Potential Regeneration and Spatial Distribution model of Saurauia pendula Blume in Mount Slamet, Central Java

Saurauia pendula Blume is a species of genus Saurauia and belong to Actinidiaceae family. Saurauia pendula spread over on several highlands or mountains in Java Island. Mount Slamet is the second highest mountain on Java with naturally good vegetations. The existence of several threats such as forest fires, destruction, deforestation and forest degradation has caused the condition of these plant species to begin to require attention. This study aims to determine the population of S. pendula, its potential regeneration and spatial distribution model in Mount Slamet area. The study was conducted on four (north, south, west and east) slopes in 2019-2020. Research on population conditions was carried out by following hiking trails and making new paths around the center of suitable habitat. Coordinate data is taken to make spatial analysis using Maximum Entropy (MaxEnt). The results showed that the number of S. pendula was found on the north, west and south slopes at an altitude of 1010-2024 masl. This species has a significant association with Saurauia microphylla de Vriese., Glochidion obscurum (Roxb. ex Willd.) Blume and Castanopsis argentea. The number of mature plants is 106 individuals, which have important role in the distribution of this plant. Analysis of the spatial distribution model shows that S. pendula is estimated to be widely distributed on the western slopes of Mount Slamet.


Introduction
Saurauia pendula Blume is a species of the genus Saurauia and belongs to Actinidiaceae family.This species spread over on several highlands or mountains in Java Island.Plants of the world online [1] 2023 reported this species has tree form, native range in Java and grows primarily in the wet tropical forest.Mount Slamet is the second highest mountain in Java with naturally good vegetation and has become the habitat of S. pendula naturally.In Mount Slamet area, this species and their genus is often called as 'umbel-umbelan' by local people.Plant populations in Indonesia is generally decline including S. pendula the populations are expected decline continuously in nature.The decreasing number of plant populations in nature is due to habitat degradation and land conversion [2] also other factors such as forest fires and other natural disaster.The IUCN redlist [3] states that S. pendula is included in the 'Least Concern' criteria.Even though it has not been included in the list of endangered or protected plant categories, several species of Saurauia in Indonesia have been included in the 'Vulnerable' and 'Critically Endangered' criteria.
Saurauia pendula is a tree-shaped plant [4] or small tree.This species has role as a pioneer plant in open areas or disturbance forest.Besides on being a pioneer spesies, this plant has not yet been further studied for its potential compound.Several species of saurauia are known used as medicine, fruit and raw material that contain many useful compounds.Based on previous research, S. bracteosa leaves are believed to curing diabetes, tumor and cholesterol [5] [6].S. bracteosa contain phenolic compounds, flavonoids and tannins which have anticancer compound [7] and antioxidants [8].The Karonese and Toba people in North Sumatra, use S. bracteosa a lot as traditional medicine [9].S. vulcani also has antidiabetic activity in the leaves [9].Saurauia fruit can also be consumed as a daily fruit [10].
The existence of several threats such as forest fires, deforestation and forest degradation has caused the condition of these plant species to begin to require attention.Regeneration is an important phase in plants to ensure the survival of the species.Research related to the regeneration of S. pendula on Mount Slamet has never been done before.Research needs to be done to determine the potential for regeneration so that the species' ability to face the threat of extinction is known.Knowledge regarding the location of the distribution of S. pendula also needs to be done to predict the area of availability of places to grow this species.The spatial distribution model will help to determining the suitable location if want to increasing the population of S. pendula using reintroducing.
This study aims to determine the S. pendula population, its potential regeneration and spatial distribution model in Mount Slamet.The results of this study are expected to be used as material for developing the potential of S. pendula and conservation efforts basis in the future.

Material and Methods
The study was conducted on the northern, southern, western and eastern slopes of Mount Slamet.Research on population was carried out by following hiking track and making new paths around the center of suitable habitat.Global Positioning System (GPS) data is taken to make spatial analysis using Maximum Entropy (MaxEnt).

