{'fraction_non_alphanumeric': 0.03451851851851852, 'fraction_numerical': 0.01925925925925926, 'mean_word_length': 4.852188990030342, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
ASSESSMENT OF THE CURRENT DISTRIBUTION, DISPERSAL TRENDS AND IMPACTS OF INVASIVE SPECIES IN BANA-NUI CHUA NATURE RESERVE, VIETNAM

Invasive species threaten the biodiversity and the function of ecosystems. Drone image, satellite images, and image analysis software were used to create the map of invasive distribution and the potential spreading of invasive plants. 13 most invasive plants were identified with 11 species listed as invasive species in Southeast Asia and 5 of them in the 100 world’s invasive species by IUCN. Three species Merremia boisiana (Gagn.) van Ooststr., Ipomoea eberhardtii Gagn, and Mimosa pigra were identified as the species with high-ranking impacts on biodiversity and ecosystem biodiversity in Ba Na Nui Chua Nature Reserve (BNNR). Ipomoea eberhardtii Gagn shows the highest spreading rate at 0.65 ± 0.06 ha/month, followed by Merremia boisiana (Gagn.) van Ooststr) and Mimosa pigra at 0.12 ± 0.01 ha/month and 0.01 ± 0.001 ha/month respectively. Fresh biomass of Ipomoea eberhardtii Gagn; Merremia boisiana (Gagn.); Mimosa pigra and Sphagnetola trilobata (L.) Pruski in BNNR are 15.67; 14.9; 8.1 and 6.8 ton/ha. The database of invasive plant distribution and potential spreading will be used to monitor strategies and invasive weeds management in BNNR.


Introduction
Ba Na -Nui Chua Nature Reserve (BNNR) has a total area of 26.8 ha [1]. It is located on the border between Da Nang city and Quang Nam province, Vietnam. Lowland evergreen forest and evergreen lower mountain forest are 2 main types of natural vegetation. There are 793 species in the flora, divided into 487 genera and 134 families. 19 species are listed in the Red Book of Vietnam [2] The fauna of BNNR has 256 species, of which there are 61 mammals, 179 birds, and 17 reptiles (belong to 8 families) Recently, Da Nang's ecology has been negatively impacted by a variety of causes, one of which is environmental weeds. Since 1999, thousands of hectares of special-use forest in Da Nang City have been reported to be overwhelmed by invasive liana species. In the nearby BNNR, about 300 ha of forest has been affected by invasive woody vine (Merremia boisiana.). In all locations these woody vines are climbing and covering the forest canopy, killing hosts and understorey plants by preventing them from absorbing sunlight. These invasive plants often increase the likelihood of forest fires because their big, dense leaves quickly catch fire, even though they are green [3]. BNNR is in danger by the rapid spread of invasive species. Many of them have covered a large area of the natural forest in the Reserve and had an impact on native biodiversity. In addition, forest loss and degradation due to the rapid development of construction such as hotels, resorts, traffic roads in BNNR have created favorable conditions for invasive plants to thrive.
The database of invasive species has an important role in controlling their impacts. However, there is no comprehensive research to determine the impacts of the invasive species in BNNR, especially new exotic species, which have occupied only a small area but are potential threats to forest and agricultural ecosystems. In this research, we identify the invasive species, assess their presence, dispersal trends, and impacts on the local biodiversity in BNNR by an invasive species assessment protocol and using satellite images, drone image, and image analysis software.

Transect-Method and Quadrat Sampling
14 transects (3 to 18 km in length) were set up and investigated from July to November 2018, crossing over different habitats: planted forests, natural forests, forest sides, alongside streams, roadsides, cropland, grasslands, orchards, vacant lands, and swamp in BNNR.
The line-intercept transect-method [1] with quadrat of (5×5m) and (1x1m) was used in the survey transects. Quadrat size depends on the type of species (tree, vine, or herb…). Inside the quadrat's perimeter, invasive plants were established, and the total number of individuals of each was registered. Transect locations and lengths are shown in Figure 1 -A comprehensive list of invasive species was documented based on the creation of a system of symbols and annotations.
-Exporting maps to PDF or PNG formats. References such as An Illustrated Flora of Vietnam [5], Vietnam Forest Trees [6] as background data for field observers. For unknown weed species, herbarium specimens were collected to identify in the laboratory [4].

