Primary Lowland Research Articles

Faunal Diversity and the Ecological Aspects of a Community-Based Fragmented Lowland Rainforest Patch in Western Province, Sri Lanka

Wawekale Rainforest Reserve (WRR) is a primary lowland tropical rainforest area in the Western Province of Sri Lanka, established with diversity, but disturbed by human activities such as rubber cultivation, logging, poaching, chemical release, and the collection of firewood. Visual Encounter Surveys (VES) were conducted for 100 hours in the year 2022, which covered wide habitat distribution. The herpetofaunal diversity was measured in the WRR which can indicate broader ecological shifts, environmental changes, or habitat degradation. Water quality was measured in the WRR area to determine the ecosystem health and human impact. The study reports 171 species in 73 families, including two Critically Endangered (1.17%), six Endangered (3.51%), 16 Vulnerable (9.36%), and 14 Near Threatened (8.19%) species according to the IUCN Red List. The study area showed 51 endemic faunal species in Sri Lanka, which represented 29.83% of endemism. Based on the observations conducted on the herpetofauna diversity, the Shannon-Wiener diversity index (H) was calculated and the overall herpetofauna (H’H) showed high diversity within the forest premises. The water quality of the forest fragment had an influence from anthropogenic activities such as removing forest cover, bathing, washing vehicles, and releasing agro-chemical compounds resulting in high water temperature, basic pH level, high electrical conductivity, and high total dissolved solid conditions. The WRR, designated under protection, exhibits the need for immediate remedial actions to mitigate human-induced pollution and deforestation, emphasizing the critical importance of implementing proactive conservation measures to sustain ecological integrity and preserve biodiversity.

Vangunu giant rat (Uromys vika) survives in the Zaira Community Resource Management Area, Solomon Islands.

Described in 2017 and known only from the holotype, Uromys vika is surely among the world's least studied rodents. This critically endangered species is facing a rapidly increasing scale for threat from logging of its primary lowland forest habitat, on the only island on which it occurs-Vangunu, Solomon Islands. However, a deep traditional ecological knowledge of U. vika is held by Vangunu's people. Using camera traps and guided by this knowledge, we aimed to make additional records of U. vika in the last major block of Vangunu's primary forest. We successfully captured 95 images of what we postulate is four different individuals. The forests at Zaira represent the last suitable habitat remaining for this species, and recent development consent for logging at Zaira will lead to its extinction if permitted to proceed.

A new species of the genus Scarlata (Lepidoptera: Sesiidae) from Laos

Scarlata namsanam sp. nov. from Laos is described and illustrated. The type series was collected on wet soil near the drying stream within a primary monsoon lowland tropical forest. This new species is most similar to S. guichardii Skowron Volponi, 2022, from which it differs in the coloration of the hind tibia, forewing and abdomen and in noticeably wider discal spot of the hindwing.

Soil nematode community assembly in a primary tropical lowland rainforest

More than half of the world's tropical lowland rainforests have been lost due to conversion to agricultural land (such as rubber plantations). Thus, ecological restoration in degraded tropical lowland rainforests is crucial. The first step to restoration is restoring soil functioning (i.e., soil fertility, carbon, and nitrogen cycling) to levels similar to those in the primary tropical lowland rainforest. This requires understanding soil nematode community assembly in primary tropical lowland rainforest, which has never been explored in this habitat. In this study, we measured species compositions of plant and soil nematode communities and soil characteristics (pH, total and available nitrogen, phosphorus, and soil water content) in a primary tropical lowland rainforest, which is located on Hainan Island, China. We performed two tests (the null-model test and distance-based Moran's eigenvector maps (MEM) and redundancy analysis-based variance partitioning) to quantify the relative contribution of the deterministic (abiotic filtering and biotic interactions) and stochastic processes (random processes and dispersal limitation) to the soil nematode community. We found that a deterministic process (habitat filtering) determined nematode community assembly in our tropical lowland rainforest. Moreover, soil properties, but not plant diversity, were the key determinants of nematode community assembly. We have, for the first time, managed to identify factors that contribute to the nematode community assembly in the tropical lowland rainforest. This quantified community assembly mechanism can guide future soil functioning recovery of the tropical lowland rainforest.

