CHAPTER 3
RESEARCH RESULTS AND DISCUSSION
3.1. Diversity of vegetation types
Based on the results of the forest status survey, based on the vegetation classification standards of Thai Van Trung (1978, 1999), Pac Bo Special Use Forest belongs to the forest type: Tropical humid evergreen closed forest. Specifically divided into 03 types according to status: Vegetation type of evergreen closed forest on rocky mountains; Vegetation type of evergreen closed forest on dirt mountains; Planted forest type.
3.1.1. Evergreen closed forest vegetation type on rocky mountains
This forest type occupies a large area in the special-use forest, 897.33 ha, accounting for 64.79%. Based on the tree layer structure and distribution location, this subtype is divided into 4 subtypes:
Closed evergreen forest at the foot of limestone mountains:
This type of forest has been heavily impacted, but has had time to recover. In this area, many tree species typical of the hills and mountains have appeared. The complex forest structure consists of 5 layers:
- Canopy layer (A1): Trees over 25m tall, few trees, mainly some species such as Excentrodendron tonkinense , Sapindus oocarpus , Garcinia fragraeoides, in addition there are some other species such as Duabaga sonneratioides , Shorea chinensis .
- Ecological dominant layer (A2): includes medium-sized trees 15 - 20m high, straight trunks, round canopy intersecting to form a continuous forest canopy. In addition to the trees of layer A1 present here, there are also other species such as: Ormosia spp ., some species in the Chestnut family ( Castanapsis spp., Quercu spp .), Cinnamomum spp., Beilschmiedia spp.), Michelia spp., Manglietia spp. , Cassia spp., Saraca spp. , Pterospermum spp ., Dipspyros spp., Cipadessa baccifera, Machilus odoratissima , Phoebe pallida , Toona sinensis , . . .
- Understory (A3): Includes trees under 10m tall, scattered in the Clusiaceae , Ulmaceae , and Annonaceae families, including some representative species such as Gratoxylum ligustrinum , Polyalthia spp .,
Gironniera subaequalis , Kim suong (I), some species in the Mulberry family ( Ficus spp .), Helicia spp. family ...
- Shrub layer (B): includes shrubs and small trees under 8 m high belonging to some families: Apocynaceae , Rubiaceae , Melastomataceae , Araliaceae , Castor family (I), Acanthaceae, including some typical species such as: Wrightia pubescens , Wrightia tomentosa , Trevesia palmata , Aporusa dioica , Croton tiglium , Gardenia jasminoides , Scyphiphora hydrophyllacea , ...
- Fresh carpet layer (C): Low herbaceous plants (under 2 m), including some species in the fern family ( Polypodiaceae ), ...
Evergreen closed forest on limestone slopes:
The forest structure consists of 4 layers, the average height of the tree layers is much lower than the forest at the foot of the mountain, the tree species composition is low, mainly appearing species typical of limestone mountain forests.
- Canopy layer (A1): Very few trees, trees over 20 m tall, including only 3 main tree species: Excentrodendron tonkinense , Garcinia fragraeoides , Sapindus oocarpus .
- A2 layer: Trees are 10 - 15m high, with monotonous tree species composition. In addition to the Nghiến and Trai lý and Sàng species in the A1 layer, there are also species such as: Streblus ilicifolius , Streblus macrophyllus , Clausena excavata , Chukrrasia tabularis , Podocarpus fleury , Knema spp., Polyalthia spp., Aglaia gigantea , Diospyros spp. and some species in the Quercus spp., Lithocarpus spp. family...
- A3 layer: Includes some tree species with an average height of 5-10m, this layer is small trees, combined with regenerated trees of the upper layer trees, such as: Orange family ( Xanthoxylum spp.), Sterculia family ( Sterculia spp.), Syzygium family ( Syzygium spp.), Schefflera family ( Schefflera spp.), some species in the Mulberry family ( Artocarpus spp., Ficus spp., Streblus spp.) ...
