Research Article |
Corresponding author: Barbara Valle ( barbara.valle@unimi.it ) Academic editor: Gianluigi Bacchetta
© 2021 Gianmaria Bonari, Edy Fantinato, Lorenzo Lazzaro, Marta Gaia Sperandii, Alicia Teresa Rosario Acosta, Marina Allegrezza, Silvia Assini, Marco Caccianiga, Valter Di Cecco, Annarita Frattaroli, Daniela Gigante, Giovanni Rivieccio, Giulio Tesei, Barbara Valle, Daniele Viciani, Giulia Albani Rocchetti, Claudia Angiolini, Emilio Badalamenti, Davide Barberis, Matteo Barcella, Giuseppe Bazan, Andrea Bertacchi, Rossano Bolpagni, Federica Bonini, Alessandro Bricca, Gabriella Buffa, Mariasole Calbi, Silvia Cannucci, Luigi Cao Pinna, Maria Carmela Caria, Emanuela Carli, Silvia Cascone, Mauro Casti, Bruno Enrico Leone Cerabolini, Riccardo Copiz, Maurizio Cutini, Leopoldo De Simone, Andrea De Toma, Michele Dalle Fratte, Luciano Di Martino, Romeo Di Pietro, Leonardo Filesi, Bruno Foggi, Paola Fortini, Roberto Gennaio, Gabriele Gheza, Michele Lonati, Andrea Mainetti, Marco Malavasi, Corrado Marcenò, Carla Micheli, Chiara Minuzzo, Michele Mugnai, Carmelo Maria Musarella, Francesca Napoleone, Ginevra Nota, Giovanna Piga, Marco Pittarello, Ilaria Pozzi, Safiya Praleskouskaya, Francesco Rota, Giacomo Santini, Simona Sarmati, Alberto Selvaggi, Giovanni Spampinato, Adriano Stinca, Francesco Pio Tozzi, Roberto Venanzoni, Mariacristina Villani, Katia Zanatta, Magda Zanzottera, Simonetta Bagella.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Bonari G, Fantinato E, Lazzaro L, Sperandii MG, Acosta ATR, Allegrezza M, Assini S, Caccianiga M, Di Cecco V, Frattaroli A, Gigante D, Rivieccio G, Tesei G, Valle B, Viciani D, Albani Rocchetti G, Angiolini C, Badalamenti E, Barberis D, Barcella M, Bazan G, Bertacchi A, Bolpagni R, Bonini F, Bricca A, Buffa G, Calbi M, Cannucci S, Cao Pinna L, Caria MC, Carli E, Cascone S, Casti M, Cerabolini BEL, Copiz R, Cutini M, De Simone L, De Toma A, Dalle Fratte M, Di Martino L, Di Pietro R, Filesi L, Foggi B, Fortini P, Gennaio R, Gheza G, Lonati M, Mainetti A, Malavasi M, Marcenò C, Micheli C, Minuzzo C, Mugnai M, Musarella CM, Napoleone F, Nota G, Piga G, Pittarello M, Pozzi I, Praleskouskaya S, Rota F, Santini G, Sarmati S, Selvaggi A, Spampinato G, Stinca A, Tozzi FP, Venanzoni R, Villani M, Zanatta K, Zanzottera M, Bagella S (2021) Shedding light on typical species: implications for habitat monitoring. Plant Sociology 58(1): 157-166. https://doi.org/10.3897/pls2020581/08
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Habitat monitoring in Europe is regulated by Article 17 of the Habitats Directive, which suggests the use of typical species to habitat conservation status. Yet, the Directive uses the term “typical” species but does not provide a definition, either for its use in reporting or for its use in impact assessments. To address the issue, an online workshop was organized by the Italian Society for Vegetation Science (SISV) to shed light on the diversity of perspectives regarding the different concepts of typical species, and to discuss the possible implications for habitat monitoring. To this aim, we inquired 73 people with a very different degree of expertise in the field of vegetation science by means of a tailored survey composed of six questions. We analysed the data using Pearson’s Chi-squared test to verify that the answers diverged from a random distribution and checked the effect of the degree of experience of the surveyees on the results. We found that most of the surveyees agreed on the use of the phytosociological method for habitat monitoring and of the diagnostic and characteristic species to evaluate the structural and functional conservation status of habitats. With this contribution, we shed light on the meaning of “typical” species in the context of habitat monitoring.
