Safeguarding biodiversity is an important component of the REDD+ scheme of the United Nations Framework Convention on Climate Change. Information on tree species and their distribution is therefore needed for successful implementation of forestry carbon projects. Forest inventory data were collected in four natural forests located in Popa Mountain Park, Myanmar. Based on the data from 4-ha sample plots, average stem density ranges from 1293 trees ha -1 in dry dipterocarp forest to 804 tree ha -1 in dry evergreen forest. According to the Jackknife estimator for species richness (trees with DBH ≥ 5 cm), the highest number of species was recorded in dry mixed deciduous forest—74 species ha -1, and the lowest number of species recorded in dry forest—40 species ha -1. Dry mixed deciduous forest occupied the highest value on the Shannon-Wiener index and Simpson diversity index while the lowest was in dry forest, indicating that dry mixed deciduous forest is the most complex whereas dry forest is the simplest community. Not only does this study provide useful information on the current status of vegetation type but the information is important for designing forestry management systems that could result in biodiversity conservation and carbon emission reductions.
Conservation of natural forest resources is an important component of climate change mitigation strategies in the region [
Biodiversity inventories are used to determine the nature and distribution of biodiversity resources of the forests to be managed [
Myanmar is a heavily forested country with the high rate of deforestation of 0.93% annually in the last decade 2000 and 2010 [
The research was carried out at Popa Mountain Park (PMP), where high diversity of plants (including medicinal plants) were found. The area was classified by Myanmar’s forest department as forest reserve in 1902. Popa Reserve was proposed as protected area by the Nature Conservation National Park Project conducted between 1981 and 1984. The area was subsequently declared a Protected Area in 1989. The park covers an area of about 10,000 ha, of which 88.7% is covered by forest [
A volcanic plug at the western foot of Mount Popa or Taung-kalat in local name, is a prominent landmark and widely known as a religious site for local people. Popa Mountain Park is also an important watershed for the surrounding area (especially for Kyaupadaung Township). Therefore, Popa Mountain Park was designated as a protected area for conservation of the forest, protection of the watershed of the Kyet-mauk-taung dam located at the southern edge of the park, conservation of medicinal plants for sustainable use, preservation of existing religious sites and to ensure sustainability of water sources, including natural springs [
Data for this study were collected from dry mixed deciduous forest, dry dipterocarp forest, dry forest and dry hill or evergreen forest. Twenty five sample plots, each with an area of 400 m2 (20 m × 20 m) were laid out in each forest type. The height (Ht) and diameter at breast height (DBH) of all trees (DBH ≥ 5 cm, Ht ≥ 1.3 m) were measured in each plot. “A Checklist of the Trees, Shrubs, Herbs and Climbers of Myanmar” [
The data were analyzed for species composition, richness, diversity, species Importance Value Index (IVI). The species richness were estimated using the Jackknife estimator [
Species richness is the basic component of diversity of any community [
Tree diversity inclines provide important information about rarity and commonness of species in a community [
Our study findings are in line with the findings of Bhat [
Parameter | DMDF | DDF | DF | DHEF |
---|---|---|---|---|
Species richness (Jackknife estimator) | 74.00 | 53.61 | 45.54 | 40.75 |
Shannon-Wiener function (H’) | 3.61 | 2.96 | 1.45 | 2.41 |
Simpson’s diversity index (1-D) | 0.96 | 0.92 | 0.50 | 0.84 |
Shannon evenness (j’) (%) | 83.95 | 74.62 | 38.08 | 65.36 |
*DMDF = dry mixed deciduous forest, DDF = dry dipterocarp forest, DF = dry forest, DHEF = dry hill/evergreen forest.
