Amplified drought induced by climate change reduces seedling emergence and increases seedling mortality for two Mediterranean perennial herbs

Sheep and hair fescue are perennial, tuft forming grasses that spread by seed and form dense sods in wild blueberry fields. These sods compete with the crop for resources and hinder harvest. Field and greenhouse studies were conducted in 2015 to evaluate 1) the effect of sequential glufosinate and foramsulfuron applications on suppression of fescues in the greenhouse and field, and 2) efficacy of glufosinate and foramsulfuron on fescue seedlings when applied at 2, 4, 6, and 8 wk after seedling emergence in the greenhouse. Glufosinate applications at 750 and 1,005 g ai ha−1followed by foramsulfuron application at 35 g ai ha−1reduced fescue leaf number and biomass relative to foramsulfuron application alone in the greenhouse. In the field study, fescue flowering tuft density, tuft inflorescence height, seed production, and seed viability were reduced by foramsulfuron alone, but there was a trend towards lower seed production and tuft height when fescues were treated with glufosinate at 1,005 g ha−1followed by foramsulfuron. Foramsulfuron caused low seedling mortality at all application timings evaluated, but glufosinate caused >90% mortality in seedlings when applied at 2, 4, 6, or 8 wk after seedling emergence. Our results suggest that sequential applications of these herbicides are less effective under field conditions relative to results obtained in the greenhouse, though burndown glufosinate applications may have a role in reducing fescue seedling recruitment. Additional research should be conducted to determine the effect of early spring and autumn glufosinate applications on fescue seedling recruitment and suppression of established fescue tufts with subsequent foramsulfuron applications.

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Effects of disturbance and rabbit grazing on seedling recruitment of six mesic grassland species

Seed Science Research ◽

10.1017/s0960258599000161 ◽

1999 ◽

Vol 9 (2) ◽

pp. 145-156 ◽

Cited By ~ 19

Author(s):

Grant R. Edwards ◽

Michael J. Crawley

Keyword(s):

Seedling Recruitment ◽

Plantago Lanceolata ◽

Plant Cover ◽

Seedling Emergence ◽

Soil Disturbance ◽

Seedling Mortality ◽

Grassland Species ◽

Rabbit Grazing ◽

Plant Densities ◽

Seed Sowing

AbstractSeeds of two grass (Arrhenatherum elatius and Festuca rubra), two herb (Plantago lanceolata and Rumex acetosa) and two legume (Lotus corniculatus and Trifolium repens) species were sown in summer 1995 at four densities (no seed, 1000, 10 000 and 50 000 seeds m−2) into an established rabbit-grazed grassland given factorial combinations of rabbit fencing (with and without fences) and soil disturbance (with and without cultivation). On plots where no seeds were sown, only the species with persistent seed banks (P. lanceolata, L. corniculatus and T. repens) showed enhanced seedling emergence in response to disturbance. In disturbed soil, seedling densities of all species increased with increasing density of sown seeds, the effects of which were still evident for plant cover 2 years after seed sowing. In undisturbed vegetation, A. elatius, F. rubra, P. lanceolata and R. acetosa showed increased seedling densities following seed sowing; but in each case, there was an upper asymptote to seedling recruitment, presumably due to microsite limitation. Rabbit grazing reduced seedling densities, with this reduction being more pronounced with disturbance than without. However, the effect of rabbit grazing did not persist for some species; seedling mortality of R. acetosa, P. lanceolata, L. corniculatus and T. repens was higher on plots without rabbit grazing, so that plant densities of these species in summer 1996 and plant cover in summer 1997 were greater on grazed plots. The results indicate interactions between soil disturbance, propagule availability and herbivory, rather than disturbance alone, will play an important role in controlling seedling recruitment and species habitat distributions in grasslands.

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Seed Germination Ecophysiology of Meadow Salsify (Tragopogon pratensis) and Western Salsify (T. dubius)

Weed Science ◽

10.1017/s0043174500052061 ◽

1993 ◽

Vol 41 (3) ◽

pp. 362-368 ◽

Cited By ~ 16

Author(s):

Meiqin Qi ◽

Mahesh K. Upadhyaya

Keyword(s):

