Are mangroves in the tropical Atlantic ripe for invasion? Exotic mangrove trees in the forests of South Florida

Two species of mangrove trees of Indo-Pacific origin have naturalized in tropical Atlantic mangrove forests in South Florida after they were planted and nurtured in botanic gardens. Two Bruguiera gymnorrhiza trees that were planted in the intertidal zone in 1940 have given rise to a population of at least 86 trees growing interspersed with native mangrove species Rhizophora mangle, Avicennia germinans and Laguncularia racemosa along 100 m of shoreline; the population is expanding at a rate of 5.6% year⁻¹. Molecular genetic analyses confirm very low genetic diversity, as expected from a population founded by two individuals. The maximum number of alleles at any locus was three, and we measured reduced heterozygosity compared to native-range populations. Lumnitzera racemosa was introduced multiple times during the 1960s and 1970s, it has spread rapidly into a forest composed of native R. mangle, A. germinans, Laguncularia racemosa and Conocarpus erectus and now occupies 60,500 m² of mangrove forest with stem densities of 24,735 ha⁻¹. We estimate the population growth rate of Lumnitzera racemosa to be between 17 and 23% year⁻¹. Populations of both species of naturalized mangroves are dominated by young individuals. Given the long life and water-dispersed nature of propagules of the two exotic species, it is likely that they have spread beyond our survey area. We argue that the species-depauperate nature of tropical Atlantic mangrove forests and close taxonomic relatives in the more species-rich Indo-Pacific region result in the susceptibility of tropical Atlantic mangrove forests to invasion by Indo-Pacific mangrove species.     

中国主要天然落叶松林的多孔菌多样性

落叶松是我国北方重要的针叶树种,天然落叶松倒木上生长有种类繁多的多孔菌,它们能够分解倒木中的纤维素、半纤维素和木质素,促进森林生态系统的物质循环,同时维持生态系统中的碳平衡,在森林生态系统中发挥重要的生态功能.本文针对我国5种主要落叶松树种上的多孔菌种类,综合分析了该类群的物种组成和分布特征,并对不同树种上的多孔菌种群进行对比分析.结果表明： 落叶松上共有多孔菌107种,分属11科43属,其中褐腐真菌种类49种,占到总数的45.4%,是中国已报道褐腐真菌种类的50%.91.7%的多孔菌生长在刚开始腐烂的倒木上.兴安落叶松上的多孔菌不论是种类还是数量均比其他4种落叶松多.兴安落叶松和长白落叶松以及新疆落叶松和西藏落叶松上的多孔菌种群相似度高,这与其林分的天然分布相一致.     

Wood Decomposition of Cyrilla racemiflora (Cyrillaceae) in Puerto Rican Dry and Wet Forests: A 13‐year Case Study1

We studied the decomposition of Cyrilla racemiflora logs over a 13‐yr period in tropical dry and wet forests in Puerto Rico. The mean mass loss, ratio of soft to hard wood, nutrient concentrations, and the diversity of wood‐inhabiting organisms were greater in logs decomposing in the dry forest than in the wet forest. Termites were also more abundant in the logs collected from the tropical dry forest than the tropical wet forest. High moisture content and a low animal diversity on the logs in the wet forest seem to retard wood decay in this habitat. Wood decay rates in the tropical dry forest can be related to the high diversity of species and functional groups of wood‐inhabiting organisms.     

Age and Long-term Growth of Trees in an Old-growth Tropical Rain Forest, Based on Analyses of Tree Rings and 14C1

In an old‐growth tropical wet forest at La Selva, Costa Rica, we combined radiocarbon (¹⁴C) dating and tree‐ring analysis to estimate the ages of large trees of canopy and emergent species spanning a broad range of wood densities and growth rates. We collected samples from the trunks of 29 fallen, dead individuals. We found that all eight sampled species formed visible growth rings, which varied considerably in distinctiveness. For five of the six species for which we combined wood anatomical studies with ¹⁴C‐dates (ring ages), the analyses demonstrated that growth rings were of annual formation. The oldest tree we found by direct ring counting was a Hymenolobium mesoamericanum Lima (Papilionaceae) specimen, with an age of ca. 530 years at the time of death. All other sampled individuals, including very large trees of slow‐growing species, had died at ages between 200 and 300 years. These results show that, even in an everwet tropical rain forest, tree growth of many species can be rhythmic, with an annual periodicity. This study thus raises the possibility of extending tree‐ring analyses throughout the tropical forest types lacking a strong dry season or annual flooding. Our findings and similar measurements from other tropical forests indicate that the maximum ages of tropical emergent trees are unlikely to be much greater than 600 years, and that these trees often die earlier from various natural causes.     