Species evenness (E) is a measure of equitability of spread. Values obtained were 0.83 in DMDF, 0.74 in DDF, 0.38 in DF and 0.65 in DHEF. The species in DMDF were more abundant, and the percentage of evenness j (%) was close to 1.0. Therefore, Shannon’s evenness (j) shows that DMDF have highest species diversity and DF have the lowest species diversity in PMP. The slope direction influences tree species diversity at different altitudes [
To assess the species composition and stand structure, the important value index (IVI) was used. No single species clearly dominated in dry mixed deciduous forest (
Among all forest types, the most frequently occurring species is Techtona hamiltoniana (in dry forest), with 610 individuals recorded with a relative frequency of 17.12%. Due almost solely to its high relative frequency, Techtona hamiltoniana also has the highest species importance value of 54.25. The next most frequently occurrance species and most important species are Vitex canescens (in DHEF) with important values of 29.13 representing by 263 individual trees with relative frequencies of 12.72%. Result of our study suggest that Techtona hamiltoniana is an ecologically important species in Popa Mountain Park. In DMDF, 52.59% of the relative abundance included 10 common species (13% of total in DMDF) while 55.45% of RA (Relative Abandance) included five common species (9% of total species) in DDF. In DF only one species made up 70.03% of RA whereas two species made up 52.61% of RA in DHEF. These findings indicate that the number of species per unit area were high in all investigated forests.
At the family level, it was found that the taxonomic composition of the forests in PMP are different. DMDF was dominated by Dipterocarpaceae, Euphorbiaceae and Combretaceae. Dipterocarpaceae also dominant family in DDF, followed by Verbenaceae, Combreaceae. While, Verbenaceae (mainly Techtona hamiltoniana), Combretaceae and Rhamnaceae were the most common forest tree families in DF. In DHEF, Verbenaceae is the dominant family of trees mostly represented by the Vitec canescens tree and Myrsinaceae and Bixaceae (
Dipterocarpaceae family was the family with the highest ecological importance given the IVI value in DMDF. The Dipterocarpaceae with only 3 species ranking 4th in the species-rich family in DMDF, is the most important family based on the IVI values. This highlights that the most species-rich families are not necessarily the most important families based on the IVI values. For example, in DDF, the Dipterocarpaceae with only 3 species ranking 3rd in the species-rich family was the most important family based on the results on IVI. This is due to the high number of individuals and high frequencies. In DF, the highest important value was found in Verbenaceae family, which has 4 species, ranking as the 2nd species-rich family. In DHEF, Verbenaceae family, although with only one species, was the highest ecologically important family according to the IVI value. This is because each species was represented with many individuals.
