With the characteristic of being distributed on rocky mountains, there is no layer of arable land, so the root system of the short-leafed false ironwood species develops very strongly, especially in mature trees. The roots help the tree cling tightly to the rocks and spread out around. The taproot penetrates deep into the rock crevices to absorb nutrients to nourish the tree and create a solid position for the tree to withstand storms, the fibrous roots spread on the thin layer of humus to absorb water and mineral nutrients.
c). Leaf morphology characteristics
- Mature leaf morphology
Leaves are simple, alternate, petioles twisted, arranged to both sides. Leaf blade is linear, has a midrib, the back of the leaf has two parallel white powdery stripes. Leaves are arranged spirally, in 2 rows, in the form of a strip with a blunt tip, the midrib is concave on the upper surface, 2 distinct stomatal stripes on the lower surface, twisted at the base. Leaf length varies from 1.5 - 2cm, petiole length is about 1mm, petiole width is from 0.5 - 1mm.
- Young leaf morphology:
Usually larger than leaves on mature branches (4-8 cm x 0.5-0.9 cm); leaf surface is light green, leaf underside has mid-vein, white stripes on both sides, veins on the edge, young leaves can be up to 5.5 cm long, 5 mm wide, striped or slightly crescent-shaped with pointed tip, two distinct stomatal bands. Buds are ovate, brown or reddish brown with many thin scales covering the outside.
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Figure 3.3. Front of the Ironwood leaf short leaf pseudo | Figure 3.4. Back of the Ironwood leaf short leaf pseudo |
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d). Morphological characteristics of cones
Monoecious cones, female cones grow singly on short, pendulous, ovoid lateral shoots, up to 6 cm long and 5 cm in diameter; scales are woody, broad, rounded; scales protrude below the cone scales, and are reflective when ripe. Female cones mature in 1 year, split and release seeds while still on the tree, the cones do not fall but persist on the branches for up to 2 years. Old female cones remain attached to the branches, always growing downward. Seeds are ovoid with three sides, seeds at both ends of the cone are usually flat, seed size 0.5 - 0.7 x 1.3
- 1.5 cm. The seeds have reddish-brown, crescent-shaped wings. When the cone splits, if the wind blows, the seeds will fly far thanks to the wings. The seeds contain aromatic and sticky resin, which is the factor that makes it difficult to preserve the seeds of the Short-leafed False Ironwood for a long time.
Male cones are egg-shaped, 1 - 1.5 cm long, reddish brown, often growing in clusters of 8 - 15 cones or more, cones grow on branch tips or leaf axils.
Figure 3.5. Morphology of cones and seeds of short-leafed Pseudocyanococcus
3.1.2. Phenological characteristics of the species Short-leafed Pseudocyanococcus
Research on the phenological characteristics of the short-leafed Pseudocyprinus species is important for conservation work. This characteristic reflects the ability to maintain the species in nature and predicts their existence in the future.
From the research results and information inherited from documents on phenological characteristics, it shows that: Short-leafed false ironwood is an evergreen tree, with no distinct leaf-shedding season, the shoots grow strongly in the spring, starting to sprout around the end of February and beginning of March, and young leaves appear in April. After 2 months, the shoots develop quite well, reaching a length of 10 - 22 cm, and the young leaves are arranged in a flat surface. After the time of young branches, cones begin to appear, and the fruit ripens at the end of November. Short-leafed false ironwood has a cyclical pattern of fruiting (interval phenomenon), the ability of the tree to flower and fruit is not uniform between years.
3.1.3. Assessment of the distribution and ecology of the short-leafed false ironwood species in Nguyen Binh district
3.1.3.1. Current distribution status of the short-leafed false ironwood species in Nguyen Binh district
The results of the investigation on 30 OTCs in 2 communes of Ca Thanh and Trieu Nguyen, Nguyen Binh district are shown in the following table:
Table 3.3. Statistics of investigated OTCs with distribution of Short-leafed Pseudocyanococcus species
OTC
Coordinates | Degree height (m) | Number amount of trees | OTC | Coordinates | Height (m) | Number amount of trees | |
CT 01 | 0434470/2513239 | 1334 | 8 | TN 01 | 0441446/2512357 | 838 | 5 |
CT 02 | 0434544/2513116 | 1358 | 10 | TN 02 | 0441442/2512368 | 860 | 4 |
CT 03 | 0434436/2513361 | 1353 | 7 | TN 03 | 0441469/2512381 | 895 | 5 |
