Plant Identification Report

Дата канвертавання19.04.2016
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Plant Identification Report

If a primary aim of the Linnaeus Experience is to follow in the footsteps of Carl von Linné, then the identification of the Lappish flora should form the crux of the expedition. Without Linnaeus’ prerogative of being able to name any new species encountered, identification of plants should be carried out with the use of floras - many of which describe floral characteristics initially depicted in the seminal ‘Flora Lapponica’ itself. Moreover, with modern ecological theories and computer statistical packages it is now possible to analyse the structure of plant communities in a way in which von Linné could not. With these aims in mind it can be said that the Linnaeus Experience of 2003 was a success.

The group managed to identify well over a 100 species; a considerable achievement given the two week time span and that Sonesson and Lundberg, in their 1974 work on the Torneträsk forests of the area, categorized around 90. The group were somewhat selective in what they chose to identify; 90% of all identified plants were angiosperms in an area where roughly 75% of the plants identified by the Tourist Station herbarium (a much appreciated aid) were flowering plants. This suggests a predilection to flowers – understandable given they are more easily identified and imminently more noticeable than the more innocuous cryptophytes.
However, this is not to say that identification of the flowering herbs was easy; there were numerous occasions in which a plant’s identity was mistaken. The most celebrated instance was that of Linnea borealis. With only a textual description initially available it was first thought to be the unlikely Loiseleuria procumbens; a plant also mistaken for Empetrum nigrum. L. borealis was also confused, albeit more understandably, for Vaccinium microcarpum – whose flowers were once ashamedly mistaken for a moss. Like L. borealis it adopts a creeping habit with protruding flower spikes, although L. borealis has twin-flowers and opposite leaves as opposed to the alternately leaved V. microcarpum.
Along with L. borealis, Andromeda polifolia provided botanical entertainment in terms of being a popular favourite and easily mistaken. Its habit of cropping up amongst patches of Empetrum hermaphroditum led it to be at first mistaken for Empetrum flowers. However, the discovery that Empetrum flowers are singularly insignificant led to the reappraisal of the remarkable pink bell-shaped flowers; worthy of Perseus’ attention in themselves. Unusually, the non-floral leaves are remarkably different than the subtending floral bracts, being almost succulent and tinged with pink contrasting with the Empetrum-like floral leaves.
A more surprising confusion arose between the more common members of the Leguminosae and Scrophulariaceae. The two main species of the Leguminosae were Astralagus alpinus and A. frigidus; the former with purple flowers and the latter with yellow. Both contain the classic teardrop pinnae of the Pea Family which helped distinguished them from the Scrophulariaceae. The five species of this family were more confusing. The two Melampyrums, M. pratense and M. sylvaticum, both had pointed leaves with M. sylvaticum possessing small round flowers in the axils unlike the tubular M. pratense. The two Pedicularis species, P. lapponica and P. hirsutum, had lobed leaves with the former possessing sulphur-yellow flowers and the latter more pigmented and hirsute. Rhinanthus groenlandicus could easily be overlooked for Pedicularis lapponica although the flowers were clustered at the top with darker calyces.
The sheer diversity of the Salicaceae led to a wild-goose chase for the name of some originally unidentified plants not immediately being identifiable as willows. The promiscuous hybridisation of Salix species also results in a gallimaufry of different forms. For the Linnaeus Experience, these were conveniently clumped into three species: S. lanata with its furry leaves, S. glauca as a non-hirsute S. lanata and S. myrsinites affectionately called ‘the giant Vaccinium myrtilus’. With regards to the low-growing willows, the diminutive Salix reticulata was at first mistaken for Arctostaphylos alpina, although it is far more hirsute and leathery. The other Salices, S. polaris and S. herbacea, possess opposite leaves with the catkin in the middle and are often confused, although S. herbacea is far smaller.
Identification of the graminae was perhaps the least successful aspect of the expedition. Only two species were certainly identified, both of which were the easily found Deschampsia caespitosa and Festuca ovina on account of their needle-like leaves and the lack of a ligule in F. ovina. In mitigation, there was a paucity of flowering specimens and a general consensus to master the angiosperms prevented a thorough investigation. The difficulty was further confounded by the vast array of sedges in the area, which even when in flower require a more specialised set of identification skills. Even the famous snow-grass, with its white pom-poms, is likely to be a blanket term for four remarkably similar Eriophorum species (referred to as E. scheuchzeri herein for convenience).
Like the grasses, the least derived plants (mosses, lichens, horse-tails etc.) were not studied in great depth. With lichenologists in the area claiming to have found hundreds of species, to expend time on these alone would have taken up the majority of the trip. Thus the group was contented to familiarise themselves with the principle groups in the area, laying the foundations for identification at a greater level.
After much fossicking, the group had clarified the main points of confusion, gained a solid grounding in the predominate plants of the area and acquainted themselves with the more unusual alpine species. Thus the expedition could take on the added dimension of some statistical ecological research; an aspect unavailable to Linnaeus. By collecting percentage cover of the different species in half-metre square quadrats over a wide range of locations it was possible to analyse the degree of similarity between plant communities using multivariate statistics.