Stable isotopic investigation of the feeding ecology of wild Bornean orangutans

AbstractObjectivesWe applied stable carbon and nitrogen isotope analyses to wild Bornean orangutans (Pongo pygmaeus morio) to investigate the feeding ecology of wild orangutans. Compared with African great ape species, orangutans are adapted to environments with chronic lower nutrition. But the usefulness of stable isotope analysis in the study of wild orangutan feeding ecology has not been fully explored.MethodsThe study site was a primary lowland dipterocarp forest in the Danum Valley, Sabah, Malaysia. A total of 164 plant and 94 fecal samples collected across 18 months were analyzed.ResultsCarbon and nitrogen stable isotope ratios of plant food samples do not systematically vary by plant parts (i.e., bark, fruits, and leaves). Elemental composition and stable isotope ratios of orangutan feces do not systematically vary by orangutans' sex and age classes, although fecal stable isotope ratios showed seasonal fluctuations. No isotopic contribution of breast milk was found in fecal samples collected from individuals at 2.7–6.5 years of age.ConclusionsThis study revealed key characteristics of the stable isotope ecology of wild orangutans living in a primary lowland forest. Although there was little isotopic variation among plant foods and orangutan individuals, seasonal fluctuations in baseline isotope ratios or orangutans' diet were found in Danum valley.

A Contribution to Trees and Shrubs Checklist in Kuala Keniam at Taman Negara, Pahang, Malaysia

Abstract The forested area around Kuala Keniam is a part of Taman Negara (Pahang) and is categorized as a primary lowland dipterocarp, riparian fringe and limestone forests. A study of flora that focuses on the trees and shrubs was conducted during the scientific expedition in September 2020, organised by Universiti Teknologi MARA (UiTM). The results identified as many as 187 taxa of trees and shrubs consisting of 124 genera and 49 plant families from the lowland dipterocarp forest. A total of nine endemic taxa to Peninsular Malaysia were also recorded namely Aporosa globifera, Baccaurea pyriformis, Cinnamomum mollissimum, Enicosanthum fuscum, Lithocarpus curtisii, Mallotus griffithianus, M. penangensis, Ryparosa fasciculata and Schoutenia kunstleri. Another three taxa viz. Elaeocarpus obtusatus ssp. apiculatus, Popowia tomentosa and Sterculia rubiginosa var. setistipula were considered as the new additional record for Pahang state. It is hoped that the information from this study can be used as references to help other researchers as well as stakeholders in ecotourism management and forest conservation plan.

Contribution to the knowledge of the oribatid mite genus Cultrobates (Acari, Oribatida, Ceratokalummidae), with description of a new species from Peru</p >

Description of a new species of oribatid mite (Oribatida) of the genus Cultrobates (Ceratokalummidae)—C. lehmanni sp. nov.—is presented, based on materials collected from upper soil and leaf litter in the primary evergreen lowland rainforest of Amazonian Peru. Summarized generic traits, distribution and habitats of all known species of Cultrobates are presented. An identification key to known Ceratokalummidae species is provided.

Contribution to the knowledge of the oribatid mite genus Gittella (Acari, Oribatida, Oppiidae), with description of a new species from Peru

A new species of the genus Gittella (Oribatida, Oppiidae) - G. kontschani n. sp. - is described, based on materials collected from upper soil and leaf litter in the primary evergreen lowland rainforest of Amazonian Peru. Generic diagnosis, an identification key, distribution, and habitats of all known species of Gittella are presented.

New species of Oribatella (Acari, Oribatida, Oribatellidae) from Peru

Two new species of oribatid mites of the genus Oribatella (Oribatida, Oribatellidae)—O. friedrichi sp. nov. and O. cornuta sp. nov.—are described from soil and leaf litter of the primary evergreen lowland rainforest in Amazonian Peru. An identification key to known species/subspecies of Oribatella from the Neotropical region is presented.

New species of oribatid mites of the family Galumnidae (Acari, Oribatida) from Peru

Descriptions of three new species of oribatid mites (Oribatida) of the family Galumnidae—Galumna (Galumna) panguanaensis sp. nov., G. (Neogalumna) moroi sp. nov. and Pergalumna (Pergalumna) neryae sp. nov.—are presented, based on materials collected from upper soil and leaf litter in the primary evergreen lowland rainforest of Amazonian Peru.

