Studying on the actual status of the vegetation cover and the process of natural forest recovery in Vi Xuyen district, Ha Giang province (Nghiên cứu hiện trạng thảm thực vật và quá trình phục hồi rừng tự nhiên ở huyện Vị Xuyên, tỉnh Hà Giang)

THE MINISTRY OF EDUCATION AND TRAINING THAI NGUYEN UNIVERSITY DO KHAC HUNG STUDYING ON THE ACTUAL STATUS OF THE VEGETATION COVER AND THE PROCESS OF NATURAL FOREST RECOVERY IN VI XUYEN DISTRICT, HA GIANG PROVINCE Speciality: ECOLOGY Code: 62 42 01 20 ABSTRACT OF PH.D. DISSERTATION IN BIOLOGY Thai Nguyen – 2014 The study has fulfilled at Thai Nguyen University of Education of Thai Nguyen University Scientific supervisors: 1. Assoc. Prof. Dr. Le Ngoc Cong 2. Prof. Dr. Sci. Tran Dinh Ly Opponent 1: Opponent 2: Opponent 3: The dissertation can be found at: - The national library - Leaning Resource Center of Thai Nguyen University - The Library at University of Education of Thai Nguyen University 1 FOREWORDS 1. Reason for choosing the study In the 21 st century, human beings have witnessed the terrible consequences caused by climate changes such warming phenomenon of the earth, the rise and unusual appearance of storms, floods, land degradation, epidemics, declining biodiversity, etc. They affect lives of hundreds of millions of people on earth. Being aware of serious harms caused by climate change, on the 17 th August 2004, the Prime Minister has approved "Strategic Orientation for Sustainable Development in Vietnam". It is until 2020, forest coverage of our country will reach 45%. Vi Xuyen district has a total large forest area. However, shifting cultivation, nomadic life, deforestation for cultivation and exploitation of forest resources make forest quality of serious deterioration. Due to the above reasons, I choose the research thesis "Studying on the actual status of the vegetation cover and the process of natural forest recovery in Vi Xuyen district, Ha Giang province ". 2. The objectives of the study It determines and analyzes several characteristics of the vegetation cover types in Vi Xuyen district. It clarifies the differences in physical, chemical and microbiological properties and land animals of different vegetation types as a basis for proposals of forest rehabilitation measures. 3. The research scope - In term of plants and soil environment, broad-leaved vegetation cover types on soil hills, higher vascular flora and soil environment under the vegetation cover types are studied. - In term of causes of forest degradation, it focuses on study activities caused forest degradation. - The studied selected site has similar characteristics such as topography, climate, exposed direction, parent rock, impacts of human, etc. - The dissertation is only to study the vegetation cover types that trends of upward succession of natural forest recovery. - Contains no climate research plant populations due to time and. - The dissertation does not study the climate of plant populations due to time and limitations of equipments. 2 4. The scientific meaning and practice of the dissertation 4.1. In term of theory, With the scientific data, the regenerated law and upward succession of natural forest recovery in Vi Xuyen district have shed light on It contributes to clarify the relationship between vegetation cover with soil environmental factors in the recovery process of natural forests in Vi Xuyen district. 4.2. In terms of practice, Some solutions are proposed to restore natural forests to reach high efficiency in Vi Xuyen district, Ha Giang province. The results of the dissertation provide the instruction material in service of specialized teaching and research at universities and colleges. 5. Novel ccontribution of the dissertation It studies systematically on the vegetation cover and flora in Vi Xuyen district, Ha Giang province. It provides the scientific material on the recovery process of natural forests in Vi Xuyen district, Ha Giang province. 