Mature Rainforest Research Articles

Structural Characterization of Island Rainforests and Secondary Groves in Southern Nigeria

This study characterized the structural attributes of island rainforests and secondary groves within Orogun region in southern Nigeria. The quasi-experimental design was used, and the vegetation structural characteristics were determined in both secondary groves (experimental sites) and island rainforests (control sites). The randomized systematic sampling was employed in dividing the study area into 6 zones which were selected upon the presence of mature rainforest islands and secondary groves respectively. Six plots were sampled in each ecosystem. Tree heights, tree girths, and plot sizes were the data collected. Both secondary groves and island rainforest plots were measured to first determine uniformity in the area covered by the trees, after which, size of 200 ft X 100 ft was chosen as the uniform area of plot from which data were gathered. Tree girths at breast height were determined using measuring tape; while tree heights were determined by the use of Abney level and measuring tape. The 15.0 version of the Statistical Package for the Social Sciences (SPSS) was used in the statistical tests of the stated hypotheses. Statistical results showed that t-value = 7.05, P(0.001) > 0.05 for tree heights; and t-value = 3.122, P(0.026) > 0.05 for the tree girths. The mean differences in the structural characteristics between the secondary and mature island rainforest were significant at 0.05 alpha level. This implies that trees within island rainforests are significantly taller and bigger. The higher structural attributes of the island rainforest revealed that over time, conservation of rainforest trees could positively impact on its structural attributes. Therefore, ecosystem-based management approach was recommended for the management and conservation of the rainforest trees and covers

Characterizing Measures of Aboveground Biomass Parameters of Irvingia gaboneensis (Bush Mango) and Rainforest in Isoko Region, Nigeria

This research characterised measures of aboveground biomass of isolated Irvingia gaboneensis stands within Isoko South Local Government Area’s rainforest, Nigeria. The design of the study was based on quasi experimental approach. The region was divided into 10 based on the existing major communities using stratified sampling technique. From each community, an isolated I. gaboneensis stand was chosen while the adjacent mature rainforest served as control thus, gave a total of 20 sampling sites. Data collected were tree heights (TH) and diameters at breast height (DBH) which were easily obtained through quadrant (10metre x 10metre) approach. Measurement and methods of trigonometry were employed in the determination of TH, while measurement using tape was employed to measure the tree DBH. The data were analysed with the use of graphs, mean, standard deviation (SD), coefficient of variation (CV), t-test and regression statistics. Findings showed that: The mean, SD and CV for the TH were 28.57m, 2.08m, 7.28% for the stands of I. gaboneensis; and 34.50m, 1.17m, 3.39% for adjacent rainforest trees (ART). The mean, SD and CV values for tree DBH were 0.43m, 0.02m, 4.65% for the stands of I. gaboneensis; and 0.73m, 0.01m, 1.37% for the ART. With t-value and p-value of 6.9810 and 0.0000 for TH; 11.9940 and 0.0000 for DBH, the differences in the aboveground biomass parameters between I. gaboneensis and ART are significant at 95% alpha level. Height of I. gaboneensis correlated weakly with DBH; while the relationship between TH and DBH is not significant at 95% alpha level, for I. gaboneensis and RF. The aboveground parameters of the standing I. gaboneensis shows that it supports effective productivity and functioning of the RF ecosystem thus, its conservation is necessary.

An Investigation of Cutting Down of Trees as Human Rights Abuse in the Global World

