Citizen Science, Plant Species, and Communities’ Diversity and Conservation on a Mediterranean Biosphere Reserve

: Citizen science can serve as a tool to address environmental and conservation issues. In the framework of Erasmus+ project CS4ESD, this study focuses on promoting the importance of plants and plant species and communities’ diversity by using available web-based information because of Covid-19 limitations and concerning the case study of Olympus mountain Biosphere Reserve (Greece). A questionnaire was designed to collect the necessary information, aiming to investigate pupils’ and students’ willing to distinguish and learn more about plant species and communities and evaluate information found on the web. Pupils, students, and experts participated in this study. The results are indicative of young citizens’ ability to evaluate environmental issues. They often underestimate plant species richness, endemism, plant communities, the importance of plants, and ecosystem services. They also use environmental or plant-based websites and online available data in a signiﬁcantly different way than experts. The age of the young citizens is a factor that may affect the quality of data. The essential issue of recognizing the importance of plants and plant communities and of assisting for their conservation is highlighted. Education for sustainable development is one of the most important tools that facilitates environmental knowledge and enhances awareness.


Introduction
Citizen science is implemented in many topics, raising awareness and enabling learning, and it can be a tool for environmental and conservation issues [1][2][3][4][5] by providing opportunities to generate new knowledge, enabling learning, facilitating environmental knowledge, enhancing awareness, building capacities, strengthening communities, and enabling civic participation [3,6,7]. Smart mobile devices and online networks are useful for citizen scientists, for data collection, storage, and dissemination [8][9][10].
Conservation-based citizen science includes individuals' awareness for sustainability [1]. Many of the most important current topics, including global warming, sustainability of terrestrial ecosystems, desertification, land degradation, biodiversity loss, food security, and need for new pharmaceuticals, include plants, plant diversity, and plant communities. Sustainable ecosystems can relate to the aims of ecological citizen-science projects, as suggested in the characteristics of citizen science defined by the EU-Citizen.Science project [11]. Citizen science has the potential to contribute to monitoring the progress of the United Nations Sustainable Development Goals (SDGs) [12,13]. Citizens with basic knowledge on plants and plant species and communities' diversity can report accurate data concerning biodiversity monitoring, protection, and sustainability, as targets of SDG 15-Life on Land. SDG 15 is under great pressure from human activities today and could raise the profile of conservation within the broader community [14]. In this context, Ferrari et al. [7] underlined that citizen science is of relevance to environmental monitoring and assessment in the implementation of SDGs. Biodiversity monitoring includes plant species and communities' diversity monitoring and is an issue that is being addressed in connection with SDG 15. The target of SDG 15 is to protect, restore, and promote sustainable use of terrestrial ecosystems, to manage forests sustainably, combat desertification, halt and reverse land degradation, and halt biodiversity loss.
There is an important issue concerning the fundamental inability of humans to recognize the contribution of plants to a functioning planet or to keeping humans and all other life forms alive [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. The inability to see or notice the plants in one's own environment, leading to the inability to recognize the importance of plants in the biosphere and in human affairs, defines broadly plant blindness [30,31]. Overcoming plant blindness, enhancing plant awareness, and promoting the importance of plants can lead to the prevention of their extinction and to their sustainable conservation [9,[32][33][34][35][36].
Education for sustainable development can enable learners develop sustainability competences [37][38][39], including, among others, place-based environmental education and traditional ecological knowledge [40]. It is important to educate young people on the importance of plants, plant species richness, and plant communities for ecosystem functioning at local scales. Biodiversity is critical for ecosystem services and human well-being [41][42][43][44] and young citizens should be informed, educated, and sensitized. Biodiversity can serve both as a regulator of ecosystem functions [45,46] or as an indicator for an ecosystem service, and for this reason, citizen science projects surveying biodiversity are related to ecosystem service assessments [47].
The COVID-19 pandemic highlighted the potential of using data from long-term citizen science projects to answer questions about the impacts of unexpected events on biodiversity [48], creating an opportunity to understand public information-seeking behavior at the human-environment nexus [49]. During the Covid-19 pandemic, it was not possible for researchers and citizen scientists to visit protected areas, national parks, and biosphere reserves for fieldwork and this situation has turned their interest to remote online interactions [50][51][52][53]. Greater visitor engagement has been developed through app-based interpretive and citizen science materials during their national park visits, and app-based citizen science programs like iNaturalist, eBird, etc. [50].
This study is realized in the framework of Erasmus+ project CS4ESD (Citizen Science for Education in Sustainable Development) that uses citizen science-based tools and mobile applications to equip students to engage more deeply with the natural environment. This project is focused on citizens' awareness, especially in protected areas, such as biosphere reserves. Modern ways of recognizing different plant species using smart devices, citizenfriendly applications, and databases concerning plants and plant communities can give them inspiration, cure plant blindness, and make citizens part of the effort to improve some of the serious environmental problems of the new decade. Field visits and field work are necessary to give young citizens the chance to walk through natural ecosystems in protected areas and be educated on how to distinguish different plant species and animal species, to monitor and evaluate plant species and communities' diversity, and to be part of their conservation. The Covid-19 pandemic has deprived pupils and students participating in the project of the opportunity to visit Olympus UNESCO Biosphere Reserve in Greece. Mount Olympus is the highest mountain in Greece, a national park, and a Natura 2000 site. It is characterized by very rich biodiversity, including unique endemic plant taxa and very well conserved vegetation communities.
The Covid-19 pandemic has affected public interest in the world's national parks and a sharp decrease was measured also by the relative search volume on Google Search [54]. In this study, we focus on promoting the importance of plants and plant species diversity to young citizens, pupils, and students, by using web-based information because of Covid-19 limitations, concerning the Olympus mountain Biosphere Reserve. The aim of the study was to investigate their ability to use web-based information on plants and plant communities, their perception of their importance and of the ecosystem services they offer through the case study of Olympus Biosphere Reserve, and to propose how young citizens could contribute more to the targets of SDG 15 and biodiversity conservation.

