Strangler Figs Research Articles

Strangler fig–host tree associations: Insights into the ecology and management of tropical urban green spaces

Societal Impact StatementThe strangler fig is known for its hemiepiphytic growth form and conspicuous strangling behavior in the tropics worldwide. It also plays an important role in providing ecological functions in tropical urban ecosystems. This study reveals strangler figs tend to colonize large trees with suitable microsites in a large tropical botanical garden and cause some negative effects on their hosts. We advocate balanced management strategies considering ecological functions, potential risks, and overall values of stranglers and their hosts. These results provide a scientific basis for us to develop better practices for plant management in urban green spaces (especially botanical gardens with high plant biodiversity) in tropical urban ecosystems.Summary Strangler figs colonize trees in tropical cities, which contribute to a unique urban ecology and enrich local ecological functions. Understanding ecological associations between strangler figs and their host trees can improve green space management in tropical urban ecosystems. We investigated 9282 trees growing in the Xishuangbanna Tropical Botanical Garden and then analyzed the diversity, characteristics, and network of strangler figs and their host trees. We found 13 strangler fig species (319 individuals) widely colonized 67 host species, with palm hosts bearing 52% of all strangler individuals. Strangler figs had a high colonization rate in large trees with appropriate microsites (e.g., persistent palm petioles and the fork of mature trees with rough trunks). Leaf nitrogen and phosphorus content of hosts decreased significantly after strangler figs' aerial roots had entered the ground. The strangler–host network was characterized by relatively high specialization and low nestedness, and simulated management of strangler figs on large hosts and palm hosts could simplify the strangler–host network. Strangler fig colonization can be managed. Planting trees with large diameters at breast height and rough bark can increase the colonization of stranglers, while cutting off aerial roots can inhibit their establishment. The epiphytic stage is the best time to manage strangler figs. We recommend taking into consideration the trade‐offs among ecological functioning, human safety, and the multifaceted value of strangler figs and their host trees and thereby implementing comprehensive management strategies tailored to different contexts for improving green space management in the tropics.

Comparative Study on the Effects of Organic fertilizer (Cow dung), Inorganic Fertilizer (N.P.K) and the Combined Effect of Fertilizers on the Growth Parameters of Strangler Fig (Ficus thonningii)

A comparative study on the effect of organic manure (Cow Dung), inorganic fertilizer (NPK 15-15-15), and their combined effect on the growth of Strangler fig (Ficus thonningii) was carried out at Government Senior Secondary School Dawakin Tofa Local Government Area, Kano State, Nigeria for 28 weeks. The objective of this study was to determine and compare the effect of organic fertilizer (Cow Dung), inorganic fertilizer (N.P.K 15:15:15) and their combined effects on the growth of Ficus thonningii seedlings. The experiment was laid out in a Randomized Complete Block Design (RCBD) with five treatments and a control replicated four times. The treatments consisted of T1= (15g NPK), T2 = (15g CD), T3 = (7.5g NPK: 7.5g CD), T4 = (11.3g NPK + 3.7g CD), T5 = (11.3g CD + 3.7g NPK) and a control (unfertilized) denoted as T6. Various growth parameters such as plant height, number of leaves, plant girth, leaf size and number of branches per plant were measured at 2-week intervals for 7 months. All the data collected were subjected to a two-way analysis of variance (ANOVA) at p<0.05 level of significance using R-software. The results from the experiment showed that most growth characters measured were significantly affected by the application of sole cow dung (15g CD). Thus, based on results obtained in this study, it is suggested to use 15g sole of cow dung for optimum and better growth of Ficus thonningii seedlings in the study area.

Field sampling of fig pollinator wasps across host species and host developmental phase: Implications for host recognition and specificity.

