Infiltration characteristics of soil under acacia and pine plantation forest in van don district quang ninh province

ACKNOWLEDGEMENT This project consumed a huge amount of work and research Still, implementation would not have been possible if I did not have a support of many individuals and organizations Therefore, I would like to extend my sincere gratitude to all of them First of all, I am thankful to Assoc Prof Bui Xuan Dung for his valuable and constructive suggestions, patient guidance, enthusiastic encouragement and useful critiques during the planning and development of this research work His willingness to give his time so generously has been very much appreciated I am also grateful to the laboratory of Vietnam National University of Forestry for provision of technical support in the implementation I would like to express my sincere thanks towards my friends who devoted their time and knowledge in the implementation of this project Nevertheless, I express my gratitude toward my family for their kind co-operation and encouragement which help me in completion of this research i TABLE OF CONTENTS ACKNOWLEDGEMENT i TABLE OF CONTENTS ii LIST OF TABLES iv LIST OF FIGURES v ABSTRACT viii I INTRODUCTION II GOALS AND OBJECTIVES 2.1 Goals 2.2 Objectives III STUDY SITE AND METHOD: 3.1 Study site: 3.1.1 Location: 3.1.2 Characteristics of tree species 3.2 Method: 3.2.1 Field experiment for infiltration measurement 3.2.2 Determining influencing factors 14 3.2.3 Data analysis by using software 17 IV RESULTS AND DISCUSSION: 18 4.1 Temporal infiltration characteristics of Pine and Acacia plantation forest: 18 4.1.1 Temporal infiltration characteristics under Acacia plantation forest 18 4.1.2 Temporal infiltration characteristics under Pine plantation forest: 22 4.1.3 Total water infiltrated in hour: 26 4.2 Spatial infiltration characteristics of Pine and Acacia plantation forest: 28 4.2.1 The first layer: 28 ii 4.2.2 The second layer: 29 4.2.3 The third layer: 30 4.2.4 The fourth layer: 31 4.2.5 Spatial infiltration of three plots: 32 4.3 The factors impact on infiltration characteristics 35 4.3.1 Characteristics of factors in two types of forest 35 4.3.2 Effect of factors on infiltration: 39 4.4 Recommending some solutions to protect soil and better management the forest 42 V CONCLUSION, LIMITATIONS AND RECOMMENDATIONS 46 5.1 Conclusion: 46 5.2 Limitations 47 5.3 Recommendation: 47 REFERENCES APPENDIX iii LIST OF TABLES Table 3.1 Data of infiltration evaluated 10 Table 3.2 Information of survey plots 12 iv LIST OF FIGURES Figure 3.1 a) Location of study site, b)Contour map of study site Figure 3.2 Morphology of Acacia mangium Figure 3.3 Morphology of Pinus Merkusii Figure 3.4 Tôpgraphic map of 30 locations in two types of forest Figure 3.5 Using double-ring infiltrometer to measure infiltration rate 10 Figure 3.6 Spatial infiltration measurement model 11 Figure 3.7 Spatial infiltration experiment a) Pouring dye, b) Digging soil 12 Figure 3.8 Illusion for layers dug 13 Figure 3.9 Calculate area by MapInfo 14 Figure 3.10 Collecting soil by using Dry Bulk Density Tube, drying and weighing in laboratory 14 Figure 3.11 Canopy Cover Free Application a) Original picture, b) After processing -> vegetation cover (%) 17 Figure 3.12 MS Excel, R-Studio and MapInfo programs 17 Figure 4.1 Infiltration rate in top part of Acacia forest 18 Figure 4.2 Infiltration rate in middle part of Acacia forest 19 Figure 4.3 Infiltration rate in bottom part of Acacia forest 20 Figure 4.4 Average infiltration rate of Acacia forest 21 Figure 4.5 Infiltration rate in top part of Pine forest 22 Figure 4.6 Infiltration rate in middle part of Pine forest 23 Figure 4.7 Infiltration rate in bottom part of Pine forest 24 Figure 4.8 Average infiltration rate in Pine forest 25 Figure 4.9 Total water infiltrated in hour in two types of forest 26 Figure 4.10 Total water in hour compared to other land uses 27 v Figure 4.11 The first layer of plots 28 Figure 4.12 The second layer of plots: a) Plot without tree; b) Plot with Acaca