6. Structure of the dissertation The dissertation consists of 127 pages. Apart from the foreword part with 3 pages and two pages of conclusions and recommendations. The main contents of the dissertation are presented in four chapters: Chapter 1. Literature review includes 34 pages; Chapter 2. Objects of contents and research methods consist of 8 pages; Chapter 3. Conditions on nature, economic – society at studies area with 15 pages; Chapter 4 research results and discussion include 65 pages. There are 27 tables, 18 figures, annexes on component of regenerated plants composition of regenerated plants and photos. Chapter 1 LITERATURE REVIEW To achieve the purpose of study and successful implementation of research contents set forth, the dissertation refers to some concepts related topics: vegetation, forest regeneration, forest secondary, etc. There are 116 research literatures referred in the dissertation (103 Vietnamese papers, 13 English papers) regarding the following major issues: * The studies on vegetation classification In the world and in Vietnam, the scientific research works on vegetation are very abundant, including quantity of research papers as well as the principles and methods of vegetation classification. Each classification system also has advantages and disadvantages. In the dissertation, we select the classified frame of UNESCO (1973) as a basis for classifying vegetation in Vi Xuyen district, Ha Giang province. 3 * The studies related to regeneration, succession and forest regeneration There are many research papers about the recovery process of natural forest or the regeneration promoted process and succession process of forest vegetations. Authors study process on regeneration, forest regeneration with multiple objects of different vegetations (secondary forest, shrub vegetation, grass vegetation) with methods abundant and suitable to each subject. * The studies the interaction between vegetation and soil In the world and in Vietnam, there are many scientific studies works on the relationship between vegetation and soil environment. Authors’ results of studies have confirmed that effects of the land reclamation vegetation are very significant Chapter 2 SUBJECTS, CONTENTS AND METHODS OF STUDY 2.1. Subjects of the study The vegetation cover types of natural recovery in Vi Xuyen district, Ha Giang province include: grass, low shrubs, high shrubs and secondary forests. 2.2. Research Contents 1. It is the current status of vegetation cover in Vi Xuyen district, Ha Giang province 2. The changes of key elements in the process of upward succession are from grass vegetation, low shrub vegetation, high shrub vegetation to the secondary forest in Vi Xuyen district, Ha Giang province. 3. It is to evaluate possibility and propose some solutions to restore of natural forests in Vi Xuyen district, Ha Giang province 2.3. Research duration Duration is from 2011 to 2013 2.4. Research method 2.4.1. Methodology 2.4.2. Specific research methods 2.4.2.1. Survey Method During the research process of data collection, we use the method of survey routes and standard plots of Hoang Chung (2008) and Nguyen Nghia Thin (2004). * The method of survey routes (SR) The first survey route is perpendicular to the fundamental contour line. The following survey routes are parallel to the first survey route. Total survey routes are 15. * The method of standard plots (SP) On each survey route, standard plots are created and distributed evenly in each vegetation cover type. Total standard plots are 60 4 In each standard plot (SP) in the secondary forest, there are five slab cells (SC) established and arranged at corners those are intersections of two diagonals of standard plots. Samples are collected in standard plots and slab cells. Method for collection of samples is similar to that of survey routes. In addition, it measures total tree height (TTH), diameter at breast height (DBH), counts regenerating trees and evaluate the original source and quality of regenerating trees. * The method of positioned cells (PC) In each vegetation cover type, some specific standard plots chosen to use as positioned cells (PC). Total positioned cells chosen are 9. 2.4.2.2. Sampling Method * Plant sampling: Data collection in survey routes and in standard plots (SP) * Soil sampling: Digging soil profile, taken land for the analysis of physical and chemical properties and microorganisms and sampling of soil animals. 