Leaf-cutting ants alter seedling assemblages across second-growth stands of Brazilian Atlantic forest

2012 ◽  
Vol 28 (4) ◽  
pp. 361-368 ◽  
Author(s):  
Paulo S. D. Silva ◽  
Inara R. Leal ◽  
Rainer Wirth ◽  
Felipe P. L. Melo ◽  
Marcelo Tabarelli
Keyword(s):  
Seed Germination ◽  
Atlantic Forest ◽  
Seedling Survival ◽  
Secondary Forests ◽  
Seedling Mortality ◽  
Seedling Survivorship ◽  
Second Growth ◽  
Species Similarity ◽  
Leaf Cutting ◽  
And Control

Abstract:Secondary forests promote an increased abundance of leaf-cutting ants (LCA) but the consequences on forest dynamics have been poorly addressed. Here we examine seedling assemblage attributes, seed germination and seedling survival across foraging zones of Atta cephalotes colonies inhabiting 15 second-growth patches (25–47 y old) of Atlantic forest. Seeds and seedlings were monitored within foraging zones and control sites over 1 y, including spots around ant nests. Overall, 1862 seedlings from 108 plant species were recorded. Seedling density decreased by 53% in foraging-zone plots (3.31 ± 0.23 seedlings m−2) when compared with control plots (7.02 ± 0.44 seedlings m−2) and a similar decrease was observed for species richness. Ant-induced alterations in the seedling assemblage were further indicated by segregation between foraging-zone and control plots (NMDS), habitat effects on species similarity (ANOSIM), and indicator tree species associated with control plots. While seed germination and seedling survivorship were uncorrelated to either nest distance or age of second-growth stands (with the exception of Tapirira guianensis), defoliation by LCAs was a significant cause of seedling mortality. Our results suggest that LCAs interfere with successional trajectories of Atlantic forest as foraging zones filter seedling establishment, supporting less-dense, impoverished and convergent seedling assemblages.

scholarly journals Myxospermous seed-mucilage quantity correlates with environmental gradients indicative of water-deficit stress: Plantago species as a model

2019 ◽  
Vol 446 (1-2) ◽  
pp. 343-356 ◽  
Author(s):  
António Teixeira ◽  
Pietro Iannetta ◽  
Kirsty Binnie ◽  
Tracy A. Valentine ◽  
Peter Toorop
Keyword(s):  
Seed Germination ◽  
Water Deficit ◽  
Stress Responses ◽  
Environmental Gradients ◽  
Seedling Survival ◽  
Water Deficit Stress ◽  
Arid Environments ◽  
Seedling Mortality ◽  
The Relationship ◽  
Seed Mucilage

Abstract Aims Myxospermous seed mucilage is multifunctional and is often found in seeds (or achenes) of species occupying arid environments where the trait may influence seed-dispersal and -germination of seeds. The seed mucilage may also enhance soil-water retention, −hydraulic conductivity and -stability. However, the relationship between seed mucilage quantity, seed germination and seedling traits across environmental gradients which determine water-deficit stress has not yet been ascertained. Methods Therefore, we characterised and tested the relationship between seed mucilage quantity, water-deficit stress responses of seeds and seedlings of 36 accessions of four different Plantago species (P. albicans L., P. coronopus L., P. lagopus L. and P. anceolata L.). These were gathered from six regions across Europe, which presented environmental gradients (of rainfall and temperature), and varying soil qualities. Results Seed mucilage was significantly greater in seeds of accessions experiencing: highest summer temperatures; lowest summer precipitation; soils of the same warm dry regions which had greater capacity to retain water within narrow pore spaces. Under water-deficit stress, seeds with most mucilage exhibited a lower base water potential for germination, suffered least seedling mortality and exhibited the most successful seedling development. Conclusions The findings indicate that seed mucilage quantity appeared as an ‘adaptive’ trait and there is a relationship between seed-mucilage quantity, seed germination plus seedling survival and development under environmental conditions of highest water-deficit stress.

Establishment of buffel grass, green panic and Siratro from seed broadcast into a speargrass pasture in Southern Queensland

1981 ◽  
Vol 32 (5) ◽  
pp. 749 ◽  
Author(s):  
SJ Cook ◽  
GR Dolby
Keyword(s):  
Seed Germination ◽  
Untreated Control ◽  
Seedling Survival ◽  
Panicum Maximum ◽  
Buffel Grass ◽  
Native Pasture ◽  
And Control ◽  
Germinable Seed ◽  
Main Factor ◽  
Survival Of Seedlings