diagnostic and characteristic species, habitat monitoring, keystone species, Natura 2000, plant community, structure and functions, typical species, 92/43/EEC Directive
In the Anthropocene, many ecosystems are increasingly at risk due to the concurrent action of a set of drivers such as habitat loss, fragmentation, invasive species and pollution, that are altering ecosystem structure and functioning, while threatening their long-term persistence and capability to provide essential ecosystem services (
In Europe, ecosystem monitoring is regulated by the Habitats Directive (Art. 17 of the 92/43/EEC), and it is mostly done at the habitat level (
While habitat area, range and future prospects are assessed at biogeographical level, the "structure and functions" parameter can be monitored at the local level starting from field data, trying to minimise the degree of subjectivity (
In Italy, the evaluation of structure and functions of habitat types, has usually been carried out relying on typical species, identified by experts. They are summarized in the “physiognomic reference combination” on the online italian version manual for the interpretation of habitats (
In the first place, it is not clear yet to what extent phytosociology and other disciplines, such as functional ecology, can be used to identify typical species. Diagnostic and characteristic species, as defined in the phytosociological method (
A further potential approach that might be valuable for habitat monitoring advocates the use of keystone species, widely applied in ecology, as typical species. Keystone species play critical ecological roles that are of greater importance than one would predict from their abundance (
An additional issue is the spatial scale at which typical species should be identified. By definition, typical species should be exclusive of a given habitat, but they should reflect favourable structure and functions (
The Italian Society for Vegetation Science (SISV) is not novel to collectively contribute to aspects related to habitat monitoring (
This study aims to provide insights on these topics, by combining different points of view of researchers and professionals of vegetation science to give a shared interpretation on typical species and the implications for habitat monitoring.
We aimed to acquire a consistent overview regarding specific topics’ opinions such as “diagnostic”, “characteristic” and “typical” species for habitat monitoring throughout the whole potential audience of Italian scientists and professionals dealing with vegetation science. To this aim, before the workshop, SISV organisers sent out a tailored survey addressing confirmed workshop participants (hereafter, ‘surveyees’). Surveyees included persons with a very different degree of expertise in habitat monitoring, spanning from students and young scientists to experienced professionals and recognized vegetation scientists. The survey was composed of 8 questions with hybrid possibilities of multiple-choice, binary and open answers (see
During the workshop, the results of the survey were presented in raw form (i.e., with no statistical analysis), and discussed among participants. Starting from this discussion, we attempted to find shared views and solutions to the raised issues. To this end, several contributions and case studies presented by the participants helped to shed light through direct monitoring experiences. We summarize the main conclusions together with the most relevant issues emerged during the debate.
We analyzed the results of all the questions (Q1-Q8) by means of a Pearson’s Chi-squared test with simulated p-value (based on 9999 randomizations) to verify that the answers diverged from a random distribution. Then, we checked the effect of the surveyees’ experience on the answers Q3-Q8. We used an Asymptotic Linear-by-Linear Association Test (
Questions and possible answers provided to the surveyees. The Q3-Q8 answers followed the “Likert scale” (
N | Question | Possible answers | ||||
Q1 | Level of expertise on habitat monitoring | No experience | Little experience | Medium experience | Solid experience | |
Q2 | Did you already use the phytosociological method to perform habitat monitoring? | Yes | No | |||
Q3 | Do you agree with the use of phytosociological method to perform habitat monitoring? | Strongly disagree | Disagree | Neither agree nor disagree | Strongly agree | Agree |
Q4 | Are diagnostic and characteristic species informative about structural and functional conservation status of habitats? | Strongly disagree | Disagree | Neither agree nor disagree | Strongly agree | Agree |
Q5 | Is the use of diagnostic and characteristic species for assessing conservation status dependent on specific habitats? | Strongly disagree | Disagree | Neither agree nor disagree | Strongly agree | Agree |
Q6 | Diagnostic, characteristic and typical species: how much do they overlap (conceptually and practically)? | Slightly | Moderately | Strongly | ||
Q7 | Keystone species. Can keystone species be used as typical species? | Strongly disagree | Disagree | Neither agree nor disagree | Strongly agree | Agree |
Q8 | Does scale matter for the definition of typical species? | Strongly disagree | Disagree | Neither agree nor disagree | Strongly agree | Agree |
Overall, 73 people participated in the questionnaire survey and 104 in the workshop. Among surveyees, 17 (23%) stated to have solid experience in habitat monitoring, whereas a comparable number had little or medium experience (23 and 21, respectively; i.e., 32% and 29%;
Answers to all questions, except Q1, showed significant differences in the frequencies among the responses provided (
Most of the surveyees (77%) agreed with the use of the phytosociological method to perform habitat monitoring, while very few (5.5%) disagreed (
Almost all surveyees (about 84%) acknowledged that the use of diagnostic and characteristic species for assessing conservation status is dependent on specific habitats (
The overlapping between diagnostic, characteristic and typical species was strongly recognized by 24% and moderately acknowledged by 71% of the surveyees (
The answers on using keystone species as typical species had an unclear pattern (
The scale for the definition of typical species resulted important (
The Asymptotic Linear-by-Linear Association Test revealed that only Q5 was affected by the level of expertise of the surveyees, while for all the other answers, the association was not significant (
Results of Pearson's Chi-squared test with simulated p-value (based on 9999 randomizations) to verify that the answers diverged from a stochastic distribution.
