Exploration of biological diversity and utilization of plant resources in Thailand has been an ongoing effort, encompassing both areas of base surveys and specific group-focused investigations (Sudchaleaw et al., 2023); (Boonma et al., 2023); (Panyadee et al., 2023); (Ragsasilp et al., 2022); (Pansumrit et al., 2022); (Sutjaritjai et al., 2022); (Saensouk et al., 2021). This research unveiled that biological diversity of plant species, varying across different regions, consistently generates new knowledge and insights. While studies on plant diversity in ecotourism areas in Thailand have provided limited information, most research has focused on national parks, such as Doi Inthanon National Park, Phu Kradueng National Park, Khao Yai National Park, and Kaeng Krachan National Park.

Chiang Mai Province, located in the northern region of Thailand, has a tropical monsoon climate. The average temperature ranges from 22.3 ^oC to 34.4 ^oC, with annual rainfall of 972.1 mm (Center, 2020). With its mountainous terrain, there are many cultural tourist attractions situated on various mountains outside the boundaries of national parks. With a well-preserved environmental system, these factors make it feasible to promote sustainable ecotourism destinations in the future, facilitating easier access for visitors.

Phra That Si Mueang Pong, also known as the White Pagoda, stands as a prominent cultural and ecological tourist destination within the province of Chiang Mai. It is situated on the summit within the Aranyawat Temple in Hang Dong District, Chiang Mai, Thailand.

There are two routes to reach Phra That Si Mueang Pong, i.e., one involves climbing the stairs, while the other allows for driving up the road. The ascent via the staircase serves as an ecotourism route, winding through mixed deciduous forest and dry dipterocarp forest. During the climb to Phra That Si Mueang Pong, both sides of the staircase are influenced by significant factors contributing to plant diversity. One side is situated near the Mae Tha Chang River, while the other side borders an agricultural area, resulting in distinct variations in plant diversity.

Therefore, this study investigated the diversity of tree species along the ascent to Phra That Si Mueang Pong in the ecotourism area, encompassing detailed analyses of biodiversity index and importance value index. The findings from this study were expected to benefit the local community, tourists, as well as educational institutions in the vicinity to utilize the area for studying ecotourism, focusing on the diversity of tree species. Additionally, this research provided foundational information for future studies in various research areas.

In the survey of tree species across all 10 subplots, a total of 157 trees were identified, representing 20 families, 28 genera and 30 species (Table 1). The dominant species with their relative abundance percentages were Lagerstroemia duperreana var. duperreana (10.2%), Shorea siamensis (9.6%), Pterocarpus macrocarpus (8.3%), Tectona grandis (7.0%) and Vitex canescens (6.4%), respectively (Table 1). Families with the highest number of species encountered were Fabaceae (6 species), Lamiaceae (3 species), Combretaceae (3 species), Malvaceae (2 species), respectively

Comparing the findings of this study with those of previous research, the identified plants were commonly encountered in mixed deciduous forests and dry dipterocarp forests in Thailand (Chernkhunthod & Hioki, 2020); (Rundel et al., 2017))=. Additionally, some plant species considered rare were identified in the area, such as Sindora siamensis, Vitex pinnata, Terminalia corticosa, Sterculia villosa, Grewia eriocarpa, Irvingia malayana, Stereospermum neuranthum, Schleichera oleosa, Croton persimilis, Aegle marmelos, Protium serratum, Antidesma ghaesembilla, Morinda coreia and Canango brandisiana. These were plant species with fewer than five individuals found within the entire study site.

n the comparison of plant species between plots 1-5 and 6-10, it was found that there were a total of 18 species identified in both areas. Among the tree species found exclusively in plots 6-10, there were 4 species, namely Sindora siamensis, Irvingia malayana, Holarrhena pubescens, and Canango brandisiana. On the other hand, a total of 8 tree species were found exclusively in plots 1-5, including Stereospermum neuranthum, Schleichera oleosa, Vitex pinnata, Sterculia villosa, Croton persimilis, Aegle marmelos, Protium serratum, and Antidesma ghaesembilla. From these results, it was evident that the presence of these plants was influenced by land use in the area. Plots 1-5, situated on the side bordering the Mae Tha Chang River, exhibited a higher number of species and less disturbed environment compared to the other side adjacent to agricultural land. However, when comparing the Shannon’s diversity index and evenness values of plots 1-5 with those of plots 6-10, no statistically significant differences were found (P < 0.05) (Figure 2).

The seven plant species with the highest Importance Value Index (IVI) were Pterocarpus macrocarpus, Lagerstroemia duperreana, Tectona grandis, Shorea siamensis, Millettia brandisiana, Vitex canescens, and Terminalia alata, respectively (Table 1). These species are prominent and commonly found in mixed deciduous forests and dry dipterocarp forests. The results highlighted that the studied area maintained a rich and diverse ecological system. Furthermore, in the comparison of plant species with the red list of threatened species, it was observed that Pterocarpus macrocarpus and Tectona grandis were classified as endangered. Dalbergia cultrate and Aegle marmelos fell under the near threatened status. Those categorized as least concern tree species included Albizia odoratissima, Xylia xylocarpa, Sindora siamensis, Vitex pinnata, Vitex canescens, Sterculia villosa, Hibiscus macrophyllus, Grewia eriocarpa, Irvingia malayana, Schleichera oleosa, and Canarium subulatum.

Analyses of soil physical and chemical properties in the studied area revealed that the soil water content was relatively low, ranging between 5.19% and 7.96%, which was considered normal for soil sampling during the dry season (Hanpattanakit & Chidthaisong, 2012). However, upon comparing the water content between plots 1-5 and 6-10, it was evident that plots 1-5 had higher moisture levels than plots 6-10, and this difference was statistically significant (P < 0.05). The higher water content in plots 1-5 was likely influenced by their proximity to the river. The soil pH was slightly acidic, ranging between 5.09 and 6.53. This mild acidity was attributed to the presence of organic matter from decomposed branches and leaves in the forest. The decomposition process contributed organic compounds, such as humic acid and fulvic acid, resulting in a slightly acidic soil condition (Makan, 2022) (Figure 3).

This study revealed that all identified plant species belong to the ecosystems of mixed deciduous forest and dry dipterocarp forest. There was no evidence of invasive species encroaching from other ecosystems. Soil water and pH levels were within the normal range for the mixed deciduous and dry dipterocarp forest ecosystems during the dry season. The dominant tree species, based on the importance value index (IVI), were Pterocarpus macrocarpus, Lagerstroemia duperreana, Tectona grandis, Shorea siamensis, and Millettia brandisiana, respectively. On both sides of the staircase leading to Phra That Si Mueang Pong, a diverse biodiversity of plant species was discovered, exhibiting distinct variations. The study also identified fifteen species listed in the Red List of Threatened Species (IUCN), with two species classified as Endangered. The Phra That Si Mueang Pong area holds potential for promoting ecotourism, including the establishment of an environmental learning center focusing on the mixed deciduous and dry dipterocarp forest ecosystems within the cultural tourism destination in Chiang Mai Province. Data gathered from this study can serve as a foundation for future research endeavors, particularly in exploring ethnobotany.