Study Area-Olympus Mountain Biosphere Reserve
Mount Olympus is a legendary area as the place of the 12 gods of Greek mythology. The highest timberline in Europe occurs on this mountain, which is also characterized by a very rich biodiversity. Mount Olympus National Park (Figure 1) was recognized as part of the international network of UNESCO Biosphere Reserves in 1981. The site of the Olympus National Park Management Agency (https://olympusfd.gr/en/ (accessed on 21 April 2021)) presents information about Olympus Biosphere Reserve's biodiversity. communities, their perception of their importance and of the ecosystem services they offer through the case study of Olympus Biosphere Reserve, and to propose how young citizens could contribute more to the targets of SDG 15 and biodiversity conservation.

Study Area-Olympus Mountain Biosphere Reserve
Mount Olympus is a legendary area as the place of the 12 gods of Greek mythology. The highest timberline in Europe occurs on this mountain, which is also characterized by a very rich biodiversity. Mount Olympus National Park (Figure 1) was recognized as part of the international network of UNESCO Biosphere Reserves in 1981. The site of the Olympus National Park Management Agency (https://olympusfd.gr/en/ (accessed on 21 April 2021)) presents information about Olympus Biosphere Reserve's biodiversity.

Plant and Vegetation Diversity
Concerning the flora of the Olympus Mountain National Park, the site of the Olympus National Park Management Agency mentions in https://olympusfd.gr/en/flora/# (accessed on 12 April 2021) that it represents 25% of all Greek flora [55], and that about 9.4% of the plant taxa recorded in the Olympus area are rare, endemic, and/or protected [56]. This site presents a table with the species protected according to Annexes II, IV, and V of the Directive 92/43/EE and photographs of 25 plant taxa (7 of them endemic and/or protected). Olympus mountain flora are rich in Greek endemic taxa among which 26 local endemics as Jancaea heldreichii (Boiss.) Boiss., a relic of the Tertiary period.
Olympus is characterized by a wide variety of vegetation types formed by its intense topographic relief, short distance from the sea, and the existence of many micro-environments (https://olympusfd.gr/en/vegetation/ (accessed on 12 April 2021)). In general, four vegetation zones can be distinguished on Mount Olympus: i.

