The Herbarium of New Caledonia (NOU): 60 years at the service of science for development

ABSTRACT The Herbarium of New Caledonia (NOU) was founded in 1961 within the Institut Français d’Océanie (now Institut de Recherche pour le Developpement) by J.P. Blanchon. Qualitatively and quantitatively enriched by the consecutive curators and associated staff, it is today rich of more than 90000 specimens including 834 nomenclatural types. These specimens represent a total of 6665 taxa coming essentially from New Caledonia but also from 15 other Pacific territories, and particularly from Vanuatu and Wallis and Futuna. With more than 300 citations on GoogleScholar and each year nearly 270 consultations, 100 requests for data and 3500 visits to the website, the NOU Herbarium is today an indispensable scientific, heritage and educational tool for New Caledonia. Its influence extends beyond the Pacific with exchanges of material with 70 international institutions. In the current context of global change and political and social instability, means must be found with all local actors so that the NOU Herbarium can continue to ensure its role in the service of sustainable development and heritage.


Introduction
Herbaria represent natural history plant collections with strong scientific, heritage and educational interests. For several centuries, these collections have been the basis for improving our knowledge of plants and their importance for the good of humanity has been demonstrated on numerous occasions (e.g. Waylen 2006;Hall and Dickson 2011;Bandini et al. 2020). The Herbarium of New Caledonia (NOU, Bruy et al. 2021) is among the largest Herbaria in Oceania (Thiers 2022) and represents one of the most comprehensive collections in the world for New Caledonia.
New Caledonia, located in the southwestern Pacific Ocean, has been a French archipelago since 1853 but with a long history of indigenous people who have inhabited the islands (Sand et al. 2012). It is known worldwide for the richness and originality of its flora (Pillon et al. 2010;Morat et al. 2012). We count 3424 indigenous vascular species, of which 74.8% are endemic to the territory ). This flora is still imperfectly known as taxonomists have described an average of one new endemic species every month since the 2000s (Gâteblé et al. 2018). The issues related to this flora are therefore important, especially since New Caledonia is the smallest of the terrestrial biodiversity hotspots recognized to date (Mittermeier et al. 2004) and nearly half of its species are threatened with extinction (Meyer et al. 2021). Thus, the NOU Herbarium is now more than ever a much sought-after tool at the interface between research, expertise and decision making.
In this article, we propose to briefly describe the history of the NOU Herbarium, the composition of its collections and the challenges it will face in the future.

Institutional and structural history
The NOU Herbarium was founded in 1961 at the Institut Français d'Océanie (IFO), which became the Office de la Recherche Scientifique et Technique Outre-Mer (ORSTOM) in 1964 and the Institut de Recherche pour le Développement (IRD) in 1998. At first a working Herbarium for local researchers, the Herbarium of New Caledonia was recognized in the Index Herbariorum under the acronym NOU (Thiers 2022) Gonzalez et al. 2021). In 2000, the Government of New Caledonia became involved in the management of the Herbarium by providing a full-time collections officer.
The NOU Herbarium was first housed in the buildings of a former military hospital bequeathed by the USA to France after the Second World War. In 1976, a new building was created for the ORSTOM center in Nouméa, in which a 70 m 2 room was dedicated for the conservation of herbarium specimens. This room was enlarged to 85 m 2 in 2010 and should be further enlarged in 2023 during an energy renovation operation to reach 125 m 2 . The herbarium sheets were successively stored on metal shelves, then in large cabinets before being integrated into more suitable wooden lockers ( Figure 1a). Today, the collections are kept in 1096 of these lockers.