Previous genetic studies of pollinator wasps associated with a community of strangler figs (Ficus subgenus Urostigma, section Americana) in Central Panama suggest that the wasp species exhibit a range in host specificity across their host figs. To better understand factors that might contribute to this observed range of specificity, we used sticky traps to capture fig-pollinating wasp individuals at 13 Ficus species, sampling at different phases of the reproductive cycle of the host figs (e.g., trees with receptive inflorescences, or vegetative trees, bearing only leaves). We also sampled at other tree species, using them as non-Ficus controls. DNA barcoding allowed us to identify the wasps to species and therefore assign their presence and abundance to host fig species and the developmental phase of that individual tree. We found: (1) wasps were only very rarely captured at non-Ficus trees; (2) nonetheless, pollinators were captured often at vegetative individuals of some host species; (3) overwhelmingly, wasp individuals were captured at receptive host fig trees representing the fig species from which they usually emerge. Our results indicate that wasp occurrence is not random either spatially or temporally within the forest and across these hosts, and that wasp specificity is generally high, both at receptive and vegetative host trees. Therefore, in addition to studies that show chemicals produced by receptive fig inflorescences attract pollinator wasps, we suggest that other cues (e.g., chemicals produced by the leaves) can also play a role in host recognition. We discuss our results in the context of recent findings on the role of host shifts in diversification processes in the Ficus genus.

EVALUATION ON THE POPULATION OF STRANGLER FIGS (Ficus subgen. Urostigma) IN MOUNT UNGARAN, CENTRAL JAVA

A group of the Ficus genus, the strangler figs (Ficus subgen, Urostigma), are known as a more potential as frugivores feed in Mount Ungaran. While the land clearance of the forest into monoculture plantation threats their existence. This study aims to evaluating strangler figs condition by the population study, i.e. densities, distribution, and the demography of each strangler fig species. A total of 25 ha area of Gentong Hill (Northwest part of Mount Ungaran) have been sampled during January-May 2018. We conducted a census of the figs within the sampled area and recorded their life stages in such area. As well as explain the current condition of host tree used by strangler figs in such area. Based on the census that have been conducted, 35 individual belongs to six species strangler figs that equal with 1.4 individual/ha in the value of density is recorded. F. kerkhovenii and the Javan endemic F. involucrata was the commonest species by their densities and abundance. Most of host tree were found dead. The remaining living host tree (16 individuals) are included in three species, i.e. Syzigium antisepticum (14 individual), Weinmannia fraxinea (1 individual), and Engelhardtia spicata (1 individual). Most of the strangler figs found was reached in stage 5 of their life demography, while the stage 1 was the rarest by only 1 individual found. The distribution of strangler figs showed a random pattern. Both of densities and distribution is reasoned by the availability of host tree.

Genome-wide sequence data show no evidence of hybridization and introgression among pollinator wasps associated with a community of Panamanian strangler figs.

The specificity of pollinator host choice influences opportunities for reproductive isolation in their host plants. Similarly, host plants can influence opportunities for reproductive isolation in their pollinators. For example, in the fig and fig wasp mutualism, offspring of fig pollinator wasps mate inside the inflorescence that the mothers pollinate. Although often host specific, multiple fig pollinator species are sometimes associated with the same fig species, potentially enabling hybridization between wasp species. Here, we study the 19 pollinator species (Pegoscapus spp.) associated with an entire community of 16 Panamanian strangler fig species (Ficus subgenus Urostigma, section Americanae) to determine whether the previously documented history of pollinator host switching and current host sharing predicts genetic admixture among the pollinator species, as has been observed in their host figs. Specifically, we use genome‐wide ultraconserved element (UCE) loci to estimate phylogenetic relationships and test for hybridization and introgression among the pollinator species. In all cases, we recover well‐delimited pollinator species that contain high interspecific divergence. Even among pairs of pollinator species that currently reproduce within syconia of shared host fig species, we found no evidence of hybridization or introgression. This is in contrast to their host figs, where hybridization and introgression have been detected within this community, and more generally, within figs worldwide. Consistent with general patterns recovered among other obligate pollination mutualisms (e.g. yucca moths and yuccas), our results suggest that while hybridization and introgression are processes operating within the host plants, these processes are relatively unimportant within their associated insect pollinators.

