Degraded tropical peatlands lack tree cover and are often subject to seasonal flooding and repeated burning. These harsh environments for tree seedlings to survive and grow are therefore challenging to revegetate. Knowledge on species performance from previous plantings represents an important evidence base to help guide future tropical peat swamp forest (TPSF) restoration efforts.
We conducted a systematic review of the survival and growth of tree species planted in degraded peatlands across Southeast Asia to examine (1) species differences, (2) the impact of seedling and site treatments on survival and growth and (3) the potential use of plant functional traits to predict seedling survival and growth rates.
Planted seedling monitoring data were compiled through a systematic review of journal articles, conference proceedings, reports, theses and unpublished datasets. In total, 94 study‐sites were included, spanning three decades from 1988 to 2019, and including 141 indigenous peatland tree and palm species. Accounting for variable planting numbers and monitoring durations, we analysed three measures of survival and growth: (1) final survival weighted by the number of seedlings planted, (2) half‐life, that is, duration until 50% mortality and (3) relative growth rates (RGR) corrected for initial planting height of seedlings.
Average final survival was 62% and half‐life was 33 months across all species, sites and treatments. Species differed significantly in survival and half‐life. Seedling and site treatments had small effects with the strongest being higher survival of mycorrhizal fungi inoculated seedlings; lower survival, half‐life and RGR when shading seedlings; and lower RGR and higher survival when fertilising seedlings. Leaf nutrient and wood density traits predicted TPSF species survival, but not half‐life and RGR. RGR and half‐life were negatively correlated, meaning that slower growing species survived for longer.
Synthesis and applications. To advance tropical peat swamp reforestation requires expanding the number and replication of species planted and testing treatments by adopting control vs. treatment experimental designs. Species selection should involve slower growing species (e.g. Lophopetalum rigidum, Alstonia spatulata, Madhuca motleyana) that survive for longer and explore screening species based on functional traits associated with nutrient acquisition, flooding tolerance and recovery from fire.
The rediscovery of Begonia promethea Ridl. for the first time since its description in 1906 led to the discovery that the later described B. beccarii Warb. is synonymous with it and that it belongs in Begonia sect. Petermannia. It is a rare, endangered species known only from three localities, two locations from the Kuching Division, Sarawak, Malaysia and another one from West Kalimantan, Indonesia. A detailed, illustrated description and a distribution map of Begonia promethea are provided. We suggest an IUCN conservation category of EN B2ab(iii). Lectotypes for both names are designated.
Two new Hanguana species from Kalimantan, Indonesian Borneo, are described here. Hanguana karimatae from Karimata Island, West Kalimantan province, is characterised by a stout habit, prominently oblique yellow fruits with raised stigma and 1- or 2-seeded fruits. Hanguana nana from Central Kalimantan province is the smallest species in the genus with the stem entirely covered by leaves, deflexed barely branched infructescences with only a few fruits, each with a single bowl-shaped seed with a large and incurved appendage. These are the first descriptions of new Hanguana species from Kalimantan (Indonesian Borneo). Colour plates as well as notes on distribution, ecology, habitat and conservation status are provided.
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