- The fresh carpet shrub layer includes many species of plants such as: Taxatrophis
ilicifolia ), Aporusa dioica , Breynia fructicosa , Byttneria aspera , and several species of the fern family Colysis spp.
Closed evergreen forest on limestone mountain top:
Simple forest structure consists of two layers of trees.
The upper layer consists of trees from 8 - 15m high such as species in the Schefflera spp. family, Cinnamomum spp. family, Quercus spp. family , Lithocarpus spp . family, Ternstroemia japonica family, Camellia sasanqua family, Trophis scanden family , Mallotus philippinensis family , Clausena excavata family and some species (Ficus spp. ) in the Moraceae family, etc.
Lowland plants are shrubs such as: Elatostema spp., Ficus retusa , Blastrus cochinchinensis , Rubus alcaefolius , Taxatrophis ilicifolia, Rubus alceaefolius , Villebrunea tonkinensis, etc.
The fresh carpet here is usually still species typical of limestone mountains such as the Fern family ( Dryopteris spp. , Colysis spp. , Tectaria spp.), Pandanus tonkinensis , etc.
Exogenous plants include species of orchids (Orchidaceae), mistletoe species ( Loranthus sp .), climbing plants , etc.
Evergreen grasslands and scrub on limestone mountains :
On the limestone mountains, there are mainly fast-growing light-loving plants and grasses, vines, and shrubs such as: Alnus nepalensis, Broussoneratia papyrifera , Ficus fulva , Styrax tonkinensis , Euodia meliaefolia , Blastus spp . , Breynia (fruticosa), Cratoxylon formosum, Aporusa dioica, Trema spp . , Croton tiglium , Mallotus cochinchineni , Claoxylon longifolium , Alchornea rugosa , Mallotus paniculatus, etc. , along with species of the Polypodiaceae family .
3.1.2. Vegetation type of evergreen closed forest on soil mountain
Closed evergreen forest on soil mountain:
The forest on the soil mountain accounts for 296.84ha (21.43% of the total area of the KBT), distributed next to residential areas (Pac Bo hamlet), around the Memorial House and conservation area.
The canopy, administrative area, large trees have been exploited a lot, the forest structure is strongly affected, there is no canopy layer (A1), the sub-layer structure includes 4 layers:
- A2 layer: Formed by trees over 15m high, few trees, poor quality, discontinuous canopy, main participating tree species are: Adenanthera microsperma, Toona surenii, Canarium spp. family , Castanopsi spp . family , Cinnamomum spp. family , Michelia spp . family , Aglaia spp. family , Engelhardtia spp. family , Bombax spp . family , etc.
- A3 layer: Includes medium-sized trees about 10m tall, straight trunk, round and narrow canopy, continuous canopy layer, mainly composed of small trees. A2 layer and tree species such as: Beilschmiedia spp . , Litsea spp., Cratoxylum cochinchinensis, Celtis sinensis, Gironniera subaequalis, Vitex quinata , Archidendron spp. , Adenanthera spp . , Neolamarkia spp . , Duabaga spp . , Ormosia spp . , Garcinia spp . , Mallotus spp . ...
- Shrub layer (B): 2 - 8m high, composed of tree species including Manihot utilissima , Leea rubra, Litsea spp. , Blastus spp . , Archidendron lucidum , Syzygium spp., Saurauia tristyla , Indosasa sp., Neohoujeaua dulloa , etc.
- Grass layer (C): Not more than 2m high, including some species in the Phrynium spp . family, Panicum amoenum , Musa spp . family , some species in the Polypodiaceae family ...
Exophytic plants include some species in the family Rose (Rubus spp .), Palm ( Calamus spp .), Silver butterfly ( Mussaenda cambodiana), etc.