Pattern and process in mangrove forests of the Andaman Islands

Abatract The structural and functional aspects of mangrove forests of the Andaman Islands were described. The mangrove forests of Andaman are highly diversified and rich in species composition. Twenty-six species were collected, Rhizophora lamarckii and R. stylosa were reported for the first time from these islands. The mangroves of Andaman are very productive in comparison to other forest types. Maximum production of biomass was found in the undisturbed Oralkatcha forest. Maximum litter fall was also found at Oralkatcha.     

Dispersal of Spores of Mycorrhizal Fungi in Scats of Native Mammals in Tropical Forests of Northeastern Australia

One hundred and thirty-eight scat (faecal) samples from 17 mammal species native to forests of northeastern Queensland were examined for the presence of spores of both ectomycorrhizal and arbuscular mycorrhizal fungi. Spores of mycorrhizal fungi were found in 57 percent of scat samples representing 12 animal species (Aepyprymnus rufescens, Antechinus godmani, Bettongia tropica, Hypsiprymnodon moschatus, Isoodon macrourus, Melomys ceruinipes, Perameles nasuta, Rattus fuscipes, R. tunneyi, Thylogale stigmatica, Trichourur uulperula, Uromys caudimaculatus). Spores were absent in scats of Antechinus stuartii, Dasyurus hallucatus, Dendrolagus lumholtzi, Petaurus australis and Mesembriomys gouldii. Spores of ectomycorrhizal fungi occurred in 38 percent of scats, and all but one of these samples were from Eucalyptus-dominated sclerophyll forests. Based on the frequency and abundance of spores in scats, five mammals were considered active consumers of hypogeous mycorrhizal sporocarps in sclerophyll forests (A. rufescens, B. tropica, I. macrourus, P. nasuta, and U. caudimaculatus). Individual scats of these animals generally contained a range of distinctive spore types. Spores of arbuscular mycorrhizal fungi were found in low abundance in almost 40 percent of scat samples collected, from both sclerophyll forest and rainforest habitats. We suggest that the majoriry of these spores were acquired incidentally through ingestion of soil during foraging activities on the forest floor. Glasshouse inoculation experiments in which seedlings of Eucalyptus grandis and Sorghum bicolor were inoculated with scat material from several species of mammal demonstrated that the spores of ectomycorrhizal and arbuscular mycorrhizal fungi retained some viability and colonized the roots of host-plant seedlings. Insufficient information is known of the ecology of mycorrhizal fungi in Australia's tropical forests to speculate as to the implications of these findings for forest conservation and rehabilitation.     

Plant-animal interactions and the structure and function of mangrove forest ecosystems*

Trophic interactions involving plants and animals in tropical mangrove forests have important controlling influences on several population, community and ecosystem-level processes. Insect herbivores remove up to 35% of leaf area from some mangrove tree species and can cause the death of seedlings. Leaf chemistry and toughness and soil nutrient status all appear to be important in explaining the between- and among-species variance in leaf damage. Insects also attack and damage, mainly by boring, a large proportion of mangrove seeds. Shadehouse experiments have shown that such post-dispersal predation can have a significant effect on seedling survival, growth and biomass allocation to leaves, stems and roots. Sesarmid crabs are also responsible for severe post-dispersal seed predation. In field trials, crabs consumed more than 70% of the seeds of five tree species. For four of these five species there was an inverse relationship between seed predation rate and the dominance of conspecific adult trees, while the within-site distribution pattern of one tree species appears to be partially controlled by crabs. The same crab species also consume 30–80% (depending on forest type and intertidal elevation), of the annual litter fall in mangrove forests and, thus, have an important role in controlling the rate of remineralization of detritus within forests and the export of particulate matter from the forests to other nearshore habitats. The other major component of litter in the forests is wood, which is broken down relatively rapidly by teredinid molluscs (shipworms). More than 90% of the weight loss from decomposing trunks of Rhizophora species during the first four years of decay is through ingestion by teredinids. The annual turnover of dead wood mass in Rhizophora forests is equivalent to that of the processing of leaf detritus by crabs. Because of the relatively low species richness of trees and consumers in tropical mangrove forests, they are likely to serve as productive sites for further investigations of the influence of plant-animal interactions on the dynamics of tropical forests.     