Location and time of research
The research was conducted in the forest area of Mount Slamet.The research location is located in a forest area on the hiking trails of the north, east, south and west slopes of Mount Slamet (Figure 1).The research location is on the southern slope starting from the Baturraden area which is included in the administration of Banyumas Regency.The eastern slope passes through Bambangan Village which is included in the administrative area of Purbalingga Regency and Pemalang Regency.Kalikidang Village was chosen as a representative from the western slope which is part of the administrative area of Brebes Regency.Meanwhile, the northern slope of the study starts from the Guci area, Tegal Regency.The elevation of the research location on each slope varies between 600-2500 meters above sea level.The research was conducted from 2019 to October 2020 which included collecting field data, inventorying plant numbers and identifying herbarium specimens.

Equipment and material
The tools what used in this study included GPS (Global Positioning System), diameter tape, roll meters, soil testers, poles, compact laser distance meters (Leica geosystem).The materials that became the main object of this research were all species of Saurauia spp.which grows naturally in the forest area of Mount Slamet.

Data colllection
The data collection method used the exploration method by following existing hiking trails in the forest area of Mount Slamet for found the presence of S. pendula.The GPS coordinate was taken at the location where S. pendula was found.The data collected included the number of individual S. pendula, stem diameter (DBH) and plant height.Height and diameter data are used to determine the tree phases of S. pendula whether it is in the seedling, sapling, poles or trees phases.Flowering and fruiting data were recorded to determine the generative phase of each individual.A 20x20 m 2 plot was made to find out the associated trees that grow around the habitat of S. pendula.Mueller-Dombois & Ellenberg in 1974 [11] mentioned purposive sampling with an area of 20x20 m2 at the location where the target species was found.Additional track was made at the location of the distribution centre of the S. pendula population. .The environment data was taken includes the habitat characteristics and elevation.These data are recorded in each plot.Other environmental parameters such as slope, aspect, temperature, air humidity, pH and soil moisture were taken.Sample plots which there are no S. pendula plant also taken for comparison the association plant analysis of S. pendula.

Data analysis 2.4.1. Population structure and composition analysis.
The population structure and composition of S. pendula was analysed based on the number and individual species found.Each individual is classified into a tree growth phase based on the height and dbh of the plant as shown in Table 1.The generative phase of the plant is determined based on the presence or absence of flowers and fruit in each individual as shown in Table 2.

Association of S. pendula with other tree species
The association between S. pendula and other tree species was analyse using a 2 x 2 contingency table for each species pair as shown in Table 3. Note: a = number of observation plots where S. pendula and species x were found, b = number of observation plots found S. pendula, but not species x, c = number of observation plots found species x, but not S. pendula, d = the number of observation plots was not found for both species.
Then tested using the Chi-Square test [12]: Note: The characteristic of the association is known by comparing the observed value for x (F(x)) with the expected value (E(x)).If F(x) > E(x), then the association is positive.If F(x) < E(x), then the association is negative [12].The magnitude of the association between S. pendula and other plant species is calculated using the Jaccard Index with the following equation [12]: (2) Note: IJ = Jaccard Index, a = number of observation plots where S. pendula and species x were found, b = number of observation plots found S. pendula, but not species x, c = number of observation plots found species x, but not S. pendula.

Spatial Distribution Analysis
Spatial distribution model was carried out using Maximum Entropy (Maxent) software v3.3 with environmental parameters data which predicted has the influence on the S. pendula presence.Leathwick et al., 2006 [13] stated that Maxent is a modelling tool for spatial distribution that shows good performance.The parameters used in the analysis include elevation (topography), slope, slope direction (aspect), maximum temperature in the dry season, minimum temperature in wet season, highest rainfall, lowest rainfall and average rainfall.Environmental parameter data is processed in the form of raster maps using ArcMap 10.3 (ArcGIS) and QGIS3 software.Modelling is done by combining several map layers on various parameters.The results of the analysis are used to predict the location of the presence of S. pendula widely in the Mount Slamet area.In addition, the results of the analysis are also used as a prediction of the location of conservation and reintroduction of S. pendula in the Mount Slamet area.

