Learning plant biodiversity beyond the classroom.

Outdoor education and outdoor learning include a set of activities and concepts such as adventure activities, outdoor recreation, place-based learning, environmental education, and experiential education (^{Mackenzie et al., 2018}). Outdoor learning is a ‘broad term that includes discovery, experimentation, learning about and connecting to the natural world, and engaging in environmental and adventure activities’ (^{Institute of Outdoor Learning, 2020}). Although the analysis of historic developments within outdoor education (which has a long history that dates back, at least, to 19^th century) is beyond the scope of this paper, it is worth emphazise not only John ^{Dewey’s foundational contribution to the movement of experiential learning (Dewey, 1938}), studied by several researchers (e.g. ^{Luff, 2018}; ^{Moss and Normore, 2006}), but also the pioneer role of Lilian Clarke in outdoor education at United Kingdom (^{Sanders, 2008}). From 1896 to 1926 she has developed at London innovative teaching practices in the design and use of school gardens. Her legacy for contemporary field studies/outdoor education was, among other things, to promulgate the use of the ‘outdoor classroom’ (^{Rickinson et al., 2004}). Later, in the 1940s, it has begun to be argued that ‘all growing children should at least be given the opportunity of gaining an insight into the nature and significance of their actual surroundings’ (^{Tansley, 1945}). In the 1950s, field trips and excursions were perceived by outdoor education researchers as beneficial to student’s educational development (^{NASSP, 1941}) being stated that ‘good learning and the outdoors are inseparable’ (^{NASSP, 1957}). In the 1970s, outdoor learning was valued as a learning methodology through first-hand experience, and as a teaching methodology which uses the real world as a resource (^{Passmore, 1972}). Outdoor recreation/education has even been referred in Scandinavian countries (Denmark, Norway and Sweden) as friluftsliv, literally meaning free/open-air life (e.g. Henderson and Vikander, 2007; Andkjær, 2005)(cit. ^{Bentsen et al., 2009}). Therefore, within outdoor learning literature although the prevalent idea that being in the outdoors provides deeper and real learning opportunities is not a new one (Henderson, 1999; Potter and Gray, 1999)(cit. ^{Zink, 2010}), it has a high relevance due to the current biodiversity loss crisis. This crisis challenge educators, scientists, among other civil society stakeholders to develop outdoor learning initiatives about biodiversity issues within biology and biosphere studies. Biodiversity, a word which is a contraction of biological diversity, is the inherent property of living systems of being distinct and is meant to describe and embrace all the diversity of life found on earth, encompassing therefore biological systems complex functions and processes. The term Biodiversity dates back to the National Forum on BioDiversity, held in Washington, D.C., in 1986, under the auspices of the National Academy of Sciences and Smithsonian Institution (^{National Academy of Sciences, 1988}). Awareness that biological diversity is enormously valuable to present and future generations, notwithstanding it keeps being threatened, lead the United Nations Environment Programme (UNEP) to convene the Ad Hoc Working Group of Experts on Biological Diversity, in November 1988, to explore the need for an international convention on biological diversity. Nowadays, the Convention on Biological Diversity occurs every two years to provide a multi-stakeholder global legal framework for action on biodiversity at the Conference of the Parties (^{Secretariat of the Convention on Biological Diversity, 2020}). However, the national and global efforts to halt biodiversity loss are known to be still far from sufficient, which is a serious threat to environment and our societies. This is currently relevant for plant biodiversity, as ^{Hiatt et al. (2021}) highlighted the need to create authentic research opportunities in plant biology as crucial to address ‘plant awareness disparity’ (PAD), formerly known as plant blindness (i.e., people tendency to neither properly notice nor value plants in their daily lives, in the environment and societies). The higher preference for, superior recall of, and better visual detection of animals compared with plants (in zoocentric societies) can be attributable not only to perceptual factors, but also to cultural factors (e.g., by giving a greater focus on animals in formal biological education) (^{Balding and Williams, 2016}). For these authors, although plant blindness is common, it is not inevitable and therefore strategies to better communicate plant biodiversity and its role in biosphere are highly valuable to counteract this phenomenon. For the purposes of this paper, the term outdoor learning refers to experiences held at two non-native nut tree collections to enrich school curricula about plant biodiversity. Concerning agricultural resources, it is well known that for each country or region, current crop distribution depends not only upon the availability of irrigation water, climate, soil type, but also on the economic and social influences, that will determine, what species of plants to grow, whenever the above specified requirements are met.

Connection to nature.