2.4.2.3. Methods of analysis and data processing * Analysis of plant samples: Determination scientific names, local names of the plant species. * Analysis of soil samples Description of soil profile under the method Le Van Khoa et al, 1998. The analysis of physical and chemical properties and microorganisms and soil animals at Institute of Chemistry, Institute of Biotechnology, Institute of Ecology and Biological Resources (Vietnam Academy of Science and Technology). The analytical results are processed by biostatistical methods of Microsoft Excel software of computer. Chapter 3 NATURAL AND SCIO-ECONOMIC CONDITIONS IN THE STUDY SITE 3.1. Natural conditions Vi Xuyen district is the low mountainous district of Ha Giang province with a forcefully divided and complex terrain. Its height above mean sea level is 500 meters. Therefore, system of rivers and streams in the district is rather dense. However, they are mostly small streams with large slopes. There is only Lo River that is the largest river. Vi Xuyen district’s climate is affected by climate of the Northeast region. It is due to be located deeply inland; entire district is less affected by rainstorms in summer and Northeast monsoon than the Northern Delta area. 5 3.2. Scio-economic conditions Vi Xuyen district has a population of 100,800, accounting for 13.5% of the provincial population with average population density of 66.7 persons per km 2 . The structure is quite diverse nation, with more than 20 ethnic groups living together: Tay, Kinh, Dao, Mong, Nung, Giay, Pa Then, Hoa, Lo Lo, etc., of which, Tay ethnic group accounts for the most proportion (36.1%). The ethnic groups have a unique cultural identity, disparities on development level, education proficiency and living standard. Chapter 4 RESULTS AND DISCUSSION 4.1. Current status of vegetation covers in Vi Xuyen district, Ha Giang province 4.1.1. Current situation of use of forest land in Vi Xuyen district, Ha Giang province Table 4.1: Current status of forest land under 3 forest types of Vi Xuyen district Soil type, forest type Production forest (ha) Protective forests (ha) Special use forest (ha) Total (ha) Forest Land 65,708.56 27,688.20 25,294.60 118,691.36 1. Land with forests 51,869.96 25,268.40 24,933.70 102,072.06 - Natural forest 39,255.26 23,066.50 22,701.10 85,022.86 - Planted forests 12,614.70 2,196.70 2,201.90 17,043.70 2. Land without forests 13,838.60 2,419.80 360.90 16,619.30 (Source: Results of planning review of forest types in Vi Xuyen district, 2012) The area of forest land of Vi Xuyen district is about 118,691.36 ha and accounts for 79.2% of natural land area. Of which, forest land is 102.072,06 ha and accounts for about 86% of forest land area and accounts for 68% of total natural land area; area without forest land proportion is less than that of total area of forest land (about 14%). A large forest area is a potential for developing forest economics (Table 4.1). 4.1.2. Current status of vegetation covers in Vi Xuyen district, Ha Giang province 4.1.2.1. Vegetation cover types in Vi Xuyen district, Ha Giang province According to the International Classification of Vegetation (UNESCO 1973), in Vi Xuyen district there are following vegetation cover types: closed forests, open forests, shrubs and grass vegetation covers. 6 4.1.2.2. Characteristics the flora in Vi Xuyen district, Ha Giang province In the study area, the list of statistics is 557 species belonging to 393 genera, 114 families of five branches of vascular plants. Of 557 species in the study area, there are 33 rare and valuable plant species in the Red Book of Vietnam and 7 species in ND 32/2006 ND-CP. 4.1.3. Causes of forest degradation in Vi Xuyen district, Ha Giang province Forest area in Vi Xuyen district has been and exhaustedly exploited, leading to serious forest degradation. The major causes of forest degradation are logging activity, exploitation of non-timber forest products, forest fires, etc. 4.2. Changes of major factors in upward succession from grass vegetation, low shrub vegetation, high shrub vegetation and secondary forest in Vi Xuyen district, Ha Giang province 4.2.1. Characteristics of studied vegetation cover types - Secondary forest (SF): It belongs to the closed forest formation that is often green at the rainy season in low terrain and low mountains. This vegetation type located in Trung Thanh commune had originated after cultivating milpa with the recovery period of 25 years. The area of forest is about 3 ha, 30 o slope and 95-100% of land cover. - The shrub vegetation cover (SV): it is shrub sub-formation available timber trees distributed scattered. This vegetation type formed on fallow and from 3 to 8 years in Dao Duc commune. Based on the height of shrubs, we have chosen two states: high shrub vegetation (HSV) and low shrub vegetation LSV). - Grass vegetation cover (GV): the drought-tolerant grass formation belongs to rice form in average of 0.5 -1 m with scattered timber trees formed after cultivating milpa in Viet Lam commune. It has the recovery time of from 2 to 3 years, with an area of 1.5 ha, 30 o slope and 