Evaluation of the Effects of Extensive Recreation on Vegetation and Soil Ecotone of Hormozgan Province

ABSTRACT
The aim of this study is to develop sensitive gully erosion models by implementing a machine learning algorithm (Support Vector Machine and Boosted Regression Tree) in the Moher basin. First, gully areas are identified, and then 13 variables predisposing to gully erosion (Slope, Slope Direction, Topographic Wetness Index, Streem Power Index, Terrain Ruggedness Index, Distance from Waterway, Drainage Density, Distance from Road, Land use, NDVI, Avera annual Rainfall, Geology, and Soil Texture) were selected. The variance inflation coefficient was used to evaluate multicollinearity between variables. Finally, a gully erosion sensitivity map was prepared in the environment (R). Also, the effect of physical and chemical characteristics of soil on gully erosion was investigated using Multivariate Regression. Regarding the importance of variables, Geology has the most significant effect on gully erosion in the SVM model, Land use, and the BRT model. The predicted sensitivity map was validated with the help of the receiver operating characteristic (ROC) curve. The results showed that the area under the curve (AUC) in the Support Vector Machine and Boosted Regression Tree models were calculated as 0.92 and 0.94, respectively, which led to accurate prediction. Also, the results showed that the sand variable (9.299), sodium absorption ratio (7.967), and TNV (6.185) have the most significant effect on gully erosion
Extended abstract
Introduction
Tourism means voluntarily spending a part of free time with the intention of having fun in a place other than permanent residence (Asadpoor Kordi et all, 2023). The tourism industry has various types and every year, millions of people travel to other parts of the world to visit historical areas, have fun, relax, etc. (Fetres et al, 2022). This industry is one of the fundamental factors of sustainable development (Papali et al, 2006), its impact on the social, economic and cultural development of countries is not hidden from anyone (Godovykh & Ridderstaat, 2020; Gursoy et al., 2019). The development of the tourism industry, in addition to the prosperity of related businesses, such as the prosperity of places of residence, restaurants, the management of resorts and travel agencies, has also caused the attraction of foreign capital and, in other words, foreign exchange, after industrial production, with a share of 3.9 percent, the largest share. In the growth of global gross production (Jordan et al., 2019). In addition to economic, cultural and social benefits, tourism also leaves effects on the natural environment of target areas, which can be positive or negative (Akbarian et al, 2021). The amount of changes and the impact of tourism activities on natural environments is a direct function of the intensity of use and the amount of tourist presence, the stability of the region and the variability of the place (Atic, 2009). Tourism activities have caused a 50% increase in soil compaction, which has resulted in a decrease in the intensity of water infiltration in the soil (Webb & Wilshire, 1983) and finally increases the amount of runoff and leaching of soil minerals (Zhongdong, 2010). Soil washing causes a decrease in the number and activity of soil microorganisms, which in turn will result in a decrease in soil fertility.
 
Materials and methods
GNU Protected Area with an area of 44,598 hectares is located 30 kilometers north of Bandar Abbas in the geographical coordinates of 49, 18, 27 to 28, 29, 27 north latitude and 18, 18, 56 to 5, 57 and 56 (Figure 1). This region has a lot of plant diversity due to its special geographical location and the unique feature of being on the border of the transformation of the vegetation of the Iranian-Turanian region to the Sindhi desert (Rezai et al, 2019).
 
Data collection
The research data includes density and percentage of plant species cover, percentage of litter and soil data of the region. For field studies of vegetation and soil profile digging, three representative areas of 5 hectares, a) without tourism pressure, b) with moderate tourism pressure and c) with high tourism pressure, were selected after GNU circulation forest. These areas were almost similar in terms of geological features, direction and slope percentage, but they were different in terms of the type of tourist presence.
The method of estimating vegetative parameters
The variables included plant characteristics recorded in the sampling plots (percentage of the total vegetation canopy, canopy cover of each species in the plot, percentage of bare soil, percentage of pebbles and percentage of litter) as well as soil profile characteristics of all three representative areas.
- Percentage of canopy cover
After the precise determination of the number of plots and the location of the samples, the desired vegetation factors were collected and measured and recorded in the preliminary forms. For this purpose, gridded plots were used to measure the percentage of vegetation cover. In order to estimate the percentage of plant crown coverage, it is assumed that there is no discontinuity in the inside or umbrella of the plant and the plant space around the crown is in the shape of an umbrella. If the root of the plant is outside the plot and the crown of that plant is inside the plot, the percentage of its coverage will be calculated inside the plot (Zerehi et al, 2022). With this calculation, gridded plots of four-square meters were used, which were divided into four hundred houses of 100 square centimeters and each house represented 0.25% (Figure 4b).
- Number of bases per hectare (density)
Density is defined as the number of individuals of each species per unit area and is one of the best numerical indicators to express the quantitative values of a plant community, especially for evaluating tree and shrub communities (Zerehi et al, 2021). In order to estimate the density, all the bases of plant species in the plots were counted and finally the density per hectare of the species was calculated. Also, the presence and absence of the species (abundance) in the recorded plots, the composition percentage of each species was calculated.
In order to obtain the average diameter of tree and shrub species, assuming that their canopy is spherical, two perpendicular diameters of the plant were measured and then the average diameter of the species was calculated (Figure 4c).
- Methods of measuring physical and chemical properties of soil In order to investigate the impact of ecotourism pressure on the soil, 10 soil profiles were dug to a depth of 40 cm in each tourism representative area (Figure 4d).
 
Results and discussion
The results of vegetation and soil measurements. The findings of soil surface cover characteristics, density and height of plant species in low, medium and high-pressure tourism areas are shown in Tables 1 and 2. The measurement of land surface cover in the three representative areas under investigation showed that the total amount of vegetation cover in the representative area of low-pressure tourism is 70%, medium pressure tourism is 45.3% and high-pressure tourism is 23.1%. Accordingly, the percentage of bare soil in these sites is 6.5, 17.3, and 25.6 respectively, the percentage of litter is 4.5, 2.2, and 1.1, respectively, and the amount of stone and gravel in these three sites is 19, respectively. 35.2 percent (Table 1).
The total density of these species in low pressure tourism area is 16,500, medium pressure tourism is 12,000 and high-pressure tourism is 10,750 plants per hectare.
The results of the research show a significant deterioration of all the characteristics of the vegetation in the GNU region, including the density, canopy percentage and height of tree, shrub and bush species with increasing tourism pressure. Most of the researches have confirmed that plants are affected by recreational activities and it has been proven that there is a negative correlation between the intensity of tourism and the percentage of vegetation cover, plant height and species diversity (Cakir et al., 2010). Some researchers have reported that increasing the number of recreational activities even leads to a decrease in the height of plant species and also reduces the percentage of foliage cover of plant species (Turton, 2005).
 
Conclusion
 In the current research, in terms of height, there is a statistically significant difference between all three tourist areas. The height of different vegetation forms of bushes, trees and shrubs has an inverse relationship with the increase in the intensity of tourism activities, and its average in the low tourism zone is higher than the average of this feature in the medium tourism zone, and it is higher than the height of the vegetation forms in the high tourism zone.
 
Funding
There is no funding support.
 
Authors’ Contribution
All of the authors approved the content of the manuscript and agreed on all aspects of the work.
 
Conflict of Interest
Authors declared no conflict of interest.
 
Acknowledgments
We are grateful to all the scientific consultants of this paper.