Comparing forest structure and biodiversity on private and public land: secondary tropical dry forests in Costa Rica

Secondary forests constitute a substantial proportion of tropical forestlands. These forests occur on both public and private lands and different underlying environmental variables and management regimes may affect post‐abandonment successional processes and resultant forest structure and biodiversity. We examined whether differences in ownership led to differences in forest structure, tree diversity, and tree species composition across a gradient of soil fertility and forest age. We collected soil samples and surveyed all trees in 82 public and 66 private 0.1‐ha forest plots arrayed across forest age and soil gradients in Guanacaste, Costa Rica. We found that soil fertility appeared to drive the spatial structure of public vs. private ownership; public conservation lands appeared to be non‐randomly located on areas of lower soil fertility. On private lands, areas of crops/pasture appeared to be non‐randomly located on higher soil fertility areas while forests occupied areas of lower soil fertility. We found that forest structure and tree species diversity did not differ significantly between public and private ownership. However, public and private forests differed in tree species composition: 11 percent were more prevalent in public forest and 7 percent were more prevalent in private forest. Swietenia macrophylla, Cedrela odorata, and Astronium graveolens were more prevalent in public forests likely because public forests provide stronger protection for these highly prized timber species. Guazuma ulmifolia was the most abundant tree in private forests likely because this species is widely consumed and dispersed by cattle. Furthermore, some compositional differences appear to result from soil fertility differences due to non‐random placement of public and private land holdings with respect to soil fertility. Land ownership creates a distinctive species composition signature that is likely the result of differences in soil fertility and management between the ownership types. Both biophysical and social variables should be considered to advance understanding of tropical secondary forest structure and biodiversity.     

Ecology of tropical marine fungi

Lignicolous material was collected from 5 marine locations in Brunei: a rocky headland, a sandy beach, a man-made brackish lake, a healthy mangrove and an oil polluted mangrove. Higher marine fungi present were identified and their percentage occurrence noted. The common marine fungi varied from habitat to habitat. Antennospora quadricornuta was most common at the rocky headland, Corollospora pulchella at the sandy beach and Halosarpheia marina at the brackish lake. In the mangroves the most common species were Halocyphina villosa (healthy) and Cirrenalia pygmea and Lulworthia grandispora (oil polluted). Differences in species composition from one habitat to the next were observed, although some fungi occurred throughout. There were significantly less diversity and numbers of fungi in the oil polluted mangrove when compared to the healthy mangrove. Observations concerning the ecology of tropical marine fungi are made.     

Host and habitat preferences of polypore fungi in Micronesian tropical flooded forests

The distribution and ecological impacts of plant-associated fungi is determined in large part by their degree of specificity for particular host species or environmental conditions. Here we evaluate the host and habitat preferences among the Aphyllophorales, a guild of wood-decay basidiomycete fungi usually considered to be host generalists. We determined the patterns of host association in three well-defined, floristically distinct, tropical wetlands — freshwater forested wetlands, saltwater mangrove forests, and peatlands with scattered trees — on the islands of Kosrae and Pohnpei in the Federated States of Micronesia. Of 33 fungal species, 20 were locally rare. Of the 11 species sufficiently common to evaluate habitat specificity, nine showed significant habitat preferences. Of eight species common enough to evaluate within-habitat host specificity, six showed strong host preferences. All except one of the nine habitat-specialized fungi showed either statistically significant host specificity or strong numerical biases toward single host species. Our results suggest that host preferences may be important in shaping the assemblages of wood-decay fungi, and that the effect of environment on the distribution of susceptible plant species, rather on the fungi themselves, may ultimately drive the apparent habitat specificity of many fungi.     

Distance‐dependent effects of soil‐derived biota on seedling survival of the tropical tree legume Ormosia semicastrata

Question: How do seed germination and subsequent seedling survival of O. semicastrata (Hance forma litchiifolia How) vary with respect to distance from parent trees and conspecific density in different types of tropical forest? Are there effects of soil biota on O. semicastrata that systematically depend on distance from parent trees and conspecific density? Do soil pathogens differently affect survival of O. semicastrata in different types of tropical forest? Location: Tropical lowland rain forest and tropical montane rain forest in Jianfengling National Nature Reserve, Hainan Island, China. Methods: Individual adult O. semicastrata trees were selected in lowland rain forest and montane rain forest. Soil was collected at a distance of 0‐5 m or 15‐20 m from the parent tree. Soil samples from each distance were combined into a bulk sample. Half of the soil sample was sterilized by autoclaving. Surface‐sterilized seeds were then added to the soil material in shade‐houses at both forests. Results: Germination of O. semicastrata seeds at low‐ or high‐seed density was barely affected by the sterilization procedure. In both forests, seedlings grown in non‐sterilized soil collected close to parent trees had significantly higher mortality compared to those in sterilized soil. In contrast, seedling survival with soil collected far from parent trees was not affected by the soil sterilization procedure. Conclusions: Host‐specific pathogens concentrated in the soil around parent trees may regulate community structure of tropical trees at the stage of seedling development.     