Drivers of Bornean Orangutan Distribution across a Multiple-Use Tropical Landscape

Logging and conversion of tropical forests in Southeast Asia have resulted in the expansion of landscapes containing a mosaic of habitats that may vary in their ability to sustain local biodiversity. However, the complexity of these landscapes makes it difficult to assess abundance and distribution of some species using ground-based surveys alone. Here, we deployed a combination of ground-transects and aerial surveys to determine drivers of the critically endangered Bornean Orangutan (Pongo pygmaeus morio) distribution across a large multiple-use landscape in Sabah, Malaysian Borneo. Ground-transects and aerial surveys using drones were conducted for orangutan nests and hemi-epiphytic strangler fig trees (Ficus spp.) (an important food resource) in 48 survey areas across 76 km2, within a study landscape of 261 km2. Orangutan nest count data were fitted to models accounting for variation in land use, above-ground carbon density (ACD, a surrogate for forest quality), strangler fig density, and elevation (between 117 and 675 m). Orangutan nest counts were significantly higher in all land uses possessing natural forest cover, regardless of degradation status, than in monoculture plantations. Within these natural forests, nest counts increased with higher ACD and strangler fig density, but not with elevation. In logged forest (ACD 14–150 Mg ha−1), strangler fig density had a significant, positive relationship with orangutan nest counts, but this relationship disappeared in a forest with higher carbon content (ACD 150–209 Mg ha−1). Based on an area-to-area comparison, orangutan nest counts from ground transects were higher than from counts derived from aerial surveys, but this did not constitute a statistically significant difference. Although the difference in nest counts was not significantly different, this analysis indicates that both methods under-sample the total number of nests present within a given area. Aerial surveys are, therefore, a useful method for assessing the orangutan habitat use over large areas. However, the under-estimation of nest counts by both methods suggests that a small number of ground surveys should be retained in future surveys using this technique, particularly in areas with dense understory vegetation. This study shows that even highly degraded forests may be a suitable orangutan habitat as long as strangler fig trees remain intact after areas of forest are logged. Enrichment planting of strangler figs may, therefore, be a valuable tool for orangutan conservation in these landscapes.

The community structure of bird assemblages on urban strangler figs

AbstractFigs have been regarded as keystone plant resources that support diverse tropical vertebrate frugivore communities. Planting or conserving large fig trees, such as stranglers, have therefore been proposed for enhancing urban biodiversity. We compared the diversity and community structure of bird assemblages on strangler figs with non‐fig urban trees as well as between the fruiting and non‐fruiting fig trees in an urban setting in Singapore. The total bird abundance across all the fig trees when in fruit was 4.5‐fold higher than on non‐fig trees and 3.5‐fold higher than when the same fig trees were not fruiting, but only attracted two more species. On individual trees, after accounting for the presence of mistletoes, tree height, the area covered by buildings, road lane density, and the distance to natural vegetation, mean diversity was not different between non‐fig trees and fig trees when they were not in fruit. On the other hand, when fruiting, each fig tree on average had 1.4 more species, 3 more counts of non‐native birds, and 1.6 more counts of insectivorous birds than when not fruiting. There was significant compositional turnover between non‐fig trees and non‐fruiting fig trees, while community dispersion was significantly lower among fig trees in fruit. Our results demonstrate that fig trees provide fruit and non‐fruit resources for birds in an urban landscape but do not necessarily support more diverse total bird assemblages than non‐fig trees. Instead, bird communities on fruiting urban figs would be highly homogeneous and dominated by a few species.Abstract in Malay is available with online material.

Community Structure and Undescribed Species Diversity in Non-Pollinating Fig Wasps Associated with the Strangler Fig Ficus petiolaris