TAXONOMIC CONTRIBUTION TO THE KNOWLEDGE OF THE ORIBATID MITE GENUS PROTORIBATES (ACARI, ORIBATIDA, HAPLOZETIDAE)

A new oribatid mite subgenus, Protoribates (Perubates) subgen. n. (Oribatida, Haplozetidae), with type species Protoribates (Perubates) davidi sp. n., is proposed from the primary evergreen lowland rainforest of Amazonian Peru. It differs from the nominate genus in the presence of lamellar cusps and extra porose areas on the notogaster. A new generic diagnosis of Protoribates is provided.

Species richness and ethnozoological annotations on mammals at the Boanamo indigenous community, Waorani territory, Orellana and Pastaza provinces, Ecuador

Abstract We present the results of a rapid ecological assessment conducted in 2012 in the community of Boanamo, in the Waorani Ethnic Reserve and Yasuní National Park, Orellana and Pastaza provinces, Ecuadorian Amazon. The study included surveys and observations of mammals by different methodologies over a 16-day sampling period. The results show the presence of 89 species of mammals, but there are several other mammal species expected in the area, increasing the projected diversity to 119 species, a high diverse community when compared with similar locations. Statistical analyses show that Boanamo is an area of high species richness and heterogeneity, consistent with comparable surveys in other areas of primary lowland rainforest in Amazonia. In addition, we documented nine distinct ways and 130 different usages in which 43 species are utilized in Boanamo. To estimate the importance of mammal diversity, we used a Cultural Importance Index, which shows that the species with the highest value are Panthera onca and Nasua nasua. However, the most frequently hunted species were Tayassu pecari and Lagothrix lagothricha. Our final conclusion is the community of Boanamo is entirely dependent on the surrounding forest, and mammals are an important part of their culture and subsistence.

Wildlife differentially affect tree and liana regeneration in a tropical forest: An 18‐year study of experimental terrestrial defaunation versus artificially abundant herbivores

Abstract Hunting and land use change modify native herbivore abundances and cause cascading effects in natural ecosystems. The outcomes for vegetation depend on changes to specific plant–animal interactions, such as seed dispersal or predation, or physical disturbances. We experimentally manipulated terrestrial wildlife populations in a primary lowland forest in Malaysia over an 18‐year period (1996–2014) to understand how artificially high or low animal densities affect tree and liana regeneration. Our study site retains a diverse wildlife community and artificially high densities of native wild pigs (Sus scrofa) that are sustained by crop raiding in distant oil palm plantations. We used fencing that excluded terrestrial animals >1 kg to experimentally simulate conditions similar to those in defaunated forests. These two treatments – abnormally high pig abundances and megafauna loss from hunting – represent common outcomes in disturbed Southeast Asian forests and are characteristic of many forests globally. We focused on trees and lianas because they are the two dominant woody life‐forms in tropical forests and crucial determinants of forest structure and function. We found that liana sapling abundances (30–100 cm height) increased by 86% in unfenced control plots with wildlife but were stable in exclosures. In contrast, tree abundances did not change in unfenced control plots but increased by 83% in exclosures without wildlife. Evidence of scaring on surviving stems suggested that these inverted outcomes were driven by selective use of tree saplings for wild pig nests. Lianas may also have greater tolerance to wildlife disturbances like nest building. By the end of the study, lianas comprised 38% of all saplings in unfenced controls but just 14% in exclosures. Synthesis and applications. We conclude that artificially abundant wildlife, such as crop‐raiding wild pigs, may shift tropical forest understories towards lianas while defaunation may shift it towards trees. These results highlight that ecological cascades from hunting or land use change can alter plant functional types and reshape to long‐term patterns of forest succession and change. Managing unnatural wild boar populations may be required to conserve native plant communities in both their native and exotic ranges.

ENSO effects on the transpiration of eastern Amazon trees.

