Moreover, collectively, emergence time, height and RCD are considered factors of growth and fitness. This result suggests that relative performances of white birch populations in the field, to some extent, could be estimated from germination and pre-planting performances. We expected that survival among the populations would be influenced by cold winter temperature at the common garden site because most of the populations in the experiment were from climates that are warmer than the common garden climate: That was not the case. Surprisingly, most of the populations with good performances in common garden were from locations with warmer climates. However, a study has shown that it is possible for species to perform differently at different climatic extremes. For instance, in a 6 year provenance study of white ash, the provenances with tallest height in the coldest climate were the shortest in a relatively warmer environment and vice versa. The authors pointed out that such result underpins the genetic basis for trade-off between growth and cold tolerance. However, white birch appears to be a generalist with regards to frost tolerance . Mortality was only observed later in the spring and could not be attributed to frost damage. More importantly, mortality was lowest among the populations from Western Canada where the climate is much warmer than in Northern Ontario. Nonetheless, we exercise caution here because short-term growth investment may lead to future mortality when populations from warm climates are transferred to cold climates.Also in this study, summer temperature proved to be a strong predictor of climatic distance to which white birch populations may be transferred. This was consistent with the parallel factorial experiment that we conducted in the greenhouse. We used two temperatures and two water regimes . Seedlings in the high temperature environment outperformed those in the low temperature environment .
In theory, it implies that white birch populations will benefit from transfers to warmer climates. However, successful transfer is most probable if the climate of the test site matches that of the populations. This is because there is a potential risk of maladaptation when transferring species along climate or geographic range. Also, nft hydroponic system populations might express adaptation to their original environments even when planted in common gardens. For these reasons, a conservative climatic distance will be more appropriate. Out of the populations tested, the closest matches for the common garden site were populations from Timmins in Northern Ontario and St George’s in Newfoundland. Although St George’s is a climatic match for the common garden site, the population’s performance was not very impressive. Apart from being a match, in the absence of a population from Thunder Bay in this experiment, populations from Timmins invariably serve as surrogate for the test site. Timmins is located in Northern Ontario with similar cold northern climate as the test site. However, this is not a conclusive outcome because the performances of the remaining two populations from Timmins are less than average even though they were from locations which are a few kilometers apart. This poses a question of how much influence do seed sources have on the post-planting performance of white birch. Also, it should be pointed out that white birch has different ploidy levels with polyploids being generally more tolerant than the diploids. It is difficult to know if there is a confounding effect of ploidy level in addition to population effects. Growth and survival is controlled by many factors other than climates and it is important to understand genotype performance from both genetic, developmental and growth viewpoints to adequately capture the dimension of variations among the populations. However, the prediction of the transfer functions is not trivial. The models summarized the important climate variables relevant to the species transfer and aided the matching of populations with the test site. This will provide a useful guide in the decision making process.
At this stage of this experiment, we use the term “match” with caution and we are itching to know what the populations’ performances might be in a few years from now.Ex situ living collections of socio-economically important plant species are an important resource for sustainable development research and use. Globally, botanic gardens propagate and grow a third of all known higher plant species.This means they have the potential to provide the scientific community with plant material and a wealth of knowledge about how to grow plants successfully, the starting points for their study and sustainable use. Although botanic garden and arboretum collections are acknowledged as important ex situ conservation repositories in FAO’s Second Global Plan of Action for Plant Genetic Resources in Food and Agriculture and their State of the World’s Forest Genetic Resources report, botanic garden collections remain largely unknown and under-utilised by the crop and forestry communities. For example, Khoury et al. recently published a paper entitled “Comprehensiveness of conservation of useful wild plants: An operational indicator for biodiversity and sustainable development targets”. This paper concludes that 70% of these taxa are conserved ex situ, and only 33.5% are adequately conserved ex situ in 11 or more collections. However, their analysis did not include data on ex situ living collections and seed bank collections in botanic gardens. This despite the fact that many botanic gardens and arboreta were established with a strong focus on economic botany, and historically were largely responsible for the establishment and the global distribution of valuable plant-based commodities such as rubber, tea, coffee and cinchona. Furthermore, plant conservation efforts led by botanic gardens over recent decades have included a strong focus on socio-economically important plant species, including crop wild relatives, wild food plants and timbers. Botanic Gardens Conservation International , a network of botanic gardens and arboreta in >100 countries, maintains a database of the plants that are grown and conserved in more than 1100 botanic gardens and arboreta around the world. In this paper, we compare this dataset with the dataset of 6941 socio-economically important plants taken from the analysis carried out by Khoury et al. to assess whether botanic garden and arboreta collections contain a significant proportion of socio-economically important plant species, and whether they have a role in contributing to future research and use of such species.