Statistical Analysis of Abisko Floral Communities

The following graphs from the multivariate program MVSP are peppered with points, each representing either a species or a quadrat sample from a particular habitat. The closer the points are on the chart, the more related they are. Thus if a group of plants are always found together they would be expected to appear as a tight cluster of points on a species plot with other plants at a greater distance away on the graph. For the habitat quadrats, it would be expected that quadrats from similar habitats would gather together in discrete groupings. It should be noted that there is no statistical test for whether the groups represent significant associations; the delineations used in our conclusions are purely arbitrary and open to objective debate.

At a glance it can be said that the researched Abisko area does not contain any outstandingly distinct habitat types. The charts from both the plots for species and quadrats (Figures 1 and 2) show a fairly uniform smear of cases showing that nothing is particularly related to each other. Compared to charts from other studies, such as with the ecologist Grime, there are no noticeably different clusters of points outlining separate communities. Thus wherever you go in the Abisko area, there is a chance that plants observed in one location could well appear in another, no matter how different the location may at first appear.
This view can be corroborated by the seemingly unrelatedness of the principle plants of the area, namely Vaccinium myrtilus, V. uligonosum, V. vitis-idaea and Empetrum hermaphroditum. Whilst these plants dominate the woodlands, which represent the majority of the Abisko area, they do not cluster together as tightly in the species plot as woodland habitats do in the quadrat plot. This suggests that these species can be found all over the area regardless of habitat. Conversely, some less common species, which are only found in woodlands, could account for the similarity within this habitat; Trientalis europea and Cornus suecicca being likely candidates.
None-the-less, whilst the overall structure of the Abisko flora is similar, closer perusal of the charts show that quadrats taken from the same area cluster together. This would suggest that microhabitats exist within the area. For example the data points for the bog are gathered towards the left of diagram one. Similarly plants found in bogs such as Menyanthes trifoliata, Vaccinium microcarpum and Luzula varieties are gathered together in a similar location in diagram two. The bog transition points are predictably between the bog and the rest of the quadrats. Likewise, clusters for Paddus, the Campsite and two riverbanks are clearly clumped. Perhaps more discretely the quadrats for disturbed land can be found to left of the chart where Alchemilla glomerulans and Anthriscus sylvestris were uniquely found.

However, this merely confirms an empirical observation almost instinctively carried out by the group; if we had not perceived the habitat to be different then we would not have decided to analyse that area. It should not be surprising the similar quadrats gather together. Moreover, it cannot be said with certainty that these habitats would appear elsewhere in Abisko; they may represent unique habitats we happened to chance upon. Only an exhaustive study of the whole area could confirm this. The real news stems from the overall picture argued earlier; the areas we perceived to be different are not that different at all.

Waterfall Analysis

Another experiment carried out was to assess the composition of a plant community along an altitudinal gradient by following the edge of a waterfall. This would show any species changes due to height which is an effective measure of temperature; for every one hundred metres altitude the temperature drops by roughly 1°C. Three quadrats were taken at every sixty metres with W1 representing the highest point. Each quadrat was labelled a, b, c with ‘a’ being closest to the water’s edge and ‘c’ farthest. The quadrats were analysed with MVSP: figure 3 shows the relatedness of quadrats.

The quadrat ordination plots suggest that altitude does have an effect on species composition. The relevés at the foot of the mountain can be observed towards the left of the diagram whilst those to the top can be found to the right. There is a degree of overlap suggesting that the changes are quite gradual. This belies the clear demarcation of the tree line, which is observable, but is most likely explained by the fact that MVSP takes into account all species present and not just the tree species. Moreover, distance from the water’s edge seemed not to have much effect. Thus altitude could explain some of the differences observed within the area.
The species ordination plot corroborates the observed changes. However, for those communities that are found towards the bottom of the mountain (the predominant heath types) there is an observable bifurcation in plant types, with one comprising of Empetrum species and the other Vaccinium species. There is no other evidence from our studies to show that these two compositions are found elsewhere in Abisko, thus more transects along a waterfall would be needed.

Figure 1: 2D species ordination plot of Abisko flora

Figure Two: 2D quadrat ordination plot of Abisko flora

Figure Three: 2D quadrat ordination plot of Waterfall flora

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