Invasive Species Assessment Protocol
The species were identified as Invasive Alien Species (IAS), Likely Invasive (L.IAS), or Potentially Invasive (P.IAS) based on the criteria described by the Massachusetts Invasive Plant Advisory Group [7], IAS in South-Southeast Asia by Global Invasive Species Programme [8] and the Circular N35/2018-BTNMT by the Ministry of Natural Resources and Environment, Vietnam.
The methodology for surveillance of invasive alien plant species was based on an Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity, Version 1, [9] We redesigned the protocol for applying in our study area condition. 13 assessmentweighted multiple-choice questions were grouped into five sections that addressed five major aspects of an invasive species' total impact: 1. Ecological impact (4 questions); 2. Current distribution and abundance (2 questions); 3. Trend in distribution and abundance (3 questions); 4. Management difficulty (2 questions); 5. Impact on production and human activities and other factors (2 questions).

Making the invasive species distribution map by using drone image and image analysis software
In this study, one of the popular drones (DJI Mavic Ari) was used. Drone images were taken during the automatic flight using a smartphone application provided by (DJI GO 4). Images were taken in BNNR and buffer zone with total of 165 points.
The steps for creating a distribution map of invasive species by using satellite images, drone image, and image analysis software were described below: (1) Collecting data -Collecting Background maps of Danang city.
-Collecting drone images of invasive species in the field.
-Using Vtool packages in MapInfo software to analyse satellite images (from Google Earth, Sentinel-2, and Landsat 8) and drone images. Comparing drone images with aerial images provided by National Geographic Information Institute.
(2) Building the database -Standardizing the content layers.
-Selecting the satellite images with the best quality, then comparing the resolution of the layers based on drone image coordinates collected.
-Checking and fixing database errors.
-Exporting a relevant datasheet.
(3) Building the map of invasive plant distribution and the potential spreading of the invasive plants.
-Overlapping layers and editing maps according to different contents.

Diversity of Invasive Species in BNNR
The composition of invasive plant species in BNNR was listed in (Table 1). A total of 13 invasive plant species have been explored, among which 5 species are listed in Standardizing the database layers Select the satellite images with high quality Capturing drone images Using Image analysis software; Distribution and potential spreading of the invasive plants Distribution and potential spreading map of invasive plants 100 of the world's worst invasive alien species by IUCN [10], 11 species in the list of invasive species in Southeast Asia, and 6 species are ranked as invasive alien species according to Circular #35/2018TT-BTNMT by the Ministry of Natural Resources and Environment [13].
The appearance of few "super invaders" can be a consequence of increased resource availability and altered disturbance regimes associated with human activities [11]. The roads cross the natural forest and the other habitats provide sufficient photosynthetic conditions for the invasive species growing when most of them are lightdemanding plants. The better light conditions and less competition in space enhance the invasion of non-native plants over mountain vegetation. More than 90 percent of invasive species can be found along the roads to the forest. In addition, the roads and constructing activities have contributed to the rapid spread and reproduction of invasive species. Indeed, their seeds can be dispersed through long distances by floodwaters, and distributed along the riverside. After that, they will be taken and transported to other locations by the sand exploitation process in the river for material building that accidentally spread the invasive species in BNNR.

Evaluating Impacts of Invasive Plants on Biodiversity
In order to assign each Invasive Species Impact Rank (IRank) of High, Medium, Low or Insignificant on natural biodiversity within the study area, the protocol includes 13 questions were used. Each species was assessed by considering these questions, with the answers used to calculate a subrank for each of the five sections. An overall I-Rank was then calculated from the subranks. The results of the Invasive Species Impact Rank (I-Rank) in BNNR are shown in Table 2.