Abstract Figs and their associated mutualistic and parasitic wasps have been a focus of intensive ecological and evolutionary research due to their diversity, unusual reproductive biology, and highly coevolved interspecific relationships. Due to the ecological dependence of their interactions, fig wasps were once considered to be fig-species specific and to cospeciate with their hosts, however, a growing body of evidence reveals mixed support for species specificity and the importance of additional evolutionary processes (e.g., host switching) structuring these long-term interactions. Our research on the genus Idarnes Walker, 1843 (Hymenoptera, Agaonidae), a common non-pollinating wasp of New World fig flowers, reveals a community in which multiple wasp species coexist on the same host in space and time. Using both molecular and morphological data, we identify five distinct Idarnes lineages associated with a single host fig species, Ficus petiolaris Kunth, 1817 (Rosales, Moraceae). A comprehensive phylogenetic analysis including Idarnes species from numerous host fig species reveals that the lineages associated with F. petiolaris do not form a monophyletic group but are distantly related, suggesting multiple independent colonization events and subsequent diversification. Morphological and ecological data provide support that the wasps are partitioning niches within the figs, explaining the coexistence of these diverse lineages on the same host fig. These results, coupled with a growing body of research on pollinating and non-pollinating fig wasps, bring into focus a more dynamic picture of fig and fig wasp coevolution and highlight how wasp lineage divergence and niche partitioning contributes to increased species diversity and community structure on a single fig host.

Masonry walls as sieve of urban plant assemblages and refugia of native species in Chongqing, China

Urbanization imposes notable threats to global biodiversity. Masonry retaining and city walls offer unusual ruderal habitats for spontaneous establishment of unique plant communities which may flourish despite urban disturbance and intensification. We comprehensively surveyed the wall-plant communities in Chongqing in southwest China to investigate their special urban ecology and their role in sustaining urban biodiversity. From 289 masonry walls, we recorded 205 plant species under 164 genera and 78 families. Perennial and annual herbs were the most common growth forms by species number. Despite accommodating 27 tree species and 6538 tree individuals, three dominant ones, respectively two Moraceae members Ficus virens which is a strangler fig and Broussonetia papyrifera, and Robinia pseudoacacia (Leguminosae), constituted 94% of the wall-tree stock. Detailed analysis of tree height distribution shed light on species recruitment dynamics. The dispersal agents differentiated sharply by growth form, with 73% herbaceous species wind-dispersed in comparison with 70.2% woody species bird-dispersed. The endemism and floristic characteristics of wall-plant communities were influenced by the regional urban flora, particularly for dominant wall trees; similar traits were found in the wall flora of Nanjing and Hong Kong. The low similarity in species composition between walls and nearby ground plant communities suggested the critical role played by walls in protecting the disturbance-intolerant native plants, including many Pteridophytes. The conservation values and biodiversity contributions of masonry walls in Chongqing are worthy of special attention. The findings could provide the basis to maintain urban ecosystem services and for nature-based ecological urban designs.

Inferring processes of coevolutionary diversification in a community of Panamanian strangler figs and associated pollinating wasps.

The fig and pollinator wasp obligate mutualism is diverse (∼750 described species), ecologically important, and ancient (∼80 Ma). Once thought to be an example of strict one-to-one cospeciation, current thinking suggests genera of pollinator wasps codiversify with corresponding sections of figs, but the degree to which cospeciation or other processes contribute to the association at finer scales is unclear. Here, we use genome-wide sequence data from a community of Panamanian strangler figs and associated wasp pollinators to estimate the relative contributions of four evolutionary processes generating cophylogenetic patterns in this mutualism: cospeciation, host switching, pollinator speciation, and pollinator extinction. Using a model-based approach adapted from the study of gene family evolution, our results demonstrate the importance of host switching of pollinator wasps at this fine phylogenetic and regional scale. Although we estimate a modest amount of cospeciation, simulations reveal the number of putative cospeciation events to be consistent with what would be expected by chance. Additionally, model selection tests identify host switching as a critical parameter for explaining cophylogenetic patterns in this system. Our study demonstrates a promising approach through which the history of evolutionary association between interacting lineages can be rigorously modeled and tested in a probabilistic phylogeneticframework.