Result and Discussion
The results showed that S. pendula can still be found in the Mount Slamet forest area.The total number of S. pendula individuals was found on Mount Slamet 382, spread over the northern, western and southern area.This plant was found at an altitude of 1010-2024 m asl which consisted of 223 seedlings, 129 saplings, 19 poles and 11 trees.S. pendula has a good population structure indicated by the number of individuals in each tree phases.The population structure with a triangle shape indicates that the regeneration potential of S. pendula is in good condition.The greater number of individuals in the younger phase indicates an ideal regeneration of S. pendula population in Mount Slamet.Saurauia pendula is species that reproduces through seeds naturally.Population growth of S. pendula is strongly influenced by the availability of fruits and seeds produced by mature individuals.Information about the number of individuals and natural fruit available is needed.Jamsari, Yaswendri and Kasim, 2007 [14] stated that knowledge that related to flowers and fertilization development wii be an important information for the species plant expansion knowledge.The distribution of the diameter and height of trees are varied.The S. pendula population has a complete distribution of stem diameters at each level.In addition, the number of individuals with a smaller diameter is greater than the level above.The population diameter was dominated by <10 cm dbh with a total number 339 individuals.
Saurauia pendula has a complete flower structure that is bisexual.Genus Saurauia has flowers that are bisexual and has several stages of development [15].The majority of S. pendula flowers are in the leaf axils and the ends of the branches.Van Steenis, 2010 [16] states that the genus Saurauia often flowers in large numbers which appear in the leaf axils.He added several species, flowers appearing on old stems and branches.The number of mature S. pendula found was 106.The number of juvenile individuals is greater than the mature.The abundance of juvenile species available to the next regeneration of S. pendula.Some species of Saurauia, have a dehiscent pericarp and slightly dry.The seeds of the genus Saurauia spread through rain and animals such as birds [17].The fruit of S. pendula is generally in the form of a berry and the seeds are in a thick, slimy liquid that is sticky, sweet and edible.Table 5 shows the overall population of S. pendula which was found to be dominated by the juvenile phase of ± 65.83% and the adult phase of ± 34.16%.These conditions strengthen the picture of ideal population conditions and the successful regeneration of S. pendula.If there is disturbance in the Mount Slamet forest area, the mature can be replaced by abundant of juvenile.Figure 2 shows the distribution at height of 1.6-2.5 m individuals of S. pendula which have flowered although the majority have not yet flowered.Picture. 2 also shows that in individuals with a height of >5.5 m it is certain that they have started to flower or bear fruit.There were no S. pendula species that had not yet flowered or fruit at a height of >5.5 m.The results of the plant association analysis showed in table 6. Saurauia pendula was associated with 28 tree species which founded around the S. pendula growth location.All of these species association belong to 20 different families.The table 6 also shows the tree species that are significantly associated with S. pendula.There are 4 tree species that have associations at the 95% confidence level, namely Pinus merkusii Jungh.et de Vriese, Saurauia microphylla de Vriese, Glochidion obscurum (Roxb.ex Willd.)Blume, and Castanopsis argentea (Blume).The Jaccard index value is below 0.22, which indicates the strength of the association is in the very low category [18].Pinus merkusii has the highest index however, there are exceptions because this species is a species planted intensively for production purposes.The natural plant that has the highest association with S. pendula is S. macrophylla.Saurauia pendula has an association value 0.1219 with S. microphylla and has negative correlation.The association of both species is negative indicated by value of F(x)<E(x) [12].Saurauia pendula and S. microphylla are different species belonging to the same genus and family.There is a competition potentially from the existence of the two species because they compete for the same nutrients in the same habitat.Morin, 2011 [19] mentioned that the negative interactions of two or three species that live in the same niche or trophic level will tend to form interspecific competition.The existence of interspecific competition results in reduced abundance, decreased phenotype or decreased in some phenotypic components such as body size, growth rate, fertility or survival.This can happen because the two species live in the same habitat so they tend to compete with each other.Note: NS= Not Significant; The Jaccard index shows the degree of association at α 0.05; df=1; a value of 0 is equivalent to no association; a value of 1 is equivalent to the maximum association level.
Saurauia pendula and S. microphylla are members of the same genus, most likely having almost the same characteristics and needs so that interspecific competition interactions emerge.Whittaker and Likens 1975 [20] state that negative associations are interpreted as having a tendency to negate one another or can mean having different influences in the same environment.Glochidion obscurum and Castanopsis argentea have significantly different associations with S. pendula.The nature of the association of the two species is positive.This shows that S. pendula has the potential to coexist with G. obscurum and C. argentea.The conservation strategy that can be implemented to protect these species is to protect forest areas on the northern and western slopes with elevations between 1010-2024 m asl.This area become a potential natural habitat for S. pendula population.This area also more suitable for S. pendula reintroduction program in the future.The results of the analysis show that the 3 most influential parameters in S. pendula modeling are elevation by contribution of 68.8%, slope direction (aspect) 15.6% and slope of 9.4%.While the rest is influenced by other parameters such as rainfall and temperature distribution.The Area under the curve (AUC) test and AUC training values in the distribution model were 0.957 and 0.973, respectively.Thus, the results of this modeling can be categorized as very accurate.

