Implications of seed traits for restoration of ultramafic plant taxa from the Goro plateau in the subtropical hotspot of New Caledonia

Abstract

The biodiversity hotspot of New Caledonia faces extensive landscape fragmentation. Progress of restoration practices is critical to address this problem for reestablishment of ecological continuities. The objective of our study, which can be considered as a first step, was to support appropriate species selection for restoration of fragmented habitats. We assessed seed dispersal, seed dormancy, and seed desiccation tolerance of 407 species from Forest (F) and Maquis (M) vegetation on ultramafic soils in southern New Caledonia. The primary seed dispersal mode was animals (zoochory, 53%). Overall, we found 34% of the taxa had some seed dormancy, and 72.9% had orthodox seeds. Wind-dispersed (anemochorous) species had predominantly nondormant and orthodox seeds, whereas zoochorous species had seeds with at least some dormancy potential and higher recalcitrance. Further assessments were performed on 70 of the taxa, those currently used in ecological restoration. Their primary seed dispersal mode was found to be anemochory, 42.5% in Maquis (M) alone, and 40% in Forest and Maquis (FM) combined. Non-dormant seeds were prevalent both in M (82.5%) and FM (90%), and orthodoxy was the seed desiccation tolerance type most common in both vegetation types (95% and 66%, respectively in M and FM). Thus, the seeds currently used in restoration projects are mainly wind-dispersed orthodox seeds. To enhance both functional and phylogenetic diversity in restored areas, we recommend including fleshy-fruited, animal-dispersed taxa in restoration programs.

Low availability of functional seed trait data from the tropics could negatively affect global macroecological studies, predictive models and plant conservation

“…Similar findings were reported by Athugala et al (2021) , with six out of 28 tropical montane species studied in Sri Lanka showing a different result in experiments to the prediction made by the phylogenetic affiliation model ( Wyse and Dickie, 2017 ). While these examples confirm the value of such predictive models, they also highlight the importance of generating new data on seed desiccation sensitivity, particularly for populations and species from tropical and sub-tropical regions (see De Jr Lima et al , 2014 ; Lan et al , 2014 ; Sánchez et al , 2018 ; Chau et al , 2019 ; Waiboonya et al , 2019 ; Mattana et al , 2020 ; Ititiaty et al , 2020 ; Athugala et al , 2021 ; Sommerville et al , 2021 ), through screening approaches such as the ‘100-seed test’. These kinds of studies are especially needed for biodiversity hotspots in Mesoamerica, West Africa, Madagascar, Sundaland and Indo-Burma ( Pritchard et al , 2022 ).…”

Study of certain technical aspects of the rehabilitation of bauxite mining sites operated at the Sangarédi mine (Parawi deposit, Compagnie des Bauxites de Guinée mining concession; CBG)

“…It is important to integrate the notion of ecological continuity into revegetation projects and to optimise land use, as this has a positive impact on both the environment and the economy. Various studies have emphasised the importance of preserving or recreating areas of biodiversity (scrubland or forest) on farmland, because the distance between revegetated areas and natural vegetation is an important factor in the diversification of species in a developing ecosystem (4).…”

Mining rare Earth elements: Identifying the plant species most threatened by ore extraction in an insular hotspot

“…Thus, thinking of ultramafic areas in the OCBIL intellectual framework brings insight on the NET conservation on mining areas, as it cannot be planned as in other areas (Hopper et al, 2021). First, the infertile nature of these areas, largely stated by L 'Huillier et al (2010), as well as the reduced dispersability of the plant species present (Ititiaty et al, 2020;Pillon et al, 2021), is a common feature of OCBILs (Hopper et al, 2016). It results locally in a hindrance for ecological restoration (Losfeld et al, 2015)-a standard way to improve and recover both quality and quantity of species' habitats in industrial environments.…”