Plant and Vegetation Diversity
Concerning the flora of the Olympus Mountain National Park, the site of the Olympus National Park Management Agency mentions in https://olympusfd.gr/en/flora/# (accessed on 12 April 2021) that it represents 25% of all Greek flora [55], and that about 9.4% of the plant taxa recorded in the Olympus area are rare, endemic, and/or protected [56]. This site presents a table with the species protected according to Annexes II, IV, and V of the Directive 92/43/EE and photographs of 25 plant taxa (7 of them endemic and/or protected). Olympus mountain flora are rich in Greek endemic taxa among which 26 local endemics as Jancaea heldreichii (Boiss.) Boiss., a relic of the Tertiary period.
Olympus is characterized by a wide variety of vegetation types formed by its intense topographic relief, short distance from the sea, and the existence of many micro-environments (https://olympusfd.gr/en/vegetation/ (accessed on 12 April 2021)). In general, four vegetation zones can be distinguished on Mount Olympus: i.
Broad-leaved evergreens, at 300-500 m, dominated by shrubs and low trees, such as Quercus ilex L., Arbutus andrachne L., Quercus coccifera L., Arbutus unedo L., Juniperus oxycedrus L., etc., and deciduous species, such as Fraxinus ornus L., Acer monspessulanum L., Cercis siliquastrum L., and Cotinus coggygria Scop. ii. Forest of beech-fir and mountain conifers, at 600-1400 m, with pure stands of Pinus nigra J.F. Arnold. Species like Abies borisii-regis Mattf., Fagus sylvatica L., Ulmus glabra Huds., and Taxus baccata L. participate in smaller clusters and stands. iii. Cold-hardy conifers, adapted to specific local conditions, at 1400-2500 m, with Pinus heldreichii Christ predominating among pines on dry with rocky slopes. iv. Non-forested high mountain meadows and grasslands displaying great plant diversity are found above 2500 m, which is also the highest tree line in the Balkans. v.
There are also azonal forests with Platanus orientalis L., Salix alba L., and Salix cinerea L.
Olympus Biosphere Reserve includes 19 habitat types included in Annex I of Directive 92/43/EE of which four are of priority for protection (species-rich Nardus grasslands, on siliceous substrates, Tilio-Acerion forests of slopes, screes, and ravines, Mediterranean pine forests with endemic black pines and Mediterranean Taxus baccata woods). Among them, the meadows, and rocky formations of the alpine zone, are of particular importance since they host most of the endemic plant taxa of Olympus Biosphere Reserve.

Data Collection
In the framework of the Erasmus+ project CS4ESD and under the limitations of COVID-19, since a visit to Olympus Biosphere Reserve was not possible, a virtual tour to the area was planned to use the information included in Olympus Biosphere Reserve website and in educational material prepared during CS4ESD concerning plants (diversity and importance), plant blindness, environmental databases, and ecosystem services. A questionnaire for the pupils and students followed this virtual tour to Olympus mountain Reserve (Supplementary Materials File S1). The questionnaire was designed to collect the necessary information, aiming to investigate pupils' and students' willing to distinguish and learn more about plant and animal species and vegetation communities and evaluate information found in the web, and their ability to use and evaluate available environmental data in online sources. This part of the CS4ESD project consisted of different activities: (1) presentation of the project aims (1 h); (2) presentations and discussion about the plant and plant communities' diversity of Olympus Mountain Biosphere Reserve, the ecosystem services, and plant blindness (2 h); (3) presentation of the questionnaire (30 min); (4) online research activity for information concerning different parts of the questionnaire (1-2 h); and (4) uploading of the responses to the questionnaire, and evaluation of the activity (45 min).
We tested this approach using distinct groups of 125 citizen scientists (volunteers, 45% of them residents of an area near or in a biosphere reserve, 55% female and 45% male): the first group included volunteers, non-experts, and school pupils aged 13-17 (69%); the second group included volunteers, non-experts, and university students aged 18-24 (24%); and the third group included experts, biologists, and persons employed in the surveillance, monitoring, and drafting of protected areas (7%). The first two groups were residents or had visited a biosphere reserve; they were informed and taught about plants, plant communities, environmental databases that are free to use, conservation, and sustainable management. The questionnaire was created through Kobo Toolbox in GitHub and had three main parts, all based on information included in the Olympus Biosphere Reserve website (https://olympusfd.gr/en (accessed on 12 April 2021)).
The first part of the questionnaire was completed if pupils and students used the names of plant and animal species as well as vegetation zones and plant communities mentioned in the Olympus Biosphere Reserve website, to find more information in other sites on the web. The second part was based on pupils' and students' ability to estimate the ecosystem services of Olympus Biosphere Reserve. This part included 5 units (selection of provisional, regulating, supporting, and cultural ecosystem services that Olympus Biosphere Reserve offers and their importance), following http://staticweb.fsl.orst.edu/ urban-forestry/questionnaire.html (accessed on 12 April 2021). The third part focused on the importance of plants, with 9 questions following https://edis.ifas.ufl.edu/pdf/4H/ 4H35900.pdf (accessed on 12 April 2021).  appreciate the importance of these ecosystem services (except air quality, where 75% of them identified this of importance, similar to the 18-22 group). Much less than 40% of the 13-17-year-old volunteers group estimated these ecosystem services as of highly valued importance ( Figure 5). The two younger groups of volunteers estimated ecosystem services as being less significant than experts (p < 0.05).The importance of plants also seemed to be highly appreciated by the volunteers aged 18-22 years and experts, since they photosynthesize; provide fresh oxygen to breathe; help in reducing the pollution level; provide a habitat for other plants, animals (including humans), and microbes; play an important role in influencing the climate; are the primary source of food; reduce erosion and prevent flooding, especially trees; and produce a number of medicines made by plants ( Figure S1). On the other hand, the proportions of the younger volunteers (13-17) who estimated that the importance of plants is high are rather low (24-48%) and the difference between them and the experts was significant (p < 0.05).   For information concerning plants, 22 different websites were used, of which three were the most frequently used (more than 15 times) and were mentioned for 41% of the records. These websites include the site of the Olympus National Park Management Agency (Olympus fd, https://olympusfd.gr/en/# accessed on 12 April 2021), the "Greek flora" (https://www.greek flora.gr/ accessed on 12 April 2021), and Flora of Greece Web (http://portal.cybertaxonomy.org/flora-greece/intro 12 April 2021). Additionally, the younger volunteers used Google images of plants with no other information and Wikipedia (Figure 2). Simple statistical analysis results showed that experts used websites in a significantly different way than the two other groups of volunteers (p < 0.05).