Conclusion
S. pendula has a good population structure.This is indicated by the number of individuals in each tree phases.The population structure with a triangle shape indicates that the regeneration potential of S. pendula is in good condition.The greater number of individuals in the younger phase indicates an ideal regeneration for S. pendula in the Mount Slamet.S. pendula is associated with 28 tree species found around its habitat belong to 20 different families.Saurauia microphylla de Vriese., Glochidion obscurum (Roxb.ex Willd.)Blume and Castanopsis argentea significantly associated with the S. pendula.The distribution of S. pendula is spread throughout the slopes of Mount Slamet with the majority being in the direction of the north-western slope.This area suitable for reintroduction and conservation area for S. pendula.

Figure 2 .
Figure 2. Correlation of individual height distribution of S. pendula (T > 1.5 m) with the flower and fruit abundance.

Figure 3 .
Figure 3.The spatial distribution model analysis result of S. pendula using Maxent software.

Figure 3
Figure3shown the results of the of S. pendula spatial distribution model.Analysis of the spatial distribution model shows that S. pendula is estimated to be widely distributed on the western slopes of Mount Slamet.The distribution of S. pendula is spread throughout the slopes of Mount Slamet with the majority being in the direction of the north-western slope and decreasing on the southern and eastern slopes at an elevation of 1010--2024 m asl.Meanwhile, the hole in the middle indicates a location that exceeds the altitude of the S. pendula habitat.The area is likely to be at an elevation of >2024 m asl.The conservation strategy that can be implemented to protect these species is to protect forest areas on the northern and western slopes with elevations between 1010-2024 m asl.This area become a potential natural habitat for S. pendula population.This area also more suitable for S. pendula reintroduction program in the future.The results of the analysis show that the 3 most influential parameters in S. pendula modeling are elevation by contribution of 68.8%, slope direction (aspect) 15.6% and slope of 9.4%.While the rest is influenced by other parameters such as rainfall and temperature distribution.The Area under the curve (AUC) test and AUC training values in the

Table 1 .
Classification of population growth phases based on height and stem diameter (dbh)

Table 3 .
Pair contingency 2 x 2 for tree species association

Table 4 .
Saurauia pendula Blume populations found in Mount Slamet area based on their life phase and location where they were found.

Table 5 .
Number of S. pendula individuals (T>1.5 m) mature (already flowering) and juvenile in each slope of Mount Slamet.

Table 6 .
Association analysis results of S. pendula with 28 other tree species.