70-80% of general coverage. The height of grass types is below 0.8m. 4.2.2. The change of the plant composition in types of vegetation covers Table 4.10 Quantity of species, genera and families in vegetation cover types Species Genera Families Vegetation cover types Quant. Rate(%) Quant. Rate(%) Quant. Rate(%) GV 209 37.52 166 42.24 65 57.02 LSV 285 51.17 219 55.73 79 69.30 HSV 375 67.32 258 72.51 98 85.96 SF 343 61.58 245 62.34 88 77.19 Under the results in Table 4.10, the composition of species in high shrub vegetation cover is the most abundant ( 375 species belonging to 258 genera and 98 families) . Then , secondary forests and low shrub 7 vegetation and the lowest abundant grass vegetation ( 209 species belonging to 166 genera and 65 families) . 4.2.3. The change of quantity of tree species in vegetation cover types Table 4.11: The change on quantity of tree species/standard plot in vegetation cover types Statistical criteria Grass vegetation Low shrub vegetation High shrub vegetation Secondary forest Total species 45 50 58 79 Species/SP 32  3 41  4 47  4 60  5 Herbal stems 14  2 18  3 20  3 21  3 shrub stems 11  2 14  2 16  2 24  3 Climbing plants with wood stems 2  1 3  1 3  1 5  1 Wood stems 5  1 6  1 8  2 10  2 Under the results at table 4.11, in the process of succession from grass vegetation to secondary forest, the average total number of tree species in each standard plot has increased gradually. Of that, in a standard plot there are 45 species in grass vegetation, 50 species in low shrub vegetation and 58 species in high shrub vegetation and 79 species in secondary forest the most species. According to the data at Table 4.12, we find that in the process of succession there are 206 tree species weeded. Eliminated process takes place the most strongly in secondary forests (133 species). In contrast with the process of elimination, there are 340 added species, of which in the stage of high shrub vegetation, there is the highest number of additional tree species (151 species). Table 4.12: Fluctuations in the number of species in vegetation cover types Vegetation types Quantity of exis. tree species Quantity of tree species weeded Quantity of tree species added GV 209 - - LSV 285 12 88 HSV 375 61 151 SF 343 133 101 Total 206 340 4.2.4. The change on density, quality and origin of regenerated plants in vegetation cover types 4.2.4.1. The density of regenerated plants The table 4.13 shows that the density of regenerated plants increases rapidly in the stage of high shrub vegetation cover and secondary forests 8 (the higest density in secondary forest is 5612 tree per ha). The reason is that in these two vegetation types, there is plentiful plant composition, a plenty of plants providing varieties, soil in high moisture, seeds easy to germinate and grow. So, quantity of regenerated plants is more numerous. Table 4.13: Density, quality and origin of regenerated plants in vegetation cover types Quality (%) Original (%) Vegetation cover types Density (tree/ha) Good Medium Bad Seeds Buds GV 3054 63.2 28.4 18.4 36.6 63.4 LSV 4057 64.7 25.7 19.6 43.5 56.5 HSV 5191 66.4 27.4 16.2 58.8 41.2 SF 5612 70.3 18.2 11.5 65.3 34.7 4.2.4.2. Quality of regenerated plants Table 4.13 shows that rates of regenerated plants with good quality, average quality and bad quality are from 63.2% to 70.3%, from 18.2% to 28.4% and from 11.5% to 19.6%, respectively. This is necessary and convenient condition for faster recovered vegetation. 4.2.4.3. The origin regenerated plants Regenerating trees originating from seeds in secondary forests and shrub vegetation account for very high rates with a rate 65.3% and 58.8% respectively. In contrast, those in grass vegetation cover and low shrub vegetation account for high percentages with 56.5 % and 63.4% respectively. 4.2.5. The change of structure of formation in vegetation cover types 4.2.5.1. The rule growing height Table 4.14: The distribution of height H (m) of timber trees of vegetation cover types (%) Vegetation cover types High levels (m) GV LSV HSV SF Level I (<0.5) 42.87 14.34 8.95 2.61 Level II (0.5 -1.0) 28.57 16.09 10.44 6.80 Level III (1.0-1.5) 20.78 19.95 12.47 7.81 Level IV (1.5-2.0) 5.42 23.87 17.59 10.06 Level V (2.0-3.0) 2.36 15.06 25.11 17.22 Level VI (3.0-5.0) - 10.69 20.09 35.20 Level VII (>5.0) - - 5.35 20.3 [...]