Tree transpiration is important in the recycling of precipitation in the Amazon and might be negatively affected by El Niño-Southern Oscillation (ENSO)-induced droughts. To investigate the relative importance of soil moisture deficits versus increasing atmospheric demand (VPD) and determine if these drivers exert different controls over tree transpiration during the wet season versus the dry season (DS), we conducted sap flow measurements in a primary lowland tropical forest in eastern Amazon during the most extreme ENSO-induced drought (2015/2016) recorded in the Amazon. We also assessed whether trees occupying different canopy strata contribute equally to the overall stand transpiration (Tstand). Canopy trees were the primary source of Tstand However, subcanopy trees are still important as they transpired an amount similar to other biomes around the globe. Tree water use was higher during the DS, indicating that during extreme drought trees did not reduce transpiration in response to low soil moisture. Photosynthetically active radiation and VPD exerted an overriding effect on water use patterns relative to soil moisture during extreme drought, indicating that light and atmospheric constraints play a critical role in controlling ecosystem fluxes of water. Our study highlights the importance of canopy and subcanopy trees to the regional water balance and highlights the resilience to droughts that these trees show during an extreme ENSO event.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.

Lowland rainforest bat communities of Ulu Temburong National Park with two new records for Brunei Darussalam

Tropical rainforest ecosystems have high levels of both animal and plant biodiversity with many aspects of their ecology understudied. In particular, extensive research is still required to gather accurate estimates of distribution and abundance of forest-interior bat species in Borneo. Accurate abundance data and further knowledge of individual species’ ecology is vital for implementing effective conservation. Bats were captured using a harp trap, set up along established trails and around buildings, at Kuala Belalong Field Studies Centre, Ulu Temburong National Park, Brunei Darussalam between 14th-19th January 2018. Ulu Temburong National Park is comprised of pristine primary mixed dipterocarp lowland rainforest that has not been exposed to logging or fragmentation. A total of nine bat species were recorded, with two new records for Brunei, Miniopterus australis (Lesser bent-winged bat, N = 1) and Myotis horsfieldii (Horsfield’s myotis, N = 5). Furthermore, a coincidental sighting of a colony of Megaderma spasma roosting on the mangrove island Selirong, in Temburong District is reported here. The bat species captured and encountered in this small-scale study expand our understanding of bat communities in Temburong as well as indicate that current records for the area are far from complete. This affirms the need for further work in building up accurate abundance and diversity estimates, both for Ulu Temburong National Park and Brunei Darussalam.

Effects of nitrogen and phosphorus fertilization on the ratio of activities of carbon-acquiring to nitrogen-acquiring enzymes in a primary lowland tropical rainforest in Borneo, Malaysia

ABSTRACTPrevious meta-analyses revealed that the ratio of activities of carbon (C)-acquiring enzyme to nitrogen (N)-acquiring enzymes in tropical forest ecosystems was nearly identical to those in other ecosystems, despite of the N-rich condition in tropical forests. This could be explained by microbes in tropical forest soils, which require a large amount of N to produce N-rich acid phosphatase (AP) for catalyzation of the organic form of phosphorus (P) and compensation for poor P availability in soils. Based on this idea, we hypothesized that experimental P fertilization would reduce the allocation to N-acquiring enzymes compared with that of C-acquiring enzymes, i.e. that it would increase the ratios of activities of β-1,4-glucosidase (BG) to β-1,4-acetylglucosaminidase (NAG) and leucine aminopeptidase (LAP). We tested this hypothesis using an experimental fertilization site with factorial N (100 kg ha−1 yr−1) and P (50 kg ha−1 yr−1) addition in a primary tropical lowland forest in Bornean Malaysia, where our earlier work demonstrated that P fertilization reduced AP activity. Contrary to our hypothesis, the BG:NAG and BG:(NAG + LAP) ratios were not altered by either N or P fertilizations. This result indicated that AP production was not a reason for the maintenance of a relatively high investment in N-acquiring enzyme at our study site. Rather, NAG and LAP production was likely driven by C acquisition, rather than N acquisition, as the target substrates contained C as well as N. This idea was supported by the fact that neither the BG:NAG ratio nor the BG:(NAG + LAP) ratio was elevated by N addition. We propose that the ratios of activities of BG to NAG and LAP do not necessarily indicate the ratio of C:N acquisition, at least in our N-rich tropical forest ecosystem.

A new species of Tapiena (Orthoptera: Tettigonioidea: Phaneropterinae) from Brunei Darussalam (Borneo, Southeast Asia).