tree; c) Plot with Pine tree 29 Figure 4.13 The third layer of plots: a) Plot without tree; b) Plot with Acaca tree; c) Plot with Pine tree 30 Figure 4.14 The fourth layer of plots: a) Plot without tree; b) Plot with Acaca tree; c) Plot with Pine tree 31 Figure 4.15 (a) Dye area in plots; (b) Dye depth in plots 32 Figure 4.16 Model of dye infiltrate in layers (a) No tree plot; (b) Acacia plot; (c) Pine plot 33 Figure 4.17 Area of dye infiltrated compares to other landuses (Source: Dung et al, 2016; Linh, 2017) 34 Figure 4.18 Compare the model of dye infiltrate in layers between different land uses (Source: Dung et al, 2016; Linh, 2017) 34 Figure 4.19 Understory vegetation cover of two kinds of forest 35 Figure 4.20 Dry bulk density of two forests 36 Figure 4.21 Porosity of two forest 37 Figure 4.22 Soil moisture of two forest 38 Figure 4.23 Acacia forest - Correlation between: (1) Initial rate and stable rate; (2) Initial rate and vegetation cover; (3) Stable rate and vegetation cover; (4) Initial rate and porosity; (5) Stable rate and porosity; (6) Vegetation and porosity; (7) Initial rate and soil moisture; (8) Stable rate and soil moisture; (9) Vegetation and soil moisture; (10) Porosity and soil moisture 39 Figure 4.24 Pine forest - Correlation between: (1) Initial rate and stable rate; (2) Initial rate and vegetation cover; (3) Stable rate and vegetation cover; (4) Initial rate and porosity; (5) vi Stable rate and porosity; (6) Vegetation and porosity; (7) Initial rate and soil moisture; (8) Stable rate and soil moisture; (9) Vegetation and soil moisture; (10) Porosity and soil moisture 41 Figure 4.25 Average precipitation in one year of Van Don District – Quang Ninh province (Source msn.com) 43 vii ABSTRACT Infiltration process is a factor that very important to control soil erosion and overland flow To determine soil infiltration characteristics of Pine and Acacia plantation forest, we used double-ring infiltrometer in 15 different locations (5 times for one part) of up-hill, midhill and down-hill part in each kind of forest The spatial infiltration characteristics of soil in three plots (with no tree, with Acacia tree and with Pine tree) was determined by Dye tracer method from 19th – 20th August 2018 We also measured and analyzed the factors impacting to infiltration process The main findings after conducting the research were: (1) The temporal infiltration rate decreases over time in both Acacia and Pine forest The rate was the highest in the bottom of the hill and the lowest in the middle hill The total water infiltrated in Acacia forest (486 mm/hr) was higher than that in Pine forest (323 mm/hr) so there was more ability to occur erosion in Pine forest than in Acacia plantation forest (2) Spatial infiltration was different in three plots Plot with no tree had the largest dyed areas (2512 cm2) and the deepest dyed point (60 cm), plot with Acacia tree had the smaller dyed area (1763 cm2) and shallower dyed depth (35 cm) and plot with Pine tree had the smallest area (616 cm2) and depth of dyeing (29 cm) (3) Infiltration rate had a close positive relationship with vegetation cover and porosity and negative with soil moisture and dry bulk density (4) Suggestion for better management: Increasing vegetation cover, strengthening soil structure and using SALT model in agriculture and forestry viii I INTRODUCTION In both arid and semi-arid areas, soil infiltration is recognized as a fundamental ecological process that affects the water budget of vegetation, runoff, and the related risk of soil erosion (Ludwig JA, 2005) Infiltration rate is one of the most critical parameters for hydrologic behavior and watershed management Infiltration is the process in which water entries downward into the immediate surface of soil or other materials (Horton, 1933) Characteristics of the infiltration process will directly affect the generation of flow processes such as surface runoff, ground runoff and underground flow At high infiltration, there is almost nonexistent of surface flow (Dien, 2009) In case