Distribution of Ficus in Way Canguk, Bukit Barisan Selatan National Park, Lampung

Abstract. Prabowo DA, Mirmanto E, Manurung BS. 2019. Distribution of figs in Way Canguk, Barisan Selatan National Park, Lampung. Proc. Sem Nas Masy Biodiv Indon 5: 155-164. Ficus is one of an important controler plants in over time process of forest ecology, so that it is widely used by many wildlife around it. The purpose of this study was observed the figs distribution of each habitus in Bukit Barisan Selatan National Park. This research was done by line transect method which is conducted in May 2018 at Way Canguk Research Station, Bukit Barisan Selatan National Park, Lampung, Indonesia. We found 318 individuals of 32 Ficus species, consisting of 173 stranglers (23 species), 95 trees (6 species), 17 stakes (5 species), 17 seedlings (6 species), 4 creepers (2 species), and 4 lianas (1 species). According to each habitus, we found that F. altissima with the Importance Value Index (IV) of 51.79 occurred for strangler figs group. F. hispida has the highest importance value for trees group (88.93) and seedlings group (58.67). In addition, there was F. fistulosa has the highest important value for stakes group (98.06). Meanwhile, lianas and creepers are only counted individually. There was only F. depressa and F. globosa that have 3 types of habitus.

Social polyandry among siamangs: the role of habitat quality

In species where females do not associate spatially with other females, males usually range over an area including the home ranges of multiple females or defend the home range of one female. Nevertheless, social polyandry (multimale–unifemale grouping) occurs in some species. We examine an ecological constraints model relating habitat quality to facultative social polyandry in siamangs, Symphalangus syndactylus, by testing predictions of two hypotheses: (H1) variation in the size and density of important food trees affects the size of siamang home ranges and areas of exclusive use; (H2) socially polyandrous groups benefit from cooperative defence of the home range and area of exclusive use. Crown volume/ha of freestanding or strangler figs (Ficus), the most important siamang food, was negatively related to the size of the home range but not to the size of the area of exclusive use. Density and crown volume/ha of the second-most important plant food, Dracontomelon dao, was not related to the size of the home range or to the size of the area of exclusive use. Multimale groups had larger home ranges and areas of exclusive use than unimale groups, and the home ranges and areas of exclusive use of multimale groups encompassed more freestanding or strangling figs than those of unimale groups. Models of home range size including fig abundance (density or crown volume/ha) and the number of males as predictor variables suggested that multimale groups have larger home ranges than predicted by the relationship between fig abundance and home range size alone. While some other facultatively polyandrous species have larger home ranges in areas of poorer habitat quality, our results suggest a more complex situation for siamangs at our study site. Specifically, the density of large figs may constrain siamang ranging patterns, but multimale groups live in home ranges with more figs than those of unimale groups. Our results suggest that multimale groups may defend higher-quality territories than unimale groups.

Natural history and courtship behavior in Tengella perfuga Dahl, 1901 (Araneae: Zoropsidae)

Tengella perfuga Dahl, 1901 is a Nicaraguan cribellate zoropsid spider found in high altitude remnant cloud forest habitats bordering coffee plantations. Since its description in 1901, and its rediscovery in 2012, almost nothing is known of its natural history, life history, courtship or web spinning behavior. Observations were made in the field, as well as in the lab. Mature female T. perfuga occurred in funnel webs with several knockdown lines comprised of cribellate silk, and that were typically placed between buttress roots of strangler figs or other outcropping structures, while males abandoned their webs upon adulthood to search for females. Here, we describe the life history, growth, web ontogeny, courtship and reproductive behaviors, as well as silk use of this spider for the first time. There are 11–12 instars to reach adulthood and cribellate silk did not appear in juvenile webs until the eighth instar. Interestingly, orbicularian-like behaviors were observed in the initial appearance of cribellate silk lines in the juvenile web in a spiral-like pattern. Males exhibited positive allometric growth in Leg I from penultimate to adult instars, which likely plays an important role in courtship; this included strumming the sheet, stroking the female and depositing a thin ‘bridal veil' of silk on the female. Virgin females had ‘mating plugs' prior to exposure to males. This suggests that T. perfuga may be an interesting species with which to further examine sexual evolution and female choice.