The establishment and survival of seedlings from pasture seed oversown into a native speargrass (Hetevopogon contortus) pasture were studied in southern Queensland. Lime pelleted and unpelleted seed of buffel grass (Cenchrus ciliaris), green panic (Panicum maximum var, trichoglume) and Siratro (Macroptilium atvopuvpureum) were either sown into a cultivated seedbed or broadcast into native pasture pretreated as follows: untreated control; mown to 3 cm; or killed with herbicide. Buffel grass was sown both as fascicles and as caryopses. Establishment was similar in all oversown seedbeds with seedling numbers accounting for 37 % of the germinable seed sown, compared to 49% in the cultivated seedbed. Pelleting increased establishment where competition was present, the effect being greatest for Siratro and least for buffel grass fascicles. Establishment of buffel grass caryopses was markedly inferior to that of fascicles. Seedling survival rather than seed germination was the main factor influencing the success of the pasture sowing. Less than 1 % of the grass seedlings survived in the mown and control plots, but 38 % survived where competition was controlled by herbicides. Siratro survived equally as well as the grasses in the herbicide-treated plots, but survived markedly better when in competition with native grasses. Surface broadcasting into native pasture is therefore considered a satisfactory, though risky method of establishment for legumes such as Siratro, but not for grasses, unless competition is controlled.

scholarly journals The Crab-eating Fox (Cerdocyon thous) as a secondary seed disperser of Eugenia umbelliflora (Myrtaceae) in a Restinga forest of southeastern Brazil

2009 ◽  
Vol 9 (2) ◽  
pp. 271-274 ◽  
Author(s):  
Eliana Cazetta ◽  
Mauro Galetti
Keyword(s):  
Seed Germination ◽  
Atlantic Forest ◽  
Southeastern Brazil ◽  
Plant Recruitment ◽  
Seed Disperser ◽  
Cerdocyon Thous ◽  
Selection For ◽  
Viable Seeds ◽  
And Control ◽  
Selection Of

The crab-eating fox (Cerdocyon thous) exhibits a very generalist habit and fruits compose a large proportion of its diet. However, few studies evaluated the importance of this animal as seed disperser. In the Restinga forest, in the Atlantic forest of Brazil, C. thous consumes fruits of Eugenia umbelliflora, a Myrtaceae species, which is dispersed chiefly by birds. This study evaluated the effects of gut transit on seed germination, and size selection of E. umbelliflora fruits by the crab-eating fox. We did not find differences on germination rates between seeds dispersed by foxes and control ones, but seeds dispersed by foxes germinated faster, which may be important for plant recruitment. Seeds consumed by C. thous were smaller than those available on the ground, indicating selection for small fruits. Regardless of the selection of small fruits, C. thous appears to be an important secondary disperser of E. umbelliflora, distributing large quantities of viable seeds of this Myrtaceae in the Restinga forest.

Leaf-cutting ants and early forest regeneration in central Amazonia: effects of herbivory on tree seedling establishment

1997 ◽  
Vol 13 (3) ◽  
pp. 357-370 ◽  
Author(s):  
Heraldo L. Vasconcelos ◽  
J. Malcolm Cherrett
Keyword(s):  
Forest Regeneration ◽  
Seedling Survival ◽  
Tree Seedling ◽  
Tree Species Composition ◽  
Seedling Survivorship ◽  
Central Amazonia ◽  
Leaf Cutting ◽  
Survival And Growth ◽  
General Mortality ◽  
Individual Seedling

ABSTRACTThe effects of herbivory by the leaf-cutting antAtta laevigataFr. Smith on the re-establishment of forest trees in an abandoned farm near Manaus, central Amazonia, were investigated. Experimental seedling transplants and observations on seedlings which emerged naturally in the study area showed that damage by leaf-cutting ants negatively affected tree seedling survival and growth. However, excluding leaf-cutting ants from experimental plots for 20 mo did not significantly increase tree seedling densities. The number of seedlings emerging varied considerably between plots and this obscured any effect the ants may have had on seedling survivorship. Taller seedlings, and seedlings attacked only once, suffered less mortality than smaller seedlings and seedlings attacked twice or more. In general, mortality was greater for those species preferred by the ants, indicating that selective herbivory by leaf-cutting ants affects tree species composition. The number of seedlings attacked byA. laevigataremained approximately constant throughout the period of this study in spite of the fact that the number available for attack increased. Thus, the chance of any individual seedling being attacked declined with time, suggesting that the effect ofAttaherbivory on tree establishment is stronger during the first few years of forest regeneration.

scholarly journals Effects of Clonostachys rosea f. catenula Inoculum on the Composting of Cabbage Wastes and the Endophytic Activities of the Composted Material on Tomatoes and Red Spider Mite Infestation