History of the collection managers
The Herbarium of New Caledonia was founded in 1961 by Jean-Pierre Blanchon. He managed the collection until 1964 and allowed its indexing under the acronym NOU in 1963 (Table 1). Holder of a diploma in Agronomy from the Institut National Agronomique, Mr Blanchon benefited from a field training in pedo-agronomy, botany and phytosociology at the ORSTOM (Cranney 1996 work of classification and determination. During this period, he also worked on the vegetation of New Caledonia and Vanuatu with the production of several florulas (e.g. Schmid 1974) and one of the first public works on the New Caledonian flora (Schmid 1981 (Morat et al. 1981) and for the current checklist of the native vascular flora (Morat et al. 2012). He was also responsible for the storage of the NOU Herbarium specimens in wooden lockers, a system still in place today ( Figure 1a). In 1986, he left ORSTOM and was recruited at MNHN as professor and director of the laboratory of phanerogamy and of the Flora of New Caledonia. He continued to work on the systematics of the Pacific flora, with two field missions in 1988 and 1990, until his retirement in 2006.
The person having remained at the head of the Herbarium for the longest time is Tanguy Jaffré since he was in charge from 1986 to 2004. He was recruited at ORSTOM in 1966 while he was doing a degree in Tropical Botany and Plant Ecology in Paris. He spent most of his career in New Caledonia with a period in Bondy and Côte d'Ivoire from 1979 to 1983. He carried out very thorough work on a wide range of subjects of the New Caledonian Flora, with a particular interest in the ecology of vegetation on ultramafic  [1961][1962][1963][1964] rocks. In particular, his pioneer work on metal hyperaccumulation deserves to be cited (Jaffré et al. 1976). Among other things, his French National Thesis in Ecology (Jaffré 1980) cited more than 235 times are now being partialy translated into English, as three articles in this issue (Jaffré 2023a(Jaffré , 2023b(Jaffré , 2023c (Munzinger 2000). In 2005 he became director of the Laboratoire de Botanique et d'Ecologie Végétale Appliquée and of the NOU Herbarium. He stayed there for 6 years during which he was involved in the taxonomic revision of several botanical families. He remains to this day the botanist having made the most determinations at the Herbarium (7866 in total). It is under his leadership that the Herbarium was attached to the AMAP Lab in 2009 and that the computerization of all phanerogam specimens was completed. In 2011 he left New Caledonia but continues to work daily on the flora of the Pacific, especially at the MPU Herbarium.
Between 2011 and 2012, the interim director of the NOU Herbarium was the botanist and ecologist Philippe Birnbaum. After working as a botanist at ORSTOM in French Polynesia between 1987 and 1989, P. Birnbaum completed a PhD thesis about forests of French Guiana, which he defended in 1997 (Birnbaum 1997). Recruited in 2001 at CIRAD, he was sent to Mali, then to Montpellier and finally to New Caledonia from 2011. During his year as director, he did a considerable work of correction and homogenization of the Herbarium's database. We also owe him the first online publication of botanical information on the application still used today (http://publish.plant net-project.org/project/nou). After 2012, P. Birnbaum remained in New Caledonia where he leads research projects in forest ecology in collaboration with many local partners.
The plant physiologist Sandrine Isnard was the head of the NOU Herbarium from 2012 to 2018. She defended her PhD thesis on climbing palms of South America and Asia in 2005 (Isnard 2005). She did several post-doctoral fellowships in functional ecology and plant evolution between Montpellier, the USA and French Guiana before being recruited to IRD in 2011. In 2012 she was sent to New Caledonia to head the NOU Herbarium and develop research projects in functional ecology. She initiated the mass digitization of the herbarium specimens. In 2019 she returned to Montpellier while continuing to work remotely on the ecology of New Caledonian plants.
Since 2018, the direction of the NOU Herbarium has been assumed by botanist David Bruy. A New Caledonian by birth, D. Bruy completed his PhD thesis in botany and plant evolution in New Caledonia (Bruy 2018). The year he defended his thesis, he was recruited as head of the NOU Herbarium for an indefinite period.