CT 04 | 0434445/2513293 | 1329 | 7 | TN 04 | 0441493/2512303 | 887 | 6 |
CT 05 | 0434489/2513407 | 1367 | 6 | TN 05 | 0441530/2512312 | 922 | 4 |
CT 06 | 0434441/2513400 | 1352 | 8 | TN 06 | 0441555/2512290 | 953 | 4 |
CT 07 | 0434455/2513420 | 1366 | 6 | TN 07 | 0441573/2512277 | 954 | 6 |
CT 08 | 0434438/2513322 | 1344 | 14 | TN 08 | 0441573/2512247 | 945 | 3 |
CT 09 | 0434593/2513498 | 1400 | 6 | TN 09 | 0441567/2512187 | 950 | 3 |
CT 10 | 0434628/2513529 | 1376 | 8 | TN 10 | 0441156/2512135 | 939 | 4 |
CT 11 | 0434648/2513553 | 1372 | 5 | TN 11 | 0441164/2512096 | 943 | 6 |
CT 12 | 0434707/2513573 | 1358 | 8 | TN 12 | 0441564/2512068 | 944 | 5 |
CT 13 | 0434738/2513571 | 1347 | 7 | TN 13 | 0441154/2512139 | 930 | 5 |
CT 14 | 0434774/2513562 | 1349 | 8 | TN 14 | 0441541/2512027 | 954 | 6 |
CT 15 | 0434796/2513586 | 1355 | 4 | TN 15 | 0441152/2511976 | 937 | 6 |
Total | 112 | Total | 72 | ||||
The results of Table 3.3 and the field investigation process show that: The area with the species of Short-leafed Pseudocyperus is mainly distributed on limestone mountain terrain, on the mountain slopes and mountain tops, with an altitude of 838m - 1376m above sea level, complex terrain, strongly divided by limestone mountain ranges, independent mountains and narrow valleys. The terrain has many places with steep slopes, average slopes from 30 - 40 0 , some places over 45 0 (Ca Thanh commune), difficult and dangerous roads, so the project can only establish a standard plot with an area of 200m 2 .
3.1.3.2. Soil characteristics at the study site
Soil is an indispensable ecological factor for every plant species, including species that grow mainly on limestone mountains such as the short-leafed Cyperus rotundus. The results of the investigation and description of soil in places where the short-leafed Cyperus rotundus is distributed show that: soil is formed
Formed by the weathering of limestone and mainly by the decomposition of animal and plant remains, dry branches and fallen leaves accumulated in the holes and crevices of rocks. The top layer is humus ferralitic soil on the mountain, the color of the soil is dark brown, the ratio of tree roots is 5 - 10%, the ratio of humus is high, loose, moist, rich in nutrients.
3.1.3.3. Climate characteristics in the study area
Nguyen Binh district, where the short-leafed false ironwood species is distributed, is a typical area for the limestone mountain ecosystem in the Northeast of Vietnam, with the main forest type being tropical moist evergreen broadleaf closed forest, typical of the forests in the northern border region of Vietnam. Nguyen Binh district belongs to the subtropical climate zone with 2 distinct seasons:
- The dry season lasts from November to April, influenced by the dry northeast monsoon, often with long cold spells accompanied by frost (December, January and February). Average air humidity is 82%/year. Average evaporation in the year is 831.6mm, with large evaporation concentrated from December to March of the following year, so droughts often occur during these months.
- The rainy season starts from May to October, the weather is hot and humid, the average rainfall is 1200mm. Of which, the heaviest rainfall is on average 2,043.7mm. The rainfall in the year is unevenly distributed, usually concentrated in June, July and October.
8. The average annual temperature is 20.9 0 C, the highest is about 28 - 29 0 C, the lowest is from 0 0 C to 6 0 C.
Table 3.4. Basic climate indicators in 3 years in Nguyen Binh district
Month
Average temperature ( 0 C) | Average rainfall (mm) | Average air humidity (%) | |||||||
2017 | 2018 | 2019 | 2017 | 2018 | 2019 | 2017 | 2018 | 2019 | |
1 | 15.3 | 13.9 | 13.6 | 182.9 | 67.6 | 82.2 | 94 | 86 | 93 |
2 | 15.5 | 13.5 | 17.4 | 11.7 | 26.7 | 36.8 | 79 | 79 | 89 |
3 | 18.1 | 18.9 | 18.5 | 146.3 | 58.7 | 47.0 | 86 | 81 | 89 |
4
21.5 | 21.2 | 23.5 | 113.6 | 71.9 | 87.0 | 82 | 82 | 85 | |
5 | 24.2 | 25.7 | 23.8 | 172.7 | 103.7 | 294.0 | 81 | 81 | 89 |
6 | 26.1 | 26.2 | 26.8 | 253.4 | 254.6 | 303.1 | 87 | 83 | 86 |
7 | 25.8 | 26.6 | 26.4 | 411.8 | 266.4 | 334.7 | 88 | 84 | 88 |
8 | 25.6 | 25.9 | 26.0 | 409.9 | 338.7 | 422.1 | 89 | 87 | 88 |
9 | 25.5 | 24.5 | 24.0 | 170.8 | 172.5 | 136.7 | 89 | 87 | 84 |
10 | 21.8 | 20.7 | 21.8 | 150.6 | 180.5 | 102.5 | 87 | 88 | 88 |
11 | 18.0 | 18.4 | 18.3 | 45.1 | 46.9 | 11.1 | 84 | 88 | 86 |
12 | 13.3 | 14.7 | 13.5 | 52.1 | 46.7 | 14.6 | 83 | 90 | 83 |
Jar army | 20.9 | 20.9 | 21.1 | 212.09 | 163.49 | 187.18 | 86 | 85 | 87 |
(Source: Statistical yearbook of Nguyen Binh district, 2017, 2018, 2019)
The average temperature in the 3 years 2017 - 2019 is from 20.9 - 21.1 o C, rainfall is from 1634.9 - 2120.9 mm and average air humidity is from 85 - 87%.
