scholarly journals Contrasting ecological roles of non-native ungulates in a novel ecosystem

2018 ◽  
Vol 5 (4) ◽  
pp. 170151 ◽  
Author(s):  
Ann Marie Gawel ◽  
Haldre S. Rogers ◽  
Ross H. Miller ◽  
Alexander M. Kerr
Keyword(s):  
Community Structure ◽  
Seed Dispersal ◽  
Sus Scrofa ◽  
Native Species ◽  
Seedling Survival ◽  
Novel Ecosystems ◽  
Plant Community Structure ◽  
Novel Ecosystem ◽  
Negative Impacts ◽  
Viable Seeds

Conservation has long focused on preserving or restoring pristine ecosystems. However, understanding and managing novel ecosystems has grown in importance as they outnumber pristine ecosystems worldwide. While non-native species may be neutral or detrimental in pristine ecosystems, it is possible that even notorious invaders could play beneficial or mixed roles in novel ecosystems. We examined the effects of two long-established non-native species—Philippine deer ( Rusa marianna ) and feral pigs ( Sus scrofa )—in Guam, Micronesia, where native vertebrate frugivores are functionally absent leaving forests devoid of seed dispersers. We compared the roles of deer and pigs on seedling survival, seed dispersal and plant community structure in limestone karst forests. Deer, even at low abundances, had pronounced negative impacts on forest communities by decreasing seedling and vine abundance. By contrast, pigs showed no such relationship. Also, many viable seeds were found in pig scats, whereas few were found in deer scats, suggesting that pigs, but not deer, provide an ecosystem function—seed dispersal—that has been lost from Guam. Our study presents a discrepancy between the roles of two non-native species that are traditionally managed as a single entity, suggesting that ecological function, rather than identity as a non-native, may be more important to consider in managing novel systems.

scholarly journals SEED DISPERSAL, SEEDBANK, SEEDLING SURVIVAL, AND INITIAL GROWTH OF THREE CAATINGA TREES

2020 ◽  
Vol 33 (4) ◽  
pp. 1007-1016
Author(s):  
IVONETE ALVES BAKKE ◽  
JOSÉ EVANALDO RANGEL DA SILVA ◽  
OLAF ANDREAS BAKKE ◽  
ANTONIO LUCINEUDO DE OLIVEIRA FREIRE
Keyword(s):  
Seed Dispersal ◽  
Rainy Season ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Tree Height ◽  
Initial Growth ◽  
Forest Density ◽  
Before And After ◽  
Viable Seeds

ABSTRACT Myracrodruon urundeuva, Handroanthus impetiginosus and Amburana cearensis are Caatinga tree species that produce valuable timber, but little is known about their ecology. The objective of this study was to evaluate the seed distribution of these species on the forest floor before and after seed dispersal; and seedling emergence, survival, and growth during the rainy season after dispersal of seeds. There were no remaining viable seeds of these species in the seedbank before seed dispersal. The average numbers of seeds after seed dispersal were 188 seed m-2 in a 30 m radius around M. urundeuva, 9 seed m-2 in a 10 m radius around H. impetiginosus, and 5 seed m-2 in a 20 m radius around A. cearensis. The distance of seed dispersal reached 30, 20, and 10 m for M. urundeuva, H. impetiginosus, and A. cearensis trees, respectively, due to differences in tree height, seed weight, forest density, and wind intensity. Seedling emergence was observed during 4 (M. urundeuva) and 9 (H. impetiginosus and A. cearensis) weeks. High mortality predominated at the beginning and end of the rainy season for M. urundeuva and A. cearensis, respectively, while practically all H. impetiginosus seedlings survived. M. urundeuva showed the highest mortality but had higher number of established seedlings than the other species. Seedling survival peaked around 5 m from the tree base. Seedling recruitment and natural regeneration of these trees are assured in the Caatinga site evaluated.

Plant Community Structure of Tropical Semi-Evergreen Forest of Reiek in Mamit District of Mizoram

2017 ◽  
Vol 5 (1) ◽  
pp. 58-62 ◽  
Author(s):  
S.T. Lalzarzovi ◽  
◽  
Lalnun Tluanga
Keyword(s):  
Community Structure ◽  
Structural Analysis ◽  
Plant Communities ◽  
Ecological Study ◽  
Life Form ◽  
Evergreen Forest ◽  
Biodiversity Hotspots ◽  
Plant Community Structure ◽  
Floristic Survey ◽  
Normal Spectrum

Ecological study of tropical semi-evergreen forest of Reiek in Mizoram was carried out to determine the stratification of the forest as well as to prepare life form spectrum of the plant communities. Mizoram is a part of Indo- Myanmar region which falls under one of the 35 biodiversity hotspots identified worldwide and therefore has a rich biodiversity. A detailed floristic survey was carried out. Plant species were collected, mounted in herbarium sheets and identified. Structural analysis was carried out and profile diagram was drawn. The forest was found to be composed of three layers in both the disturbed and undisturbed areas of the forest. The life form spectrum has been compared with Raunkiers normal spectrum to find out the phytoclimate of the region. The study area was found to have an abundance of phanerophytes indicating a phanerophytic climate