Purpose: To investigate the current cutting down of trees as a human rights abuse in the global world.
 Methodology: The study employed a documentary review secondary data collection method. Documentary review is a data collection technique in which data is gathered from reports, journals, Magazines, Newspapers, and articles that have data linked to the research being undertaken (Creswell, 2014). A documentary review was employed to investigate the current cutting down of trees as a human rights abuse in the global world by examining the causes, impacts, and how it’s an abuse of human rights.
 Findings: It was found out that cutting down trees in the forest is deforestation. The direct causes are caused by people who clear land for crops, and animal grazing and obtain wood for fuel, manufacturing, and construction. The study found that deforestation affects many species that are so specialized to microhabitats within the forest that they can only be found in small areas. Their specialization makes them vulnerable to extinction. In addition to the species lost when an area is totally deforested, the plants and animals in the fragments of forest that remain also become increasingly vulnerable, sometimes even committed, to extinction. The edges of the fragments dry out and are buffeted by hot winds; mature rainforest trees often die standing at the margins. Cascading changes in the types of trees, plants, and insects that can survive in the fragments rapidly reduce biodiversity in the forest that remains. The study further found that deforestation is a human rights abuse because it denies people the right to life. Trees reduce the amount of stormwater runoff, which reduces erosion and pollution in our waterways and may reduce the effects of flooding but when they are cut they cause flooding which erodes people’s houses and cause losing lives which is a human rights abuse against the declaration of human rights 1948 (Everyone born in this world has human rights that must be protected by the law).
 Unique Contribution to Theory, Practice and Policy: the governments of the global world should work as the team to fight this devise by ending deforestation and thwarting pandemics to address six of the United Nations’ 17 Sustainable Development Goals: the guarantee of healthy lives, zero hunger, gender equality, responsible consumption and production, sustainably managed land, and climate action (intact tropical forests absorb carbon dioxide, whereas burning them sends more CO2 into the atmosphere).

Observations on the utilisation of a restored wildlife corridor by echo‐locating microbats in North Queensland's Wet Tropics

SummaryMicrobat studies are uncommon in the Wet Tropics of north‐east Queensland, despite the group comprising 20% of the bioregion's mammal fauna. The significance of fragmentation and habitat connectivity to the echolocating insectivore group is unknown. Over a 12‐month period in 2021–2022, microbat presence was recorded in a 25‐year‐old restored wildlife corridor 1.2 km in length. We deployed Anabat detectors in the restored corridor, in adjacent open paddocks and in mature rainforest at either end of the corridor. Species in reference forest and corridor vegetation were consistently ‘clutter‐adapted’ bats, with low aspect ratio wings; there was little overlap with high aspect ratio species of the open pasture. Low aspect ratio microbats appear to respond to the similarity in structure between restored and adjacent natural vegetation. Re‐establishing structural and functional connectivity may improve the local persistence of ‘clutter‐adapted’ microbats.

Large Felid and Peccary Habitat Use in Isolated and Contiguous Forest in Panamá: Implications for Conservation

Background and Research Aims Wildlife research in Panamá has focused primarily on protected areas along the Central Cordillera, where much of the remaining mature rainforest habitat is located. Information on large felid and prey habitat use in isolated habitats in Panamá is therefore limited. Here, we estimated occupancy and detection probabilities, as affected by habitat and anthropogenic influences, for 2 felid species (jaguars [ Panthera onca] and pumas [ Puma concolor]), and 2 prey species (white-lipped peccaries [ Tayassu pecari] and collared peccaries [ Pecari tajacu]). Methods Camera trap surveys were conducted during 2014–2015 at Cerro Hoya National Park (CHNP), an isolated remnant of tropical rainforest habitat, and Darién National Park (DNP), a large tract of continuous rainforest habitat. We used single-season, single-species occupancy modeling to estimate probabilities of detection and habitat use of our focal species. Results Three of the 4 focal species were detected at both sites, excluding white-lipped peccary at CHNP. Detection of jaguars and white-lipped peccaries at DNP was highest in February, while detection of collared peccaries at DNP and pumas at CHNP was highest in May and April, respectively. Peccary habitat use was uniform across sites and unaffected by habitat covariates. Both felids preferred habitat further away from anthropogenic disturbance, and jaguars preferred habitat at higher elevations than pumas. Conclusion We further confirm the presence of jaguars and likely local extirpation of white-lipped peccaries in CHNP. Temporal variations influenced detections of focal species. Habitat use of felids was negatively affected by anthropogenic disturbance and elevation. Implications for Conservation Habitat fragmentation and human activities negatively influenced habitat use of felids at both study areas. Given that CHNP serves as one of the last remnants of forest habitat outside the Central Cordillera, we recommend that CHNP be considered a top priority area for wildlife conservation in Panamá.