Human societies are deeply interwoven with nature in several different ways. All around the world it is known that connection to nature and issues of nature conservation vary deeply among different human communities and cultures. Nowadays, with the urbanization of the globe and increasing numbers of people living in cities (^{U.N., 2015}), it seems clear that opportunities for them to establish a connection with nature may be decreasing, while concomitantly, human sprawl threatens the habitat of most wild living species (^{Thompson, 2000}). However, for all societies, nature constitutes the main resource system that provides humans with a huge variety of materials or services, such as foods and medicines, water, furnishings, building materials or, within the set of ecosystems services, air purification, flood regulation and aesthetic appeals or recreation. This later is particularly relevant in societies where an asphalt jungle (Thompson, 2000) brought by an increasing urbanization, has led to a growing need to reconnect young people with nature and to promote outdoor recreation in forests, in green spaces and associated ecosystems (^{Charles et al., 2008}). For these reasons, even if there is a distance between some people and nature, awareness about not only human dependence upon natural systems, but also of the shift to the ethic which sees humanity as part of the biosphere (^{Wilson, 2000}) deserves to be highlighted. This is also ^{Martin and Holdgate (1994}) point of view as they highlighted that even city inhabitants are part of wider ecosystems, based on wild plants and natural vegetation. For this paper scope, connection to nature is studied with a sample of 130 young students aged between 15 and 17 years, with a focus on outdoor visits to two non-native nut fruit tree collections held in Portugal. Around the world, for children living in cities of developing countries and industrialized societies, which are increasingly out of touch with nature, their knowledge about nature differs from the one held by children living in contact with natural systems on a daily basis (e.g. within indigenous cultures of tropical areas in countries such as Brazil, Mexico and other South American countries)(Barraza, 2001; Kinoshita et al., 2006; Bang et al., 2007)(cit. ^{Bartoszeck et al., 2015}). For urban contexts, ^{Thaman (2013}) recommendation concerning young people’s knowledge about nature was that we should assure our children know the names and types of animals, plants and other organisms and the ways ecosystems functions. It has been evidenced that effective environmental education, or simply quality time spent outdoors, could increase care for nature (^{Chawla, 2007}) and connection to nature in individuals (Ernst and Theimer, 2011)(cit. ^{Laird et al., 2014}). For this paper, students’ connection to nature is framed in this perspective of outdoor learning and quality time spent outdoors during students’ exploratory visits to tree collections. It is worth mentioning that there have been developed frameworks and scales to assess the affective, the cognitive and the experiential aspects of individuals' connection to nature, such as the ‘NR scale- Nature Relatedness’ (^{Nisbet et al., 2009}) or the ‘ACHUNAS- Assessment framework for Children’s Human Nature Situations’ (^{Giusti et al., 2018}). Although it is beyond this paper’s purpose to assess any relationship between connection to nature and conservation behavior, previous research has shown that childhood experiences of camping, hiking, playing in woods or picking flowers is positively related to protective environmental behaviors in adults (James et al., 2010, Wells and Lekies, 2006)(cit. ^{Hughes et al., 2018}). Therefore, for these authors, there is a positive relationship between connection to nature and conservation behavior. This connection aroused from a direct experience of nature which ^{Zylstra et al. (2014}) considered, based upon their literature review, as necessary to form an ecological consciousness, which motivates care and action.

Assessment of student’s knowledge about Pistachio and Pecan species.

Previously to outdoor visits, a pre-test was fulfilled by participating school students to assess their previous knowledge about Pistachio and Pecan tree species. Pre-test questionnaire had the following two questions: ‘Q1- Do you know Pistachio?’ and ‘Q2- Do you know Pecan?’. Students answered the pre-test before the visit to tree collections and results were quantitatively analyzed in terms of percentage values of students who know the trees versus those who were unaware.

Outdoor visits to Pecan and Pistachio tree collections.

Outdoor visits were held at a Research Institute Campus located nearby the two invited schools; with one located at less than 1 km distance and a second one at 17 km distance. The former group did not need transportation but teachers from the second one managed to provide their students with the required transportation to the Campus by bus. Outdoor visits were scheduled to last 2 hours with a methodology centered on a playful approach, allowing students to freely explore and observe Pecan and Pistachio tree collections, which are located apart one another only by a few meters distance. These tree collections exist in a Portuguese region with a mild climate, that allows outdoor visits to occur almost during all year, except between the coolest periods of late November and February, when minimum average temperatures range between 46ºF (8ºC) to 52ºF (11ºC). These two non-native nut tree collections were planted in the 1980s for agronomic research projects and are currently useful for outdoor learning visits, structured as a complement to enrich classroom curricula about agriculture, plant biodiversity and botany.