3.1.3. Type of planted forest
In Pac Bo Special-use Forest, there are 24.22 hectares of planted forests , mainly Pinus merkusii and Cunninghamia lanceolata , with grasslands growing interspersed with planted forests dominated by Imperata cylindrica , Chrysopogon aciculatus , Dicranopteris spp . , and Thai .
purple jasmine (Tradescantia zebrina), Cybotium barometz, ... and some species of ferns.
3.2. Diversity of woody plants
3.2.1. Species-level diversity
After determining the scientific names of the species, we proceeded to edit the information about life forms, uses, and conservation levels according to highly reliable specialized documents such as: " List of Vietnamese plant species " (Volume 1, Volume 2), " Flora of Vietnam ", " Flora of Vietnam "... and arranged the species into a list according to the Takhtajan system (2009).
The survey results have collected and compiled a list of woody plant species (details in Appendix 1). A summary of the list is presented in Table 3.1.
Table 3.2 Summary of woody plant list in Pac Bo special-use forest
TT
Taxon name | Number of species | Number of expenses | ||
Scientific name | Vietnamese name | |||
I | Pinophyta | Information industry | ||
1 | Pinaceae | Pine family | 1 | 1 |
2 | Podocarpaceae | Kim family | 1 | 1 |
3 | Taxodiaceae | The Buddha Family | 1 | 1 |
ii | Magnoliophyta | Magnolia Industry | ||
4 | Aceraceae | They Like | 1 | 1 |
5 | Actinidiaceae | Peach family | 1 | 1 |
6 | Alangiaceae | They Thoi Ba | 2 | 1 |
7 | Altingiaceae | Sau Sau Family | 1 | 1 |
8 | Anacardiaceae | They Cashew | 7 | 6 |
9 | Annonaceae | Na family | 3 | 3 |
10 | Apocynaceae | Oleander family | 3 | 2 |
11 | Aquifoliaceae | Holly Family | 2 | 1 |
12 | Araliaceae | Acanthopanax family | 5 | 3 |
13 | Asteraceae | Asteraceae | 1 | 1 |
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14
Aetulaceae | The Cang Lo Family | 1 | 1 | |
15 | Aignoniaceae | Dinh family | 4 | 3 |
16 | Bombacaceae | Rice Family | 1 | 1 |
17 | Burseraceae | Canarium | 4 | 1 |
18 | Caesalpiniaceae | Vang family | 7 | 6 |
19 | Clusiaceae | Pomelo family | 6 | 2 |
20 | Dillenniaceae | Family Book | 1 | 1 |
21 | Dipterocarpaceae | Dipterocarpaceae | 2 | 1 |
22 | Ebenaceae | Thi family | 5 | 2 |
23 | Elaeocarpaceae | Com family | 2 | 1 |
29 | Euphorbiaceae | Euphorbia | 19 | 13 |
24 | Fabaceae | Beans | 4 | 3 |
25 | Fagaceae | Chestnut family | 10 | 3 |
26 | Flacourtiaceae | Bo Quan family | 2 | 2 |
27 | Hamamelidaceae | Kim Mai family | 1 | 1 |
28 | Hypericaceae | They are stubborn | 3 | 1 |
29 | Icacinaceae | Peach family | 1 | 1 |
30 | Ixonanthaceae | Ha Nu family | 1 | 1 |
31 | Juglandaceae | Walnut family | 2 | 2 |
32 | Lauraceae | Re family | 24 | 11 |
33 | Lythraceae | Lagerstroemia family | 1 | 1 |
34 | Magnoliaceae | Magnolia family | 2 | 2 |
35 | Meliaceae | Xoan family | 9 | 7 |
36 | Mimosaceae | Virgin Family | 4 | 2 |
37 | Moraceae | Mulberry family | 17 | 4 |
38 | Myricaceae | Thanh Mai family | 1 | 1 |
39 | Myristicaceae | Dog Blood Family | 3 | 2 |
40 | Myrtaceae | Sim Family | 6 | 2 |
41 | Pandanaceae | Bromeliads | 1 | 1 |
