scholarly journals Fungi and insects compensate for lost vertebrate seed predation in an experimentally defaunated tropical forest

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Peter Jeffrey Williams ◽  
Robert C. Ong ◽  
Jedediah F. Brodie ◽  
Matthew Scott Luskin
Keyword(s):  
Seed Dispersal ◽  
Seed Predation ◽  
Tree Species ◽  
Species Interactions ◽  
Simulation Models ◽  
Tree Species Composition ◽  
Exclusion Experiment ◽  
Complex Species ◽  
Seed Mortality ◽  
Plant Animal Interactions

AbstractOverhunting reduces important plant-animal interactions such as vertebrate seed dispersal and seed predation, thereby altering plant regeneration and even above-ground biomass. It remains unclear, however, if non-hunted species can compensate for lost vertebrates in defaunated ecosystems. We use a nested exclusion experiment to isolate the effects of different seed enemies in a Bornean rainforest. In four of five tree species, vertebrates kill many seeds (13–66%). Nonetheless, when large mammals are excluded, seed mortality from insects and fungi fully compensates for the lost vertebrate predation, such that defaunation has no effect on seedling establishment. The switch from seed predation by generalist vertebrates to specialist insects and fungi in defaunated systems may alter Janzen–Connell effects and density-dependence in plants. Previous work using simulation models to explore how lost seed dispersal will affect tree species composition and carbon storage may require reevaluation in the context of functional redundancy within complex species interactions networks.

scholarly journals Frugivore loss limits recruitment of large-seeded trees

2011 ◽  
Vol 278 (1723) ◽  
pp. 3345-3354 ◽  
Author(s):  
Debra M. Wotton ◽  
Dave Kelly
Keyword(s):  
New Zealand ◽  
Plant Regeneration ◽  
Seed Dispersal ◽  
Seed Predation ◽  
Tree Species ◽  
Seedling Survival ◽  
Fruit Pulp ◽  
Synergistic Interactions ◽  
Local Plant ◽  
Pulp Removal

Although global declines in frugivores may disrupt seed dispersal mutualisms and inhibit plant recruitment, quantifying the likely reduction in plant regeneration has been difficult and rarely attempted. We use a manipulative factorial experiment to quantify dependence of recruitment on dispersal (i.e. fruit pulp removal and movement of seed away from parental area) in two large-seeded New Zealand tree species. Complete dispersal failure would cause a 66 to 81 per cent reduction in recruitment to the 2-year-old seedling stage, and synergistic interactions with introduced mammalian seed and seedling predators increase the reduction to 92 to 94 per cent. Dispersal failure reduced regeneration through effects on seed predation, germination and (especially) seedling survival, including distance- and density-dependent (Janzen–Connell) effects. Dispersal of both species is currently largely dependent on a single frugivore, and many fruits today remain uneaten. Present-day levels of frugivore loss and mammal seed and seedling predators result in 57 to 84 per cent fewer seedlings after 2 years. Our study demonstrates the importance of seed dispersal for local plant population persistence, and validates concerns about the community consequences of frugivore declines.

Differential effects of mammalian seed predators on the regeneration of five Papua New Guinean tree species and implications for sapling recruitment

2008 ◽  
Vol 24 (3) ◽  
pp. 259-267 ◽  
Author(s):  
Elizabeth R. Jones ◽  
Lisa M. Curran ◽  
Debra D. Wright ◽  
Andrew L. Mack
Keyword(s):  
Seed Predation ◽  
Tree Species ◽  
Life Stage ◽  
Seedling Mortality ◽  
Differential Effects ◽  
Focal Species ◽  
Seed Predators ◽  
Seed Mortality ◽  
Species Specific ◽  
Papua New Guinean

Abstract:Although herbivores may account for a significant source of seed and seedling mortality in many tropical tree species, plant species differ in their response to seed damage. Here we investigate the relative effects of seed predation on the regeneration of five tree species in a mid-elevation Papua New Guinean rain forest. Exclosure treatments and shade-house experiments were monitored from November 2004 to March 2006 to assess the differential effects of seed predation on seed viability and seedling growth. Results indicate that although seed predators attack all five focal species, they influence the seedling populations in two, Cerbera floribunda and Microcos grandiflora, and minimally affect the seedling populations of Terminalia impediens, Pandanus penicillus and Endiandra latifolia in the years measured. Predation and germination frequencies were compared to the abundance of focal species at several life stage classes to explore potential correlations between species-specific seed mortality patterns and life stage distributions. We found that the species-specific influence of mammalian seed predators correlated with abundance distributions in three life stages. Species with high survivorship after seed predator attacks displayed a significant decrease in abundance from the seedling-to-sapling transition, while those species with high seed mortality demonstrated relatively even distributions of seedlings, saplings and adults (> 10 cm dbh). These contrasting patterns suggest that differential seed predation effects on regeneration may play a key role in the recruitment of individuals to the sapling stage.