Preparation of specimens and conservation conditions
Four types of collections are kept at the NOU Herbarium: Herbarium sheets (the great majority), specimens of fruits and non-standard infrutescences (carpothecae), specimens in alcohol (alcoothecae) and fragments of leaves in silica gel for DNA studies (silicathecae).
Herbarium specimens are kept in the collection room in a conditioned atmosphere thanks to air conditioners maintaining a relative humidity of 50% and a temperature of 20°C with a minimal daily and annual variation. As this collection room is not completely secure at the moment (no airlock, nonwatertight windows, etc.), a fumigation with Aquastar solution (whose active compound is bifenthrin) is carried out every year. Although some insect attacks had to be treated occasionally, these conservation conditions allow a good preservation of the specimens since none has ever been severely degraded. The most important damages come from bad handling of the specimens by the users. After the securisation of the collection room scheduled for early 2023, the preventive fumigation process will only be used as a curative measure in case of insect infection. For this purpose, a sanitary watch will be maintained through the use of insect tape. The current policy implies that herbarium specimens are mounted on white herbarium-mounting card (200 gsm, 27 × 43 cm, 100% bleached chemical paper, acidfree, lignin-free and optical brightener-free, with alkaline reserve, pH 8.5) using a hot glue gun (Figure 1b). Small specimens such as Bryophytes are packed in envelopes made of the same paper as the herbariummounting cards (90 gsm, 17 × 26 cm, pH 8.5) which are themselves stacked with hot glue on herbariummounting cards with their labels (Figure 1c). The herbarium sheets are then digitized either with an Herbscan for the types (600 dpi) or with a camera mounted on a bracket (300 dpi) for the standard collections ( Figure 1d). After a cold treatment (−20°C for 3 weeks), the Herbarium sheets are inserted in sub-sheets of the same composition as the herbarium-mounting card (90 gsm, 44 × 28 cm, pH 8.5) and then integrated into the collections. All herbarium sheets are stored in termite-resistant wooden lockers 46 cm high, 32 cm wide and 101.5 cm deep, divided into 3 compartments along the height (Figure 1a). The collection room is separated into two parts: the larger part houses the New Caledonian collections, and the smaller part houses collections from other countries and territories. In the New Caledonian part, the collections are first classified by Kingdoms, Subkingdoms, Division and Class, in order: Lichen, Fungi, Phycophytes, Bryophytes, Lycophytes, Pteridophytes, Gymnosperms, Angiosperms monocotyledons and Angiosperms dicotyledons. Within each of these major groups, specimens are arranged alphabetically by family (which is listed on each lockers), then by genus, then by species. Within the non-New Caledonian part, the specimens are also classified by major clades (Kingdoms, Subkingdoms, Division and Class), then by alphabetical order of families within these clades. For each family, the specimens are then grouped by territory of origin (identified with a color code) and within each territory by alphabetical order of genera and species. Type specimens are kept in red folders in the same room but in separate lockers and classified in the same way as the general collection.
The specimens in the carpothecae (large fruits or infrutescences, mainly from species of Pandanus Parkinson), once dried and cold treated, are packaged in transparent plastic bags with their labels (Figure 1e). These bags are divided into large plastic bins by family, genus or species depending on the volume of collections. The plastic bins of the carpothecae are located in the collection room, above some of the lockers containing the herbarium sheets.
The alcoothecae consists of two fireproof cabinets located in a room annexed to the collection room. The plant parts (often flowers) are put in small plastic tubes filled with 70° ethanol with a small label mentioning the collector and the collection number in pencil. Each tube is placed in a plastic zipbag with its label and the zipbags are grouped by collector and collection number series in airtight plastic boxes which are then stored in the fireproof cabinets ( Figure 1f).
If the herbarium sheets, the specimens in alcoothecae and the specimens in carpothecae all have a unique barcode belonging to the same series (NOUXXXXXX), the specimens in the silicathecae have barcodes of a different series (NOU-SILXXXXX) because they are not necessarily permanent. Each silicathecae specimen must be attached with at least one collection object of the three other types. Fresh leaf fragments are put in paper envelopes (9 × 6 cm) annotated with the name of the collector, the collection number and the taxon which are directly dipped in silica gel. Then the envelopes are placed in plastic zip-bags (12 × 8 cm) which are stored by barcode numbers in airtight plastic boxes (13 × 35 × 11 cm) with silica gel (Figure 1g). These boxes, which constitute the silicathecae, are kept in the collections room, above one of the racks containing the herbarium sheets.