Roads Disrupt Frugivory and Seed Removal in Tropical Animal-Dispersed Plants in French Guiana

Ecological interactions are being affected at unprecedented rates by human activities in tropical forests. Yet, the continuity of ecological functions provided by animals, such as seed dispersal, is crucial for forest regeneration and species resilience to anthropogenic pressures. The construction of new roads in tropical forests is one of the main boosters of habitat destruction as it facilitates human access to previously isolated areas and increases defaunation and loss of ecological functions. It, therefore, becomes increasingly urgent to rapidly assess how recently opened roads and associated anthropogenic activities affect ecological processes in natural habitats, so that appropriate management measures to conserve diversity can be taken. In this study, we aimed to evaluate the effects of anthropogenic pressures on the health status of a mature rainforest crossed by a newly opened road in French Guiana. For this, we combined different methods to conduct a rapid assessment of the forest’s health status. Firstly, we evaluated the activity of frugivores using camera traps deployed in four forest patches located near (<1 km) ecological corridors preserved as canopy bridges over the road during the fruiting periods of four animal-dispersed tree species. Secondly, we analyzed the fate of seeds enclosed in animal-dispersed tropical fruits by calculating the proportions of fruits consumed and seeds removed (either dispersed or predated) by frugivores. Results show that the proportion of fruits opened and consumed was lower in the forest areas located near the road than in the control forest, and this difference was more significant for plant species strictly dependent on large-bodied primates for seed dispersal than for species relying on both primates and birds. Camera traps showed the presence of small primates and kinkajous feeding on Virola fruits in the forest impacted by the road, where large primates were absent. It is thus likely that smaller frugivores exert a compensatory effect that maintains ecological functions near the road. Despite efforts made to preserve forest continuity through ecological corridors, anthropogenic pressures associated with road proximity are affecting wildlife and disrupting associated ecological functions crucial for plant regeneration, contributing to further forest degradation.

Sturnira tildae(Chiroptera: Phyllostomidae)

AbstractSturnira tildae de la Torre, 1959, Tilda’s yellow-shouldered bat, is a phyllostomid with wide geographic distribution across South America. It inhabits preferably lowland mature rainforests, but also has been captured in modified vegetation and tropical savannas, where it is less abundant. Globally, it is listed as “Least Concern” (LC) by the International Union for Conservation of Nature and Natural Resources, but local red lists in southern Brazil have recorded this species as “Vulnerable,” mainly due to habitat destruction (Atlantic Forest deforestation).

Bird composition of different valley habitats after land-use changes in Northern Honduras

The northern coast of Honduras is potentially covered with tropical rainforests, reaching from the Caribbean Sea up to the cloud forests of the Pico Bonito summits. Therefore, it was blessed with the mega-diverse avifauna of the Central American humid neotropics. Although local bird species have been generally well documented, there are hardly any updates on the biodiversity of northern Honduras. Thus, this study contributes to our knowledge of the natural shift of bird life, following up the Cangrejal River with its different slight land use intensification in the region. Standardized bird records along the valley are analyzed, reaching from the beaches of La Ceiba up to the managed rainforests of El Toncontíns in the lower montane rainforests. Nine points were checked over the course of at least 6 days, taking point counts between 16 March and 20 June 2005. A NMDS of the joined nine point-lists elucidates four main groups, namely the beach/city ecosystems, open habitats along the river banks, slightly cleared forests (park landscape), and a mature rainforest. In total, 115 bird species, from 102 genera and 44 families, were found in 2005. As methods are limited, results can represent merely a prodromus of bird composition of neotropical valleys of the Central American isthmus. However, avi-diversity is affected by forest degradation and increasing land-use changes. Since deforestation is still soaring in the region, bird species composition should be monitored, as it will be as dynamic as land use changes in the region.