of low infiltration, large surface runoffs occur, erosion and landslides also occur, causing degradation of the soil That is why maintaining soil infiltration is important for managing and using land resources efficiently The process of infiltration is affected by many different factors but plant cover significantly affects the penetration of water Runoff and soil infiltration are important determinants of vegetation patterns (Chartier, 2011), but vegetation patterns also modify the infiltration capacity directly (Arnau-Rosalén, 2008) For the vegetation type, plantation becomes more popular nowadays (Linh, 2017) Regardless of climate or soil type, many plant systems have a marginal safety factor when the minimum observed leaf pressure is compared with pressures needed to induce cavitation in the plant hydraulic system (Sperry, 2000) Agroforestry management has been widely applied to reduce soil erosion and water losses, as well as to increase the land utilization rate and yield economic benefits (Li WH, 1994), thereby generating more products and increasing the incomes of farmers compared with traditional farming and forestry in Vietnam Acacia and pine are the two most widely grown species in Vietnam Vegetation or mulches protect the soil surface from the effects of rain drops Long and large root systems penetrate the soil and increase its porosity Organic matter from plants promotes a crumbly structure by improving the permeability of the soil Forest clearance protects the soil surface while tree crops provide less protection to the soil (Aditya Kumar, 2017) “The loss of understory vegetation can reduce infiltration capacity of soil and lead to some serious problems such as Horton overland flow and soil erosion” (Linh, 2017) Acacia belongs to Fabaceae family, which is believed to have nitrate fixation ability and make soil become better (May et al, 2003) Meanwhile, pine trees are easy to plant, in nature it grows in poor, dry soil, where other species that cannot grow but this species grows pure and normal (Nguyen et al, 2013) Therefore, pine forest is important to be planted on the bare land, bare hills, degraded, poor, arid soil In this study, an experiment on spatial infiltration was effectuated to see the water movement inside the soil particles under Acacia and Pine trees compared to the plot that does not have trees, and compare temporal and spatial infiltration characteristics of two types of forest to determine the accuracy of this hypothesis In fact, studies on infiltration rates in Vietnam are still limited Dung (2015), Dung et al (2016), Linh (2017) also had researches on the characteristics of soil infiltration in Pine and Acacia forests and found out that infiltration rate has close relationship with soil moisture, porosity and underground vegetation cover but in Quang Ninh, there have not been any researches yet Researches of soil infiltration and the impact of rain, soil and vegetation factors on them Haws et al, (2004), Dune et al (1991) Hiraoka et al (2010) had made it clear that when the surface coverage increases, the infiltration rate of the soil increases but those researches did not perform on Acacia and Pine species In particular, spatial infiltration is a new experiment that has been of interest in recent years for the purpose of detecting the The porosity of Pine forest was varied from 45.25 to 57.54 %, averaged 51.02 % The 8th sample had the lowest porosity and the 14th sample had the highest Porosity was a parameter that used to determine how good a soil is Water can easier to be infiltrated with a large pore in higher porosity The porosity of Acacia forest varied from 50.86 % to 64.78 % averaged 59.4 % The largest porosity belonged to the 11th sample and the lowest porosity was in the 3rd soil sample Soil porosity is significant for agricultural production and crops as water and air move in the soil due to soil gaps Soil nutrients can be mobilized for the plant, and major soil microbial activity is also occurring here, so it is said that soil fertility is