We also examine the reasons why botanic garden/arboreta collections are under-utilised, and make recommendations for increasing their visibility and use.PlantSearch does not provide accession-level data. It is a database of the names of plants in the living collections and seed banks of the world’s botanic gardens. It is therefore not possible to assess the uniqueness or diversity of accessions for any given species, and therefore their genetic representation in ex situ collections. However, PlantSearch does record how many collections a taxon is held in . These data are a useful surrogate for the diversity of accessions for a species and for genetic representation. Therefore, for each species, the number of collections they are held in was used to assess the genetic representation of all collections with 11 or more having comparatively good representation.The comparison between Khoury et al.’s WEP dataset and Plant Search showed that 6017 of the species identified as of socio-economic importance by Khoury et al. are currently conserved within the living and seed collections of the botanic gardens and arboreta in BGCI’s network. Using data from the crop and forestry communities as recorded in Genesys, Khoury et al reported that 30% of socio-economically important plant species are not currently conserved in any ex situ collections. However, when taking into account species in that list that are found in at least one botanic garden collection, hydroponic nft system our study reduces this number to 732 taxa. BGCI’s Garden Search database currently lists 2952 botanic gardens globally. Since BGCI’s Plant Search database currently contains accession records from 1157 botanic gardens, arboreta and similar institutions, despite it being the most comprehensive database of its kind, this means that 61% of gardens have not made their collections data available through Plant Search. The figures in Table 1 are therefore likely to be an underestimate of the coverage of socio-economically important plants in botanic garden ex situ collections. In addition, PlanSearch and the WEP dataset on which the Khoury et al. study is based use different phylogenies and taxonomies. It is therefore likely that, due to synonymy, this analysis, which is based on direct name matches, is an underestimate of the taxa the two databases share in common, and therefore of the representativeness of botanic garden collections.Of the 6941 useful wild taxa included in the Khoury et al. WEP dataset, 6748 were assigned a medium or high conservation priority by Khoury et al. This analysis shows that only 924 of these taxa are currently not present in any BG collection, and 3238 taxa are comparatively well conserved in 11 or more ex-situ collections. Of the 3017 taxa to which Khoury et al. assign a high conservation priority, their analysis suggested that 1407 are not in ex situ collections. However, this analysis shows that just 544 of these taxa are currently not present in any BG collection. In addition, 911 of the 1407 taxa Khoury et al. suggest are not in any ex situ collection can be found in at least 1 botanic garden and 161 can be found in 11 or more collections each. Finally, a more objective measure of conservation priority is provided by BGCI’s ThreatSearch database, which is the most comprehensive database of threat assessments for plant species available. Of the taxa assessed by Khoury et al. as of medium or high conservation priority, 5253 have threat assessments included in ThreatSearch but only 1153 of these are classified as “Threatened”. The breakdown of threat status categories is in Table 3 below. Of the threatened species that are also medium or high conservation priority according to the Khoury et al. analysis, currently 86% are found in at least 1 ex situ botanic garden collection and 41% are found in 11 or more ex situ botanic garden collections.
Our analysis confirms this supposition. However, they go on to say, “Some information on these holdings likely exists in additional, scattered online databases or in off-line datasets, while other conservation repositories may not yet have digitized their data.” PlantSearch is a public facing meta-database, which is well known in the botanic garden and arboretum community that contributes data to it. In addition, BGCI, the global membership body that maintains PlantSearch, GardenSearch and several other global plant databases is well known to the crop and forestry communities. It is therefore likely that the reasons for not taking the collections of botanic gardens into account are more complex than the lack of available data. One obvious problem is that, with a few exceptions, the botanic garden community does not share its collections level data with Genesys and the crop and forestry sectors. This is in part because the botanic garden sector has no equivalent data portal that enables the sharing of accessions level information. Instead, botanic gardens maintain their own accessions databases and currently only share the names of those accessions on PlantSearch. Accession-specific information, such as collection number, date of collection, origin and so on, is not recorded in PlantSearch. This is about to change in that BGCI is developing an accessions-level module on PlantSearch which will enable responsible and informed exchange of plant material between institutions and which will be compatible with Genesys. This will greatly facilitate import of accessions level data from PlantSearch into Genesys. A second problem is cultural rather than technical. Botanic garden collections are often grown or conserved for different reasons from those of the crop or forestry communities. These reasons include public display, conservation and scientific research. In addition, botanic garden collections are far more taxonomically diverse than the crop or forestry sectors are. Mounce et al. estimate that, as a minimum, botanic gardens grow over 105,000 flowering plant species, increasingly collected from the wild. To this can be added several hundred thousand cultivars but, in general, botanic gardens do not cultivate or conserve large amounts of infra-specific genetic diversity. In contrast, crop and forestry gene banks conserve relatively few species but concentrate their efforts on conserving a huge diversity of landraces and cultivars of those species of greatest utility for food security, timber production and other human uses. This means that collection priorities, data and methodologies are not always comparable.