Verbenaceae, Caesalpiniaceae and Moraceae were observed as species rich families for DMDF, representing 5 species (8% of the total species) in each family (
An approximate indication of the homogeneity of a stand and of high diversity of tree species can be expressed by frequencies [
Scientific name | SD (n/ha) | BA (m2/ha) | V (m3/ha) | RD (%) | RF (%) | RBA (%) | IVI (%) | |
---|---|---|---|---|---|---|---|---|
Dry mixed deciduous forest | Shorea obtusa Wall. | 103 | 3.78 | 29.48 | 9.71 | 2.25 | 13.76 | 8.58 |
Croton roxburghianus N. P. Balakr | 100 | 1.91 | 11.95 | 9.43 | 5.63 | 6.95 | 7.34 | |
Pittosporum napaulensis (DG) Rehder Wilson | 76 | 0.93 | 5.15 | 7.16 | 3.94 | 3.39 | 4.83 | |
Bixa orellana L. | 64 | 1.08 | 6.84 | 6.03 | 3.10 | 3.95 | 4.36 | |
Terminalia crenulata (Heyne) Roth | 41 | 1.83 | 14.07 | 3.86 | 2.25 | 6.66 | 4.26 | |
Flacourtia cataphracta Roxb. | 45 | 0.97 | 5.71 | 4.24 | 3.10 | 3.53 | 3.62 | |
Litsaea glutinosa (Lour) C. B. Cl. | 43 | 0.94 | 6.15 | 4.05 | 3.38 | 3.43 | 3.62 | |
Strychnos potatorum L.f | 40 | 0.52 | 2.66 | 3.77 | 3.38 | 1.89 | 3.01 | |
Dipterocarpus tuberculatus Roxb. | 17 | 1.327 | 16.14 | 1.60 | 1.69 | 4.82 | 2.70 | |
Diospyros spp. | 29 | 0.47 | 3.18 | 2.73 | 3.38 | 1.71 | 2.61 | |
Others | 204 | 5.12 | 42.99 | 47.41 | 30.99 | 18.60 | 22.94 | |
Total | 1061 | 27.52 | 214.69 | 100.00 | 100.00 | 100.00 | 100.00 | |
Dry dipterocarp forest | Shorea obtusa Wall. | 251 | 6.63 | 34.82 | 19.41 | 6.19 | 28.91 | 18.17 |
Dipterocarpus tuberculatus Roxb. | 172 | 5.19 | 34.21 | 13.30 | 5.93 | 22.65 | 13.96 | |
Shorea siamensis (Kurz) Miq. | 121 | 2.16 | 12.38 | 9.36 | 5.67 | 9.43 | 8.15 | |
Terminalia crenulata (Heyne) Roth | 93 | 1.42 | 6.86 | 7.19 | 6.19 | 6.20 | 6.53 | |
Dalbergia oliveri Gamble | 80 | 0.97 | 5.93 | 6.19 | 5.67 | 4.23 | 5.36 | |
Buchanania lanzan Spreng. | 49 | 0.99 | 6.03 | 3.79 | 5.93 | 4.33 | 4.68 | |
Premna pyramidata Wall. | 47 | 1.05 | 6.33 | 3.63 | 4.64 | 4.58 | 4.29 | |
Chionanthus ramiflora Roxb. | 54 | 0.41 | 1.52 | 4.18 | 4.12 | 1.79 | 3.36 | |
Diospyros burmanica Kurz | 49 | 0.59 | 2.93 | 3.79 | 3.61 | 2.56 | 3.32 | |
Wendlandia tinctoria DC. | 44 | 0.34 | 1.15 | 3.40 | 3.87 | 1.47 | 2.91 | |
Others | 333 | 3.18 | 14.66 | 25.75 | 48.20 | 13.85 | 29.27 | |
Total | 1293 | 22.93 | 126.81 | 100.00 | 100.00 | 100.00 | 100.00 | |
Dry forest | Tectona hamiltoniana Wall. | 610 | 20.32 | 160.97 | 70.03 | 17.12 | 75.59 | 54.25 |
Terminalia oliveri Brandis | 75 | 3.48 | 39.71 | 8.61 | 13.01 | 12.94 | 11.52 | |