Strangler figs may support their host trees during severe storms

While strangler figs in the genus Ficus have been assumed to have only epiphytic and parasitic relationships with the host trees on which they grow, we suggest that a mutualistic relationship may also exist that benefits host trees during severe storms. Twenty-nine months after a cyclone, uprooted and standing trees in Lamington National Park, Queensland, Australia were compared for the presence of attached strangler figs. A significantly smaller percentage of uprooted (12.8%) than standing trees (58.5%) had large attached strangler figs. Strangler figs might provide four different mechanisms that make it less likely that their host trees will be uprooted in storms. Aerial roots may provide two distinct mechanisms, first through attachments to surrounding vegetation, and second through attachments to rooting points in the ground. The canopy closure added by strangler fig canopies may provide shielding from winds. Anastomosing root networks adhering to host tree trunks may also provide scaffolding support.

Observing ecosystems with lightweight, rapid‐scanning terrestrial lidar scanners

A new wave of terrestrial lidar scanners, optimized for rapid scanning and portability, such as the Compact Biomass Lidar (CBL), enable and improve observations of structure across a range of important ecosystems. We performed studies with the CBL in temperate and tropical forests, caves, salt marshes and coastal areas subject to erosion. By facilitating additional scanning points, and therefore view angles, this new class of terrestrial lidar alters observation coverage within samples, potentially reducing uncertainty in estimates of ecosystem properties. The CBL has proved competent at reconstructing trees and mangrove roots using the same cylinder-based Quantitative Structure Models commonly utilized for data from more capable instruments (Raumonen et al. 2013). For tropical trees with morphologies that challenge standard reconstruction techniques, such as the buttressed roots of Ceiba trees and the multiple stems of strangler figs, the CBL was able to provide the versatility and the speed of deployment needed to fully characterize their unique features. For geo-morphological features, the deployment flexibility of the CBL enabled sampling from optimal view-angles, including from a novel suspension system for sampling salt marsh creeks. Overall, the practical aspects of these instruments, which improve deployment logistics, and therefore data acquisition rate, are shown to be emerging capabilities, greatly increasing the potential for observation, particularly in highly temporally dynamic, inaccessible and geometrically complex ecosystems. In order to better analyze information quality across these diverse and challenging ecosystems, we also provide a novel and much-needed conceptual framework, the microstate model, to characterize and mitigate uncertainties in terrestrial lidar observations.

Germination of seeds of New World Urostigma (Ficus) and of Morus rubra L. (Moraceae)

The New World strangler figs of the subgenus Urostigma and possibly most of the epiphytes, stranglers and banyans of the subgenera Urostiga and Ficus in the Old World bave viscid achenes. When these achenes are ingested by birds and bats they are voided without offering any apparent change in viability or in the vise id coat. Digestion of the viscid coat by soil bacteria prior to germination explains why Urostigma seeds in the New World always germinate where there is soil and organic matter as well as humidity (floor of the forest, soil-containing cracks or cavities in tree trunks and rocks). Urostigm a and mulberry ( Morus rubra ) seeds planted experimentally in sterilized soil failed to germinate, but responded favorably when inoculated with untreated soil.

Spatial Scales of Genetic Structure in Free-Standing and Strangler Figs (Ficus, Moraceae) Inhabiting Neotropical Forests.

Wind-borne pollinating wasps (Agaonidae) can transport fig (Ficus sp., Moraceae) pollen over enormous distances (> 100 km). Because of their extensive breeding areas, Neotropical figs are expected to exhibit weak patterns of genetic structure at local and regional scales. We evaluated genetic structure at the regional to continental scale (Panama, Costa Rica, and Peru) for the free-standing fig species Ficus insipida. Genetic differentiation was detected only at distances > 300 km (Jost´s Dest = 0.68 ± 0.07 & FST = 0.30 ± 0.03 between Mesoamerican and Amazonian sites) and evidence for phylogeographic structure (R ST>>permuted R ST) was only significant in comparisons between Central and South America. Further, we assessed local scale spatial genetic structure (SGS, d ≤ 8 km) in Panama and developed an agent-based model parameterized with data from F. insipida to estimate minimum pollination distances, which determine the contribution of pollen dispersal on SGS. The local scale data for F. insipida was compared to SGS data collected for an additional free-standing fig, F. yoponensis (subgenus Pharmacosycea), and two species of strangler figs, F. citrifolia and F. obtusifolia (subgenus Urostigma) sampled in Panama. All four species displayed significant SGS (mean Sp = 0.014 ± 0.012). Model simulations indicated that most pollination events likely occur at distances > > 1 km, largely ruling out spatially limited pollen dispersal as the determinant of SGS in F. insipida and, by extension, the other fig species. Our results are consistent with the view that Ficus develops fine-scale SGS primarily as a result of localized seed dispersal and/or clumped seedling establishment despite extensive long-distance pollen dispersal. We discuss several ecological and life history factors that could have species- or subgenus-specific impacts on the genetic structure of Neotropical figs.

