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The accumulation of seeds in the soil (the seedbank) can set the template for the early regeneration of habitats following disturbance. Seed dispersal is an important factor determining the pattern of seed rain, which affects the interactions those seeds experience. For this reason, seed dispersal should play an important role in structuring forest...
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Context 1
... islands of Guam, Saipan and Rota are located within the Mariana Island chain, in the Western Pacific (Fig. 1). They have a mean annual temperature of 27 8C, with little seasonal variation. All islands experience frequent typhoons, which can cause considerable damage to vege- tation (Kerr 2000), and pronounced wet and dry ...
Context 2
... if we excluded seeds of L. leucoce- phala, the only species we recorded that is primarily wind or gravity dispersed and was found predominantly on Saipan, the difference between Guam and Saipan was no longer significant (z ¼ 21.87, P ¼ 0.06) [see Supporting Information- Figure S1]. ...
Citations
... The aggregate effect of each of these local interactions between bats and plants can have profound impacts on the structure of their habitats at the ecosystem scale (Fig. 1). For example, the functional extirpation of vertebrate seed dispersers (i.e., birds and bats) led to a reduction in seed bank richness in Guam compared to Saipan and Rota-where these dispersers still exist-suggesting that bats play a significant role in structuring plant communities (Wandrag et al., 2015). Across the tropics, ~80% of seed dispersal in general is performed by birds and bats (Howe & Smallwood, 1982). ...
Global biodiversity and ecosystem function are the result of complex networks of interactions and feedbacks between animals and their environments, which in turn are affected by the interactions and feedbacks between animals and the organisms they host. Understanding these complex networks, including the main drivers of and responses to ecological and environmental changes and their global implications, requires adopting a systems-based perspective. We advocate for this approach by characterizing a framework centered around bats, a globally-distributed mammalian order, and their dual roles as both inhabitants of ecosystems and as habitats themselves. Like other organisms, bats interact with habitats by providing ecosystem services that impact the survival and distribution of other species, and may be affected by such factors as land use change, climate change, fluctuations in food availability, and hunting pressure. Habitat conditions (e.g. food availability, temperature, etc.) can affect the physiological condition of individuals, which in turn can affect the prevalence and/or virulence of hosted organisms and potential pathogens (e.g. ectoparasites, bacteria, viruses, fungi, and protozoa). In addition, the interactions among individuals (e.g. co-roosting, migration, etc.) influence the habitat connectivity for their hosted organisms (e.g. opportunities for dispersal). Bats have a unique relationship with infectious disease, both biological and cultural. With this in mind, when applied to bats this framework has special importance to how we understand and apply the One Health concept, whereby healthy natural environments foster both human and animal health, which in turn also promotes healthy environments. By leveraging a hierarchical approach among these different levels of biological organization, we can arrive at a clearer picture of the specific threats facing bats—as well as the risk of pathogen spillover to humans and other domesticated and wild animals generated by disrupting this delicate balance—and identify possible measures to mitigate adverse impacts. Thus, to understand these complex interactions and their implications for conservation, ecosystem health, and human health, we need a new ecological framework that recognizes that changes in habitats not only affect macrofauna and the ecosystem services they provide, but also have the potential to cascade through the diversity and evolution of the organisms they host. This review provides a case study for the application of this framework, which is extensible to other organisms with their own unique relationships with habitats and as habitats.
... Disturbances may also provide opportunities for the spread of nonnative species, many of which have become integrated into dispersal networks (as described above). Frugivory and seed dispersal are responsible for the regeneration of forests in situ (i.e., cyclic regeneration), and for new successional forests recolonizing deforested landscapes (Carlo & Morales, 2016;Wandrag et al., 2015Wandrag et al., , 2017González-Castro et al., 2019;Albert et al., 2020). ...
