Landsat-8 and Sentinel-2 data for mapping plastic-covered greenhouse farming areas: a study from Dalat City (Lam Dong Province), Vietnam.

Plastic-covered greenhouse (PCG) farming has been practiced worldwide, particularly in highland areas, for planting fruits and garden plants. Highland areas in south-central Vietnam have been witnessing an expansion of PCG farming in recent decades. For sustainable management of plastic-covered greenhouse farming areas, a proper and continuous monitoring of their spatial patterns is necessary. In this study, we used spaceborne multispectral imagery (Landsat-8 OLI and Sentinel-2 MSI) for automatic detection and mapping of plastic covered greenhouse farming areas in and surrounding areas of Dalat City in Lam Dong province, south-central Vietnam. Unsupervised (K-Means algorithm) and automatic delineation using spectral indices were applied to the Sentinel-2 and Landsat-8 data for mapping plastic-covered greenhouses in Dalat City and surrounding areas. The results were evaluated using field data; automatic spectral index-based mapping of PCGs using Sentinel-2 and Landsat-8 data was found as robust in terms of the overall accuracy. The overall accuracies of PCG maps derived from Sentinel-2 and Landsat-8 data by applying spectral indices were 90.8% and 88.7%, respectively, and those of unsupervised K-Means classification were estimated as 73.2% and 71.7%, respectively. This study estimated that about 2425 ha of plastic-covered greenhouses existed within in Dalat City in 2020.

A new genus of air-breathing marine slugs from South-East Asia (Gastropoda, Pulmonata, Onchidiidae).

As part of an ongoing effort to revise the taxonomy of air-breathing, marine, onchidiid slugs, a new genus, Laspionchis Dayrat & Goulding, gen. nov., is described from the mangroves of South-East Asia. It includes two new species, Laspionchis boucheti Dayrat & Goulding, sp. nov., and Laspionchis bourkei Dayrat & Goulding, sp. nov., both distributed from the Malacca Strait to the Philippines and Australia. This study is based on extensive field work in South-East Asia, comparative anatomy, and both mitochondrial (COI and 16S) and nuclear (ITS2 and 28S) DNA sequences. The two new species are found in the same habitat (mud surface in mangrove forests) and are externally cryptic but are distinct anatomically. Both species are also strongly supported by DNA sequences. Three cryptic, least-inclusive, reciprocally-monophyletic units within Laspionchis bourkei are regarded as subspecies: L. bourkei bourkei Dayrat & Goulding, ssp. nov., L. bourkei lateriensis Dayrat & Goulding, ssp. nov., and L. bourkei matangensis Dayrat & Goulding, ssp. nov. The present contribution shows again that species delineation is greatly enhanced by considering comparative anatomy and nuclear DNA sequences in addition to mitochondrial DNA sequences, and that thorough taxonomic revisions are the best and most efficient path to accurate biodiversity knowledge.