Figure 3. (a) Merremia boisiana covers the nature forest and (b) planted forest canopy
Acacia auriculiformis planted forests were threatened by Merremia boisiana. Vines are climbing and covering the forest canopy, killing the trees below by preventing them from the sunlight. Most native trees cannot compete with these species.
Most of Pinus kesiya Royle ex Gordon in the study area was covered by Ipomoea eberhardtii Gagn. Pinus mixed with broad-leaved trees is the main forest type of Nam Hai Van forest types and BNNR buffer zone.
Ipomoea eberhardtii Gagn and Merremia boisiana (Gagn.) van Ooststr were growing very fast. According to the Phuong Vo [12], the growth rate of Ipomoea eberhardtii Gagn was 6.4cm/day by marking and measuring treetops length at least once every 2 days. The growth rate of Ipomoea eberhardtii Gagn was higher than that of Merremia boisiana (Gagn.) van Ooststr by 0.45cm/day in the Son Tra Nature Reserve. Merremia boisiana (Gagn.) can be found from 300 m to 900m above sea level [12].
In this research, the growth rate of Merremia boisiana (Gagn.) and Ipomoea eberhardtii Gagn were 2.0 and 2.4 cm/day, Ipomoea eberhardtii Gagn distributed at higher 300m hight of sea level (in Nam Hai Van area.). Merremia boisiana (Gagn.) distributed almost all of differents elevation from 15m to 1031m above sea level.
Mimosa pigra can be found commonly along roadsides, vacant lands, grasslands, croplands, orchards, swamps. This species has a high potential to harm the farmland by reducing the cultivating area and the corresponding carrying capacity. Miosa pigra reproduces easily by means of buoyant seed pods that can be spread long distances by floodwaters; the seeds can also be widely distributed via agriculture, construction and traffic activities. Fresh biomass of Ipomoea eberhardtii Gagn and Merremia boisiana (Gagn.) in BNNR were respectively 15.67 ton/ha and 14.9 ton/ha that are lower than the results from the research in Son Tra Nature Reserve (25 and 21 (ton/ha) respectively) [12]. However, these species in BNNR are growing very fast and covering a larger forest canopy. The fresh biomass of invasive plants is shown in Table 3. Sphagneticola trilobata (L.) Pruski was introduced as ornamental plants and street trees. This species is increasing in abundance, competing with other common wild plants. Fresh biomass in each plot was high at 6.8 (ton/ha).

Assessment of The Potential Spread of Invasive Plants in BNNR
Drone images were taken in 3 consecutive months and combined with field measurement results. These then were compared with satellite images to create the map of invasive species distribution and potential spreading of the invasive plants. Based on 120 points of monitoring, the results show that the spreading rate of Ipomoea eberhardtii Gagn.was the highest at 0.65±0.06 ha/month, followed by Merremia boisiana (Gagn.) van Ooststr.) and Mimosa pigra. If there are no invasive control methods, nearly 8ha of the forest will be covered by only Merremia boisiana (Gagn.) each year. Assess the potential spreading of the 3 most invasive plants is presented in Table 4.

Conclusion
13 most invasive species were identified in BNNR, of those, 5 species are listed in 100 world's invasive species, 11 species in the list of invasive species in southeast Asia, and 6 species are ranked as invasive alien species according to Circular N o 35/2018-BTNMT. Three species Merremia boisiana (Gagn.) van Ooststr, Ipomoea eberhardtii Gagn, and Mimosa pigra are listed in high ranked impact on biodiversity and ecosystem. Sphagneticola trilobata (L.) Pruski was considered at medium ranked. Fresh biomass of Ipomoea eberhardtii Gagn and Merremia boisiana (Gagn.) in BNNR were 15.67 and 14.9 ton/ha. Merremia boisiana (Gagn.) growth rate was very high around 2.0 to 2.4 cm/day, distributed almost all of differents elevation from 15m to 1031m hight of sea level. The spreading rate of Ipomoea eberhardtii Gagn. was highest at 0.65 ± 0.06 ha/month, followed by Merremia boisiana (Gagn.) van Ooststr.) and Mimosa pigra at 0.12 ± 0.01 ha/month; 0.01 ± 0.001 ha/month respectively. Controlling the potential spreading of these plants should also be emphasized.
Ethics statement: This research is unique and has never been published before. During this review, no animals were treated or given any kind of care. Any of the data was gathered in an unobtrusive and passive manner.