Tectona grandis L.f | 42 | 0.50 | 2.51 | 4.82 | 6.16 | 1.88 | 4.29 | |
Lannea coromandelica (Houtt). Merr. | 18 | 0.28 | 1.74 | 2.07 | 8.22 | 1.03 | 3.77 | |
Dalbergia oliveri Gamble | 18 | 0.56 | 5.05 | 2.07 | 6.16 | 2.10 | 3.44 | |
Diospyros burmanica Kurz | 10 | 0.12 | 0.52 | 1.15 | 2.74 | 0.45 | 1.44 | |
Morinda tinctoria Roxb. | 8 | 0.07 | 0.21 | 0.92 | 2.74 | 0.24 | 1.30 | |
Acacia catechu Willd. | 6 | 0.12 | 0.74 | 0.69 | 2.74 | 0.43 | 1.29 | |
Dalbergia cultrata Grah. | 4 | 0.09 | 0.52 | 0.46 | 2.74 | 0.32 | 1.17 | |
Albizzia chinensis (Osbeck) Merr. | 3 | 0.25 | 2.80 | 0.34 | 2.05 | 0.94 | 1.11 | |
Others | 77 | 1.10 | 5.57 | 8.84 | 36.30 | 4.09 | 16.41 | |
Total | 871 | 26.88 | 220.33 | 100.00 | 100.00 | 100.00 | 100.00 | |
Dry hill/evergreen forest | Vitex canescens Kurz | 263 | 20.07 | 284.52 | 32.71 | 12.72 | 41.96 | 29.13 |
Rapanea af. Neriifolia (Seib & Zucc) Mez. | 160 | 5.47 | 50.42 | 19.90 | 8.09 | 11.43 | 13.14 | |
Bixa orellana L. | 63 | 1.95 | 15.20 | 7.84 | 9.25 | 4.09 | 7.06 | |
Eriobotrya bengalensis (Roxb.) Hook. f. | 32 | 3.17 | 57.19 | 3.98 | 5.78 | 6.63 | 5.46 | |
Syzygium cumini (L.) Skeels. | 22 | 2.23 | 24.49 | 2.74 | 8.09 | 4.65 | 5.16 | |
Wendlandia tinctoria DC. | 43 | 1.31 | 13.11 | 5.35 | 6.36 | 2.75 | 4.82 | |
Croton roxburghianus N. P. Balakr | 44 | 1.48 | 11.18 | 5.47 | 4.62 | 3.10 | 4.40 | |
Litsaea glutino (Lour) C.B.Cl. | 30 | 2.62 | 25.79 | 3.73 | 3.47 | 5.48 | 4.23 | |
Cinnamomum obtusifolium (Roxb.) Nees | 27 | 0.62 | 5.12 | 3.36 | 4.62 | 1.29 | 3.09 | |
Cissus discolor Blume | 20 | 0.19 | 0.90 | 2.49 | 5.20 | 0.40 | 2.70 | |
Others | 100 | 8.71 | 122.80 | 12.44 | 31.79 | 18.22 | 20.82 | |
Total | 804 | 47.83 | 610.72 | 100.00 | 100.00 | 100.00 | 100.00 |
SD = stand density, BA = basal area, Vol = volume, RD = relative density, RF = relative frequency, RBA = relative basal area.
Family name | NS | SD (n/ha) | BA (m2/ha) | V (m3/ha) | RD (%) | RF (%) | RBA (%) | IVI (%) | |
---|---|---|---|---|---|---|---|---|---|
Dry mixed deciduous forest | Dipterocarpaceae | 3 | 146 | 5.98 | 52.69 | 13.76 | 3.00 | 21.72 | 12.83 |
Euphorbiaceae | 5 | 118 | 2.32 | 17.29 | 11.12 | 8.00 | 8.41 | 9.18 | |
Combretaceae | 4 | 58 | 2.88 | 27.44 | 5.47 | 5.00 | 10.47 | 6.98 | |
Fabaceae | 3 | 52 | 1.41 | 9.81 | 4.90 | 6.33 | 5.11 | 5.45 | |
Pittosporaceae | 1 | 76 | 0.93 | 5.15 | 7.16 | 4.67 | 3.39 | 5.07 | |
Verbenaceae | 6 | 46 | 1.35 | 10.19 | 4.34 | 5.33 | 4.92 | 4.86 | |
Bixaceae | 1 | 64 | 1.09 | 6.84 | 6.03 | 3.67 | 3.95 | 4.55 | |
Caesalpiniaceae | 6 | 39 | 1.28 | 13.41 | 3.68 | 4.67 | 4.64 | 4.33 | |
Lauraceae | 1 | 43 | 0.95 | 6.15 | 4.05 | 4.00 | 3.43 | 3.83 | |
Flacourtiaceae | 1 | 45 | 0.97 | 5.71 | 4.24 | 3.67 | 3.53 | 3.81 | |
Others | 43 | 374 | 8.37 | 60.02 | 35.25 | 51.67 | 30.42 | 39.11 | |