Effects of habitat transitions on rainforest bird communities across an anthropogenic landscape mosaic

AbstractWe compared bird community responses to the habitat transitions of rainforest‐to‐pasture conversion, consequent habitat fragmentation, and post‐agricultural regeneration, across a landscape mosaic of about 600 km2 in the eastern Australian subtropics. Birds were surveyed in seven habitats: continuous mature rainforest; two size classes of mature rainforest fragment (4–21 ha and 1–3 ha); regrowth forest patches dominated by a non‐native tree (2–20 ha, 30–50 years old); two types of isolated mature trees in pasture; and treeless pasture, with six sites per habitat. We compared the avifauna among habitats and among sites, at the levels of species, functional guilds, and community‐wide. Community‐wide species richness and abundance of birds in pasture sites were about one‐fifth and one‐third, respectively, of their values in mature rainforest (irrespective of patch size). Many measured attributes changed progressively across a gradient of increased habitat simplification. Rainforest specialists became less common and less diverse with decreased habitat patch size and vegetation maturity. However, even rainforest fragments of 1–3 ha supported about half of these species. Forest generalist species were largely insensitive to patch size and successional stage. Few species reached their greatest abundance in either small rainforest fragments or regrowth. All pastures were dominated by bird species whose typical native habitats were grassland, wetland, and open eucalypt forest, while pasture trees modestly enhanced local bird communities. Overall, even small scattered patches of mature and regrowth forest contributed substantial bird diversity to local landscapes. Therefore, maximizing the aggregate rainforest area is a useful regional conservation strategy.

Functional trait representation differs between restoration plantings and mature tropical rainforest

The planting and attempted restoration of tropical forest landscapes is increasing rapidly across the globe. Two limiting aspects of large-scale forest restoration are the demand for appropriate quantities of seeds and seedlings of native species, and the ability to facilitate succession in planted sites. Species functional traits such as seed type, tree size, germination time, and wood density may influence the quantity of seedlings that can be produced for restoration, and the potential of these seedlings to persist and facilitate site succession. Therefore, it is important to understand the species composition and functional trait representation of restoration plantings. We explored the species composition and functional trait representation of 846 restoration plantings in the Australian Wet Tropics containing > 465,000 seedlings from 599 species, using seedling supply records from six nurseries over a six year period (2012–2017). Despite restoration plantings in the Australian Wet Tropics containing an impressive number of species, just 52 species contributed over half of all individual seedlings. We found that species with small animal-dispersed seeds and low wood density were more abundant, on average, and had greater representation in restoration plantings than in mature rainforest. Despite this, we did not find evidence that restoration plantings had a diminished capacity to grow tall or sequester carbon as there was no significant difference in the relative abundance of tall tree species or species with high wood density. Small seeded and fast growing species may be cheaper to produce in nurseries and may accelerate site succession as these characteristics are associated with pioneer and early successional species, however these traits are also associated with higher mortality rates. Understanding how functional trait representation influences the success of restoration plantings will require further insight into temporal aspects of site succession.

Estimation of Carbon Stock Monetary Value of a Tropical Rainforest in Nigeria

The study estimated the carbon stock contents of a lowland rainforest in Nigeria, Okomu National Park. Four major Carbon pools were estimated, they were: above-ground biomass; below-ground biomass: dead wood; and litter. Nested plot design was used for sample plot demarcation. All trees (living and dead) with Dbh ≥ 10cm were enumerated within the 50 m X 50 m and 20 m X 20 m plots, while the 1 m X 1 m quadrant was for litter samples collection. Core samples and sub-samples were collected from live tree and dead wood respectively. The total carbon stock estimated for the study area was 177.58 tons/ha, of which above-ground biomass accounted for 134.01 tons/ha and below-ground biomass was 33.50 tons/ha. Dead wood was 6.05 tons/ha while litter was 4.02 tons/ha. The Carbondioxide equivalent was estimated to be 651.14 tons/ha. The monetary value for the carbon stock estimated at $ 4/tCO2 was $ 52,674,679. Thus, carbon sequestration is one of the significant ecosystem services provided by mature rainforests. Keywords : Carbon pool, Rainforest, Ecosystem Service, Climate Change, Forest Management DOI: 10.7176/JRDM/63-06 Publication date: March 31 st 2020