We provide an overview of the current state of knowledge of island frugivory and seed dispersal and identify knowledge gaps that are important for fundamental research on—and applied conservation of—island ecosystems. We conducted a systematic literature search of frugivory and seed dispersal on islands, omitting large, continental islands. This revealed a total of 448 studies, most (75%) published during the last two decades, especially after 2010. Nearly 65% of them were focused on eight archipelagos. There is a paucity of studies in Pacific archipelagos near Asia and Australia, and in the Indian Ocean. Data on island frugivory and seed dispersal are diverse but highly uneven in geographic and conceptual coverage. Despite their limited biodiversity, islands are essential reservoirs of endemic plants and animals and their interactions. Due to the simplicity of insular ecosystems, we can assess the importance of seed dispersal theory and mechanisms at species and community levels. These include the ecological and biogeographical meaning and prevalence of non-standard mechanisms of seed dispersal on islands; the seed dispersal effectiveness and the relative roles of different frugivore guilds (birds and reptiles being the most important); and patterns of community organization and their drivers as revealed by interaction networks. Island systems are characterized by the extinction of many natives and endemics, and high rates of species introductions. Therefore, understanding how these losses and additions alter seed dispersal processes has been a prevailing goal of island studies and an essential foundation for the effective restoration and conservation of islands.
... Forest restoration is a global priority and the question of how to promote the restoration of secondary forests has become a research hotspot (Cruz-Alonso et al. 2019). Forest regeneration involves the stages of seed production, seed dispersal, germination, and seedling survival (Cole et al. 2011;Calama et al. 2017), and its success depends on the physical characteristics of the surrounding landscape (Sprengelmeyer and Rebertus 2015), the intensity and frequency of disturbances (Sanou et al. 2018), and the plant colonization by propagules moving into the area (Chazdon and Guariguata 2016;Wandrag et al. 2015). Compared with plants, seeds are more resistant to stress and disturbance (Gutterman 2012), and therefore the role of soil seed bank is particularly important in the natural recovery process after vegetation destruction. ...
Soil seed bank plays a significant role in the natural recovery and the succession of forest. A large number of natural secondary forests are distributed in the Qining Mountains, China. However, it remains unclear how the soil seed banks develop and influence the recovery of secondary forests.
We explored the aboveground vegetation and soil seed bank at 27 plots along forest developmental stages of pine and oak forests in the Qinling Mountains. Species composition and abundance of aboveground vegetation as well as seed bank composition and density were surveyed and their correlations with forest developmental stages were determined.
The results showed that the species richness of seed banks was the highest in middle-aged forests, as well as the aboveground vegetation. The seed density and abundance increased with forest developmental stages and varied among different forest types. The similarity between seed banks at different developmental stages of the same forest type was high, as well as aboveground vegetation. The seed bank and aboveground vegetation showed low similarity across the three developmental stages of both forest types, and the persistent soil seed bank did not reflect the changes in aboveground vegetation.
Our findings demonstrate that developmental stages play an important role in the composition of seed banks and aboveground vegetation. Our results also highlight the persistent soil seed bank contributes less to the forest recovery. We can assume that the natural recovery of disturbed natural secondary forests is largely dependent on transient soil seed bank and seed dispersal.
... While mammals may escape the slash and the burn by moving into surrounding unaffected vegetation, many reptiles and amphibians are killed when forest is cleared and burned, as they cannot escape quickly. Depending on the season and the temporal pattern of activity, animals that hibernate through the dry season may escape the fire if burning happens before larger rains have fallen.Where vertebrate and particularly mammal and bird densities decrease after slash-and-burn agriculture, the potential for fallow recovery may be reduced because many vertebrates are responsible for seed dispersal (Wandrag et al., 2015). ...
... Birds dispersed Elaeocarpus, Dianella, Hernandia (main mode of dispersal is thalassochory), Pittosporum, and Planchonella (Chandler et al., 2007;Michalak et al., 2010;Phoon, 2015;Wandrag et al., 2015;Muscat et al., 2019) to the region via the Austro-Melanesian, S1b dispersal scenario, underscoring the importance of the birds′ south to north flight pattern, while fruit bats disperse seeds over shorter distances (Van der Pijl, 1982). Fruit bats are either islanddwellers or restricted to one island (Fleming et al., 2009). ...
