by Dan Turtureanu
I spent almost one month in Southern Transylvania doing vegetation sampling. During this time I had a lot of discussions with colleagues about the ecology of various groups and also about the sampling design implemented here.
One thing I noticed was that management interventions may be strongly context-dependent. For instance, grazing with buffalo and cow in wood-pastures may create and maintain optimal habitats for certain animals like the yellow bellied toad. Old trees are important habitats for some woodland related birds, mushrooms and various insects and so on. Thus, having these elements here it’s great!
However, the news are not so good for plants: wood-pastures harbor only extremely common plant species and their richness at fine scales seems to be very low compared to other grasslands in Transylvania. In my perception, these pastures and wood-pastures are degraded, and are dominated by species like Agrimonia eupatoria, Lolium perenne, Trifolium repens, Dactylis glomerata. I admit that these plants are valuable for biomass production (which is crucial for maintaining livestock), and may be important drivers for ecosystem functioning.
Recently, we put the problem of sampling the grassy vegetation of these landscapes in order to assess their state. Should we focus on more rare or common species? Rare species and those that are locally known to be indicators of ‘healthy grasslands’ may be some ‘ecological delicatesses’, indeed, but don’t contribute too much to ecosystem functioning – this was one, and acceptable argument. Amount matters, and not only in publications :). And indeed, many western-European examples show: common species can be also in decline – this seems to be evident e.g. in farmland birds too, but not only. Therefore, let’s focus on the drivers, we are not the only ones who do that. Here I would like to add one point: if the aim is to understand these landscapes and systems (i.e. from Eastern Europe), and to promote management plans to conserve their biota, we need to consider rare and indicator taxa as well, and reflect on some realities which are present here. The ecological delicatesses (sensu written above) may have little importance as ecosystem drivers, true, but they may be extremely important as mirrors / indicators of the quality of the natural environment (including the environment assured by the common species). Common species may not show significant changes in abundance or diversity when systems are affected by disturbance. In contrast, the frequency of more rare or indicator species is very likely to change fast, mainly because of they are known to have higher sensitivity. These species still occur in Transylvanian Lowlands, but are locally disappearing very often, mainly because of land use intensification. Such species are for example: Sanguisorba officinalis, Gentiana pneumonanthe, Echium russicum and Salvia nutans.
Therefore, how an ideal approach should be?
I guess it depends on context. The management interventions which result in good yellow bellied toad habitats may not be the best for many plants. It may be that the ecologically ‘decisive’ phenomena happen in the major landcovers and the common species are crucial for this. But one needs to know: there is biodiversity beyond the common species, and the rest of the species need to be considered also, even if they occur sporadically or quite rarely, and thus not having too much functional importance in the landscape. These may be vulnerable to change both at regional and local scales. Conservation biologists need to consider understand both, simultaneously, in order to capture the whole and give voice for the ecological minorities too – and not only for the majority.