Altitude and species identity drive leaf litter decomposition rates of ten species on a 2950 m altitudinal gradient in Neotropical rain forests

AbstractIdentifying the environmental factors controlling litter decomposition is key to understanding the magnitude and rates of nutrient cycling in tropical forests, and how they may be influenced by climate variability and environmental change. We carried out a leaf litter translocation experiment in mature rain forest over a 2,520 m altitudinal gradient in Costa Rica. Leaf litter decomposition rates (k) of ten tree species, two dominant species from each ecosystem, plus two standard species, were calculated over 540 days in four life zones. k was lowest in montane with 0.83 per year and lower montane forests with 2.21 per year. k did not differ between lowland and premontane forests at 3.12 per year, in spite of the 3℃ difference of mean annual temperature between these life zones. k varied fourfold among species. Species decomposition rates ranked as follows, and were predictably related to leaf economic spectrum traits of the species: Acalypha communis (standard, fast decomposer)» Hyeronima oblonga > Alchornea latifolia, Quercus bumelioides, Jarava ichu (standard, slow decomposer)> Minquartia guianensis > Magnolia sororum > Vochysia allenii > Pourouma bicolor, Carapa guianensis. These two slowest‐decomposing species were native premontane and lowland forest dominants, respectively, with tough, low‐nutrient leaves. The ranking of species by k varied very little among life zones suggesting that decomposer organisms in very different ecosystems and environments react in similar ways to the litter quality in general. We conclude that while k decreases with temperature in rain forests on tropical mountains, bioclimatic zones defined as premontane may be “functionally lowland.” The effects of species identity on decomposition rates on tropical mountains are consistent and independent of environment for both standard and native species. Under climate change on these mountains, if moisture regimes do not change, decomposition rates will increase due to rising temperatures. Soil carbon storage may therefore decrease. Changes in the altitudinal distributions of currently dominant species will also affect this critically important biogeochemical process.

Rainforest conservation in Mexico’s lowland Maya area: Integrating local meanings of conservation and land-use dynamics

In several tropical forested areas in which biodiversity conservation and indigenous cultures are interwoven, current conservation policies do not consider how the indigenous communities understand the concept of conservation that is promoted and implemented by conservation programs led by external actors, nor do they consider local traditional practices of resource management. To move towards more inclusive conservation policies that take these two aspects into account, research is required in indigenous settings that can inform policy makers. The present study, carried out in the lowland Maya area of Mexico, aims to investigate local meanings of rainforest conservation and dynamics of land use in two Maya common property holdings or ‘ejidos’ (Noh cah and X-Maben). The study used a Social-Ecological Systems approach comprising: (i) the Maya communities and their local meanings of conservation as a Social Subsystem, assessed through social surveys, and (ii) the rainforest of each studied ejido - which was regarded as an Ecological Subsystem and assessed through satellite images (from 2000 to 2012). In the former, interviewees were asked: “when you hear the phrase ‘conservation of the rainforest’ what do you think is being said?” They were also asked if there were local words in Maya or Spanish that were similar in meaning to the aforementioned phrase. The results relating to the meanings of conservation demonstrate that Maya people, who rely on the rainforest for multiple livelihoods, understand two types of meanings for looking after the rainforest; one promoted by governmental conservation programs, and the other called Kanan K’áax, a Maya phrase that represents their customary or community-based rainforest conservation. Differences between these two models of conservation encompass differences with respect to scale, gender and the Maya people’s own cultural practices. The results of the local dynamics of land use demonstrate that the landscapes of both study sites are dominated by mature rainforest (ranging from 73.9–82.7%), and are therefore in a good state of conservation, and that their agricultural frontiers have not expanded. Our empirical results are valuable in terms of informing the scientific community about the state of rainforest conservation in the Maya Zone, and providing policy makers (from the Maya area and elsewhere) with information to devise new, more inclusive conservation policies that take full account of the indigenous cultural practices of rainforest management.