scholarly journals Secondary seed removal in a degraded forest habitat in Madagascar

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paula M. A. Fiedler ◽  
Alice De Lapparent ◽  
Jeremie Razafitsalama ◽  
Justin Sanamo ◽  
Kim J. E. Steffens ◽  
...  
Keyword(s):  
Seed Dispersal ◽  
Seed Predation ◽  
Tree Species ◽  
Natural Regeneration ◽  
Forest Restoration ◽  
Forest Degradation ◽  
Degraded Forest ◽  
Seed Removal ◽  
Forest Habitat ◽  
Removal Experiments

AbstractForest restoration is a prime goal within the 2021–2030 UN “Decade of Ecosystem Resoration”. As part of these activities, natural regeneration has to be promoted for biological as well as for economic reasons. For this, the processes of seed dispersal, seed predation and germination have to be understood in the original as well as in degraded vegetation formations. We used seed removal experiments to assess post-dispersal processes that influence recruitment along a gradient of forest degradation in Madagascar analyzing seeds of three animal dispersed tree species. The percentage of seeds consumed or dispersed, declined from forest (28.6%) to degraded forest (17.2%) to savanna (10.8%). Only three out of 1080 seeds were cached and remained intact during the 14-day experiment. All three seeds were cached in the forest habitat and none in the degraded forest and savanna. The low percentage of seeds removed may be due to the lack of endemic rodents caching seeds, as only introduced rats were recorded in the area. The species-poor fauna of potential secondary seed dispersers of the region and especially in the degraded areas might represent an obstacle for diverse regeneration in degraded regions of Madagascar.

scholarly journals Vegetation structure and biodiversity recovery in 19-year-old active restoration plantations in a Neotropical cloud forest

2021 ◽  
Vol 30 (1) ◽  
pp. 3004
Author(s):  
Rosa-Amelia Pedraza ◽  
Guadalupe Williams-Linera ◽  
Teresa Nicolás-Silva
Keyword(s):  
Seed Dispersal ◽  
Species Composition ◽  
Tree Species ◽  
Vegetation Structure ◽  
Cloud Forest ◽  
Basal Area ◽  
Dispersal Mode ◽  
Tree Species Composition ◽  
Montane Cloud Forest ◽  
Active Restoration

Aim of the study: To evaluate how middle-aged active restoration plantations of native tree species contribute to the recovery of the tropical cloud forest in terms of vegetation structure, tree richness, species composition, and to shade-tolerance and seed dispersal mode functional groups.Area of the study: We studied two 19-year-old active restoration sites and their reference mature forests in the tropical montane cloud forest belt, Veracruz, Mexico.Materials and methods: The basal area, density and height as well as the tree species composition and number of species and individuals classified by shade tolerance (pioneer and non-pioneer trees), and seed dispersal mode (anemochorous, barochorous-synzoochorous and endozoochorous) were compared between active restoration plantations and reference forests.Main results: Planted trees and the woody vegetation growing under them represented a high proportion of reference forests’ basal area. Tree richness and Shannon’s equitability index were similar in both reference forests and one active restoration plantation and slightly different in the other. Tree species composition differed among sites; however, each 19-year-old plantation already had several non-pioneer species and a similar species proportion of the seed dispersal syndromes present in their reference forests.Research highlights: Active restoration accelerated the recovery of cloud forest in degraded pasture and bracken fern lands. Planted trees promoted the rapid development of vegetation structure and natural tree regeneration. Although species composition is still different, these middle-aged restoration plantations already have forest species and a proportion of functional groups of species similar to those of their own reference montane cloud forests.Keywords: active restoration; forest recovery; passive restoration; seed dispersal mode; succession; tree species; tropical montane cloud forest.