significant, the roots would grow well, the infiltraition, drainage and exchange of air takes place very easy and fast In hilly areas, if the soil is very porous, most of the rainwater will be infiltrate deep, limiting the phenomenon of runoff on the ground and thus reducing erosion on the surface (Anh, 2011) Soil porosity in Acacia forest was higher than in Pine forest, it could explain why the water infiltrated in Acacia forest was larger than in Pine c Soil moisture: Figure 4.22 Soil moisture of two forest 38 Soil moisture in Acacia forest was lower than in Pine forest, the average value was 20.62 % (that in Pine forest was 22.56 %) This was one of the reasons why infiltration rate in Acacia forest was higher than that in Pine forest The highest moisture in Acacia forest was 31.12% at the 4th sample and the lowest soil sample was 12.10 and at the 3rd sample of soil Soil moisture plays an important role in infiltration process “The water infiltrates faster (higher infiltration rate) when the soil is dry, than when it is wet As a consequence, when irrigation water is applied to a field, the water at first infiltrates easily, but as the soil becomes wet, the infiltration rate decreases.” (Brouwer et al, 1985) Soil moisture of Pine forest varied from 10.20 – 35.21 % (averaged 22.56 %) The highest soil moisture was in the 8th sample and the lowest in the 11th sample 4.3.2 Effect of factors on infiltration: a Effect of factors on infiltration rate in Acacia forest Figure 4.23 Acacia forest - Correlation between: (1) Initial rate and stable rate; (2) Initial rate and vegetation cover; (3) Stable rate and vegetation cover; (4) Initial rate and porosity; (5) Stable rate and porosity; (6) Vegetation and porosity; (7) Initial rate and soil moisture; (8) Stable rate and soil moisture; (9) Vegetation and soil moisture; (10) Porosity and soil moisture 39 The relationship between vegetation cover and Infiltration rate in Acacia forest was high with the correlation coefficient equals to 0.85 between understory vegetation cover and initial rate The coefficient between stable rate and vegetation cover was 0.7 This relationship agreed with the finding of Peng Li (2004) that in plot that had vegetation cover, the infiltration rate was high There was the weak correlation between the initial infiltration rate and porosity (r = 0.25) That meaned the initial infiltration rate did not depend on the density and porosity of the soil It implied that there could be other factors affacting to initial rate in Acacia forest such as moisture content of the topsoil and the mechanical components of the soil Stable infiltration rates had a moderate relationship with porosity of the soil (r = 0.44) When the porosity of the soil increased, the stable rate increased This showed that stable rate depended not only on the density and porosity, but also on other soil factors such as soil thickness, soil structure, mechanical compositions (Dung, 2016) The relationship between soil moisture and infiltration in Acacia forest was quite similar to it in Pine forest The initial rate also had a medium correlation with moisture (r = 0.47), this was the negative relationship Stable rate had weak correlation with moisture (r = 0.22) and was not affected so much by soil moisture 40 b Effect of factors on infiltration rate in Pine forest Figure 4.24 Pine forest - Correlation between: (1) Initial rate and stable rate; (2) Initial rate and vegetation cover; (3) Stable rate and vegetation cover; (4) Initial rate and porosity; (5) Stable rate and porosity; (6) Vegetation and porosity; (7) Initial rate and soil moisture; (8) Stable rate and soil moisture; (9) Vegetation and soil moisture; (10) Porosity and soil moisture Both initial and stable infiltration rate in Pine seemed to have a quite strong relationship with understory vegetation cover The correlation coefficient between initial rate and stable rate were equal to 0.80 and 0.67 in turn There is evidence that under the cover of vegetation, the accumulation of organic matter and the regulation