... This scenario was concluded by analyzing eight plant genera (Artocarpus, Aglaia, Cyrtandra J.R. Forest & G. Forest (Gesneriaceae) Combretaceae)) that originated in Southeast Asia. For Aglaia, Morinda, and Meiogyne, most dispersal events were facilitated by birds, but Aglaia and Morinda might show thalassochory as well (Razafimandimbison et al., 2010;Grudinski et al., 2014b;Wandrag et al., 2015). A Morinda fossil from Hainan Island, China, informed a late Paleocene or early Eocene origin of the genus (Shi et al., 2012). ...
Micronesian islands taxa exhibit high endemism rates but very little is known about their biogeographical histories. The lack of systematic biogeography is mainly due to insufficient phylogenetic research in Micronesia. With the recent rise of molecular biogeographic data published, we were able to, for the first time, answer fundamental biogeography questions by reviewing and analyzing numerous geological, ecological, and evolutionary studies. This review, in addition to providing an overview of Micronesian geological history, confirmed the importance of long‐distance dispersal mechanisms and founder‐event speciation, and morphological and physiological adaptations of plant propagules to cross vast stretches of ocean by wind, ocean currents, bird, or bat dispersal. These adaptations to habitat and geological features including reef types, determined colonization success as well as inland dispersal and speciation mechanisms. We further identified the source areas of the Micronesian biota and reconstructed historical dispersal scenarios: a dominant Austro‐Melanesian dispersal scenario, an Indo‐Malaysian connecting to the Austro‐Melanesian dispersal scenario, and a Neotropical American and an African dispersal scenario towards Micronesia. Most generic origins were estimated between the Eocene and Miocene and dispersed to Micronesia between the Miocene and Pleistocene. This article is protected by copyright. All rights reserved.
... Size-biased patterns of seed rain may influence the successional dynamics of plant communities in forest edges over time because these patterns may create opportunities for some species with particular traits to become more prevalent in the edge community (Brodie and Aslan, 2012;Kurten et al., 2015). Seed rain also may influence the composition of the seed bank for future recruitment (Wandrag et al., 2015). The forest edge habitat could become dominated by small-seeded pioneer plants, lose rare tree species, and become homogeneous in terms of floristic composition over time (Oliveira et al., 2004;Melo et al., 2010;Lôbo et al., 2011). ...
Edge effects, driven by human modification of landscapes, can have critical impacts on ecological processes such as species interactions, with cascading impacts on biodiversity as a whole. Characterizing how edges affect vital biotic interactions such as seed dispersal by frugivores is important for better understanding potential mechanisms that drive species coexistence and diversity within a plant community. Here, we investigated how differences between frugivore communities at the forest edge and interior habitats of a diverse tropical rainforest relate to patterns of animal-mediated seed dispersal and early seedling recruitment. We found that the lemur communities across the forest edge-interior gradient in this system showed the highest species richness and variability in body sizes at intermediate distances; the community of birds showed the opposite pattern for species richness. Three large-bodied frugivores, known to be effective dispersers of large seeds, tended to avoid the forest edge. As result, the forest edges received a lower rate of animal-mediated seed dispersal compared to the interior habitats. In addition, we also found that the seeds that were actively dispersed by animals in forest edge habitats were smaller in size than seeds dispersed in the forest interior. This pattern was found despite a similarity in seed size of seasonally fruiting adult trees and shrubs between the two habitats. Despite these differences in dispersal patterns, we did not observe any differences in the rates of seedling recruitment or seed-size distribution of successful recruit species. Our results suggest that a small number of frugivores may act as a potential biotic filter, acting on seed size, for the arrival of certain plant species to edge habitats, but other factors may be more important for driving recruitment patterns, at least in the short term. Further research is needed to better understand the potential long-term impacts of altered dispersal regimes relative to other environmental factors on the successional dynamics of edge communities. Our findings are important for understanding potential ecological drivers of tree community changes in forest edges and have implications for conservation management and restoration of large-seeded tree species in disturbed habitats.