Langfristige Entwicklung von zwei Waldgesellschaften im Białowieża-Urwald

2008 ◽  
Vol 159 (4) ◽  
pp. 80-90 ◽  
Author(s):  
Bogdan Brzeziecki ◽  
Feliks Eugeniusz Bernadzki
Keyword(s):  
Species Composition ◽  
Tree Species ◽  
Stand Structure ◽  
Temporal Dynamics ◽  
Structural Parameters ◽  
Forest Communities ◽  
Natural Forests ◽  
Tree Species Composition ◽  
Strong Trend ◽  
Long Term Study

The results of a long-term study on the natural forest dynamics of two forest communities on one sample plot within the Białowieża National Park in Poland are presented. The two investigated forest communities consist of the Pino-Quercetum and the Tilio-Carpinetum type with the major tree species Pinus sylvestris, Picea abies, Betula sp., Quercus robur, Tilia cordata and Carpinus betulus. The results reveal strong temporal dynamics of both forest communities since 1936 in terms of tree species composition and of general stand structure. The four major tree species Scots pine, birch, English oak and Norway spruce, which were dominant until 1936, have gradually been replaced by lime and hornbeam. At the same time, the analysis of structural parameters indicates a strong trend towards a homogenization of the vertical stand structure. Possible causes for these dynamics may be changes in sylviculture, climate change and atmospheric deposition. Based on the altered tree species composition it can be concluded that a simple ≪copying≫ (mimicking) of the processes taking place in natural forests may not guarantee the conservation of the multifunctional character of the respective forests.

Site classification in a mixed hardwood forest (Hallerbos, Belgium) with a homogeneous ground vegetation dominated by Hyacinthoides non-scripta (L.) Chouard ex. Rothm.

1994 ◽  
Vol 59 ◽  
Author(s):  
D. Maddelein ◽  
B. Muys ◽  
J. Neirynck ◽  
G. Sioen
Keyword(s):  
Tree Species ◽  
Ph Value ◽  
Soil Analysis ◽  
Base Cation ◽  
Site Quality ◽  
Ground Vegetation ◽  
Site Classification ◽  
Species Classification ◽  
Tree Species Composition ◽  
Understorey Vegetation

The  forest of Halle (560 ha), situated 20 km south of Brussels is covered by a  beech (Fagus sylvatica)  forest, locally mixed with secundary species (Tilia,  Fraxinus, Acer, Quercus,... ). In almost all  stands, herbal vegetation is dominated by bluebell (Hyacinthoides  non-scripta).     The research intended to classify 36 plots of different tree species  composition according to their site quality. Three classification methods  were compared: the first one based on the indicator value of the understorey  vegetation, a second one on the humus morphology and a last one on some  quantitative soil characteristics. According to the plant sociological site  classification, the plots have the same site quality. However, humus forms  differ apparently and significant differences were found in pH value and base  cation saturation of the soil, abundance and biomass of earthworms and  biomass of the ectorganic horizon. Tree species proved to be the main cause  of these differences.     The results illustrate that the herbal vegetation is not always a reliable  indicator of site quality. In the case of a homogeneous vegetation dominated  by one or more indifferent species, classification on humus morphology or  soil analysis are more appropriate. In the forest of Halle, the tree species  is probably the main cause of the observed differences in site quality.

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 The composition and diversity of natural regeneration of tree species in gaps under different intensities of forest disturbance

2021 ◽  
Author(s):  
Maame Esi Hammond ◽  
Radek Pokorný ◽  
Daniel Okae-Anti ◽  
Augustine Gyedu ◽  
Irene Otwuwa Obeng
Keyword(s):  
Tree Species ◽  
Natural Regeneration ◽  
Forest Disturbance ◽  
Forest Site ◽  
Gap Formation ◽  
Tree Species Composition ◽  
Forest Sites ◽  
Significant Difference ◽  
Shade Tolerant Species ◽  
Disturbed Forest

AbstractThe positive ecological interaction between gap formation and natural regeneration has been examined but little research has been carried out on the effects of gaps on natural regeneration in forests under different intensities of disturbance. This study evaluates the composition, diversity, regeneration density and abundance of natural regeneration of tree species in gaps in undisturbed, intermittently disturbed, and disturbed forest sites. Bia Tano Forest Reserve in Ghana was the study area and three gaps each were selected in the three forest site categories. Ten circular subsampling areas of 1 m2 were delineated at 2 m spacing along north, south, east, and west transects within individual gaps. Data on natural regeneration < 350 cm height were gathered. The results show that the intensity of disturbance was disproportional to gap size. Species diversity differed significantly between undisturbed and disturbed sites and, also between intermittently disturbed and disturbed sites for Simpson’s (1-D), Equitability (J), and Berger–Parker (B–P) indices. However, there was no significant difference among forest sites for Shannon diversity (H) and Margalef richness (MI) indices. Tree species composition on the sites differed. Regeneration density on the disturbed site was significantly higher than on the two other sites. Greater abundance and density of shade-dependent species on all sites identified them as opportunistic replacements of gap-dependent pioneers. Pioneer species giving way to shade tolerant species is a natural process, thus make them worst variant in gap regeneration.