Results
The younger group of volunteers seemed to need less time to complete, fully or partly, the questionnaire, in comparison with the group of volunteers aged 18-22 years, who needed more time than the experts (Figure 2).
Out of the five main vegetation units of Olympus Biosphere Reserve, all vegetation zones were registered together with two more (i.e., tropical forests were registered by about Sustainability 2021, 13, 9925 6 of 11 12% of both groups of non-experts), which are not found in the biosphere reserve and its website. Figure 3 presents differences in the recognition of different vegetation units of Olympus Biosphere Reserve for the two younger age groups.    Figure 4 presents the proportions of the answers concerning the existence of (a) provisional and regulating ecosystems services and (b) supporting and cultural ecosystem services offered by Olympus Biosphere Reserve. The proportions of the answers concerning the ecosystems services offered by Olympus Biosphere Reserve, estimated as of highly valued importance, present significant differences among the three groups ( Figure 5). The most highly valued ecosystem services selected by the volunteers aged 18-22 years and experts included air quality regulation, wildlife habitat, clean water/water quality, contact with nature, biological control, and biodiversity, all directly or indirectly connected with plants and plant and vegetation diversity. The youngest volunteers (13-17) seemed to not appreciate the importance of these ecosystem services (except air quality, where 75% of them identified this of importance, similar to the 18-22 group). Much less than 40% of the 13-17-year-old volunteers group estimated these ecosystem services as of highly valued importance ( Figure 5). The two younger groups of volunteers estimated ecosystem services as being less significant than experts (p < 0.05).The importance of plants also seemed to be highly appreciated by the volunteers aged 18-22 years and experts, since they photosynthesize; provide fresh oxygen to breathe; help in reducing the pollution level; provide a habitat for other plants, animals (including humans), and microbes; play an important role in influencing the climate; are the primary source of food; reduce erosion and prevent flooding, especially trees; and produce a number of medicines made by plants ( Figure S1). On the other hand, the proportions of the younger volunteers (13)(14)(15)(16)(17) who estimated that the importance of plants is high are rather low (24-48%) and the difference between them and the experts was significant (p < 0.05).

Discussion
Successful citizen science and citizen biodiversity monitoring programs and environmental citizenship include three strategies: collectiveness, situatedness, and connectedness [1,57]. Well-organized strategies can drive better use of citizen science associations, online toolkits, data repositories, and network portals, and can improve citizen science's contribution to biodiversity monitoring [57].
The citizen science approach is often applied in the framework of biodiversity monitoring projects [4]. The quality of the data collected by non-experts and the shortcomings of these data in comparison to data collected by experts is a demand and a critical step for evaluating and utilizing such data [4,5,[58][59][60][61]. The answers to the questionnaire, which was built in the framework of this project, are indicative of young citizens' ability to evaluate environmental issues, such as plant characteristics and importance, plant species diversity, different plant communities, conservation, and ecosystem services.
Younger citizens found information for more plant taxa, especially endemics, than others, but the mean number of records was lower, they visited a higher percentage of websites than the citizens of the 18-22-year-old group, and higher proportions of their records were from Google images and from the site of Olympus National Park Manage-