... Brown treesnakes are widely considered to have caused the decline, extirpation, and extinction of almost all native vertebrates on Guam and have documented top down effects on prey (Savidge, 1987;Rodda et al., 1999;Wiles et al., 2003;Campbell et al., 2012;Rogers et al., 2012). As a consequence their introduction resulted in significant alterations in the trophic and ecological community structures on Guam (Rodda and Savidge, 2007;Caves et al., 2013;Wandrag et al., 2015;Rogers et al., 2017). Island species are often naïve to the threats posed by non-native predators (Cummins et al., 2020), and the snake remains a dominant threat for Guam species (Pollock et al., 2019) and future reintroductions. ...
Broad foraging classifications, such as generalist or specialist forager, are generally beneficial for population management in defining expectations of typical behavior. However, better understanding as to how individual variance in behavior interfaces with management actions, such as control of an invasive predator (such as brown treesnakes; Boiga irregularis) responsible for ecological collapse of a taxonomic group (birds), may affect conservation goals. In the context of predator control, better understanding of foraging ecology and prey specificity helps to ensure that food-based control programs are removing the target individuals. We sought to quantify whether differences in a dietary generalist snake species was measurable during captive trials using mice or birds as the prey choice. We presented snakes with prey choices that could be or are integrated with tools deployed by managers for control to directly relate choice or preference to management action. We collected wild brown treesnakes and classified them as bird eaters or of unknown diet based on food items present in their digestive tract at the time of capture. In experimental tests, we used live birds and live mice in traps, as well as bird and mouse carrion presented on platforms, to measure interest, take rates, and repeatability (preference) by snakes. We found that all individuals spent more time investigating live birds than they did mice, independent of dietary history, which resulted in twice as many snakes being captured in traps with live birds compared to live mice. There was, however, roughly equal interest in mouse and bird carrion. Within individuals, there was evidence for decreased interest in mouse carrion, if individuals ate birds in the wild. Choice of carrion type was repeatable across trials, suggesting preference may exist. Overall, interest in both live mice and mouse carrion was greatest for medium-bodied snakes, while interest in bird carrion was independent of snake size. Our results indicate that management of invasive predators, including reptiles, may more rapidly achieve conservation targets when managers consider individual heterogeneity in behavior. For brown treesnakes more interested in birds, managers may remove more snakes if they use avian food lures; increased removal of avian specialists may facilitate avian recovery.
... Shrubby legumes belonging to the genus Acacia are highly diverse and widespread across the Australian continent. Acacias form major components of many ecosystems across the continent including many arid ecosystems with poor soils (Bui et al., 2014;Maslin et al., 2003) and play an important role in ecosystem functioning including through the provision of resources and habitat to a broad range of insects and animals (Wandrag et al., 2015;Ward & Branstetter, 2017;Young et al., 2008). It also helps rapid colonization supporting ecosystem recovery following disturbance (Spooner, 2005). ...
Restoring degraded landscapes has primarily focused on re‐establishing native plant communities. However, little is known with respect to the diversity and distribution of most key revegetation species or the environmental and anthropogenic factors that may affect their demography and genetic structure. In this study, we investigated the genetic structure of two widespread Australian legume species (Acacia salicina and Acacia stenophylla) in the Murray–Darling Basin (MDB), a large agriculturally utilized region in Australia, and assessed the impact of landscape structure on genetic differentiation. We used AFLP genetic data and sampled a total of 28 A. salicina and 30 A. stenophylla sampling locations across southeastern Australia. We specifically evaluated the importance of four landscape features: forest cover, land cover, water stream cover, and elevation. We found that both species had high genetic diversity (mean percentage of polymorphic loci, 55.1% for A. salicina versus. 64.3% for A. stenophylla) and differentiation among local sampling locations (A. salicina: ΦPT = 0.301, 30%; A. stenophylla: ΦPT = 0.235, 23%). Population structure analysis showed that both species had high levels of structure (6 clusters each) and admixture in some sampling locations, particularly A. stenophylla. Although both species have a similar geographic range, the drivers of genetic connectivity for each species were very different. Genetic variation in A. salicina seems to be mainly driven by geographic distance, while for A. stenophylla, land cover appears to be the most important factor. This suggests that for the latter species, gene flow among populations is affected by habitat fragmentation. We conclude that these largely co‐occurring species require different management actions to maintain population connectivity. We recommend active management of A. stenophylla in the MDB to improve gene flow in the adversity of increasing disturbances (e.g., droughts) driven by climate change and anthropogenic factors.