of microclimate (Kittredge, 1948) are beneficial for the microbial activity and the formation of stable soil aggregates (La, 1987) The soil structure enhanced by these factors improves the infiltration Typically, infiltration rates are often observed differently under different life forms (Blackbum 1975; Wood 1981; Knight 1984; Thurow, 1986) Recently, a number of studies have demonstrated 41 the effectiveness of increasing the cover of ground floor plants, particularly grasses, reducing runoff and erosion (Pressland, 1982; Eldridge, 1993) Therefore, with such a low underground vegetation cover in the Pine forest, erosion would easy to occur The initial rate of Pine forest had relationship with porosity with the correlation of 0.67 When porosity increased, the initial rate also increased The stable rate of Pine forest depent on porosity with the correlation coefficient of 0.47 The relationship was positive between porosity and stable rate This value showed the medium relation, which meaned that there were other factors affecting to infiltration rate not only dry bulk density and porosity but also soil structure and content, and so on The initial infiltration rate and soil moisture in Pine forest had a moderate relationship with the correlation coefficient of 0.42 When the soil moisture went up, the initial infiltration rate went down and vice versa Soil moisture and stable rate seemed like had a weak relationship, the coefficient of two parameters was equal to 0.21 showed that the stable rate did not depend much on soil moisture 4.4 Recommending some solutions to protect soil and better management the forest Soil is a reservoir for plant growth Water in the soil is added by infiltration Infiltration rates may be limited by poor management Under these conditions, water does not easily penetrate into the soil and it moves downward like a stream or pond on the surface where it evaporates As a result, less water is stored in the soil for plant growth, and reduced plant yields, leading to less organic matter in the soil and reduced soil structure, can further reduce infiltration Overland flow can cause soil erosion and gullies formation It also contains nutrients and organic matter, along with sediment, which reduces water quality in streams, rivers and lakes Sediment reduces 42 the capacity of reservoirs to store water Excessive flow can cause flooding, eroding waterways and damaging roads Flows from adjacent slopes can cause siltation in low areas or can create ponds and lakes, thus killing upland crops Evaporation in degraded areas reduces the availability of water for crops (NRCS, 2001) 600 Precipitation (mm) 500 400 300 200 100 01 02 03 04 05 06 07 08 09 10 11 12 Month Figure 4.25 Average precipitation in one year of Van Don District – Quang Ninh province (Source msn.com) This graph shows the precipitation in a year in Van Don District The average precipitation of July and August (the conducted research) was 515 and 459 mm/hour The average infiltration in Acacia and Pine forest was 487 and 323 mm/hour, which means in July, there was a high ability for overland flow to occur and create erosion In August, the infiltration rate was higher in Acacia forest and lower in Pine forest than precipitation That implied there was high chance for forming of overland flow in Pine forest while the infiltration was quite good at Acacia forest To avoid and reduce possibility of surface runoff and erosion, we should have planned to improve the soil quality in such areas In order to have an effective plan for increasing infiltration rates and reducing erosion, soil properties as well as vegetation cover should be considered above all 43 because they have a great influence on soil infiltration as the results of this study Restoring higher infiltration rates can be difficult and time-consuming when changing vegetation, for example, from grassland to canopy tree, especially when erosion has occurred and causes the depletion of organic matter in the soil (NRCS, 2001) So we need to have strategies such as: - Increasing plant covers, in case Acacia has higher infiltration than Pine, we need to increase acacia plantation area, use acacia tree for bald hills, and this measure would improve soil quality as well as bring economic efficiency to the local - Strengthening soil structure: Well-structured soil enhances water retention, improves ventilation and retains nutrients in soil Increasing soil organic fertilizers has important implications for improving soil structure - Reducing the level of compression by avoiding grazing and using machinery when the soil is still wet Plowing, cultivating, rational farming is the most effective way to improve compacted soil Dredging, plowing, making the soil porous, seed germination and destroying the weeds help plants grow better due to improved nutrients, water and air - Reducing the formation of physical layers by maintaining or improving vegetation cover or trash and thus reducing the impact of rain - Increasing aggregate stability by increasing the amount of organic matter added to the soil through residual decomposition and strong root growth - Using SALT model to protect and improve soil Sloping Agricultural Landuse Technologies (SALT) is a sustainable farming ecosystem for sustainable sloping land use that is finalized and finalized by the Rural Life Center of the Philippines Developed from 1970, there are some models of sustainable farming techniques that 44 are recognized and applied in Vietnam but SALT and SALT model was the most suitable models for the soil of study site:  Model SALT 1: This model arranges the planting of short-day rows of tree alternating with long-term rows to match the characteristics and soil requirements of the species and ensure regular harvest These rows are planted in a contour line, between the main crops 4-6m wide with narrow stripes of nitrogen fixation to keep the soil from erosion and for composting or logging Nitrogen fixation plants are planted in thick double rows, when the tree is 1m high, cut branches, leaves folded into the root Plant structure in the model is usually 75% of agricultural crops, 25% of forest trees This is a simple sloping land model, farmers can earn up to 1.5 times higher than conventional cassava growing This technique reduces erosion by 50% compared to conventional upland farming systems  Model SALT - Sustainable agro-forestry cultivation model: This model combines a small-scale plantation with food production Appropriate land use structure is 40% for agriculture and 60% for forestry In this way, the land is effectively protected and at the same time provides more food, fuel, wood and other products, increasing income for farmers This model is also a harmonic coordination and reasonable expansion of the model above, but with special emphasis on forest development This model can be extended to a household with relatively large landholdings (about 5-10 ha) in many terrain types, or larger for a group of households 45 V CONCLUSION, LIMITATIONS AND RECOMMENDATIONS 5.1 Conclusion: Based on the results of the study, the following conclusions can be drawn: - The temporal infiltration rate was decrease over time in both Acacia and Pine forest The initial infiltration rate of the Acacia plantation forest ranged from 9.1 mm/min to 37.6 mm/min, the stable rate varied from 2.5 to 7.3 mm/min The initial rate of the Pine plantation forest varied from 6.9 mm/min to 36.9 mm/min, the stable rate ranged from 0.5 to 6.3 mm/min The middle hill had the lowest infiltration rate and the highest belonged to the downhill The total water infiltrated in Acacia forest was 486 mm/hr and in Pine forest was 323 mm/hr so there was more ability to occur erosion in Pine than in Acacia plantation forest - With the layer was nearer to the last point, dye tended to go deeper Dye areas was the biggest in plot without tree (46 – 1452 cm2), next was the plot with Acacia tree (26 – 1286 cm2) and smallest in plot with Pine tree (14 – 527 cm2) Dye went deepest with plot without tree (60 cm), then plot with Acacia tree (35 cm) and