Rate of forest recovery after fire exclusion on anthropogenic savannas in the Democratic Republic of Congo

Deforestation in the tropics is often followed by the creation of anthropogenic savannas used for animal husbandry. By discontinuing burning regimes, forests may recolonize the savanna and carbon stocks may recover. However, little is known about the success and speed of tropical forest recovery, while such information is vital for a better quantification of efforts to reduce emissions from deforestation and forest degradation (REDD+) as well as supporting Forest Landscape Restoration (FLR) practices. Therefore, we designed a forest regeneration experiment within a savanna patch in the Mayombe hills (Democratic Republic of Congo), by discontinuing the annual burning regime in an 88 ha exclosure since 2005. 101 permanent inventory plots (40.4 ha) were installed in 2010 and remeasured in 2014. Tree species were classified as savanna or forest specialists. We estimate a forest specialist encroachment rate of 9 stems ha−1 yr−1 and a savanna specialist disappearance rate of 16 stems ha−1 yr−1. Average diameter of forest specialists did not change due to an increasing influx of recruits, while average diameter of savanna trees increased due to decreasing recruitment. Carbon stored by forest specialists increased from 3.12 to 5.60 Mg C ha−1, suggesting a forest carbon recovery rate of 0.62 Mg C ha−1 yr−1. Using the average carbon stock of 19 nearby mature rainforest plots as a reference, we estimate a total forest carbon recovery time of at least 150 years. The Manzonzi exclosure may potentially become an important reference experiment to quantify REDD+ schemes in Central Africa. Furthermore, this natural regeneration experiment demonstrates how carbon sequestration and biodiversity conservation can go hand-in-hand. However, more censuses are needed to better quantify the long-term carbon recovery trajectory within the protected area.

Arbuscular mycorrhizal fungi along secondary forest succession at the eastern periphery of Amazonia: Seasonal variability and impacts of soil fertility

As anthropic transformation of Amazonian rainforests into degraded lands continues, the consequences of this on arbuscular mycorrhizal fungi (AMF) remain in the dark. This paper describes changes in AMF (glomerospore abundances, species composition and diversity and glomalin contents) along secondary forest succession, and we explore the impacts of seasonality and of soil texture and chemistry. Research was conducted in a shifting cultivation region at the eastern periphery of Amazonia, in ‘young’ (3–4 yrs old – SEC1) and ‘mid-aged’ (6-8yrs old –SEC2) degraded secondary forest regrowth, and in mature (>120yrs old – SEC3) rainforest, both in dry (November 2015) and in rainy (May 2016) seasons. We identify a total of 36 AMF species, corresponding to 24.1% of Braziĺs and 12.5% of the worldwide known AMF species richness. The genera Glomus and Acaulospora predominated in both seasons and over all successional stages, in terms of species richness and of relative abundances and frequencies. Though AMF species diversity did differ significantly between young / mid-aged degraded secondary forests and >120 yrs-old mature rainforests, differences were altogether small and – contrary to vegetation species diversity – higher in stages SEC2 + 3 than in SEC1. Neither easily-extractable nor total glomalin contents differed significantly between seasons or successional stages, though they did contribute substantially (overall 2.5% average) to total soil organic carbon. BCA suggests that AMF species composition was driven mainly by seasonality (15.9%) and only marginally (though likewise significantly) by succession (8.0%). A subset of soil variables (pH, OM, Al, CEC, Ca) related strongly (r2 = 0.46) with glomerospore abundance and AMF species composition. Our results support the view of a remarkably resilient limited set of AMF species with only subtle differences between young (degraded) secondary regrowth and mature rainforests. Thus, the successional trajectories of vegetation recovery after repeated shifting cultivation cycles are likely not limited by AMF species availability.