Seed Germination ◽

Storage Temperature ◽

Seedling Emergence ◽

Separate Study ◽

Optimum Temperature ◽

Seedling Mortality ◽

Secondary Dormancy ◽

Persistence Strategies

To understand persistence strategies of meadow and western salsify, ecophysiological characteristics of their seed germination were studied. Anaerobiosis (immersion in deoxygenated water) induced secondary dormancy in seeds of both species. Dormancy could be induced in 86% of meadow salsify seeds and in 65% of western salsify seeds by a 1-d anaerobiosis treatment. The induced dormancy was gradually released during storage of air-dried secondary dormant meadow salsify seeds, and the rate of this release was influenced by storage temperature; 30 C was more effective than 10 or 20 C in releasing secondary dormancy. These results suggest that the two species may rely on induced dormancy as an option in their persistence strategy. The optimum temperature for germination of nondormant seeds of both species was 15 C. Maximum germination percentages for both species were established within 4 to 6 d of incubation at 15 C and within 14 to 28 d of incubation at 25 C. Nondormant seeds did not germinate below 10 or above 30 C. Stratification (at 5 C for 2 to 10 wk) stimulated germination of secondary dormant seeds of meadow salsify. This stratification requirement can be important in preventing germination of dormant salsify seeds in the fall, thereby avoiding high seedling mortality in the winter. Light (red and far-red) had no effect on germination of seeds in secondary dormancy. In a separate study, seeds of both species were planted in pots at depths of 2 to 14 cm and seedling emergence was observed. Maximum emergence occurred when seeds were buried 2 cm deep. Seeds planted 8 cm or deeper germinated but did not emerge.

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Germination, survival, and early growth of red alder seedlings in the central Coast Range of Oregon

Canadian Journal of Forest Research ◽

10.1139/x95-178 ◽

1995 ◽

Vol 25 (10) ◽

pp. 1639-1651 ◽

Cited By ~ 14

Author(s):

Sybille Haeussler ◽

John C. Tappeiner II ◽

Brian J. Greber

Keyword(s):

Soil Moisture ◽

Seedling Survival ◽

Seedling Emergence ◽

Mineral Soil ◽

Survival Rates ◽

Moisture Stress ◽

Coast Range ◽

Seedling Mortality ◽

Central Coast ◽

Red Alder

Effects of forest disturbance and soil moisture levels on establishment of red alder (Alnusrubra Bong.) seedlings were studied at four sites representing a climatic moisture gradient within the central Coast Range of Oregon. On average, there was no difference in seedling emergence between recent clearcuts and second-growth forests, but emergence was much higher on mineral soil than on organic seedbeds. Emergence, on both types of seedbed, was positively correlated with spring soil moisture conditions (R2 = 0.60). Seedling survival, on the other hand, differed greatly between clearcut and forest. In clearcuts, heat and drought injuries were the primary causes of seedling mortality. In the forest, seedlings had poor vigour and quickly succumbed to pathogens, herbivores, and rain splash. First-year survival rates were strongly correlated with minimum summer soil moisture levels (R2 = 0.71). Height growth of seedlings on clearcuts (2–5 cm after 1 year; 8–23 cm after 2 years) was much slower than rates typically described for red alder. Best establishment occurred on skid trails and landings, suggesting that young seedlings may suffer less from heat or moisture stress on these heavily disturbed microenvironments.

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Climate change effects on early stages of Quercus ariifolia (Fagaceae), an endemic oak from seasonally dry forests of Mexico

Acta Botanica Mexicana ◽

10.21829/abm126.2019.1466 ◽

2019 ◽

Author(s):

Ernesto I. Badano ◽

Francisco A. Guerra-Coss ◽

Erik J. Sánchez-Montes de Oca ◽

Carlos I. Briones-Herrera ◽

Sandra M. Gelviz-Gelvez

Keyword(s):