Total | 74 | 1061 | 27.52 | 214.69 | 100.00 | 100.00 | 100.00 | 100.00 | |
Dry dipterocarp forest | Dipterocarpaceae | 3 | 544 | 13.99 | 81.40 | 42.07 | 9.26 | 60.98 | 37.44 |
Verbenaceae | 5 | 101 | 1.55 | 8.61 | 7.81 | 8.52 | 6.75 | 7.69 | |
Combretaceae | 3 | 98 | 1.46 | 7.07 | 7.58 | 8.89 | 6.37 | 7.61 | |
Anacardiaceae | 4 | 95 | 1.30 | 7.09 | 7.35 | 8.89 | 5.66 | 7.30 | |
Fabaceae | 2 | 89 | 1.07 | 6.40 | 6.88 | 8.52 | 4.67 | 6.69 | |
Rubiaceae | 4 | 64 | 0.49 | 1.86 | 4.95 | 7.78 | 2.15 | 4.96 | |
Ebenaceae | 2 | 51 | 0.59 | 2.95 | 3.94 | 5.56 | 2.59 | 4.03 | |
Oleaceae | 1 | 54 | 0.41 | 1.52 | 4.18 | 5.93 | 1.79 | 3.96 | |
Loganiaceae | 2 | 30 | 0.50 | 2.28 | 2.32 | 5.19 | 2.16 | 3.22 | |
Mimosaceae | 3 | 24 | 0.32 | 1.94 | 1.86 | 4.44 | 1.37 | 2.56 | |
Others | 24 | 143 | 1.26 | 5.68 | 11.06 | 27.04 | 5.50 | 14.53 | |
Total | 53 | 1293 | 22.93 | 126.81 | 100.00 | 100.00 | 100.00 | 100.00 | |
Dry forest | Verbenaceae | 4 | 657 | 20.85 | 164.16 | 75.43 | 10.66 | 77.57 | 54.55 |
Combretaceae | 4 | 83 | 3.65 | 40.29 | 9.53 | 0.82 | 13.56 | 7.97 | |
Rhamnaceae | 1 | 1 | 0.00 | 0.01 | 0.11 | 20.49 | 0.01 | 6.87 | |
Rubiaceae | 2 | 9 | 0.07 | 0.21 | 1.03 | 17.21 | 0.24 | 6.16 | |
Dipterocarpaceae | 2 | 3 | 0.06 | 0.23 | 0.34 | 9.02 | 0.22 | 3.19 | |
Flacourtiaceae | 1 | 2 | 0.07 | 0.29 | 0.23 | 9.02 | 0.25 | 3.16 | |
Fabaceae | 5 | 27 | 0.67 | 5.63 | 3.10 | 2.46 | 2.49 | 2.68 | |
Mimosaceae | 5 | 17 | 0.42 | 3.74 | 1.95 | 1.64 | 1.57 | 1.72 | |
Sapindaceae | 1 | 6 | 0.06 | 0.18 | 0.69 | 4.10 | 0.22 | 1.67 | |
Burseraceae | 1 | 2 | 0.08 | 0.48 | 0.23 | 4.10 | 0.29 | 1.54 | |
Others | 19 | 64 | 0.96 | 5.66 | 7.35 | 20.49 | 3.58 | 10.47 | |
Total | 45 | 871 | 26.88 | 220.87 | 100.00 | 100.00 | 100.00 | 100.00 |
Dry hill/evergreen forest | Verbenaceae | 1 | 263 | 20.07 | 284.52 | 32.71 | 13.25 | 41.96 | 29.31 |
---|---|---|---|---|---|---|---|---|---|
Myrsinaceae | 1 | 160 | 5.47 | 50.42 | 19.90 | 8.43 | 11.43 | 13.25 | |
Bixaceae | 1 | 63 | 1.95 | 15.20 | 7.84 | 9.04 | 4.09 | 6.99 | |
Euphorbiaceae | 2 | 48 | 3.22 | 35.40 | 5.97 | 7.23 | 6.74 | 6.65 | |
Rosaceae | 1 | 32 | 3.17 | 57.19 | 3.98 | 6.02 | 6.63 | 5.54 | |
Myrtaceae | 1 | 22 | 2.23 | 24.49 | 2.74 | 8.43 | 4.65 | 5.27 | |
Rubiaceae | 2 | 45 | 1.35 | 13.23 | 5.60 | 7.23 | 2.82 | 5.21 | |
Fabaceae | 3 | 39 | 3.06 | 29.86 | 4.85 | 4.22 | 6.39 | 5.15 | |
Lauraceae | 1 | 27 | 0.62 | 5.12 | 3.36 | 4.82 | 1.29 | 3.16 | |
Vitaceae | 1 | 20 | 0.19 | 0.90 | 2.49 | 5.42 | 0.40 | 2.77 | |
Others | 26 | 85 | 6.51 | 94.40 | 10.57 | 25.90 | 13.60 | 16.69 | |
Total | 40 | 804 | 47.83 | 610.71 | 100.00 | 100.00 | 100.00 | 100.00 |
NS = number of species, SD = stand density, BA = basal area, Vol = volume, RD = relative density, RF = relative frequency, RBA = relative basal area.