Structure of insect communities inhabiting old‐growth forest specialist bracket fungi

1. This paper describes the structure of the insect communities inhabiting two old‐growth forest specialist bracket fungi, Amylocystis lapponica and Fomitopsis rosea. To study the consequences of old‐growth forest fragmentation on community structure, non‐fragmented and fragmented forest areas in eastern and southern Finland were compared. 2. Both fungal species are inhabited by more than 50 insect species. The most abundant species in the A. lapponica community is a melandryid beetle Hallomenus sp., and in the F. rosea community a tineid moth Agnathosia mendicella. The occurrence of several nationally or globally rare species underscores the importance of specific insect microhabitats, such as the specialist fungi A. lapponica and F. rosea, for the persistence of specialised insects in old‐growth forests. 3. The species composition in both fungal species differs greatly from each other. The food webs are characterised by one numerically dominant host‐specific primary fungivore, which implies that fungivorous species inhabiting bracket fungi may be more specialised on a particular host than is generally thought. 4. The community structure was the same in the highly fragmented and in the non‐fragmented study areas, probably because fragmentation has occurred relatively recently.     

Regeneration in fringe mangrove forests damaged by Hurricane Andrew

Mangrove forests along many tropical coastlines are frequently andseverely damaged by hurricanes. The ability of mangrove forests to regeneratefollowing hurricanes has been noted, but changes that occur in vegetationfollowing disturbance by hurricane winds and storm tides have not been studied.We measured changes in plant community structure and environmental variables intwo fringe mangrove forests in south Florida, USA that experienced high windvelocities and storm tides associated with Hurricane Andrew (August1992). Loss of the forest canopy stimulated regeneration via seedlinggrowth and recruitment, as well as resprouting of some trees that survived thehurricane. Initial regeneration differed among species in both forests:Rhizophora mangle L. regenerated primarily via growth ofseedlings present at the time of the hurricane (i.e., release of advancerecruits), but many trees of Avicennia germinans(L.) Stearn and Laguncularia racemosa Gaertn.f.resprouted profusely from dormant epicormic buds. In one forest, which wasformerly dominated by Laguncularia, high densities ofRhizophora seedlings survived the hurricane and grew toform dense stands of saplings and small trees ofRhizophora. In the other forest, there were lowerdensitiesof surviving Rhizophora seedlings (possibly due tohigher storm tide), and extensive bare areas that were colonized byAvicennia, Laguncularia, andherbaceous species. This forest, predominantly Rhizophoraat the time of the hurricane, now contains stands of saplings and small treesofall three species, interspersed with patches dominated by herbaceous plants.These findings indicate that moderately damaged fringe forests may regenerateprimarily via release of Rhizophora advance recruits,leading to single-species stands. In severely damaged forests, seedlingrecruitment may be more important and lead to mixed-species stands.Regeneration of mangrove forests following hurricanes can involve differentpathways produced by complex interactions between resprouting capability,seedling survival, post-hurricane seedling recruitment, and colonizationby herbaceous vegetation. These differences in relative importance ofregeneration pathways, which may result in post-hurricane forestsdifferent from their pre-hurricane structure, suggest that models forregeneration of mangrove forests will be more complex than directregeneration models proposed for other tropical forests whereregeneration after hurricanes is dominated by resprouting.     