3.2 . Forestry characteristics of short-leafed Pseudocyanococcus species in Nguyen Binh district
3.2.1. Characteristics involved in the structure of forest plant communities with the distribution of Short-leaved Pseudocyanococcus species
a). Characteristics involved in the structure of the secondary layer
The stratum is a structural indicator reflecting the vertical morphology of the forest stand, the result of competition for survival between tree species in the community and with the surrounding environment during the growth and development process. In natural forests, the stratum structure reflects the internal ecological nature of the forest ecosystem and simulates the relationships between forest layers and between different tree species. Research on the stratum structure is very meaningful in practice, aiming to improve the efficiency of forest use, suitable for business purposes. The results of the investigation on the standard plots show that the short-leafed false ironwood distributed on the slopes and mountain tops in Nguyen Binh district basically has a simple stratum structure including 1 tree layer, a shrub layer and a fresh carpet layer:
The woody layer has an average height of 6-7m with simple species composition, including some main species such as: Pseudotsuga brevifolia
WC Cheng & LKFu, 1975) , E. griffithii (Wight) A.Gray , Machilus sp , Quercus resinifera A.Chev , Illicium difengpi , Toona sinensis , Castanopsis sp , Polyalthia sp ., Helicia sp ,... The canopy coverage of the forest is about 0.5. In which, the most dominant component is the short-leafed false ironwood species.
The shrub layer includes several species: Melastoma candidum, Melastoma dodencandrum , Melastoma sanguineum , Maesa perlarius , Pleomele cochinchinensis , Memecylon edule Roxb, Psychotria rubra , Blastus borneensis , ... about 1m in height.
The fresh carpet layer includes species: Phyllanthus Urinaria L , Miccostegium ciliatum , Mircostegium vagans , Centosteca latifolia , Chloris barbata , Saccharum spontaneum , Taenitis blechnoidea, Cyathea sp. , Selaginella sp ., Lemmaphyllum microphyllum , Thysanolaena maxima , Calanthe triplicate, Tropidia curculigoides ... Some climbing plants: Tetrastigma planicaule , Pueraria montana , Mucuna pruriens , Cissus modeccoides , Caesalpinia minax , Tetrastigma rupestre), Ampelopsis antoniensis, Uncaria laevigata ... Coverage is about 30%.
b). Characteristics of density structure and composition
The results of the investigation on the structural characteristics and density of forests with short-leafed Pseudocyanococcus species distributed in Nguyen Binh district are shown in Table 3.5:
Table 3.5. Forest density structure where the species of Short-leaved Pseudocyrrhiza glabra is distributed
Location
Number of species/ | Density (Trees/ha) | Percentage |
OTC | Forest | Short leaf imitation silk | Short leaf imitation silk | |
Side | 13 | 612 | 377 | 61.64 |
Top | 12 | 518 | 265 | 51.14 |
TB | 12.5 | 564 | 321 | 56.4 |
The results of Table 3.5 show that the forest density at the rocky mountain slope where the short-leafed Cyperus rotundus species is present is 612 trees/ha. The density of the short-leafed Cyperus rotundus species at the mountain slope is 377 trees/ha. At the mountain top, the forest density is 518 trees/ha; the density of the short-leafed Cyperus rotundus species is 265 trees/ha. The number of tree species in the forest is only 12-13 species. With such species composition, it can be seen that this is a forest type with a low species diversity, in which the short-leafed Cyperus rotundus species is the dominant species of the forest with a density ratio of 51.14% at the mountain top to 61.64% at the mountain slope.
Table 3.6. Forest structure with short-leaved Pseudocyanococcus species distributed at the mountain slopes
TT
Plant species | Density (Trees/ha) | N% | G% | IV% | |
1 | Short leaf imitation silk | 377 | 61.64 | 70.71 | 66.17 |
2 | Flat oak | 50 | 8.18 | 5.28 | 6.73 |
3 | Handbook | 42 | 6.92 | 5.88 | 6.40 |
3 main species | 469 | 76.73 | 81.86 | 79.30 | |
10 other species | 142 | 23.27 | 18.14 | 20.7 | |
Total | 612 | 100 | 100 | 100 | |
The results of Table 3.6 show that at this location, there are 13 species of trees appearing. The natural forest composition at the mountainside where the short-leafed false ironwood species is distributed is very simple. There are only 3 dominant species participating in the forest composition formula: Short-leafed false ironwood, Flat oak, and Cam chi, with a total IVI % index of 79.3%, in which