Composition of the collections
All the barcoded collections of the NOU Herbarium are fully computerized and all the Herbarium sheets are digitized. The Herbarium database is named Virot in honor of Robert Virot , eminent botanist and precursor in the characterization of New Caledonian vegetation (Virot 1956). Initially implemented under Access software, the database is managed by the Specify application (https://www. specifysoftware.org) since 2017. The results presented below are from a global extraction of the data computerized before the end of 2021 and may include a number of errors, as all natural history collection databases.
The Herbarium of New Caledonia has a total of 92,942 computerized specimens: 91,720 Herbarium sheets, 961 specimens in alcohols, 268 specimens in carpothecae. To these classically barcoded specimens are added 4110 specimens in silicathecae. Many of the specimens preserved at NOU are unique in their nomenclatural type status or more broadly in their taxonomic position and geographic origin. Moreover, 22,683 specimens (24% of the collections) appear to have no duplicates in other Herbaria.
Of the almost 93,000 specimens in the Herbarium, 11,863 (12%) are not determined at their lowest taxonomic rank (species, subspecies, variety or forma as appropriate). The total number of conserved taxa is 6665 for 260 families. Cryptogams are almost nonexistent in the database (only 16 specimens) because they have been less studied to date and because a large part of the cryptogamic collections is not yet computerized. In particular, nearly 35,000 algae from the collections of the Entropie Lab (https://umr-entropie. ird.nc/index.php/home) are being integrated into the Herbarium of New Caledonia. In terms of number of specimens, the most represented families are in order Rubiaceae Juss., Myrtaceae Juss., Poaceae, Apocynaceae Juss. and Cunoniaceae R.Br. (Figure 2). These are generally the families with the most species in collections, although some families are particularly poorly represented (e.g. Poaceae, Fabaceae Lindl. or Orchidaceae) and others particularly well represented (e.g. Rubiaceae, Cunoniaceae or Araliaceae Juss.) considering their respective number of species (Figure 2). This reflects some disparities in the study of the Flora by specialists. The families most represented in the Herbarium of New Caledonia are not necessarily the most diverse families of the New Caledonian flora (cf. Munzinger et al. 2022) because they include introduced species or collected elsewhere than in New Caledonia (e.g. Poaceae).
In addition to the biological material described above, the NOU Herbarium also holds bibliographic items including all the volumes of the

Geography
The collections conserved at NOU come from 15 overseas countries and territories (Table 2). Madagascar, with 2 specimens from exchanges, is the only non Pacific Ocean country. New Caledonia represents the great majority of specimens (86%). Among these, the great majority was collected in Province Sud (52%) and in Province Nord (45%). The Province des Îles Loyautés is represented by only 2.5% of the collections. This can be explained, among other things, by the greater difficulty of access to this locality for scientists. Although presenting a smaller area and a less important diversity, the flora of the Loyalty Islands remains one of the big gaps of the NOU Herbarium. A partnership project in progress to set up a Herbarium in Lifou could be an interesting lever to fill this gap. The remote islands and reefs (Walpole, Chesterfield, d'Entrecasteaux, Matthew and Hunter), much less rich in native plant species, are represented by only 462 specimens (Table 2). Apart from New Caledonia, the most represented countries and territories are Vanuatu and Wallis and Futuna. The NOU Herbarium represent probably one of the richest collections in the world for these territories, with respectively 1/4 and 1/3 of all the corresponding GBIF occurrences (GBIF.org 2022). These important collections, coming from countries with interesting flora  under-represented in the Herbaria and particularly threatened by global changes (Morat and Veillon 1985;Meyer 2017;Plunkett et al. 2022), would deserve to be more used. Ninety percent of the collections are geolocated. The vast majority (74%) have been georeferenced a posteriori thanks to the gazeeter of H.S. MacKee who collected on the whole territory of New Caledonia. The rest of the collections (21,759 in total) were more precisely geolocated by the collectors either with GPS or from satellite images. Among all these points of occurrence, many remain inaccurate and a thorough work on the correction of the NOU Herbarium occurrences will be held in the years to come.

