Abstract. Solfiyeni, Syamsuardi, Chairul, Mukhtar E. 2022. Impacts of invasive tree species Bellucia pentamera on plant diversity, microclimate and soil of secondary tropical forest in West Sumatra, Indonesia. Biodiversitas 23: 3135-3146. The invasion of alien species in a region can alter species diversity. Bellucia pentamera Naudin is considered an alien invasive plant that has spread from Mexico to tropical America, and it is now invading some areas in Indonesia, including the tropical forest of Sumatra. Yet, the effects of its invasion on vegetation and the abiotic environment are not yet well understood. The objective of this study was to investigate the impacts of B. pentamera on species diversity and structure of vegetation, and microclimate and soil conditions of secondary tropical forests in West Sumatra. Vegetation analysis was conducted in secondary forest Bukit Tengah Pulau, South Solok, with three levels of dominance of B. pentamera namely: site 1 and 2 (60% and 16% dominance of B. pentamera respectively) and site 3 (no individual of B. pentamera). Sampling was conducted using a nested plot to collect data for tree, sapling and understorey vegetation for each site. The results showed the total number of tree species at sites 1, 2, and 3 were 23 species, 46 species, and 74 species respectively. For sapling, 20 species were found at site 1, 31 species at site 2, and 58 species at site 3. For understorey plants, 13, 16 and 36 species were detected at site 1, 2 and 3 respectively. The number of species at tree and sapling levels differed significantly among sites. The basal area also differed significantly among sites but not for sapling level. Site 1 was dominated by B. pentamera with Important Value Index (IVI) 130.8%), followed by Croton argyratus (27.63%), and Ficus variegata (26.47%). At site 2, B. pentamera dominated with IVI of 33.68%, followed by Lepisanthes sp. (20.01%) and Sizygium sp. (14.44%). Site 3 was dominated by Palaquium warsurifolium with IVI of 21.15% followed by Croton argyratus (20.02%) and Macaranga hypoleuca (13.21%). Diversity index (H') for tree-level was moderate at site 1 (H' = 1.78) and high at sites 2 and 3 (H' = 3.48 and 4.05). Similarly, the index for sapling was moderate at site 1 (H'= 2.12) and high at sites 2 and 3 (H'= 3.22 and 3.84). For understorey, the diversity index was low at site 1 (H'= 0.82) and moderate at sites 2 and 3 (H'= 1.8 and 2.86). Sites invaded by B. pentamera had a lower soil water content and higher temperature and light intensity, although they had higher nitrogen and phosphorus contents. Our findings suggest that the invasion of B. pentamera had negative impacts on plant biodiversity and microclimate, yet the impact was not clear cut on the soil.

Abstract. Solfiyeni, Mukhtar E, Syamsuardi, Chairul. 2022. Distribution of invasive alien plant species, Bellucia pentamera, in forest conservation of oil palm plantation, West Sumatra, Indonesia. Biodiversitas 23: 3667-3674. Bellucia pentamera has been found in disturbed forests across Indonesia, but little is known about how it spreads under its tree canopy. The spread of the invasive plant B. pentamera in the PT KSI conservation forest area was investigated. The goal of this research is to study B. pentamera's strategy for exploiting forest gaps horizontally and vertically on degraded forest vegetation invaded by B. pentamera at various degrees of invasion. An Unmanned Aerial Vehicle (UAV) and direct field mapping are used for the mapping approach. Aerial photographs revealed 40 B. pentamera trees and 32 non-B. pentamera trees in forest areas with varying degrees of B. pentamera invasion (based on the ratio of B. pentamera non-B. pentamera: dense and loose). Bellucia pentamera trees were distributed evenly in a large gap and randomly in a small gap/space between the canopy, whereas sapling and seedling B. pentamera trees were distributed in groups, uniformly and randomly, according to microhabitat conditions under the canopy of B. pentamera and non-tree trees. Bellucia pentamera seedlings and saplings were detected under the parent tree's canopy rather than in the canopy gaps. Different responses were seen in seedlings, saplings, and juvenile stages concerning the explanatory factors investigated and between the two stands. The purpose of the study was to determine the factors that influence the distribution of the B. pentamera species in conservation forest areas with different compositions of existence, both vertically and horizontally, using drones and direct measurements in the field.

The Silokek Geopark area, Sijunjung Regency, is one of the tourist areas in West Sumatra Province which has a high level of biodiversity, which can be disrupted due to the presence of invasive plants. A study has been carried out which aims to determine the composition and structure of undergrowth in habitats invaded by weeds in the Silokek Geopark tourist area, Sijunjung Regency. This research was conducted from September to December 2022 using the quadratic method and plotting by purposive sampling with a plot size of 10 x 10 m with a sub-plot measuring 2 x 2 m. The composition of undergrowth in the habitat invaded by weeds found 24 families, 38 genera, 38 species, and 1049 individuals. Among the undergrowth found, there were 12 families, 20 genera, 20 species and 532 individuals of invasive plants with the dominant family being Asteraceae (30.41%), and the co-dominant family being Nephrolepidaceae and Poaceae with a percentage of 17 each. .83% and 11.63%. The highest important value index was in Nephrolepis biserrata (28.42%) and the lowest was in Musa acuminata (0.76%). The most dominant weed species was Mikania michranta with an IVI of 18.79%. The diversity index of the understorey plants in this area is categorized as high with a diversity index (H' = 3.24). Weed plant species are more successful in dominating open and disturbed areas with high levels of light intensity, gaps or wide gaps and forest edges can be utilized by invasive plant species to grow optimally.

Gel baits product sold commercially to the public has long been used to control German cockroach populations in urban areas. The effectiveness and resistance level of gel bait products need to be known for the successful control of German cockroaches in the field. However, there have been no reports of resistance in Indonesia. This study used toxicity tests of six gel bait products (MF, CBG, SPB, OTG, BTX, and UBA) against two populations of adult male German cockroaches (VCRU-WHO and RKMN-BKT). Fipronil, boric acid and emamectin benzoate containing gel baits were effective to knock down and kill the German cockroaches. In contrast, gel bait with imidacloprid as an active ingredient was only useful to knock down the German cockroaches. Commercial gel bait product in Indonesia are still useful in controlling German cockroaches’ populations with a time of effectiveness to cause mortality between three to four weeks after being exposed in the field and the level of cockroach resistance to gel bait are susceptible until low resistance.