INTRODUCTION
Forests are crucial for their social and environmental functions, providing timber and non-timber products, protecting watersheds, and serving as habitats for diverse species Additionally, they play a significant role in alleviating poverty and enhancing income for local communities living near these ecosystems In Vietnam, the challenge lies in balancing the socio-economic benefits of forests with their environmental responsibilities.
In the 1970s, a new phase in forest policy development led to the emergence of Community-based Forest Management (CBFM), which has since gained popularity in Asia and Africa CBFM is a government-sanctioned approach that involves direct forest users in decision-making and implementation of forestry activities, granting them autonomy in setting objectives and managing resources This strategy aims to improve livelihoods, reduce poverty, conserve natural resources, and promote good governance through decentralization CBFM encompasses initiatives and processes designed to enhance local people's roles in forest governance, encouraging indigenous communities to protect forests while benefiting from their resources It arose as an alternative approach to forest management amid increasing global interest in participatory development and land rights movements CBFM has been crucial in nurturing scarce natural resources, as local communities have historically managed forests based on traditional knowledge and rules that ensure long-term ecological sustainability aligned with local priorities.
The primary limitation of the current approach to Community-Based Forest Management (CBFM) is that management plans lack a foundation in forest inventory data, which is essential for sustainable forest management Forest inventory assesses the quantity and quality of available resources, enabling the development of effective management plans that meet user demands for forest products while ensuring sustainability (Wode, 2003) For effective decision-making in forest management, it is crucial to establish overarching management goals that can be compared with actual conditions However, existing forest inventories are conducted only at the national level, providing data for policy and statistics but failing to deliver the detailed growth and yield information necessary for sustainable management at the individual stand level.
Xuan Le commune, located in Thuong Xuan district of Thanh Hoa province, Vietnam, covers an area of 98.94 km² and has a population of 3,614, resulting in a low population density of 37 persons/km² The commune faces challenges such as low educational standards and high poverty levels, compounded by limited access due to numerous rivers and streams, which hinders connections to regional markets However, it is rich in natural resources, particularly mature forests Recognizing the significance of effective management based on appropriate forest resource assessments for sustainable planning, I undertook a thesis titled “Research on Building Ideal Models for Community Forest at Xuan Le Commune, Thanh Hoa Province.”
GOAL, OBJECTIVES AND METHODS
Goal
The primary objective is to evaluate both the quantity and quality of forest resources to enhance management practices within the framework of community-based forest management in Xuan Le commune, Thanh Hoa province.
Objectives
- To assess current status of forest statuses in Xuan Le commune;
- To propose ideal models for each forest status and solutions for community forest management;
- The demand of timber exploitation of local user groups;
- The diameter/age derived form annual growth rings of two ideal forest stands;
- The suitable basal area of two ideal forest stands;
- Stem numbers in single diameter classes;
- Solutions for community forest management.
Methodology
The ideal model seeks to represent a managed natural forest that balances both protection and production functions To achieve this, distinct models must be developed for each forest type The first step involves assessing the various forest types in Xuan Le commune, followed by specific tasks such as adjusting diameter classes, estimating basal area, and analyzing stand structure for each individual forest type.
Two one-hectare plots were established in distinct forest types: regenerated forest and degraded forest Each plot encompasses 10,000 m² and is subdivided into 25 sub-plots, each measuring 400 m² (20m x 20m).
Figure 2.1 Layout of plot establishment
2.4.3 Annual growth increment and suitable diameter – class a, Data collection
Determining suitable diameter-class widths is essential during the preliminary forest survey, as illustrated in Figure 2.2, which outlines the various pathways for establishing diameter classes within a local context.
Figure 2.2 The sequence of tasks necessary for the determination of suitable diameter- class widths as input parameters for ideal models
The classification of diameter-classes is crucial for enabling local communities to effectively collect and analyze data about their forests, enhancing their understanding of forest structure In addition to providing a snapshot of current conditions, the stem number-diameter distribution serves as a dynamic model for forecasting forest growth and yield By establishing a fixed time frame for diameter class progression, it is assumed that all trees will mature into the next higher class within that period This approach is essential for developing 5-year management plans, as aligning the time frame with the planning period allows for accurate estimation of harvestable trees in each diameter class during the management process.
After completing the annual increment measurements of representative samples, it's essential to analyze the data Table 2.1 outlines the specific steps involved in the data analysis process, which leads to identifying diameter classes that represent equal times of passage.
Table 2.1 Overview of the single steps leading to the calculation of diameter-classes, representative of equal times of passage
1 Calculate the arithmetic mean of respective annual diameter increments of all samples (referred to as AIn)
2 Add up the arithmetic mean values of respective annual diameter increments to obtain cumulative increment values for each year (referred to as CDI n )
To identify diameter-classes that represent equal time passages, sum five consecutive CDI n values to obtain a diameter-class indicative of a five-year growth interval This method allows for a clearer understanding of growth patterns over time.