Climate Change ◽

Functional Traits ◽

Rainy Season ◽

Extinction Risk ◽

Seedling Emergence ◽

Dry Forest ◽

Tree Seedlings ◽

Dry Forests ◽

Tree Recruitment ◽

Seasonally Dry

Background and Aims: Tree recruitment in seasonally dry forests occurs during the rainy season. However, higher temperatures and reduced rainfalls are expected in these ecosystems because of climate change. These changes could induce drought conditions during the rainy season and affect tree recruitment. Plants subjected to thermal or water stress often display morphological and physiological shifts addressed to prioritize their survival. If recently emerged tree seedlings display these responses, this could improve their development during the rainy season and increase their survival chances. Our aim was to test whether recently emerged oak seedlings display these responses.Methods: We performed a field experiment with Quercus ariifolia, an oak species endemic to seasonally dry forests of central Mexico. At the beginning of the rainy season (September 2016), we sowed acorns of this species in control plots under the current climate and plots in which climate change was simulated by increasing temperature and reducing rainfall (CCS plots). Seedling emergence and survival were monitored every seven days during the rainy season (until January 2017). At the end of the experiment, we measured several functional traits on surviving seedlings and compared them between controls and CCS plots.Key results: Higher temperature and lower rainfall generated water shortage conditions in CCS plots. This did not affect emergence of seedlings but reduced their survival. Seedlings that survived in CCS plots displayed shifts in their functional traits, which matched with those of plants subjected to thermal and water stress.Conclusions: Our results suggest that climate change can increase the extinction risk of Q. ariifolia in seasonally dry forest of Mexico by reducing the survival of its offspring. Nevertheless, the results also suggest that seedlings developed under climate change conditions can display functional shifts that could confer them tolerance to increased drought.

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SEED GERMINATION PLASTICITY OF TWO ENDANGERED SPECIES OF FERULA IN THE CONTEXT OF CLIMATE CHANGE

Plant Breeding and Seed Science ◽

10.37317/pbss-2019-0009 ◽

2020 ◽

Vol 80 ◽

pp. 13-33

Author(s):

Parvin Salehi Shanjani ◽

Amir Mousavi ◽

Faeze Rasoulzadeh Farsad

Keyword(s):

Climate Change ◽

Medicinal Plants ◽

Low Temperatures ◽

Seedling Emergence ◽

Cold Stratification ◽

Local Adaptations ◽

Germination Characteristics ◽

In The Wild ◽

Different Populations ◽

Germination Cues

Ferula assa-foetida and F. gummosa, Apiaceae, are important endemic and endangered medicinal plants. Survival of the species is threatened by climate change, overexploiting (as source of oleo-gum resin and for-age) and lack of organized cultivation. Cultivation of these valuable medicinal plants is restricted by insuffi-cient domestication knowledge. Germination characteristics of different populations of Ferula taxa were studied with the aim of describing and comparing their responses to continuous cold stratification condition. Germination cues for the species were complex, with dormancy mechanisms present to restrict germination until cold stratification are fulfilled. Results indicated that a period of 4 weeks of stratification is sufficient for germination of F. assa-foetida, but optimal germination of F. gummosa require stratification for periods of 8 weeks. Both species were able to germinate at very low temperatures (4°C). Within-taxon differences in dor-mancy breaking and seedling emergence may interpret as local adaptations. The continued regeneration and propagation of the species in the wild will depend on the temperature and moisture status of the soil during winter and the maintenance of conditions suitable for stratification for an appropriate length of time.

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Ecological Studies of the Endangered Rutidosis leptorrhynchoides. II. Patterns of Seedling Emergence and Survival in a Native Grassland

Australian Journal of Botany ◽

10.1071/bt9950013 ◽

1995 ◽

Vol 43 (1) ◽

pp. 13 ◽

Cited By ~ 26

Author(s):

JW Morgan

Keyword(s):

Soil Moisture ◽

Seedling Recruitment ◽

Seedling Survival ◽

Seedling Emergence ◽

Moisture Stress ◽

Seedling Mortality ◽

Themeda Triandra ◽

Established Plant ◽

Survival And Growth ◽

Growth Of Seedlings

The emergence, survival and growth of seedlings of the endangered Rutidosis leptorrhynchoides F.Muell. were followed in a Themeda triandra grassland during 1991 and 1992. The effect of summer irrigation on seedling survival was also investigated. Seedling emergence occurred in both years within 2 weeks of the 'autumn break' when soil moisture rose above 20%. Ninety percent of emergence was observed within 4 weeks of the onset of germination and 87% of seedlings were within 20 cm of an established plant. No emergence was observed after 8 weeks. Thirteen percent of the 1991 cohort survived for 14 months. Mortality of most seedlings (63%) was attributed to soil moisture stress in summer. Small seedlings (Ͱ4 3 leaves) were no more susceptible to drought than larger seedlings. Seventy two percent of the 1991 cohort produced four leaves before subsequently dying. In 1992, however, most early seedling mortality was amongst cotyledonary seedlings. No seedlings flowered in their first year. Above-ground growth was slow and by 14 months, 60% of surviving seedlings had seven or fewer live leaves. Irrigation in a year of below-average rainfall had no significant effect on the survival and growth of seedlings. This suggests that seedling recruitment is not restricted to climatically favourable years (i.e. is not episodic) but rather, is potentially on-going provided suitable microsites are available for seedling survival.