2021 ◽  
Vol 9 (6) ◽  
pp. 1184
Author(s):  
Nomfusi Ntsobi ◽  
Morris Fanadzo ◽  
Marilize Le Roes-Hill ◽  
Felix Nchu
Keyword(s):  
Seed Germination ◽  
Spider Mite ◽  
Fungal Treatment ◽  
Tomato Seed ◽  
Clonostachys Rosea ◽  
Tomato Plants ◽  
Red Spider Mite ◽  
Phytotoxicity Test ◽  
The Difference ◽  
And Control

Globally, fungal inocula are being explored as agents for the optimization of composting processes. This research primarily evaluates the effects of inoculating organic vegetable heaps with the entomopathogenic fungus Clonostachys rosea f. catenula (Hypocreales) on the biophysicochemical properties of the end-product of composting. Six heaps of fresh cabbage (Brassica oleracea var. capitata) waste were inoculated with C. rosea f. catenula conidia and another six were not exposed to the fungus. The composted materials from the fungus- and control-treated heaps were subsequently used as a medium to cultivate tomatoes (Solanum lycopersicum). The biophysicochemical characteristics of the composted materials were also assessed after composting. In addition, the protective effect of the fungal inoculum against red spider mite (Tetranychus urticae) infestations in the tomatoes was evaluated through the determination of conidial colonization of the plant tissue and the number of plants infested by the insect. Furthermore, phytotoxicity tests were carried out post experiment. There were few significant variations (p < 0.05) in heap temperature or moisture level between treatments based on the weekly data. We found no significant differences in the levels of compost macronutrient and micronutrient constituents. Remarkably, the composted materials, when incorporated into a growth medium from fungus-treated heaps, induced a 100% endophytic tissue colonization in cultivated tomato plants. While fewer red spider mite infestations were observed in tomato plants grown in composted materials from fungus-treated heaps, the difference was not significant (χ2 = 0.96 and p = 0.32). The fungal treatment yielded composted materials that significantly (p < 0.05) enhanced tomato seed germination, and based on the phytotoxicity test, the composted samples from the heaps exposed to the C. rosea f. catenula inoculum were not toxic to tomato seeds and seedlings. In conclusion, this study showed that C. rosea f. catenula improved the quality of composted materials in terms of fungal endophytism and seed germination.

scholarly journals Fire suppression and seed dispersal play critical roles in the establishment of tropical forest tree species in southeastern Africa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tomohiro Fujita
Keyword(s):  
Seed Dispersal ◽  
Tree Species ◽  
Seedling Survival ◽  
Fire Suppression ◽  
Forest Tree ◽  
Tree Seedlings ◽  
Seedling Mortality ◽  
Forest Tree Species ◽  
Seed Deposition ◽  
Syzygium Guineense

AbstractThis study examined the mechanisms of facilitation and importance of seed dispersal during establishment of forest tree species in an Afrotropical woodland. Seedling survival of Syzygium guineense ssp. afromontanum was monitored for 2.5 years at four different microsites in savannah woodland in Malawi (southeastern Africa) under Ficus natalensis (a potential nurse plant), Brachystegia floribunda (a woodland tree), Uapaca kirkiana (a woodland tree), and at a treeless site. The number of naturally established forest tree seedlings in the woodland was also counted. Additionally, S. guineense ssp. afromontanum seed deposition was monitored at the four microsites. Insect damage (9% of the total cause of mortality) and trampling by ungulates (1%) had limited impact on seedling survival in this area. Fire (43%) was found to be the most important cause of seedling mortality and fire induced mortality was especially high under U. kirkiana (74%) and at treeless site (51%). The rate was comparatively low under F. natalensis (4%) and B. floribunda (23%), where fire is thought to be inhibited due to the lack of light-demanding C4 grasses. Consequently, seedling survival under F. natalensis and B. floribunda was higher compared with the other two microsites. The seedling survival rate was similar under F. natalensis (57%) and B. floribunda (59%). However, only a few S. guineense ssp. afromontanum seedlings naturally established under B. floribunda (25/285) whereas many seedlings established under F. natalensis (146/285). These findings indicate that the facilitative mechanism of fire suppression is not the only factor affecting establishment. The seed deposition investigation revealed that most of the seeds (85%) were deposited under F. natalensis. As such, these findings suggest that in addition to fire suppression, dispersal limitations also play a role in forest-savannah dynamics in this region, especially at the community level.

scholarly journals Pollination of two species of Vellozia (Velloziaceae) from high-altitude quartzitic grasslands, Brazil

2007 ◽  
Vol 21 (2) ◽  
pp. 325-333 ◽  
Author(s):  
Claudia Maria Jacobi ◽  
Mário César Laboissiérè del Sarto
Keyword(s):  
High Altitude ◽  
Pollen Limitation ◽  
Cross Pollination ◽  
Se Brazil ◽  
Self Compatibility ◽  
Leaf Cutting ◽  
Pollen Theft ◽  
Floral Displays ◽  
Facultative Xenogamy ◽  
And Control