The first stage of data analysis involves calculating the mean annual diameter increments by summing the annual increments of all samples and dividing the total by the sample size.
Subsequently, the mean annual diameter-increments (annual growth increment) are added up in order to arrive at the cumulative diameter-increment:
Based on the cumulative diameter-increment, diameter-class widths are determined representative of equal times of passages b, Interview of local forest user groups
Ideal models are tailored to meet the needs of local forest user groups, ensuring the protection of managed natural stands To gather detailed insights into the demands of these users, it is essential to survey both women and men who regularly collect and utilize various forest products.
The adjustment of diameter-classes aims to ensure equal times of passage, with the minimum harvestable diameter for the largest timber being crucial for local forest users To determine this, an assessment of forest product demand is necessary It's important to note that while the upper diameter-class limit is influenced by user demand, villagers are not compelled to harvest trees upon reaching the minimum diameter; they retain the freedom to choose when to harvest, provided they adhere to the model's guidelines If forest users allow too many trees to mature, the number of stems in lower diameter classes may fall below the ideal model's thresholds, highlighting the need for interventions by comparing the actual diameter distribution with the ideal model.
2.4.4 Suitable basal area and stem numbers in single diameter-classes a, Data collection
The basal area of a forest, measured at breast height (1.3 meters), is the total cross-sectional area of all trees, typically expressed in square meters per hectare This metric serves as an essential silvicultural measure of forest yield Adjustments to basal area and stand structure are illustrated in Figure 2.3.
Figure 2.3 The sequence of task necessary for the determination of suitable basal area and stand structure as input parameters for ideal models
It was estimated a suitable basal area of 30m2 for managed natural forest stands in Son
The province utilized scientific sources from both domestic and international research, alongside findings from participatory forest inventories (Wode 2003) The similarities in climate and vegetation between Thanh Hoa and Son La, largely attributed to their geographical proximity, facilitated the application of basal area values for managed natural forests in Thanh Hoa.
In a sample plot, all trees, saplings, and seedlings are counted, with their diameter at breast height (DBH) measured and species identified The data is categorized into 1 cm diameter classes, allowing for the calculation of the total basal area for each plot by summing the basal areas within these classes Finally, the average basal area per hectare is determined based on the plot area.
To calculate the average stem number per diameter-class per hectare, data is organized by diameter-classes The stem numbers from individual diameter-classes within sample plots are extrapolated to obtain per hectare values by dividing the stem count by the sample plot size These per hectare values for each diameter-class across all sample plots are then summed and averaged by the total number of sample plots in the forest stand Additionally, adjustments are made to the basal area and stand structure.
The basal area obtained from sample plots, which should be situated in forest patches with optimal growing conditions, establishes the framework for the distribution of stem numbers across diameter classes Additionally, the average stem numbers per diameter class derived from this data can be used as a benchmark for developing ideal stand models.
To develop an optimal stand model, it is essential to accurately determine stem numbers within individual diameter classes, adhering to the principle of diminishing stem numbers as diameter class increases Additionally, insights gained from interviews with local forest users must be taken into account to ensure the model's relevance and effectiveness in the context of community forestry.
STUDY SITE CHARACTERISTICS
Natural conditions
Xuan Le commune is a mountainous area located in the west of Thuong Xuan district, Thanh Hoa province It’s about 90 km southwest Thanh Hoa city
Figure 3.1 Map of Xuan Le Commune
Topography : Xuan Le commune has various topographical characteristics with an average height of 500-700m with many hills The topography causes soil erosion
The climate features an average temperature ranging from 22-24°C, with extremes reaching up to 37-40°C in the heat of summer and dropping to 1-3°C during the coldest months Rainfall averages between 1,600-2,000mm, occurring unevenly throughout the year, while humidity levels remain high at 85-86% The North East monsoon prevails from October to April, followed by a hot, dry Southwest wind from April to July This hot, humid, and rainy weather creates an ideal environment for plant growth.
Socio-economic conditions
There are 3 ethnic groups living in Xuan Le Commune, in which Thai people account for 55%, Kinh people is 41%, Muong people is 3.2% According to demographic statistics of
2016, the total population is 3614 people The population density is 37 people / km²
Xuan Le is a mountainous commune facing economic challenges, where the primary sources of income for residents stem from forestry and agricultural production The local economy is structured with the forestry, agriculture, and fisheries sector contributing 31.3%, while industry, handicrafts, and construction account for 39.2% Additionally, trade and services make up 29.5% of the economic activities in the area.
RESULTS
Forest statuses in the study area
In Xuan Le commune, three distinct forest statuses are identified: young regenerated forests following shifting cultivation (IIA), regenerated forests post-exploitation (IIB), and degraded natural forests that have been exploited (IIIA1) The young regenerated forests are recovering from shifting cultivation, while the matured forests, classified as protection forests, are typically located further from settlement areas.