Discussion
Successful citizen science and citizen biodiversity monitoring programs and environmental citizenship include three strategies: collectiveness, situatedness, and connectedness [1,57]. Well-organized strategies can drive better use of citizen science associations, online toolkits, data repositories, and network portals, and can improve citizen science's contribution to biodiversity monitoring [57].
The citizen science approach is often applied in the framework of biodiversity monitoring projects [4]. The quality of the data collected by non-experts and the shortcomings of these data in comparison to data collected by experts is a demand and a critical step for evaluating and utilizing such data [4,5,[58][59][60][61]. The answers to the questionnaire, which was Sustainability 2021, 13, 9925 8 of 11 built in the framework of this project, are indicative of young citizens' ability to evaluate environmental issues, such as plant characteristics and importance, plant species diversity, different plant communities, conservation, and ecosystem services.
Younger citizens found information for more plant taxa, especially endemics, than others, but the mean number of records was lower, they visited a higher percentage of websites than the citizens of the 18-22-year-old group, and higher proportions of their records were from Google images and from the site of Olympus National Park Management Agency (https://olympusfd.gr/en/ (accessed on 12 April 2021)). The age of the citizens is a factor that may affect the quality of citizen science data and could be a more accurate predictor of citizen scientists' abilities [4,62]. Citizens of the 18-22-year-old group needed more time for their answers than younger ones since they mainly found information from two sites concerning the vascular plant diversity of Greece (Flora of Greece Web and Greek Flora). Concerning vegetation units, both groups of young citizens followed information found on the site of Olympus National Park Management Agency, but there were two vegetation units included in the answers that showed uncertainty, indifference, or a possible lack of proper attention. For non-experts, more time is required if they really want to delve into a subject and at least some preliminary training before starting to carry out the task [4,5].
Environmental monitoring and assessment needs citizen science and participatory processes to be relevant for Agenda 2030 and SDGs [7]. Biodiversity monitoring can be supported by citizen science for taxonomic, geographic, and essential biodiversity variables coverage, by building on the interests and needs of participants and providing volunteers and citizen scientists with education, scientific information, tools, and services [57,63].
Education is one of the most important tools and the UN 2030 Agenda acknowledges Quality Education (SDG#4) as a means for achieving the remaining SDGs, with sustainability as a goal for Education [64]. Education allows both experts and young volunteers to understand the importance of sustainable development [39]. Early educational experiences providing equal exposure to plants, microbes, and animals is also crucial for counteracting plant blindness [27], improving children's perceptions of biodiversity [65,66] and young citizens' awareness, especially in protected areas, such as biosphere reserves. Young people can be educated to have the capacity to detect, recall, and evaluate plants [15] and move plants into the foreground of their hearts and minds [33]. Plant species recognition and outdoor education are the easiest way to come closer to nature, ecosystems, and biodiversity [20].
Plants are a particularly important component of biodiversity, playing a fundamental role in ecosystem functioning and have a positive influence on the provision of ecosystem services [67]. Many of the young citizens involved in the current study did not estimate most of the ecosystem services provided by plants and plant communities. There is a need for further affect service provision [44,[67][68][69][70][71][72]. On the other hand, when trying to improve young citizens' knowledge on ecosystem services provided by plants and plant communities, educators should not focus only on plants that are useful to us and lure young citizens into a utility trap [32], which can place the wildness of Earth inside the garden of human concerns [35,73].

Conclusions
Even though it had a narrow scope, this case study revealed young citizens' ability to use web-based information on plants and plant communities of Olympus Biosphere Reserve, which could be much improved through educational experiences as well as their perception of plants and plant communities' importance and of the ecosystem services they provide. It is important to take such results seriously and give young citizens the chance to know the most common plant species in their own place of residence, to know how to find more information about plants, and to understand why plant species are important, through specific educational guidelines [20]. It cannot be denied that mobiles and smart devices, in general, are much more attractive to young citizens than plants and plant communities, but their use can help to promote conservational thinking and to create conceptual knowledge since they also make the learning unit more impressive by rapidly changing images and videos and enabling the education of young citizens with direct feedback [21].
Supplementary Materials: The following are available online at https://www.mdpi.com/article/10 .3390/su13179925/s1, Supplementary File S1: Questionnaire concerning biodiversity of Olympus Biosphere Reserve. Figure S1: Proportions of the answers concerning the highly valued importance of plants.