scholarly journals Stand Stability of Pure and Mixed-Eucalyptus Forests of Different Tree Species in a Typhoon-Prone Area

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 458
Author(s):  
Haiyan Deng ◽  
Linlin Shen ◽  
Jiaqi Yang ◽  
Xiaoyong Mo
Keyword(s):  
Tree Species ◽  
Forest Restoration ◽  
Large Scale ◽  
Stand Structure ◽  
Pinus Elliottii ◽  
Stem Form ◽  
Tree Species Composition ◽  
Eucalyptus Plantation ◽  
Mixed Plantation ◽  
Preservation Rate

Background and Objectives: The stable stand structure of mixed plantations is the basis of giving full play to forest ecological function and benefit. However, the monocultural Eucalyptus plantations with large-scale and successive planting that caused ecological problems such as reduced species diversity and loss of soil nutrients have presented to be unstable and vulnerable, especially in typhoon-prone areas. The objective of this study was to evaluate the nonspatial structure difference and the stand stability of pure and mixed-Eucalyptus forests, to find out the best mixed pattern of Eucalyptus forests with the most stability in typhoon-prone areas. Materials and Methods: In this study, we randomly investigated eight plots of 30 m × 30 m in pure and mixed-Eucalyptus (Eucalyptus urophylla S. T. Blake × E. grandis W. Hill) plantations of different tree species (Neolamarckia cadamba (Roxb.) Bosser, Acacia mangium Willd., and Pinus elliottii var. Elliottii Engelm. × P. caribaea Morelet) on growth status, characterized and compared the distribution of nonspatial structure of the monoculture and mixtures, and evaluated the stand quality and stability from eight indexes of the nonspatial structure, including preservation rate, stand density, height, diameter, stem form, degree of stem inclination, tree-species composition, and age structure. Results: Eucalyptus surviving in the mixed plantation of Eucalyptus and A. mangium (EA) and in the mixed plantation of Eucalyptus and P. elliottii × P. caribaea (EP) were 5.0% and 7.6% greater than those in pure Eucalyptus plantation (EE), respectively, while only the stand preservation rate of EA was greater (+2.9%) than that of the pure Eucalyptus plantation. The proportions of all mixtures in the height class greater than 7 m were fewer than that of EE. The proportions of EA and mixed plantation of Eucalyptus and N. cadamba (EN) in the diameter class greater than 7 m were 10.6% and 7.8%, respectively, more than that of EE. EN had the highest ratio of branching visibly (41.0%), EA had the highest ratio of inclined stems (8.1%), and EP had the most straight and complete stem form (68.7%). The stand stability of the mixed plantation of Eucalyptus and A. mangium presented to be optimal, as its subordinate function value (0.76) and state value (ω = 0.61) of real stand were the largest. Conclusions: A. mangium is a superior tree species to mix with Eucalyptus for a more stable stand structure in the early growth stage to approach an evident and immense stability and resistance, which is of great significance for the forest restoration of Eucalyptus in response to extreme climate and forest management.

Impact of Deer Browsing on Regeneration in Mixed Stands in Southern New England

1995 ◽  
Vol 12 (3) ◽  
pp. 115-120 ◽  
Author(s):  
David B. Kittredge ◽  
P. Mark S. Ashton
Keyword(s):  
New England ◽  
Tree Species ◽  
Sugar Maple ◽  
Red Maple ◽  
White Pine ◽  
Mixed Stands ◽  
Tree Species Composition ◽  
Southern New England ◽  
Pine Seedlings ◽  
Species Specific

Abstract Browsing preferences by white-tailed deer were evaluated for 6 tree species in northeastern Connecticut. Deer density averaged 23/mile². Deer exhibited no species-specific preferences for seedlings greater than 19 in. For seedlings less than 19 in., hemlock and black birch were preferred. Red maple, sugar maple, and white pine seedlings were avoided. Red oak seedlings were neither preferred nor avoided. A much higher proportion of seedlings greater than 19.7 in. in height was browsed, regardless of species. Browsing preferences for species in the smaller seedling class, combined with a lack of preference for species in the larger class may result in future stands with less diverse tree species composition. Deer densities in excess of 23/mile² may be incompatible with regeneration of diverse forests in southern New England. North. J. Appl. For. 12(3):115-120.

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