Forest stands exhibit significant differences in species composition, with IIA and IIB typically featuring species such as Ginoniera sp (Ngat), Engelhardtia drysolepsis (Cheo tia), and Cassia pinnata (Rang rang mit) In contrast, mature forests host valuable but slower-growing species, including Shorea roxburghii (Sen), Vatika tonkinensis (Tau), Fokienia hodginsii (Po mu), Erythrophorum fordii (Lim), Diospyros mun (Mun), Cinnamomum albiforum (Re), and Mangletia fordiana (Vang tam).
Forest structure varies significantly between forest types IIA and IIB In IIA areas, larger trees are generally absent, resulting in an open canopy and dense underbrush, often creating small mosaic patterns with bare or grass-covered patches In contrast, IIB areas feature a higher abundance of pole-sized trees (15-20 cm in DBH), leading to more closed canopies, though their vertical structure typically consists of only two strata, with a significant presence of bamboo, weeds, and climbers In undisturbed mature forest sites, emergent trees rise above a closed canopy, and the vertical structure is often divided into three or four strata, with bamboo and weeds being relatively scarce.
Demand of local forest user groups on timber exploitation
During our visit to Xuan Son village in Xuan Le commune, we conducted interviews with individuals of diverse genders and age groups to gather comprehensive insights into the demand for timber and non-timber forest products.
Timber for house construction is primarily sourced from matured forest stands, which often lack sufficient size and preferred species, especially in areas recovering from shifting cultivation While some construction timber can be obtained from degraded forest stands, it typically consists of relic trees from past exploitation, such as Quercus wallichiana, Engelhardtia drysolepsis, and Gironniera sp Farmers indicate that the minimum harvestable diameter for timber is around 33 cm, but larger trees are preferred, which are predominantly found in mature forests Consequently, even emergent trees are logged and transported regardless of their size, as on-site processing is carried out using simple handsaws.
Tree selection for harvesting in Xuan Le commune is guided by criteria such as species, stem form, and diameter, leading to a method known as "single tree selection," where harvested trees are dispersed throughout the forest Timber required for each new house must receive approval from the forest protection department, allowing families to harvest timber from various locations post-approval Despite an old traditional law limiting new house construction to two per year, villagers have reported that some logs from the mature forest are sold to neighboring villages.
Harvestable diameters of 30-35 cm are primarily used for constructing house pillars, with villagers noting that the outer 1.5 to 2.5 cm of the log is typically removed and not utilized In degraded forest stands, smaller poles ranging from 8 cm to 20 cm in diameter are cut for building pig-stalls (8-12 cm DBH) and buffalo-stalls (around 20 cm DBH) However, some forest users express a preference for cutting 20 cm poles from mature forest stands, as they tend to yield more durable species.
Annual growth increments of forest statuses
The collection of diameter discs and the subsequent analysis of growth rates after sanding is a destructive method, with the only alternative being the use of stumps from recently cut trees, as logging was prohibited for this survey The findings from the measurements for both degraded and matured forest types are presented below.
As far as the degraded forest stands are concerned, annual growth rings of 14 trees have been measured The list of species is presented in table 4.1
Table 4.1 List of species included in the measurement of annual growth rings from former shifting cultivation areas
Local name Latin name Abundance (n)
Com tai trau Not identified 1
The first step in data analysis involves calculating the mean annual diameter increments for each year by summing the increments of all samples and dividing by the number of samples To determine the cumulative diameter increment for each year, these mean annual increments are then aggregated Figure 4.1 illustrates the mean diameter in relation to the age of the sampled species.
The study identifies diameter-class widths based on cumulative diameter increments, suggesting that trees typically transition between diameter-classes approximately every five years Due to competition among juvenile trees and differing physiological responses to drought compared to mature trees, the correlation between diameter and age is weak during juvenile stages Consequently, the lowest diameter-class is defined as less than 6 cm to ensure precise age intervals for the upper diameter-class.
This step is necessary in order to add the dynamic component of forest growth (allowing for the prediction of yield) to the otherwise static stem number-diameter distribution
Figure 4.1 Diameter/age estimation derived from annual growth ring measurement of
14 samples from degraded forest sites in Xuan Le commune
In degraded forests, trees with a diameter at breast height (DBH) exceeding 20-25 cm are typically scarce Villagers have noted that the most commonly required minimum harvestable diameter is between 30-35 cm, leading to the establishment of the largest diameter class at over 32.9 cm DBH.
Due to the remoteness and vastness of mature forest areas, only seven reasonable stumps were located for analysis The mean annual diameter increment across all sampled species and years was found to be 0.5 cm, significantly lower than the 1.01 cm observed in degraded forests This difference, along with variations in stand and age structure between the two forest types, supports the need for developing separate models for each A list of the sampled species is provided in Table 4.2.