... La regeneración exitosa de las especies depende de la dispersión adecuada en la cual un gran número de las semillas producidas alcancen sitios seguros desde el punto de vista competitivo y depredador (5). El modo de dispersión es altamente variable en cuanto al tipo de agentes utilizados para la diseminación de las semillas (15) y depende de muchos factores bióticos y abióticos (3,8), entre los cuales destaca la disponibilidad de animales dispersores (16). De acuerdo a lo anterior, la gran diversidad de animales y plantas en bosques de montaña indican que la dispersión biótica representa un importante mecanismo de diseminación en este tipo de comunidades. ...
La dispersión de semillas de Zanthoxylum rhoifolium fue estudiada en un remanente de bosque montano en la ciudad de Mérida, Venezuela. El estudio morfológico de los frutos mostró que tanto el fruto como la semilla representan la unidad de dispersión. Los frutos rojo granate y las semillas negras lustrosas son dispersados por un ensamblaje no especializado de ocho especies pertenecientes a cuatro familias de aves. Todas las especies de aves mostraron un patrón de visita durante las primeras horas de la mañana y últimas de la tarde. La selección de frutos o semillas es discutida con relación al grado de especialización alimentaria de las especies de aves dispersoras.
... Seed disperser loss will impact passive restoration pro- grams, if seeds from intact forests fail to reach degraded areas (Ingle 2003;Caves et al. 2013). Without seed dispersers, seeds of fruit-producing, woody perennials rarely move far (Caves et al. 2013;Wandrag et al. 2015). The impact of seed disperser loss on entire communities is, however, rarely studied because such experiments are seldom feasible. ...
... The absence of native birds is a probable cause of negligible native plant recruitment in exclusion plots. A large proportion of native plant species found on Guam are dependent on frugivores as primary seed dispersers ( Wandrag et al. 2015). Prior stud- ies detected no seed rain from bird-dispersed trees in Guam's degraded forests, which contrasted to almost two seeds per m 2 on the nearby island of Saipan that has avifauna communities ( Caves et al. 2013). ...
... Natu- ral forest regeneration is necessary for widespread recovery of deforested areas and is desirable to preserve biodiversity, as well as for economic reasons (Chazdon & Guariguata 2016). Guam's forests, however, are a remarkable and poignant study on the negative ramifications of bird loss for forest succession, struc- ture, and function on island ecosystems (Schreiner 1997;Caves et al. 2013;Wandrag et al. 2015). Reintroductions and recovery of native animals that provide valuable ecosystem services on Guam are likely critical for long-term forest restoration. ...
Overabundant ungulate populations can alter forests. Concurrently, global declines of seed dispersers may threaten native forest structure and function. On an island largely devoid of native vertebrate seed dispersers, we monitored forest succession for 7 years following ungulate exclusion from a 5-ha area and adjacent plots with ungulates still present. We observed succession from open scrub to forest and understory cover by non-native plants declined. Two trees, native Hibiscus tiliaceus and non-native Leucaena leucocephala, accounted for most forest regeneration, with the latter dominant. Neither species is dependent on animal dispersers nor was there strong evidence that plants dependent on dispersers migrated into the 5-ha study area. Passive restoration following ungulate removal may facilitate restoration, but did not show promise for fully restoring native forest on Guam. Restoration of native forest plants in bird depopulated areas will likely require active outplanting of native seedlings, control of factors resulting in bird loss, and reintroduction of seed dispersers.