On pluralism in ecology: seeing the forest and the trees

In response to our paper testing whether mistletoe represents a keystone resource [[1][1]], Thomsen & Wernberg (TW) [[2][2]] integrated our experiment with previous work and introduced a novel hypothesis to explain how structural complexity influences community composition. While we share their

Ecology and conservation of strangler figs in urban wall habitats

Hong Kong’s rugged topography demands creation of developable land by reclaiming the harbor and terracing hillslopes. The vertical faces between adjoining hillslope-platforms are often stabilized by stone retaining walls. Such artificial cliffs embedded in the urban matrix, as a habitat analogue of rocky cliffs, have been colonized by spontaneous-ruderal vegetation. Detailed field assessment of 289 walls with 793 trees permitted in-depth analysis of this unique tropical urban ecology to inform conservation. The 28 stonewall tree species, mainly native, are dominated by six keystone and companion Ficus (Moraceae) species. They can develop into large cliff hangers > 20 m height on the apparently precarious and inhospitable walls. The many joints between masonry blocks provide opportunities for lodging and germination of seeds brought by frugivorous birds and bats. The aft-soil behind walls provides catchment for normal root functions. Beginning as pioneers and persisting as climax members, they short-circuit the seral processes. Wall-gripping capability as large epilithic woody hemi-epiphytes is due to the strangler-fig habit, an evolutionary trait that originated in the tropical forest. The polymorphic roots with morphological plasticity and self-grafting ability, and their multiple modes of interactions with wall niches, account for firm attachment on the vertical habitat and exploration of proximal soils. A model of strangler-fig growth on stone walls serving as surrogate host tree is developed. The diverse and versatile rooting modes are the basis to sustain strangler-fig wall conditions to permit continuation of strangler-fig habit. Such unique nature-in-city and natural-cum-cultural gems deserve conservation as urban ecological heritage.

Urbanized landscapes favored by fig‐eating birds increase invasive but not native juvenile strangler fig abundance

Propagule pressure can determine the success or failure of invasive plant range expansion. Range expansion takes place at large spatial scales, often encompassing many types of land cover, yet the effect of landscape context on propagule pressure remains largely unknown. Many studies have reported a positive correlation between invasive plant abundance and human land use; increased propagule pressure in these landscapes may be responsible for this correlation. We tested the hypothesis that increased rates of seed dispersal by fig-eating birds, which are more common in urban habitats, result in an increase in invasive strangler fig abundance in landscapes dominated by human land use. We quantified abundance of an invasive species (Ficus microcarpa) and a native species (F. aurea) of strangler fig in plots spanning the entire range of human land use in South Florida, USA, from urban parking lots to native forest. We then compared models that predicted juvenile fig abundance based on distance to adult fig seed sources and fig-eating bird habitat quality with models that lacked one or both of these terms. The best model for juvenile invasive fig abundance included both distance to adult and fig-eating bird habitat terms, suggesting that landscape effects on invasive fig abundance are mediated by seed-dispersing birds. In contrast, the best model for juvenile native fig abundance included only presence/absence of adults, suggesting that distance from individual adult trees may have less effect on seed limitation for a native species compared to an invasive species undergoing range expansion. However, models for both species included significant effects of adult seed sources, implying that juvenile abundance is limited by seed arrival. This result was corroborated by a seed addition experiment that indicated that both native and invasive strangler figs were strongly seed limited. Understanding how landscape context affects the mechanisms of plant invasion may lead to better management techniques. Our results suggest that prioritizing removal of adult trees in sites with high fig-eating bird habitat may be the most effective method to control F. microcarpa abundance.