Beyond the tropics: forest structure in a temperate forest mapped plot

Question: How do the diversity, size structure, and spatial pattern of woody species in a temperate (Mediterranean climate) forest compare to temperate and tropical forests? Location: Mixed evergreen coastal forest in the Santa Cruz Mountains, California, USA. Methods: We mapped, tagged, identified, and measured all woody stems (≥1 cm diameter) in a 6‐ha forest plot, following Center for Tropical Forest Science protocols. We compared patterns to those found in 14 tropical and 12 temperate forest plots. Results: The forest is dominated by Douglas‐fir (Pseudotsuga menziesii) and three species of Fagaceae (Quercus agrifolia, Q. parvula var. shrevei, and Lithocarpus densiflorus), and includes 31 woody species and 8180 individuals. Much of the diversity was in small‐diameter shrubs, treelets, and vines that have not been included in most other temperate forest plots because stems <5‐cm diameter had been excluded from study. The density of woody stems (1363 stems ha^?1) was lower than that in all but one tropical plot. The density of large trees (diameter ≥30 cm) and basal area were higher than in any tropical plot. Stem density and basal area were similar to most other temperate plots, but were less than in low‐diversity conifer forests. Rare species were strongly aggregated, with the degree of aggregation decreasing with abundance so that the most common species were significantly more regular than random. Conclusions: The patterns raise questions about differences in structure and dynamics between tropical and temperate forests; these need to be confirmed with additional temperate zone mapped plots that include small‐diameter individuals.     

Food web structure of the fungivorous insect community on bracket fungi in a Bornean tropical rain forest

1. If fungivorous insect diversity is maintained by host specialisation on particular fungi, it should be higher in the tropics than in temperate or boreal regions owing to high macrofungus species diversity. 2. To reveal the community and food web structure of fungivorous insects on bracket fungi, fungivorous insects were collected from 427 fruiting bodies belonging to 22 genera throughout the development and deterioration process in a 3‐ha plot of lowland dipterocarp tropical rain forest on Borneo Island. 3. Eight hundred and twenty‐nine individuals of 82 coleopteran species in 13 families from 111 fruiting bodies of 15 fungal genera were collected. Tenebrionidae and Staphylinidae were most common. Fifty‐three and 19 insect species were observed on Ganoderma and Phellinus, respectively. The numbers of insect species and individuals on a particular fungal genus were positively correlated with the abundance of that fungal genus. 4. Quantitative food web analysis revealed a high degree of specialisation at the whole‐community level. At least 65% of insect individuals were observed on Ganoderma at every stage of development and deterioration. Diverse insects coexist on one dominant fungal genus, Ganoderma, in contrast to our hypothesis. 5. The high abundance of Ganoderma fruiting bodies, which lack obvious defences against insect feeding, probably influences the bracket fungus–insect food web in this tropical rainforest.     

Drivers of Mangrove Litterfall within a Karstic Region Affected by Frequent Hurricanes

Tropical storms can shape the structure and productivity of mangrove forests. In this study, we compared current litterfall with historical tropical storm disturbance in the karstic Yucatan Peninsula (YP). We also explored the relationship between litterfall and the fresh/seawater mixture of floodwater. Our hypotheses were that litterfall peaks at moderate perturbations and in sites where seawater dominates the floodwater mixture, and thus, where soil total phosphorus (TP) is relatively high. Litterfall was sampled for 2 yr, from eight mangrove forests around the YP. At each site, forest structure, interstitial salinity, TP, nitrogen, carbon, pH, and bulk density were measured. Our results show that mangrove forest from northeast YP are historically impacted by stronger and more frequent tropical storms compared with those in northwest and southeast YP, where tropical storm intensity is moderate and mild, respectively. Litterfall was higher in northwest YP (≥3 g/m² d) compared with northeast and southeast (≤ 2 g/m² d), mimicking a subsidy‐stress gradient where highest productivity is reached at moderate perturbations. Neither salinity nor forest structure alone satisfactorily explained litterfall variability. Soil TP followed a similar geographical pattern as the disturbance gradient: highest concentrations in the northwest YP (≥0.05%) and lowest in the northeast and southeast (≤ 0.03%). Thus, it is likely that TP, and not tropical storm disturbance, is the main driver of litterfall in mangrove forests of the YP. Alterations in TP availability (e.g., sea level rise and aquifer contamination) have the potential to modify mangrove productivity in the region.     

Genetic population structure and distribution of a fungal polypore, Datronia caperata (Polyporaceae), in mangrove forests of Central America