There are now more than 28,000 described orthopterans globally (Cigliano et al., 2018) and this figure is likely to increase in the future. The same is true for Southeast Asia, where we are still at a stage of discovering species new to science, and this is partly an artefact of incomplete sampling (Tan et al., 2017a). In one of the most popular biodiversity hotspots, i.e., Borneo, is the Kuala Belalong Field Studies Centre. It is located in the primary lowland and ridge dipterocarp forests of the Ulu Temburong National Park, Brunei Darussalam. Recent collection of orthopterans in the area led to the discovery of several new species of katydids (Tan et al., 2017b; Tan Wahab, 2017a) and crickets (Tan et al., 2017c; Tan Wahab, 2017b). Here, we describe another new species of katydid, from the genus Tapiena Bolívar, 1906. Tapiena currently consists of 26 species (Tan et al., 2015) and is distributed around Asia and even Africa. In Borneo, only one species is known: Tapiena incisa Karny, 1923 from Sarawak (see Karny, 1923). The new species Tapiena paraincisa sp. nov. represents the second species described from Borneo.

Spatial Heterogeneity of Fruit Bats in a Primary Tropical Lowland Evergreen Rainforest in Northeastern Luzon, Philippines

In the Philippines, little is known beyond the most basic information on the ecology and biogeography of fruit bats. This is aggravated by the increasing risks on their populations, particularly in primary lowland forests, the most threatened habitat in the country, which these species inhabit and also where chiropteran diversity is highest. In this study, the spatial heterogeneity of fruit bats within a primary lowland forest in Palanan, Isabela, northeastern Luzon was investigated. In addition, habitat partitioning patterns were compared with wing morphology variations. Mist nets were used to sample two vertical strata and three forest landscapes. Wing loading and aspect ratio were measured for all species captured. A total of 1,243 fruit bats representing eight species were caught from a sampling effort of 398,736 m2·h. All species were captured in the canopy, while only six species were captured in the understory. All species were also captured along ridges and forest edges, while only seven were captured along streams. Based on permutational MANOVA, a significant difference was found between the species assemblages in the understory and canopy, but not among ridges, streams, and forest edges. At the population level, Kruskal-Wallis tests were performed on capture rates per species. All eight species exhibited strong preference for the canopy, while only two species were observed to have significantly different capture rates across forest landscapes. Wing morphology patterns based on wing loading and aspect ratio did not show consistent association with vertical strata preference. The varying capture rates of bats along ridges, streams and forest edges may have been influenced by their feeding behavior. This study demonstrates the spatial heterogeneity of fruit bats across vertical strata and across forest landscapes, the most significant of which is the preference for the canopy. Possible factors that could explain these patterns include fruit availability, a cluttered habitat, and tree species distribution, which should be assessed in future studies.

Leptomorphus sevciki sp. nov., a remarkable new wasp-mimicking fungus gnat from Brunei (Diptera: Mycetophilidae)

Abstract A new species of Mycetophilidae (Diptera), Leptomorphus sevciki sp. nov., is described from primary lowland rainforest in Ulu Temburong National Park in Brunei. The type specimens were reared from pupae hanging from an unidentified wood encrusting fungus growing on a fallen tree. DNA sequences, including fragments of the nuclear 28S region and the mitochondrial 12S, 16S, CytB and COI (barcode region) genes, were extracted from two specimens, including the holotype.

Contribution to the Uropodina mites of Peru (Acari: Mesostigmata)

Soil dwelling Uropodina mites were collected from a primary lowland rainforest in Amazonian Peru. The species found belong to three different families. A new diagnosis and the type genus of Tetrasejaspidae fam. nov. are given, and the family is recorded from Peru for the first time on the basis of Tetrasejaspis sellnicki Hirschmann, 1973. Two rotundabaloghid mites were collected (Rotundabaloghia (Circobaloghia) magna Hirschmann, 1992 and Rotundabaloghia (Circobaloghia) iquitosensis Hirschmann, 1992), both already reported from Peru. A new species (Origmatrachys peruensis sp. nov.) from the family Trachyuropodidae was collected in large numbers from soil, and is described on the basis of females, males, nymphs and larvae. This is the first description of the protonymphs and larvae of Origmatrachys. The new species differs from the previously described ones in the basis of sculptural pattern of dorsal, ventral, sternal shields and the length of the setae in the central part of the dorsal shield. A new key to the known adults and deutonymphs of Origmatrachys is given.