Forest stand | Families similarity | Species similarity | ||
---|---|---|---|---|
Sorencen’s index (%) | Jaccard index (%) | Sorencen’s index (%) | Jaccard index (%) | |
DMDF and DDF | 86.67 | 79.79 | 64.57 | 67.41 |
DMDF and DF | 64.29 | 59.55 | 45.38 | 54.49 |
DMDF and DHEF | 77.42 | 77.73 | 52.63 | 50.54 |
DDF and DF | 72.00 | 71.67 | 46.94 | 65.40 |
DDF and DHEF | 64.29 | 77.67 | 43.01 | 57.74 |
DF and DHEF | 53.85 | 75.87 | 25.88 | 53.44 |
frequency values in I/II classes are higher than in IV/V classes indicating that all forests in PMP have a high degree of floristic heterogeneity and high diversity of species.
The similarities in species composition between the forests are presented in
It was found that dry evergreen forest has the highest mean diameter at breast height (DBH) 24.03 cm and dry dipterocarp forest has the lowest mean DBH, 11 cm (
Diameter frequency distributions provide a useful substitute for development trends of the stands [
The findings in this study indicate that, where tree density is generally higher in small DBH classes compared to large DBH classes, this is a secondary forest characteristic. In all the forest stands, the greater numbers of trees were observed in the lowest diameter class (5 - 10 cm). This indicates that the density of smaller trees in a stand is sufficient to replace the current population of larger tree. The diameter distribution of the trees followed the inverse J-shape pattern (
The diameter classes 15.1 - 20 cm, 10.1 - 15 cm, 15.1 - 20 cm and 25.1 - 30 cm occupied the largest basal
Parameter | DMDF | DDF | DF | DHEF |
---|---|---|---|---|
Mean DBH (cm) | 17.50 | 11.00 | 13.34 | 24.03 |
Mean Ht (m) | 13.80 | 6.69 | 7.38 | 13.20 |
BA (m2∙ha−1) | 27.50 | 22.93 | 26.87 | 47.80 |
Vol (m3∙ha−1) | 214.69 | 126.80 | 220.33 | 610.71 |
Stand density (trees ha−1) | 1061 | 1293 | 871 | 804 |
No. of families | 33 | 27 | 23 | 29 |
No. of species | 74 | 53 | 45 | 40 |
*DMDF = dry mixed deciduous forest, DDF= dry dipterocarp forest, DF= dry forest, DHEF = dry hill/evergreen forest, DBH = diameter at breast height, Ht = height, BA = basal area, Vol = volume.