shallowest in plot with Pine tree (29 cm) - The correlation infiltration rate and influencing factors: The initial and stable water infiltration rate was proportional to the vegetation cover, initial rate of Acacia forest was not affected much by dry bulk density and porosity, and however, in Pine forest it was a negative relationship with bulk density and positive relationship with porosity Stable rate had strong relationship with soil porosity and bulk density, when bulk density increased, stable rate decreased whereas porosity increased, stable rate increased Initial rate was inversely proportional to the soil moisture when stable rate had a weak correlation with humidity of the soil 46 - Increasing vegetation cover, strengthening soil structure and using SALT model in agriculture and forestry were some suggestions for improving and protecting soil and better management the forest 5.2 Limitations Although this research was carefully prepared, I am still aware of its limitations and shortcomings First of all, because of time consuming the study was conducted in the rainy season so that there was lack of data on the dry condition Secondly, the double-ring infiltrometer method use stimulated rainfall so it cannot assess the characteristics of infiltration rate in the nature rainfall condition The third limitation is that because of rainy season, the soil became wet after poured dye into soil, then when we dug the soil layer, it was so hard to identify the traces of dye in the layers so that there might have a little mistake in detect the soil area but not so serious 5.3 Recommendation: Research on soil infiltration is very important in the field of environmental protection and water resources management On the other hand, this research contributes significantly in predicting forest floods, limiting surface runoff and preventing soil erosion It is therefore necessary to determine the infiltration and retention of soil As the research is very limited, it is desirable if the conditions allow for further study to cover many forest conditions and different types of land use as well as in-depth study of the factors affecting the infiltration rate to improve soil permeability, study the effectiveness of technical measures to improve soil permeability in research areas 47 REFERENCES May, B M., & Attiwill, P M (2004) Nitrogen-fixation by Acacia dealbata and changes in soil properties years after mechanical disturbance or slashburning following timber harvest Forest Ecology and Management, 181(3), 339-355 Blackburn, W H (1975) Factors influencing infiltration and sediment production of semiarid rangelands in Nevada Water Resources Research, 11(6), 929-937 Bui Xuan Dung (2015), Infiltration characteristics of some land use types in Luot mountain – VNUF, Forestry Science and Technology magazine vol 4, pp.4758 C Brouwer, A Goffeau, M Heibloem (1985) Irrigation Water Management: Training Manual No - Introduction to Irrigation Chapter - Soil and Water FAO - Food and Agriculture Organization of the United Nations, pp.914 Chyba, M.Kroulik, J.Lev and F.Kumhala (2013) Influence of soil cultivation and farm machinery passes on water preferential flow using brilliant blue dye tracer, Agronomy Research 11(1):25-30 Dien PV, Tuan, PD (2006) Research on water holding capacity in some types of vegetation cover in Hoa Binh Hydropower Plant Doctorate in Agriculture, Hanoi National University of Forestry (Vietnamese document) Dung B.X, Linh P.T, Thuy T.T, Linh N.T.M, Kha L.N, Trang P.T.T (2016), Infiltration characteristics of soil under Eucalyptus plantation forest in headwater of Viet Nam, Forestry Science and Technology magazine vol 2, pp.63-74 Eldridge, D.J and Koen, T.B (1993) Runoff and sediment removal on a semiarid soil in eastern Australia II Some variationsin hydrological properties along a gradient in soil surface condition Rangeland Journal 15, 234-46 Haws NW, Liu B Boast CW, Rao PSC, Kladivko EJ, Franzmcier DP (2004) Spatial variability and measurement scale of infiltration rate on an agricultural landscape