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Seedling emergence responds to both seed source and recruitment site climates: a climate change experiment combining transplant and gradient approaches

Plant Ecology ◽

10.1007/s11258-013-0193-y ◽

2013 ◽

Vol 214 (4) ◽

pp. 607-619 ◽

Cited By ~ 23

Author(s):

Eric Meineri ◽

Joachim Spindelböck ◽

Vigdis Vandvik

Keyword(s):

Climate Change ◽

Seedling Emergence ◽

Seed Source ◽

Climate Change Experiment

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Experimental sand burial affects seedling survivorship, morphological traits and biomass allocation of <i>Ulmus pumila var. sabulosa</i> in Horqin Sandy Land

10.5194/se-2016-55 ◽

2016 ◽

Author(s):

Jiao Tang ◽

Carlos Alberto Busso ◽

Deming Jiang ◽

Ala Musa ◽

Dafu Wu ◽

...

Keyword(s):

Biomass Allocation ◽

Morphological Traits ◽

Seedling Emergence ◽

Seedling Height ◽

Horqin Sandy Land ◽

Sandy Land ◽

Seedling Mortality ◽

Ulmus Pumila ◽

Sand Burial ◽

Seedling Survivorship

Abstract. As a native tree species, Ulmus pumila var. sabulosa (Sandy elm) is widely distributed in Horqin Sandy Land. However, seedlings of this species have to withstand various depths of sand burial after emergence because of increasing soil degradation. So an experiment was conducted to evaluate the changes in the survivorship, morphological traits and biomass allocation buried with different burial depths (unburied, and seedlings buried vertically up to 33, 67, 100 or 133 % of the initial mean seedling height). The results showed that partial sand burial treatments (i.e., less than 67 % burial) did not influence seedling survivorship, which still reached 100 %. However, seedling mortality increased as sand burial was equal to or greater than 100 %. Seedling height and stem diameter increased at least by 6 to 14 % with partial burial in comparison with control treatment. Whilst seeding taproot length, total biomass, and relative growth rates at least enhanced by 10 %, 15.6 %, and 27.6 %, respectively, with the partial sand burial treatment. Furthermore, sand burial decreased total leaf area and changed biomass allocation on seedlings, transferring more biomass to aboveground rather than belowground parts. Complete sand burial after seedling emergence inhibited its growth, and even lead to death. Our findings indicated that seedling of sandy elm had a certain resistance to partial sand burial and acclimated to sandy environments. The negative effects of common excessive sand burial after seedling emergence help to understand failures in recruitment of sparse elm woodland in the Horqin sandy land.

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Effects of environmental variables on seedling distribution of rare and endangered Dacrydium pierrei

Open Life Sciences ◽

10.1515/biol-2017-0040 ◽

2017 ◽

Vol 12 (1) ◽

pp. 345-355

Author(s):

Chunyan Wu ◽

Yongfu Chen ◽

Qiao Chen ◽

Wenquan Wang ◽

Xiaojiang Hong ◽

...

Keyword(s):

Climate Change ◽

Soil Moisture ◽

Environmental Variables ◽

Seedling Emergence ◽

Principal Component ◽

Gaussian Mixture ◽

Available Phosphorus ◽

Strong Impact ◽

Growth Environment ◽

Rare And Endangered

AbstractBecause growth environment is affected by climate change, Dacrydium pierrei resources are becoming less and less. Therefore, understanding the effects of environmental variables on seedling-sapling distributions can help gain insight into changes in population recruitment in the context of climate change. The seedling-saplings distribution and variability of Dacrydium pierrei in environmental variables at Bawangling, Hainan, China, was surveyed over a 3-year period. In addition, laboratory experiments measuring the effects of soil moisture on seedling emergence were conducted to identify seedling development characteristics; principal component analysis (PCA) and Gaussian mixture model (GMM) were used to assess how different factors influenced Dacrydium pierrei seedlings-saplings distribution. The results demonstrated that the influence degree of seedling-sapling distribution is soil temperature>litter thickness>available phosphorus>canopy density> available potassium>nitrate nitrogen; a large number of seedling-saplings occurring at altitudes 1140-1300 m; a GMM trained with a C2-L3-H4-A5-I6 combination yielded an accuracy of 72.23% in simulating seedling-saplings distribution; temperature and precipitation have strong impact on seedling-sapling distribution, with increasing soil moisture, seedling emergence shows a positive relationship. This study focuses more on developing a new method for research on the seedling-sapling distribution of Dacrydium pierrei to get reference for its adaptive management with the intense extreme climate change.

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