The analysis of increment data followed the same methodology used for degraded forest stands However, a clear linear correlation was observed between tree age and diameter increment, leading to uniformly distributed diameter classes.
Table 4.2 List of species included in the measurement of annual growth rings from matured forest stands
Local name Latin name Abudance (n)
Diameter classes of 5 cm widths have been established to represent approximately 10-year growth intervals Figure 4.2 illustrates the mean diameter in relation to the age of the sampled species The largest diameter class is defined as greater than 39.9 cm, reflecting the preferences of forest users who primarily utilize wood that is 30 cm and larger.
Stem numbers in single diameter-classes, suitable basal area and ideal models for
The completion of ideal stand models for both mature and degraded forest stands involves specifying the number of stems within single diameter classes Table 4.3 presents the determined stem numbers for the ideal models developed for degraded forest stands.
Table 4.3 Stem number and basal area of single diameter-classes representing the ideal stand model for degraded forest sites
To promote sustainable forest management, a higher emphasis has been placed on trees in lower diameter classes, reflecting both the current natural conditions and the demand for timber from these sizes as identified in forest user group interviews Future management strategies should aim for at least 80 trees per hectare, including half from the 27-32.9 cm diameter class and an additional 40 trees larger than 32.9 cm, with the expectation that these will exceed a diameter at breast height (DBH) of 30 cm within about 20 years The primary objective is to gradually rehabilitate degraded forests into mature, productive ecosystems, facilitating the harvest of trees when their numbers exceed the model's specified thresholds, while adhering to established silvicultural guidelines.
Table 4.4 presents the stem numbers for matured forest stands, highlighting that the abundance of smaller-sized trees is slightly lower in these areas compared to degraded forests This observation can be attributed to the closed canopies of matured forests, which limit light availability in the lower strata, consequently reducing the presence of smaller trees Although villagers did not indicate a specific upper diameter limit, they expressed a preference for harvesting larger trees, leading to the establishment of the largest diameter class at 39.9 cm.
Table 4.4 Stem number and basal area of single diameter-classes representing the ideal stand model for mature forest sites
The basal areas of stems per diameter class were calculated using the averages of each class, with the lower limits applied for the largest diameter classes The stem number-diameter distributions for both ideal models are illustrated in Figures 4.3 and 4.4.
Figure 4.3 Ideal stem number-diameter distribution for matured forest stands
Figure 4.4 Ideal stem number-diameter distribution for degraded forest stand
Proposed solutions for community forest management
Effective forest management is essential for community development, and ideal models play a pivotal role in this process To achieve this, it is important to focus on three key aspects: utilization, improvement, and protection of forest resources.
To promote sustainable harvesting practices, the community should designate specific areas for tree harvesting, focusing exclusively on trees within the diameter class of 30 to 34.9 cm It is essential to limit harvesting to rare species and ensure that seed-bearing mother trees are located nearby to facilitate natural regeneration These seed trees should be evenly distributed throughout the designated area.
Before harvesting, it is essential to mark timber trees, with responsible forest rangers and a representative from the Communal Forest Management Board responsible for checking and approving the selection process.
Third, after harvesting, no further logging activities are to be carried out in the area for a minimum of 20 years People should not concentrate logging activities in one small area
Local governments and forestry organizations must prioritize raising awareness and providing technical support to local communities while developing and implementing effective forest management plans.
CONCLUSION 25 REFERENCES
Important conclusion about participatory forest resources assessment in the context of community based forest management can be drawn
The annual diameter increment in degraded and matured forests reveals the growth timeline for tree diameter classes In degraded forests, trees take approximately 5 years to grow into the next 5 cm diameter class, while in matured forests, this growth period extends to 10 years for the next 10 cm diameter class This information is crucial for local communities to plan their harvest operations effectively.
The ideal models for virgin natural forests adhere to the "inverse-J curve," which serves as a guideline for sustainable close-to-nature forestry To ensure ecological balance, only trees that exceed this curve should be harvested.
Experts and local communities can collaborate to develop a comprehensive community forest management plan, which will be refined during village meetings to encourage participation from local forest user groups, ensuring its reliability and effectiveness This plan should span a 10-year period to provide the necessary medium-term stability for the consistent implementation of sustainable forest management activities It is essential for all decision-makers to utilize the plan, which is grounded in a thorough forest resource assessment to guarantee a shared understanding of management practices Additionally, the plan outlines approved management objectives and effectively communicates these goals to stakeholders involved in its execution.
The assessment of forest resources in Xuan Le commune presents significant potential for sustainable forest management To realize this potential, it is crucial to emphasize the importance of training local communities in effective forest management practices, particularly in providing comprehensive silvicultural guidelines.
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