Soil Science Sociery of America Journal 68 18181326 10 M., Onda, Y., Kato, H., Mizugaki, S., Gomi, T and Nanko, K (2010) Effects of understory vegetation on infiltration capacity in Japanese cypress plantation Journal of the Japanese Forest Society, 92(3), pp.145-150 11 Horton, Robert E (1933) "The role of infiltration in the hydrologic cycle" Trans Am Geophys Union 14th Ann Mtg: 446–460 12 Kadir W.R, Kadir A.A., Van Cleemput O., Zaharah Abdul Rahman (1996) Field grown Acacia mangium: How intensive is root growth? Journal of Tropical Forest Science 10(3): 283–291 13 Kittredge, J (1948) The effects of woody vegetation on climate, water, and soil, with applications to the conservation of water and the control of floods and erosion Book: Forest Influence, 369-386 14 Knight, R.W., W.H Blackburn, and L.B Merrill (1984) Characteristics of oak mottes, Edwards Plateau, Texas J Range Manage 37:534-537 15 Lal, R (1987) Tropical ecology and physical edaphology (No 574.52623 L193t) London, GB: Wiley, 17-21 16 Li WH, Lai S ((1994) Agroforestry in China Beijing: China Science Press.; pp:14–18 17 Pham Thuy Linh (2017), Infiltration Characteristic of soil under Cinnamon and Acacia plantation forest in Mau A town -Van Yen district - Yen Bai province Student thesis 2017, vfu:13 18 Pressland, A.J Lehane, K.J (1982) Runoff and the ameliorating effect of plant cover in the mulga communities of southwestern Queens land Australian Rangeland Journal 4, 16-20 19 Quang Ninh Provincial People's Committee (2014) Proposed Forestry Development Seed Stage in Quang Ninh Province 2016 – 2020 20 Sperry, J S (2000), Hydraulic constraints on plant gas exchange, Agric.For Meteorol., 104(1), 13–23 21 Thurow, T.L., W.H Blackburn, and C.A Taylor, Jr (1986) Hydrologic characteristics of vegetation types as affected by livestock grazing systems, Edwards Plateau, Texas J Range Mange 39:505-509 22 Voigtlaender M et al (2012) Introducing Acacia mangium trees in Eucalyptus grandis plantations: consequences for soil organic matter stocks and nitrogen mineralization Plant and Soil 352(1–2):99–111 doi:10.1038/511155d APPENDIX Understory Initial Stable Rate Rate Soil moisture Name D (g/cm3) X (%) vegetation (%) cover (%) (mm/min) (mm/min) P1 1.35 49.03 26.1 31.23 7.4 2.5 P2 1.38 48.05 4.3 28.01 12.2 1.8 P3 1.21 54.38 13.8 26.91 10.1 1.5 P4 1.32 50.17 18.6 27.87 11.8 0.6 P5 1.41 46.69 17.1 26.4 11 1.4 P6 1.42 46.26 10.2 25.5 8.9 1.6 P7 1.38 47.87 11.26 6.9 0.5 P8 1.45 45.25 11.9 19.12 8.6 0.8 P9 1.16 56.14 16.3 35.21 10.8 1.7 P10 1.39 47.36 27.5 22.73 10.2 2.1 P11 1.23 53.69 9.2 10.2 15.5 2.3 P12 1.16 56.11 36.4 15.41 14.2 0.8 P13 1.15 56.74 54.7 13.58 30.9 6.3 P14 1.13 57.54 65.5 16.7 39.6 3.2 P15 1.32 50 38.7 28.33 8.7 2.2 A1 1.17 55.96 16.1 22.31 12.6 3.7 A2 1.15 56.74 30.2 13.45 14.3 3.6 A3 1.3 50.86 49.3 12.1 17.2 2.7 A4 0.97 63.53 21.4 31.12 9.6 3.8 A5 0.93 64.78 27.3 14.17 11.3 3.4 A6 1.14 56.89 21.6 21.37 13.2 3.5 A7 1.18 55.53 25.2 20.43 9.9 A8 1.03 61.13 13.4 22.99 9.1 2.6 A9 1.09 58.93 10 28 12.4 3.4 A10 62.17 11.9 24.8 10.9 2.5 A11 0.97 63.5 73.7 13.26 37.6 6.1 A12 1.04 60.84 45.3 24.55 19.2 4.5 A13 1.16 56.17 36.8 19.53 14.8 3.2 A14 1.05 60.36 38.1 23.76 11.5 A15 0.98 62.92 53.2 17.49 34.7 7.3 Parameters No tree plot Acacia plot Pine plot 19th – 20th August 2018 19th – 20th August 2018 19th – 20th August 2018 10 12 13 31 0 DBH (cm) 18 27 Heigh of tree (m) 10 19 Age of tree (year) 20 Date Slop (o) Understory vegetation Cover (%) ... Acacia and Pine forest in different locations Compare to those researches, the amount of water infiltrated into the soil in hour at Acacia and Pine forest in Van Don District – Quang Ninh province. .. purpose of detecting the movement of water within the soil (Chyba et al, 2013) Therefore, the research ? ?INFILTRATION CHARACTERISTICS OF SOIL UNDER ACACIA AND PINE PLANTATION FOREST IN VAN DON DISTRICT. .. determine infiltration characteristics of soil under Pine and Acacia plantation forest, from then propose some solutions for better and sustainable management land and water resource in plantation