area per ha in DMDF, DDF, DF and DHEF, respectively (
DBH class (cm) | DMDF | DDF | DF | DHEF | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
SR | D | H' | SR | D | H' | SR | D | H' | SR | D | H' | |
5 - 10 | 55 | 348 | 0.37 | 47 | 565 | 0.36 | 32 | 250 | 0.36 | 20 | 151 | 0.31 |
10.1 - 15 | 52 | 292 | 0.36 | 40 | 371 | 0.36 | 22 | 240 | 0.36 | 19 | 174 | 0.33 |
15.1 - 20 | 40 | 158 | 0.28 | 20 | 157 | 0.26 | 18 | 144 | 0.30 | 21 | 144 | 0.31 |
20.1 - 25 | 44 | 121 | 0.25 | 15 | 98 | 0.20 | 8 | 89 | 0.23 | 16 | 90 | 0.25 |
25.1 - 30 | 29 | 66 | 0.17 | 10 | 62 | 0.15 | 9 | 56 | 0.18 | 16 | 75 | 0.22 |
30.1 - 35 | 20 | 39 | 0.12 | 4 | 26 | 0.08 | 6 | 34 | 0.13 | 11 | 44 | 0.16 |
35.1 - 40 | 13 | 19 | 0.07 | 5 | 11 | 0.04 | 3 | 21 | 0.09 | 10 | 32 | 0.13 |
40.1 - 45 | 7 | 8 | 0.04 | 1 | 1 | 0.01 | 3 | 15 | 0.07 | 11 | 26 | 0.11 |
45.1 - 50 | 1 | 1 | 0.01 | 0 | 0 | 0.00 | 2 | 13 | 0.06 | 4 | 9 | 0.05 |
50.1 - 55 | 4 | 4 | 0.02 | 2 | 2 | 0.01 | 2 | 4 | 0.02 | 6 | 20 | 0.09 |
55.1 - 60 | 2 | 4 | 0.02 | - | - | - | 1 | 2 | 0.01 | 5 | 10 | 0.05 |
60.1 - 65 | - | - | - | - | - | - | 1 | 2 | 0.01 | 3 | 5 | 0.03 |
65.1 - 70 | 1 | 1 | 0.01 | - | - | - | 1 | 1 | 0.01 | 3 | 8 | 0.05 |
70.1 - 75 | - | - | - | - | - | - | - | - | - | 2 | 2 | 0.01 |
75.1 - 80 | - | - | - | - | - | - | - | - | - | 2 | 5 | 0.03 |
80.1 - 85 | - | - | - | - | - | - | - | - | - | 2 | 2 | 0.01 |
85.1 - 90 | - | - | - | - | - | - | - | - | - | 1 | 3 | 0.02 |
90.1 - 95 | - | - | - | - | - | - | - | - | - | 2 | 3 | 0.02 |
95.1 - 100 | - | - | - | - | - | - | - | - | - | 1 | 1 | 0.01 |
*SR = species richness, D = density, H’ = Shannon-Wiener diversity index.
The species-area curves showed that sampling was adequate in all forests to provide representative estimates of species diversity in PMP. The number of species increased substantially up to the point of 0.40 ha in DMDF, 0.48 ha in DDF, 0.64 ha in DF and 0.48 ha in DHEF. The increment of species was then less than 10% until the sampling area reached 1.00 ha. According to Cain and Castro [
It was found that dry hill or evergreen forest (DHEF) has the highest mean diameter at breast height (DBH) 24.03 cm and highest volume (610.72 m3∙ha−1) while stand density (804 trees ha−1) was the lowest among forest types showing that the DHEF is more mature than other forest types in PMP with less human disturbance in the area. This may be due to the distance from the surrounding settled areas as DHEF was found in high elevation and more remote from the park boundary. The highest stand density (1293 trees ha−1) was found in dry deciduous forest (DDF) with lowest standing volume (126.80 m3∙ha−1) signifying that DDF has human disturbance and large trees had been harvested prior to data collection, probably due to nearness of roads and ease of access. DDF was found between 400 m - 700 m asl and the park circular road was close to the DDF. Forest cover loss was more severe in the areas near roads and therefore the likelihood of encroachment by local communities is high in the accessible forest at low elevations [
The diameter distribution of trees was investigated in order to know the population structure of the forest. In all forests, higher species richness and diversity were found in small DBH classes (
also higher in the small DBH classes indicating that small tree were in sufficient numbers to replace mature trees when necessary. Diameter distribution curves show the pattern of population structure. The inverse J shaped curves for the entire investigated stands show that the stands have a growing population structure. However, the mean DBH in all forest is small; 17.50 cm in DMDF, 11.00 cm in DDF, 13.34 cm in DF and 24.03 cm in DHEF. These may be the actual lower thresholds of DBH in the inventory. This study however measured all trees of DBH ≥ 5 cm. The highest tree density was found in the DBH classes 5 - 10 cm and 10 - 15 cm which contribute more than 50% of total tree density. From the shape of the inversed J shape curve of relative abundance over DBH of small DBH trees, we can conclude that it is a common pattern of stand structure of the forests in logged and deforested areas.