During the outdoor visits to the two tree collections students observe different trees organs (e.g., leaves, nuts), feel their texture and look closely with magnifying glasses. A paper map brochure describing the two collection tree varieties names is distributed to students to facilitate their exploration during the visit. They also became aware of their geographic origin, reproduction cycle, among other biological and agronomic features. Pecan [Carya illinoensis (Wangenh.) K. Koch] and Pistachio (Pistacia vera L.) tree collections visited by students were initially planted by researchers with the purpose of evaluating these nut trees’ adaptability to several distinct Portuguese local geophysical and climatic conditions.

Pecan tree collection.

Pecan tree (Fig. 1a , 1b) is the most important nut tree of North America growing on the rich forested bottomlands of the Mississippi Valley as far north as Illinois and west into Texas and Kansas (^{Menninger, 1977}), occurring locally on highlands of Mexico (^{Sargent, 1961}; ^{Menninger, 1977}). They produce edible nuts that have a high percentage of fat, being extensively used in candies and cookies (Stephens, 1973, cit. ^{USDA, 2001}), besides other uses of their by-products (^{FAO, 1995}). According to Texas Pecan Growers Association (^{TPGA, 2015}), United States of America was the world largest producer of pecans, which were also produced in other countries such as Mexico, South Africa, Israel, China, Argentina, Australia and Brasil. Commercial planting of pecans started in the 1880s at USA and since then, they took off as a commercial crop in other geographic regions during the following decades.

Figure 1a: Students outdoor visit to the Pecan tree collection. 

Figure 1b: Pecan nut collected by a student. 

Pistachio tree collection.

Pistachio tree (Pistacia vera L., Fig. 2a, 2b) is native from Asia Minor but its cultivation now extends to other geographic places such as India, the Far East, southern United States to California, Mexico into Europe and north Africa (^{Menninger, 1977}). Pistacia vera L. is economically important as the source of pistachio nuts (FAO, 1995), which is broadly cultivated in Mediterranean countries (^{Humphries, 1982}).

Figure 2a: Pistachio tree collection. 

Figure 2b: Pistachio fruits. 

Students’ knowledge about tree species.

To assess students’ knowledge about these two non-native trees, whose fruits are consumed in Portugal, as whole nuts and/or processed food ingredients, the two pre-test questions were: ‘Q1- Do you know Pistacia?’ and ‘Q2- Do you know Pecan?’. Results from the 130 enrolled students’ answers are shown in Table 1.

Students’ participation in outdoor visits.

During outdoor visits students were eager to observe pecan and pistachio trees. They had the opportunity to collect some biological material and to learn details about each tree geographic origin: Asia for ‘Pistachio’; and North America and Mexico for ‘Pecan’. Students were given the tools to see these nut trees, to understand their differences and became aware about the agronomic studies carried out about these trees’ adaptability to geophysical and climatic conditions in Portugal and their usefulness to help diversify human diets.

Pre-tests results.

Pre-tests results evidenced existing students’ knowledge gaps about these non-native trees. Pecans were less known for most of students (unknown for 83 %) than Pistacia (unknown for 61%) and during the outdoor visits it was possible to overcome these knowledge gaps.

Outdoor visits results.

The drive to discover, to explore, to understand and use natural resources is perceived as a basic human trait. However, in western societies, the increasing trend of young people to be disconnected from nature (^{Louv, 2005}; Unesco, 2020) is challenging outdoor learning educators, teachers, civil society organizations, among other stakeholders to develop networks to effectively engage them, both cognitively and physically, with natural habitats (e.g., ‘Children & Nature Network C&NN’ in United States of America, ^{Charles et al., 2008}; or ‘Reef Guardian Schools Program in Australia’, ^{GBRMPA, 2020}). Nowadays young people engagement with nature, biodiversity and even with humanized biodiversity of cities, namely agricultural fields (^{Arya, 2012}; ^{Thaman, 2013}) is increasingly relevant and it is even perceived as a must. According to ^{Uno (2018}) we need to expose students to the beauty, excitement and wonder of plants, and to their importance for people lives and our countries’ future. Effective outdoor learning initiatives, or simply quality time spent outdoors, have been suggested to help increase connection to nature in individuals (Ernst and Theimer, 2011)(cit. ^{Laird et al., 2014}) and for this study, connection to nature was precisely interpreted and framed as such. Therefore, in this study, connection to nature consisted in students’ outdoor visits, which allowed them to train their observational skills, using eagerly the magnifying glass provided. These are results in agreement with Arya’ (2012) findings about field studies concerning botany, held at different settings such as agricultural fields, natural parks or botanical gardens. Students also become aware that the worldwide diffusion of plants, which has occurred throughout millennia, is still highly relevant nowadays within the current climate change scenarios. Concomitantly, the Food and Agriculture Organization (FAO, 2015) presumed as likely that climate change will need more international exchanges of genetic resources as countries seek to obtain well-adapted crops, livestock, trees and aquatic organisms