Aim We examine the genetic structure of a fungal polypore, Datronia caperata (Berk.) Ryvarden (Polyporaceae), colonizing white mangrove, Laguncularia racemosa (L.) Gaertn. f. (Combretaceae), of Central America. Location Mangrove forests of Costa Rica and Panama. Methods Sequences of elongation factor alpha (EFA), beta tubulin (BTUB) and nuclear ribosomal internal transcribed spacer (ITS) regions were obtained from 54 collections of D. caperata collected from Caribbean and Pacific L. racemosa forests in Central America. Measures of haplotype and nucleotide diversity, nested clade analyses and coalescent analyses were used to estimate the direction and extent of migration of the fungus, and the factors promoting population divergence. We also conducted phylogenetic analyses using Bayesian estimation to test whether putative D. caperata collected from L. racemosa was conspecific with D. caperata colonizing other hosts from diverse Neotropical forests. Results Our results demonstrate that there is genetic isolation between D. caperata populations from Caribbean mangroves and those from Pacific mangroves. Our data suggest that the best explanation for the observed haplotype distribution is a recent range expansion from the Caribbean to the Pacific coasts, with subsequent isolation. This is supported by the infrequent overlap of haplotypes, unidirectional migration estimates from the Caribbean to the Pacific and the older estimated age of mutations in the Caribbean low‐copy BTUB and EFA loci. In addition, our data suggest that D. caperata from mangroves are not conspecific with collections from other hosts found in diverse Neotropical forests. Main conclusions The low frequency of shared haplotypes between coasts, coupled with the incomplete lineage sorting after cessation of gene flow, is consistent with isolation during the last Pleistocene glaciation. We hypothesize that the greater haplotype and nucleotide diversity in the Pacific occurs either because larger effective population sizes of D. caperata are maintained in Pacific mangroves or because D. caperata populations underwent a significant bottleneck as a result of local extinction followed by recolonization. In addition, we found that D. caperata found on L. racemosa was not conspecific with D. caperata from non‐mangrove hosts and suggest that D. caperata found on L. racemosa may be a host specialist.     

Frugivoría por Aves en un Paisaje Fragmentado: Consecuencias en la Dispersión de Semillas1

Few data exist on seed dispersal by frugivorous birds in fragmented landscapes, originating from tropical dry forests, in contrast to more abundant data from tropical rain forests. In this study, we assessed the effect of frugivorous birds in a fragmented landscape of Veracruz, Mexico, now occupied by remnant fragments of tropical semi‐deciduous forest and dry deciduous forest, grassland, and shrubby patches on sand dunes. We determined four characteristics related to seed dispersal by birds: the interacting species of plants and birds, the characteristics of these species, spatio‐temporal variation in the dispersal system, and the outcome of the process. During one year, we recorded 54 frugivorous bird species and 33 ornithochorous plant species, which engaged in 176 different bird‐plant species interactions. Similarity (Sorensen index) of frugivorous bird communities using different vegetation types was high (>70%), suggesting that many bird species used all of the vegetation types. In contrast, the similarity of ornithochorous plant communities among vegetation types commonly was low (<37%), suggesting that most plant species were restricted to particular sites in this landscape. At the landscape level, as well as for tropical deciduous forest, we detected a significant positive relationship (Spearman's correlation of rank coefficient >0.65, P <0.05) among richness per month of frugivorous birds and plant species bearing fleshy fruits. Seeds of many plant species previously detected in studies of seed rain at the site were eaten by birds during this study. Most seeds of zoochorous species, which are deposited in the dry and decidous tropical forests patches, are produced within these vegetation types (i.e., they are autochthonous species), whereas bird‐dispersed seeds arriving in grassland and shrubby patches are produced outside (i.e., allochthonous) and are mostly woody species. Birds are important seed dispersers among vegetation types in this landscape but they have different effects in each one. The four characteristics studied, as well as the landscape approach of this research, allowed us to detect spatial and temporal patterns that otherwise would have remained undetected.     

Local Mangrove Planting in the Philippines: Are Fisherfolk and Fishpond Owners Effective Restorationists?

Local fisherfolk and fishpond owners have been practicing “restoration” of mangrove forests in some parts of the Philippines for decades, well before governments and non‐government organizations began to promote the activity as a conservation tool. This paper examines ecological characteristics of these mangrove plantations and compares them to natural mangroves in the same areas. Mangrove planters were interviewed and plantation and natural mangrove forests were surveyed to measure forest structure, composition and regeneration. Compared with natural forests, mangrove plantations were characterized by high densities of small stems, shorter and narrower canopies, and fewer species. For both economic and ecological reasons, the vast majority of people dispersed and planted only Rhizophora mucronata/stylosa and, furthermore, they often thinned other species out of planted areas. There was remarkably little subsequent recruitment of other, nonplanted mangrove species into plantations up to 50 and 60 years of age. This pattern held across a diversity of sites, including plantations that had not been selectively cut or weeded. Important ecological and economic benefits result from local mangrove planting, but catalyzing diverse forest regeneration—at least in the short to medium term—is not one of them. The lesson: if you want to restore diverse mangrove forests, you have to plant diverse mangrove forests.