Collectors
The collections of a total of 412 different collectors are preserved in the NOU Herbarium. The largest collector is H.S. Mackee who deposited over 20,000 specimens collected with his wife Margaret in the NOU Herbarium (Supplementary material 2). H.S. MacKee is by far the largest collector of plants from New Caledonia and among the largest in the world with a total of about 46,000 collections Hugh 1912-1995). In particular, he made many duplicates of each collection which supplied many Herbaria around the world. However, we note that nearly one-third of his New Caledonian collections are absent from the local Herbarium. Next in order are various NOU Herbarium staff as well as G. McPherson and P.P. Lowry, two specialists in New Caledonian flora working for the Missouri Botanical Garden. Two amateurs among the 20 most important collectors of the NOU Herbarium are H. Brinon and D. Fleurot (Supplementary material 2).
The oldest specimen is a collection by Gaudichaud-Beaupré from the Sandwich Islands dating from 1836.  [1947][1948] and L. Chevalier (25 specimens from 1955). These specimens dating from before the foundation of the NOU Herbarium (903 in total) were donated by other institutions, in particular the Muséum National d'Histoire Naturelle (Le Bras et al. 2017). Specimens of some collectors, including P.S. Green, H.E. Moore and R. Virot, were kept at the Bernheim library before the foundation of the NOU Herbarium and were bequeathed after 1961 by L. Chevalier. However, we deplore the poverty of these historical collections in the Herbarium of New Caledonia and, a fortiori, the total absence of collections with a very high heritage value such as those of the father and son Forster, of J.J.H. de Labillardière or of the Révérend Père X. Montrouzier. Discussions will have to be undertaken with the large European Herbariums so that the duplicates of these collections are returned to their territory of origin (Park et al. 2021).
From 1961, date of the foundation of the NOU herbarium, the number of annual collections increased progressively until reaching a first peak in 1965-1971 and a second in 1977-1984
The NOU Herbarium is open for consultation every Tuesday and Thursday. Since 2019, the NOU Herbarium hosts an average of 272 annual consultations. Most consultants come from research institutes (Figure 4a), mainly IRD and the Institut Agronomique néo-Calédonien (IAC) but also the University of New Caledonia (UNC) and the Cirad. Institutions outside the territory are underrepresented in this analysis due to the Covid-19 pandemy limiting travel since 2019.
Associations -in particular the Endemia associationas well as consulting firms are also among the biggest users of the Herbarium. Most consulting firms make their living from impact studies related to mining activities, one of the most important financial resources in New Caledonia. As a result, mining operators rarely come to the NOU Herbarium in person, nor do local authorities (Government, Provinces and Communes, Figure 4a).
Each year (since 2019), an average of 106 requests for data extraction are processed by the herbarium's  technical team. The biggest requesters remain research institutes but are closely followed by associations, local authorities and to a lesser extent consulting firms ( Figure 4b). Moreover, as all the collections are computerized, digitized and put online , the data are often consulted directly on the Herbarium's website, which is visited more than 3500 times during the year. In addition, scans of specimens made before 2018 are available on the Recolnat platform (https://www.recolnat.org/fr/) and all images of type specimens are referenced in Jstor (https:// plants.jstor.org/).
The exchange policy and the international interest for the new Caledonian flora make that many specimens are sent every year from all over the world. Since the foundation of the Herbarium, at least 33,325 specimens have been sent as gifts and 2609 specimens sent on loan to a total of 70 different institutions (Supplementary material 3). Specimens are most frequently sent to Europe (P, MPU, K, S, G), to the USA (MO, NY) and to a lesser extent to the Pacific (NSW, PVNH, CANB, SUVA, WAIK). Exchanges with Asia, Africa and South America are much more rare. The NOU Herbarium database does not reliably track gifts from other Herbariums to the NOU Herbarium but they are very rare; between 2018 and 2021 only three gifts with a total of about 50 specimens from P, MPU and NSW were received. However, the NOU Herbarium is always open to donations of specimens from the Pacific Islands.
Thus, the NOU Herbarium is heavily used by the local and international community but its academic importance, like that of many Herbaria, remains difficult to trace due to heterogeneity (or lack) of citations in publications (cf. Supplementary material 1). To overcome this, a DOI has been generated so that a clear, persistent and referencable reference in bibliometric databases can be cited by users . As an indication, fifty-six scientific publications were published in 2021 only, the results of which stem from the use of the NOU Herbarium.
The NOU Herbarium is also a very important tool locally for the diffusion of scientific knowledge to the public. For this purpose, two open days for the general public are organized each year during larger events such as la fête de la science, le mois du patrimoine or the international celebration of plants day. In addition, several classes of all school levels are welcomed each year. The Herbarium of New Caledonia staff is also involved in several botany and plant ecology courses given at the University of New Caledonia.