The pollinators and breeding system of two species of Vellozia (Velloziaceae) from high-altitude quartzitic grasslands in SE Brazil were studied. Vellozia leptopetala is shrubby and grows solely on rocky outcrops, V. epidendroides is herbaceous and grows on stony soils. Both bear solitary, hermaphrodite flowers, and have massive, short-lasting annual blooms. We evaluated the level of self-compatibility and need for pollinators of 50 plants of each species and 20-60 flowers per treatment: hand self- and cross-pollination, spontaneous pollination, agamospermy and control. The behavior of floral visitors on flowers and within plants was recorded. Both species are mostly self-incompatible, but produce a small number of seeds by self-fertilization. The pollen-ovule ratio suggests facultative xenogamy. They were visited primarily by bees, of which the most important pollinators were two leaf-cutting bees (Megachile spp.). Vellozia leptopetala was also pollinated by a territorial hummingbird. Low natural seed production compared to cross-pollination seed numbers suggests that pollen limitation is the main cause of low seed set. This was attributed to the combined effect of five mechanisms: selfing prior to anthesis, enhanced geitonogamy as a result of large floral displays, low number of visits per flower for the same reason, pollen theft by many insect species, and, in V. leptopetala, delivery of mixed pollen loads on the stigma as a consequence of hummingbird promiscuity.

Effects of heat and smoke on germination of soil-stored seed in a south-eastern Australian sand heathland

2002 ◽  
Vol 50 (2) ◽  
pp. 197 ◽  
Author(s):  
Timothy J. Wills ◽  
Jennifer Read
Keyword(s):  
Seed Germination ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Seedling Emergence ◽  
Type Systems ◽  
Treated Soil ◽  
South Eastern ◽  
Heat Treated ◽  
Eastern Australia ◽  
And Control

Various fire-related agents, including heat, smoke, ash and charred wood, have been shown to break dormancy and promote germination of soil-stored seed in a broad range of species in mediterranean-type systems. However, relatively little work has been conducted in south-eastern Australian heathlands. This study examined the effects of heat and smoked water on germination of the soil seed bank in a mature sand heathland within the Gippsland Lakes Coastal Park, in south-eastern Australia. Heat was clearly the most successful treatment for promoting seed germination, followed by smoked water, then controls, with 55% of species present in the germinable soil seed bank requiring a heat or smoke stimulus to promote seed germination. Mean species richness of the germinable soil seed bank was found to be significantly higher in heat-treated soil than in smoke and control treatments. Seedling density of heat-treated soil was almost 10 times that of controls, while smoke-treated soil was almost five times that of controls. Seedling emergence was fastest in heat-treated soil, followed by smoke and control soils. Of the species found in the soil seed bank, 25% were absent from the extant vegetation, suggesting the existence of post-fire colonisers in the soil seed bank. The results have implications for the design of soil seed bank experiments and the use of fire as a tool in vegetation management.

scholarly journals Estimation of interrelationships among some quality factors of jute seeds

2016 ◽  
Vol 25 (1) ◽  
pp. 9-17
Author(s):  
Md Al Mamun ◽  
S Shamsi ◽  
MA Bashar
Keyword(s):  
Seed Germination ◽  
Negative Correlation ◽  
Agar Plate ◽  
Curvularia Lunata ◽  
Rhizopus Stolonifer ◽  
Quality Factors ◽  
Seedling Mortality ◽  
Corchorus Capsularis ◽  
Paper Towel ◽  
Blotter Paper

The storage mycoflora associated with seeds of 21 accessions of Corchorus capsularis L. were isolated and identified. Blotter, Paper towel and Agar plate methods were used to isolate the fungi associated with seeds. A total of ten species of fungi viz. Aspergillus flavus, A. fumigatus, A. niger, A. terreus, Curvularia lunata, Colletotrichum corchori, Fusarium oxysporum, Eurotium sp., Penicillium sp. and Rhizopus stolonifer were isolated from the selected jute seeds. Aspergillus spp. and Colletotrichum corchori were predominant in most of the jute accessions. Accession No. A-3047 showed the highest fungal incidence and Accession Nos. A-3361, A-2734 and A-877 showed the lowest. Accession No. A-3361 showed the highest seed germination while Accession No. A-3309 showed the lowest. Mortality of seedling showed the highest in Accession No. A-3309 and the lowest in Accession No. A-3361. Physical purity of seed recorded the highest in Accession No. A- 3361 and the lowest in Accession No. A-3309. There were negative correlation between percentage of fungi and percentage of germination and between percentage of fungi and physical purity of seeds. Positive correlation was observed between percentage of fungi and seedling mortality and between purity of seed and germination of seed.Dhaka Univ. J. Biol. Sci. 25(1): 9-17, 2016

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