Pre‐Pleistocene origin of phylogeographical breaks in African rain forest trees: New insights from Greenwayodendron (Annonaceae) phylogenomics

AbstractAimPalaeoecological records indicate that Pleistocene glaciations affected the African rain forest, probably causing its fragmentation, which could explain phylogeographical breaks documented in many tree species. This refuge hypothesis was further tested through species distribution models, hindcasting persistence during the Last Glacial Maximum. However, previous studies failed to estimate with sufficient precision the divergence time between phylogeographical entities to confirm their Pleistocene origin. Developing genomic tools on a representative tree of mature rain forests, we test if parapatric genetic clusters documented in widespread tree species can be interpreted as the legacy of past population fragmentation during the last glacial period(s).LocationTropical Africa, Guineo‐Congolian forests.TaxonGreenwayodendron (Annonaceae).MethodsTo further test the Pleistocene refuge hypothesis by molecular dating, we sequenced the plastome of 145 individuals of the shade‐tolerant rain forest tree Greenwayodendron suaveolens and congeneric species, and genotyped the same samples using nuclear microsatellites to identify genetic clusters.ResultsFive plastid phylogroups of G. suaveolens occur in parapatry throughout Central Africa, following a spatial pattern generally congruent with genetic clusters. Four of them diverged 3.5–4.5 Ma, whereas the fifth one, located in the Cameroon volcanic line (CVL), diverged 8.3 Ma, in the range of divergence times between Greenwayodendron species, highlighting the key role of the CVL in hosting ancient lineages. Within phylogroups, most nodes were dated from 0.9 to 3.2 Myr and a correlation between haplotype divergence and spatial distance was still perceptible, indicating a slow population dynamic.Main conclusionsThe phylogeographical structures of Central African trees probably established during the Pliocene or early Pleistocene, and while they might have been reinforced during subsequent glacial–interglacial cycles, interglacial phases did not lead to genetic homogenization. Therefore, interpreting phylogeographical patterns of African trees must account for a much deeper past than previously assumed, and cannot be limited to the last glacial period.

Floristics of soil seed banks on agricultural and disturbed land cleared of tropical forests

Little is known about how soil seed banks vary in germination, composition, and density under different land uses after tropical forest conversion. Seed banks can potentially act as one source of regeneration for reforestation of old agricultural lands. Our study documents the composition and density of germinants in soil seed banks from four land uses types surrounding the Sinharaja forest in southwest Sri Lanka. These include: (1) kekilla fern lands; (2) pine plantations; and (3) tea. These were compared to the adjacent (4) mature rainforest. During the 6‐month period of monitoring, we recorded 1,674 germinants (0.036 germinants/cm3 soil), representing 46 species. Germinants of tree and shrub species were restricted to the pine and rainforest soils and all of them are considered pioneers. The soils of the rainforest had the lowest species richness, density, and diversity of germinants; tea lands comprised much higher richness, Shannon diversity, and density. However, almost all germinants in tea were grasses and herbs as compared with other land uses. A multivariate analysis of the germinants of soil seed banks revealed that the four land use types comprise very different compositions and abundances, some of which can be associated with differences in growth habit (trees, shrubs, vines, herbs, grasses). Our results suggest that pine plantations may facilitate some tree and shrub regeneration. However, the seed banks beneath tea and kekilla fern land do not comprise any woody plant species. This may explain why agricultural lands such as tea do not revert back to forest easily.