Stand structures of the DHEF suggested that this forest is less disturbed because many large trees were still found in this forest compared to the other forests. This may be due to the fact that DHEF is located at high elevations and remote from the park boundaries and human habitation. These findings support Htun [
Patrolling is the main method for forest conservation in the PMP. Limited infrastructure however made conservation activities difficult. In addition, budgets for conservation activities were insufficient. Total government budget for conservation of PMP for 2007-2008 was US $115,000, of which government staff salaries consumed 83%, and much of the remainder was used for administration and maintenance rather than for conservation activities [
This study focused on analyzing tree species diversity and stand structures in the Popa Mountain Park in Myanmar. Forest inventory was conducted in four forest types, namely dry mixed deciduous forest, dry dipterocarp forest, dry forest and dry hill/evergreen forest. We used Jackknife estimator, Simpson’s index, Shannon’s index and Evenness indices for data analysis. The distribution of trees in all forest types in PMP displays an inverse J distribution where stem frequencies decrease with the increase in DBH, indicating stable condition of naturally regenerated trees in the study sites. The study also shows that all forests in PMP have a high degree of floristic heterogeneity. In terms of tree species in individual forest, the number of species found in each of the forests does not vary much among DDF, DF and DHEF. However, the total of 74 species in DMDF is significantly greater than the other forests. The basal area for the DMDF along with the DDF and DF was significantly lower than that of DHEF. On the contrary, the density of trees was significantly lower in DHEF than that in other forest types. But the density of trees in the largest size class was higher in DHEF than that in other forest types. The occurrence of high basal area and high density of trees in the largest size class suggested that DHEF was less disturbed than other forests in the PMP. DF and DMDF had a relatively low proportion of trees in larger size classes due to population pressure and timber harvesting. Large trees with DBH greater than 55 cm in DDF were harvested but there were plentiful trees with small DBH, suggesting that natural regeneration capacity for this forest is good.
Our study findings suggested that PMP was rich in terms of tree species but many large trees in accessible forests were harvested except in dry hill or evergreen forest, where large trees still remained in the forests. This was due to less population pressure and limited access to this forest. Considering the structural diversity and the substantially lower density observed in large DBH classes, the PMP has not been effectively protected although it is a designated protected area by the government. Lack of effective mechanisms and funding may have contributed to this failure. Management interventions that take into account the need of local people, tree diversity, and transition of forest stand structures would protect this PMP. Law enforcement mechanism is also important to ensure that government regulation and policies regarding protected area are not violated or punished otherwise. In addition, it is necessary to clarify the land use policy and to cooperate with local communities to maintain the integrity of designated protected areas. It is also fairly necessary to provide incentives to forest-depen- dent communities for their activities to protect this protected area. Forest-dependent communities should be allowed to participate in all decision making processes for sound management of protected areas. Implementing activities on the ground such as restoring degraded forests and protecting the park require participation from both government agency and local communities. Effective forest restoration strategies need to know the condition of the degree of forest degradation, tree species composition, and stand structures. Information provided in our study is useful for introducing future policy interventions, conservation measures, and forest restoration in Popa Mountain Park. Future study on long term monitoring of forest composition change would provide additional information on the pattern of structural changes useful for revising policy intervention and conservation system in PMP.
We would like to appreciate the Forest Department of Myanmar for providing assistance during the data collection in Myanmar. This study was partially supported by a grant-in-aid for Scientific Research Category A (No. 24252002) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.