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 Nesting, Sex Ratio and Natural Enemies of the Giant Resin Bee in Relation to Native Species in Europe

Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 545
Author(s):  
Sara Straffon Díaz ◽  
Luca Carisio ◽  
Aulo Manino ◽  
Paolo Biella ◽  
Marco Porporato
Keyword(s):  
Sex Ratio ◽  
Natural Enemies ◽  
Native Species ◽  
Wild Bees ◽  
Trap Nests ◽  
Native Bee ◽  
New Locations ◽  
Negative Impacts ◽  
Set Up ◽  
North Western

Megachile sculpturalis (Smith, 1853) is the first exotic bee species in Europe. Its remarkably fast expansion across this continent is leading to a growing concern on the extent of negative impacts to the native fauna. To evaluate the interactions of exotic bees with local wild bees, we set up trap nests for above-ground nesting bees on a semi-urban area of north-western Italy. We aimed to investigate the interaction in artificial traps between the exotic and native wild bees and to assess offspring traits accounting for exotic bee fitness: progeny sex ratio and incidence of natural enemies. We found that the tunnels occupied by exotic bees were already cohabited by O. cornuta, and thus the cells of later nesting alien bees may block the native bee emergence for the next year. The progeny sex ratio of M. sculpturalis was strongly unbalanced toward males, indicating a temporary adverse population trend in the local invaded area. In addition, we documented the presence of three native natural enemies affecting the brood of the exotic bee. Our results bring out new insights on how the M. sculpturalis indirectly competes with native species and on its performance in new locations.

scholarly journals Predicting the potential distribution of the vase tunicate Ciona intestinalis in Canadian waters: informing a risk assessment

2008 ◽  
Vol 65 (5) ◽  
pp. 788-794 ◽  
Author(s):  
Thomas W. Therriault ◽  
Leif-Matthias Herborg
Keyword(s):  
Risk Assessment ◽  
Native Species ◽  
Potential Distribution ◽  
Negative Impact ◽  
Ciona Intestinalis ◽  
Environmental Niche ◽  
Environmental Models ◽  
Introduced Range ◽  
Negative Impacts ◽  
Almost All

Abstract Therriault, T. W., and Herborg, L-M. 2008. Predicting the potential distribution of the vase tunicate Ciona intestinalis in Canadian waters: informing a risk assessment. – ICES Journal of Marine Science, 65: 788–794. A crucial step in characterizing the potential risk posed by non-native species is determining whether a potential invader can establish in the introduced range and what its potential distribution could be. To this end, various environmental models ranging from simple to complex have been applied to predict the potential distribution of an invader, with varying levels of success. Recently, in marine waters, tunicates have received much attention, largely because of their negative impacts on shellfish aquaculture. One of these species is the vase tunicate Ciona intestinalis, which recently has had a negative impact on aquaculture operations in Atlantic Canada and could pose a risk in Pacific Canada. To inform the risk assessment of this species, we evaluated two different types of environmental model. Simple models based on reported temperature or salinity tolerances were relatively uninformative, because almost all waters were deemed suitable. In contrast, a more complex genetic algorithm for rule-set prediction (GARP) environmental niche model, based on documented Canadian occurrence points, provided informative projections of the potential distribution in Canadian waters. In addition to informing risk assessments, these predictions can be used to focus monitoring activities, particularly towards vectors that could transport C. intestinalis to these favourable environments.

Dispersal ofAcaciaseeds by ungulates and ostriches in an African savanna

1996 ◽  
Vol 12 (3) ◽  
pp. 345-356 ◽  
Author(s):  
Maxine F. Miller
Keyword(s):  
South Africa ◽  
Seed Dispersal ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Tree Crown ◽  
African Savanna ◽  
Large Herbivores ◽  
Mammalian Herbivores ◽  
Open Environments ◽  
Presence And Absence

ABSTRACTThe dispersal of AfricanAcaciaseeds in the presence and absence of large mammalian herbivores and ostriches was assessed in a savanna ecosystem in South Africa. In the absence of large herbivores,A. tortilisandA. niloticapods were mainly dispersed in the shade, directly beneath the tree crown and seeds remained in pods for over 18 months. In the presence of large herbivores,A. tortilis, A. niloticaandA. karrooseeds were freed from pods and were dispersed into open, non-shaded habitats. Impala dispersed mostA. tortilisseeds (18,900 ha−1), giraffe mostA. niloticaseeds (1060 ha−1) and giraffe and kudu mostA. karrooseeds (452 and 448 ha−1, respectively). Seedling survival in dung in open environments may exceed that of seedlings in soil shaded beneath the tree crown. It appears that seed dispersal by large herbivores may be advantageous to future seedling recruitment.

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