... solutions to recover natural forests in Vi Xuyen district, Ha Giang province 4.3.1 Assessment of ability and proposal of some solutions to recover natural forests in Vi Xuyen district, Ha Giang province - The forestry industry of Vi Xuyen district always receives the attention and close guidance of leaders of Ha Giang province - In Vi Xuyen district, there are many programs and projects supported by the. .. Proposing some solutions to recover natural forests in Vi Xuyen district, Ha Giang province 4.3.2.1 The foundations of the forest restoration process * Legal foundations + Goveronment’s documents + Documents of Ha Giang province 22 * Factual foundations - Policies of assignment of land and forest and support the farmers participating in protecting and taking care of the forest have been carried - There... forests in Vi Xuyen district, Ha Giang province * Selecting and determining forest zoning subjects Based on the results of forest classification in Vi Xuyen district, Ha Giang province, we select the subject to apply the afforestation zoning of forest restoration, namely - Sub-formation of broadleaf trees with state of fresh shrub vegetation cover after exploited exhaustedly cultivating milpa It belongs... TO THE DISSERTATION 1 Do Khac Hung, Le Ngoc Cong, Ho Duy Kien, Nguyen The Anh (2010), Studying on some basic chemical properties of the soil in the process of forest restoration in Vi Xuyen district, Ha Giang province" , Journal of Forest and Environment Science.(46), pp 8-11 2 Do Khac Hung, Le Ngoc Cong (2012), Studying on factual status of vegetation covers and floras in Vi Xuyen district, Ha Giang. .. content of Ca2+ exchange in soil of secondary forests (11.36 mg/100g) * Content of Mg2+ exchange The content of Mg2+ exchange in soil of vegetation cover types has similar rules to that of the content of Ca2+ exchange It is the lowest content of Mg2+ exchange in the grass vegetation (3.27 mg / 100g) and the highest content of Mg2+ exchange in the secondary forest (4.42 mg / 100g) 4.2.11 The change of. .. The Institute of Ecology and Biological Resources p 497-503 4 Do Khac Hung, Le Ngoc Cong (2013) “Classification of vegetation cover types of natural forest in Vi Xuyen district, Ha Giang province" , Journal of Forest and Environment Science.(60), pp 7-10 5 Do Khac Hung, Le Ngoc Cong, Nguyen Thi Thu Ha (2014) Studying on changes of Mesofauna under vegetation cover types in natural forest restoration in. .. increases the level of vegetation cover increases The pHKCl is the lowest in the topsoil layer (0-10 cm) of grass vegetation cover (3.67), then that of the low shrub vegetation (3.73) and high shrub vegetation (3.75) and the highest pHKCL in the forest secondary is 4.13 4.2.10.2 Total protein content (%) Table 4.20 shows that the total protein content in the soil of vegetation cover types are mostly concentrated... and encourages people to preserve and develop vegetation covers through forest economically 2 In zoning for afforestration of forest restoration in Vi Xuyen district, Ha Giang province, organizations and individuals should not be only interested in economic purposes, but also pay attention to the solutions of ecological environment protection efficiently and sustainably RESEARCH PAPERS PUBLISHED AND. .. humus content (%) Table 4.20 shows that the total humus content in the topsoil (0-10 cm) of vegetation cover types increase gradually through the stages of the succession process of forest restoration Humus contents in the grass vegetation cover, the low shrub vegetation cover and high shrub vegetation cover and secondary forest are 3.65%, 3.80%, 4.13% and 4.86% respectively In the same vegetation cover. .. Giang province" , Scientific paper on research and teaching biology in Viet Nam, The 1st National Science Conference at Ha Noi University of Education pp 115-120 3 Do Khac Hung, Le Ngoc Cong (2013), “classification of natural vegetation cover and reasons causing forest recession in Vi Xuyen district, Ha Giang province" , Scientific paper at the 5th National Conference on Ecology and Biological Resources The . status of vegetation covers in Vi Xuyen district, Ha Giang province 4.1.2.1. Vegetation cover types in Vi Xuyen district, Ha Giang province According to the International Classification of Vegetation. deterioration. Due to the above reasons, I choose the research thesis " ;Studying on the actual status of the vegetation cover and the process of natural forest recovery in Vi Xuyen district, Ha Giang. covers in Vi Xuyen district, Ha Giang province 4.1.1. Current situation of use of forest land in Vi Xuyen district, Ha Giang province Table 4.1: Current status of forest land under 3 forest