Question | Chi Square statistic | p-value |
Q1 | 4.53 | 0.216 |
Q2 | 13.16 | <0.001 |
Q3 | 57.75 | <0.001 |
Q4 | 66.47 | <0.001 |
Q5 | 69.92 | <0.001 |
Q6 | 47.75 | <0.001 |
Q7 | 21.51 | <0.001 |
Q8 | 31.22 | <0.001 |
Results of the Asymptotic Linear-by-Linear Association Test to verify whether contributors’ answers were influenced by their level of expertise (Q1), and of the Pearson's Chi-squared test with simulated p-value (based on 9999 randomizations) for the effect of the previous use of phytosociological method in habitat monitoring (Q2).
Test on the effect of Q1 | Test on the effect of Q2 | |||
Test statistic (Z) | p-value | Test statistic (Χ²) | p-value | |
Q3 | -1.063 | 0.288 | 6.431 | 0.130 |
Q4 | 0.461 | 0.645 | 1.312 | 0.897 |
Q5 | -2.774 | 0.006 | 3.667 | 0.303 |
Q6 | -1.630 | 0.103 | 3.147 | 0.214 |
Q7 | -0.450 | 0.653 | 3.547 | 0.494 |
Q8 | -0.186 | 0.853 | 2.595 | 0.475 |
The answers to the questionnnaire highlighted a substantially shared point of view on the debated topic, though diverging opinions on some specific issues emerged.
We present them by summarizing the main messages, highlighting pros and cons, and offering proactive ideas to shed light on the meaning and use of typical species for habitat monitoring.
During the workshop, a large part of the discussion focused on the phytosociological method. Surveyees agreed that using the floristic-vegetation sampling, i.e., the phytosociological method sensu
Besides the methodological aspects, the workshop addressed substantial conceptual issues, such as selecting typical species sensu 92/43/EEC among the diagnostic and characteristic species. Diagnostic and characteristic species were originally defined for diagnostic purposes, i.e., for identifying and classifying syntaxa (
According to the mass ratio hypothesis (
Importantly, workshop participants recalled the need of reporting, when tracking habitat conservation status, the occurrence of invasive, ruderal and in general of all those species indicating negative changes in habitat conditions (
Another open issue regards the conceptual and factual overlap between typical and keystone species. Keystone species have a disproportionate impact on biological communities, which means that their contribution to the maintenance of an ecosystem structure and functioning is more significant than we could infer from their abundance only (
During the workshop, the need for a broad perspective in habitat monitoring also emerged, especially when discussing the importance of the scale, which was deemed crucial in the definition of typical species by the majority of the surveyees. Ecosystem functioning is based on ecological mechanisms and processes mostly trespassing the borders of single habitats (
Finally, it should be noted that defining a list of species that “reflect favourable structure and functions of the habitat type” (
With this contribution, we attempted to shed light on the meaning and interpretation of typical species in the context of habitat monitoring. To this aim, we combined different perspectives belonging to researchers and professionals in vegetation science. In particular, most of the surveyees and participants to the workshop agreed on two issues: i) the phytosociological method is adequate for habitat monitoring and ii) diagnostic and characteristics species are informative about the structural and functional conservation status of habitats. The definition of typical species useful for habitat monitoring should be accompanied or even preceded by the parallel identification of the habitats’ structures and functions. Accomplishing these two tasks calls for a multidisciplinary approach that can be implemented only by combining different scientific knowledge and expertise. Although many open issues remain unsolved, this study represents a first attempt to provide a shared view of key concepts for habitat monitoring and conservation.
G.Bo. was funded by the Free University of Bozen-Bolzano through the CONplant project (TN201H). C.Ma. was funded by the Czech Science Foundation (Project No. 19-28491X).
The authors have declared that no competing interests exist.
This paper was conceived to summarize the view of the Italian Society for Vegetation Science (SISV) as the outcome of a participatory process on the topic of typical species for habitat monitoring. This contribution arises as the planned publication of the scientific workshop organized by SISV held online on 2020 October 20th entitled: “Dalla fitosociologia al monitoraggio degli Habitat (Dir. 92/43/EEC): specie caratteristiche, specie diagnostiche, specie tipiche” (From phytosociology to habitat monitoring (Dir. 92/43/EEC): characteristic, diagnostic, typical species). We thank all the participants.
G.Bo., E.F., L.L. M.G.S. joint first authorship.
S.B. conceived the idea of the workshop. S.B., G.Bo., E.F., L.L., M.G.S. conceptualization of the manuscript. A.T.R.A, M.A., S.P.A., S.B., G.Bo., M.Cac., V.D.C., E.F., A.R.F., D.G., L.L., G.R., M.G.S., G.T., B.V., D.V. organized the workshop. S.B., G.Bo., M.Cac., D.G., E.F., L.L., M.G.S. structured the workshop sessions. G.Bo., E.F., L.L., M.G.S. drafted the original manuscript, with contribution of A.T.R.A., S.B., D.G. All the co-authors commented on the manuscript.