Early anthropogenic impact on Western Central African rainforests 2,600 y ago

A potential human footprint on Western Central African rainforests before the Common Era has become the focus of an ongoing controversy. Between 3,000 y ago and 2,000 y ago, regional pollen sequences indicate a replacement of mature rainforests by a forest-savannah mosaic including pioneer trees. Although some studies suggested an anthropogenic influence on this forest fragmentation, current interpretations based on pollen data attribute the ''rainforest crisis'' to climate change toward a drier, more seasonal climate. A rigorous test of this hypothesis, however, requires climate proxies independent of vegetation changes. Here we resolve this controversy through a continuous 10,500-y record of both vegetation and hydrological changes from Lake Barombi in Southwest Cameroon based on changes in carbon and hydrogen isotope compositions of plant waxes. [Formula: see text]13C-inferred vegetation changes confirm a prominent and abrupt appearance of C4 plants in the Lake Barombi catchment, at 2,600 calendar years before AD 1950 (cal y BP), followed by an equally sudden return to rainforest vegetation at 2,020 cal y BP. [Formula: see text]D values from the same plant wax compounds, however, show no simultaneous hydrological change. Based on the combination of these data with a comprehensive regional archaeological database we provide evidence that humans triggered the rainforest fragmentation 2,600 y ago. Our findings suggest that technological developments, including agricultural practices and iron metallurgy, possibly related to the large-scale Bantu expansion, significantly impacted the ecosystems before the Common Era.

Using soundscapes to detect variable degrees of human influence on tropical forests in Papua New Guinea.

There is global concern about tropical forest degradation, in part, because of the associated loss of biodiversity. Communities and indigenous people play a fundamental role in tropical forest management and are often efficient at preventing forest degradation. However, monitoring changes in biodiversity due to degradation, especially at a scale appropriate to local tropical forest management, is plagued by difficulties, including the need for expert training, inconsistencies across observers, and lack of baseline or reference data. We used a new biodiversity remote-sensing technology, the recording of soundscapes, to test whether the acoustic saturation of a tropical forest in Papua New Guinea decreases as land-use intensity by the communities that manage the forest increases. We sampled soundscapes continuously for 24 hours at 34 sites in different land-use zones of 3 communities. Land-use zones where forest cover was fully retained had significantly higher soundscape saturation during peak acoustic activity times (i.e., dawn and dusk chorus) compared with land-use types with fragmented forest cover. We conclude that, in Papua New Guinea, the relatively simple measure of soundscape saturation may provide a cheap, objective, reproducible, and effective tool for monitoring tropical forest deviation from an intact state, particularly if it is used to detect the presence of intact dawn and dusk choruses.

Ants as ecological indicators of rainforest restoration: Community convergence and the development of an Ant Forest Indicator Index in the Australian wet tropics.

Ecosystem restoration can help reverse biodiversity loss, but whether faunal communities of forests undergoing restoration converge with those of primary forest over time remains contentious. There is a need to develop faunal indicators of restoration success that more comprehensively reflect changes in biodiversity and ecosystem function. Ants are an ecologically dominant faunal group and are widely advocated as ecological indicators. We examine ant species and functional group responses on a chronosequence of rainforest restoration in northern Australia, and develop a novel method for selecting and using indicator species. Four sampling techniques were used to survey ants at 48 sites, from grassland, through various ages (1–24 years) of restoration plantings, to mature forest. From principal components analysis of seven vegetation metrics, we derived a Forest Development Index (FDI) of vegetation change along the chronosequence. A novel Ant Forest Indicator Index (AFII), based on the occurrences of ten key indicator species associated with either grassland or mature forest, was used to assess ant community change with forest restoration. Grasslands and mature forests supported compositionally distinct ant communities at both species and functional levels. The AFII was strongly correlated with forest development (FDI). At forest restoration sites older than 5–10 years that had a relatively closed canopy, ant communities converged on those of mature rainforest, indicating a promising restoration trajectory for fauna as well as plants. Our findings reinforce the utility of ants as ecological indicators and emphasize the importance of restoration methods that achieve rapid closed‐canopy conditions. The novel AFII assessed restoration status from diverse and patchily distributed species, closely tracking ant community succession using comprehensive species‐level data. It has wide applicability for assessing forest restoration in a way that is relatively independent of sampling methodology and intensity, and without a need for new comparative data from reference sites.