42
Polygalaceae | Polygala family | 1 | 1 | |
43 | Potaliaceae | They Lau Binh | 1 | 1 |
44 | Proteaceae | Golden Rice Family | 1 | 1 |
45 | Rhizophoraceae | Mangrove family | 2 | 1 |
46 | Rosaceae | Rose Family | 1 | 1 |
47 | Rubiaceae | Coffee Family | 6 | 4 |
48 | Rutaceae | Orange Family | 6 | 5 |
49 | Sapindaceae | Soapberry family | 7 | 4 |
50 | Scrophulariaceae | Myrrh family | 1 | 1 |
51 | Simaroubaceae | Thanh That family | 1 | 1 |
52 | Sonneratiaceae | The Poor Family | 1 | 1 |
53 | Sterculiaceae | The Thief | 3 | 2 |
54 | Styracaceae | Bodhi family | 2 | 2 |
55 | Symplocaceae | Dung family | 3 | 1 |
55 | Tetramelaceae | They Thung | 1 | 1 |
56 | Tiliaceae | Jute Family | 4 | 3 |
57 | Theaceae | Tea Family | 5 | 3 |
58 | Ulmaceae | Du family | 3 | 3 |
59 | Verbenaceae | Verbena family | 3 | 1 |
Total | 225 | 136 | ||
The results in Table 3.1 show that: In the Pac Bo special-use forest area, woody plant species include 225 species belonging to 136 genera, 59 families of 2 higher plant branches.
When comparing the data (Table 3.2) on the number of species in the branches of woody plants in Pac Bo special-use forest with the data on the number of species in the branches in the natural reserves of Than Sa - Phuong Hoang (Nguyen Thi Thoa, 2014), Dong Son - Ky Thuong (Do Xuan Truong, 2011), Xuan Lien (Nguyen Ngoc Thao, 2012), Yen Tu special-use forest (Nhu Thi Tam, 2011) shows an uneven distribution between the two plant branches, in which the magnolia branch in all areas is dominant (from 96.68%
up to 99.02%). This is completely reasonable because woody plants are mainly concentrated in this industry.
Table 3.3. Number of species and percentage of woody plant species of Pac Bo special-use forest with Than Sa - Phuong Hoang, Yen Tu, Dong Son - Ky Thuong, Xuan Lien Nature Reserves
Branch
Pac Bo Special Use Forest | Than Sa - Phuong Hoang | Yen Tu | Dong Son - Ky Thuong | Xuan Lien | ||||||
Number species | % | Number species | % | Number species | % | Number species | % | Number species | % | |
Pinophyta | 3 | 1.33 | 6 | 0.98 | 7 | 1.92 | 6 | 1.6 | 11 | 3.04 |
Magnoliophyta | 222 | 98.67 | 605 | 99.02 | 356 | 97.78 | 369 | 98.4 | 350 | 96.68 |
Total | 225 | 100 | 611 | 100 | 364 | 100 | 375 | 100 | 362 | 100 |
3.2.2. Diversity index of woody plant taxa
The diversity indices of plant taxa are shown in tables 3.3 and 3.4.
Table 3.4. Diversity indices of woody plant taxa
Index
Branch
Expenditure Index | Family index | Branch number/Family number | |
Pinophyta | 1 | 1 | 1 |
Magnoliophyta | 1.67 | 3.96 | 2.38 |
Woody flora | 1.65 | 3.81 | 2.31 |
The results of Table 3.3 show that woody plants have a family index of 3.81 (meaning that each family has an average of 3.81 species), and a genus diversity index of 1.65 (meaning each genus has an average of 1.65 species). The average number of genera per family is 2.31 (meaning each family has an average of 2.31 genera). The Magnoliophyta is the most diverse phylum in terms of index, with an average of 1.67 species per genus, 3.96 species per family, and 2.38 genera per family.