Conclusion and perspectives
The Herbarium of New Caledonia is a scientific, heritage and pedagogical platform with more than 60 years of history. Its collections are today at the forefront of research, development and dissemination of knowledge in New Caledonia. The New Caledonian flora being very rich and imperfectly known, the taxonomic updates and the integration of several thousands of specimens each year require a large investment in human resources. One of the daily challenges of the herbarium managers is therefore to find funding and solutions to maintain a competent and sufficiently large technical team to allow the collections to remain functional. The mutualization of the management of the collections with the local collectivities (Government and Provinces) and research actors (CRESICA, Consortium pour la recherche, l'enseignement supérieur et l'innovation en Nouvelle-Calédonie) could be an interesting solution to maintain the human resources. The provision of a collection officer by the Government of New Caledonia in 2000 was a first step towards this pooling, which should be pursued.
The continuous enrichment of the collections also implies a saturation of the spaces. The Herbarium's 1096 lockers are now full and the Herbarium will take advantage of an energy renovation operation planned for the end of 2022 to enlarge its collection room and make it completely airtight. This is a necessary and welcome development but remains a short-term solution. In the longer term, we hope that a territorial vision of the management and promotion of the natural history collections will emerge. This would allow the various local actors to coordinate and pool their resources in order to set up a collections building, or even a territorial natural history museum. The local trend is towards a regrouping of natural history collections, as shown by the integration of the algal collection of the Entropie Lab in the Herbarium of New Caledonia, but this effort will remain minimal without the involvement of the local collectivities.
In this dynamic of local valorization of natural history collections, we regret the poverty of ancient collections with a high heritage value that have historically been conserved in the large European Herbariums. Discussions will have to be undertaken with these Herbariums so that duplicates of these collections are returned to New Caledonia, whose history they are a witness to.

Acknowledgments
I thank all the contributors of the Herbarium of New Caledonia who are far too numerous to be mentioned here. A special thanks to Jacqueline, Vanessa, Williams and Mathieu who accompany me daily in the management of collections. The statistics on the consultation of the website of the Herbarium was provided by Pierre Bonnet. Thanks to Yohan Pillon and the editors of Botany Letters for their invitation to submit this paper, and to the direction of AMAP Lab for their support. This article has been improved thanks to the comments of Yohan Pillon, Tanguy Jaffré, Jean-Marie Veillon, Jérôme Munzinger, Jacqueline Fambart-Tinel and two anonymous reviewers whom I thank.

Data availability statement
The data from the Herbarium of New Caledonia (NOU) database used for this article are freely available at http://pub lish.plantnet-project.org/project/nou. Any publication resulting from the use of these data should cite Bruy et al. (2021).

Disclosure statement
No potential conflict of interest was reported by the author(s).