alone did not overcome dormancy. One hundred percent of the seeds incubated in a simulated summer → autumn → winter → spring sequence of temperature regimes germinated, whereas none of those subjected to a winter → spring sequence did so. That is, cold stratification is effective in breaking dormancy only after seeds first are exposed to a period of warm temperatures. Likewise, embryos grew at cold temperatures only after seeds were exposed to warm temperatures. Thus, the seeds of S. orbiculatus have nondeep complex morphophysiological dormancy. As a result of dispersal phenology and dormancy-breaking requirements, in nature most seeds that germinate do so the second spring following maturity; a low to moderate percentage of the seeds may germinate the third spring. Seeds can germinate to high percentages under Quercus leaf litter and while buried in soil; they have little or no potential to form a long-lived soil seed bank.

Seed germination ecophysiology of the Asian species Osmorhiza aristata (Apiaceae): comparison with its North American congeners and implications for evolution of types of dormancy

American Journal of Botany, 2002

Germinating seeds of: Lesquerella perforata and stonensis: substrate effects and mucilage production

Native Plants Journal, 2007

Ombrohydrochory and Its Relationship to Seed Dispersal and Germination Strategies in Two Temperate North American Oenothera Species (Onagraceae

International Journal of Plant Sciences, 2007

... of capsule. Precipitation was measured with a Tru‐Chek rain gauge mounted on a 1.5‐m‐tall pos... more

Evolutionary considerations of the presence of both morphophysiological and physiological seed dormancy in the highly advanced euasterids II order Dipsacales

Seed Science Research, 2006

... China,Viburnum has been reported from the Late Cretaceous, Palaeocene, Eocene, Miocene and Pl... more

Dormancy-breaking and germination requirements for seeds of Diervilla lonicera (Caprifoliaceae), a species with underdeveloped linear embryos

Canadian Journal of Botany-revue Canadienne De Botanique, 2000

Fruits (drupes) of Symphoricarpos orbiculatus ripen in autumn and are dispersed from autumn to sp... more Fruits (drupes) of Symphoricarpos orbiculatus ripen in autumn and are dispersed from autumn to spring. Seeds (true seed plus fibrous endocarp) are dormant at maturity, and they have a small, linear embryo that is underdeveloped. In contrast to previous reports, the endocarp and seed coat of S. orbiculatus are permeable to water; thus, seeds do not have physical dormancy. No fresh seeds germinated during 2 wk of incubation over a 15Њ/6Њ-35Њ/20ЊC range of thermoperiods in light (14-h photoperiod); gibberellic acid and warm or cold stratification alone did not overcome dormancy. One hundred percent of the seeds incubated in a simulated summer → autumn → winter → spring sequence of temperature regimes germinated, whereas none of those subjected to a winter → spring sequence did so. That is, cold stratification is effective in breaking dormancy only after seeds first are exposed to a period of warm temperatures. Likewise, embryos grew at cold temperatures only after seeds were exposed to warm temperatures. Thus, the seeds of S. orbiculatus have nondeep complex morphophysiological dormancy. As a result of dispersal phenology and dormancy-breaking requirements, in nature most seeds that germinate do so the second spring following maturity; a low to moderate percentage of the seeds may germinate the third spring. Seeds can germinate to high percentages under Quercus leaf litter and while buried in soil; they have little or no potential to form a long-lived soil seed bank.