KẾT HỢP KIẾN THỨC SINH THÁI BẢN ĐỊA VÀ ĐIỀU TRA RỪNG ĐỂ LỰA CHỌN LOÀI CÂY CHỈ THỊ NHẰM PHỤC VỤ CÔNG TÁC GIÁM SÁT TRẠNG THÁI RỪNG TẠI MIỀN TRUNG VIỆT NAM In tropical central Viet Nam, as part of a forest allocation program, forest condition should be monitored by local stakeholders. If local ecological knowledge can be integrated into the development of indicator species, then improvements in both the rigor of the indicator list and the involvement of local people in the monitoring process may occur. We used a dual methodology to derive two forest condition indicator species lists using trees, based on local ecological knowledge and quantitative forest surveys. Combining these lists allowed us to produce a final list of thirteen ‘probable’ and eight ‘possible’ indicator tree species for forest
Short communication Combining local ecological knowledge and quantitative forest surveys to select indicator species for forest condition monitoring in central Viet Nam Ngo Tri Dung a,b, * , Edward L. Webb a a Natural Resources Management, School of Environment, Resources, and Development, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani 12120, Thailand b Faculty of Forestry, Hue University of Agriculture and Forestry, 102 Phung Hung Street, Hue City, Viet Nam 1. Introduction Ecologists and conservation practitioners have increasingly utilized indicators species for environmental monitoring and assessment (McGeoch, 1998; Kati, 2003). Plant species can be used as indicators because they are easily sampledand stored, taxonomically well known, and distributed over range of habitats or environments (Faith and Walker, 1996). However, development of indicator species usually employs intensive survey methods that require well-developed researcher qualifications (Dufreˆne and Legendre, 1997), and has often not integrated local ecological knowledge intothe indicator set (Salam et al., 2006). Thus, the application of the indicators at the local level remains limited, particularly in rural settings of developing countries. In Nam Dong district of Thua Thien Hue province, central Viet Nam, the local authorities have allocated natural forests to local people for long-term management since 2001. Because allocated forests are heterogeneous in levels of disturbance and stages of ecological recovery (‘condition’), they should be ecological indicators 8 (2008) 767–770 article info Article history: Received 4 December 2006 Received in revised form 3 September 2007 Accepted 18 September 2007 Keywords: Degradation Disturbance Participation Regeneration Succession Tropical forest Tree community abstract In tropical central Viet Nam, as part of a forest allocation program, forest condition should be monitored by local stakeholders. If local ecological knowledge can be integrated into the development of indicator species, then improvements in both the rigor of the indicator list and the involvement of local peopl e in the monitoring process may occur. We used a dual methodology to derive two forest condition indicator species lists using trees, based on local ecological knowledge and quantitative forest surveys. Combining these lists allowed us to produce a final list of thirteen ‘probable’ and eight ‘possible’ indicator tree species for forest condition monitoring. Despite some possible limitations to the methodology, we encourage the use of multiple data sets when working with rural communities that are involved in the monitoring process. Local people can propose timely and appropriate measures of forest conservation and improvement, and can definitely integrate indicator species into mon- itoring community forests. # 2007 Elsevier Ltd. All rights reserved. * Corresponding author at: Natural Resources Management, School of Environment, Resources, and Development, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani 12120, Thailand. Tel.: +84 54 529137; fax: +84 54 524923. E-mail address: dzungtringo@gmail.com (N.T. Dung). available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/ecolind 1470-160X/$ – see front matter # 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.ecolind.2007.09.002 monitored regularly to collect information for appropriate management practices. Developing a list of indicator species based on local ecological knowledge and quantitative vegeta- tion plot data could contribute to long-term forest monitoring since these two sources of information help to increase the statistical rigour of those indicators. This would also improve levels of interest and confidence of local people when monitoring forests that are under local community control. In this study we combined local ecological knowledge with quantitative vegetation data to propose a set of forest condition indicator species of trees for tropical forest in Nam Dong district, Viet Nam. 2. Materials and methods Nam Dong district is located in southwestern Thua Thien Hue province in central Viet Nam. The district ranges in elevation from 300 m to 1700 m above sea level, and approximately 65% of the district is covered with seasonal evergreen broadleaf forest (Tordoff et al., 2003). Three communes selected for this study were Thuong Quang, Thuong Long, and Huong Son. Major livelihood activities were paddy agriculture, swidden agriculture, non-timber forest product (NTFP) collection and small wildlife hunting. Based on a combination of the government forest classification system and local descrip- tions, we classified forests into three groups. Relatively intact forest (RIF) had a closed canopy, well-defined stratification, and the majority of large trees with a stem diameter greater than 20 cm. Selectively logged forest (SLF) had been logged and exhibited a significantly altered structure from RIF. Swidden forest (SWF) had regenerated after swidden agriculture or clear cutting since a logging ban was implemented in 1995. Most of the allocated forests have been RIF and SLF, with small areas of SWF allocated for plantation or upland crop cultivation (cassava, maize, and upland rice). In order to develop a list of indicator species for these three forest types, we collected complementary sets of qualitative and quantitative data. Qualitative data were obtained through village meetings and questionnaire interviewing of 118 experienced local people (woodsmen). Species were ranked for each forest type according to respondent value (ResVal), which was the percent of respondents listing that species as being exclusively or nearly exclusively found in one of the three forest types (i.e., an indicator). Quantitative data were collected from 110 circular plots established across the three forest types, across the three study communes. Each plot had a radius of 10 m and was placed randomly. We did not survey woody seedlings or climbers because they were not comparable to the locally derived indicator list, which focused on life forms larger than seedlings. Taxonomy followed Ho (2000) and the Plant Name Table 1 – Probable and possible indicator species for relatively intact forest (RIF), selectively logged forest (SLF), and Swidden forest (SWF) in Nam Dong district of Central Viet Nam Forest type Species name Family Life form Local ecological knowledge Plot data ResVal Rank IndVal Rank Probable indicator species RIF Hopea pierrei DIPTEROCARPACEAE L-tree 69.5 1 25.0 10 Gironniera subaequalis ULMACEAE M-tree 22.9 7 49.4 1 Palaquium annamense SAPOTACEAE L-tree 17.8 9 43.9 2 Syzygium sp. MYRTACEAE S-tree 21.2 8 39.4 3 Rhapis laosensis ARECACEAE Palm 28.8 6 11.7 21 Madhuca pasquieri SAPOTACEAE L-tree 13.6 10 28.0 7 SLF Horsfieldia amygdalina MYRISTICACEAE L-tree 18.6 1 38.5 7 Gardenia annamensis RUBIACEAE S-tree 15.3 3 35.9 8 Garcinia cochinchinensis CLUSIACEAE M-tree 10.2 6 26.2 16 SWF Mallotus paniculatus EUPHORBIACEAE M-tree 59.3 2 77.8 1 Macaranga denticulata EUPHORBIACEAE S-tree 16.9 7 70.2 2 Thysanolaena maxima POACEAE Grass 67.8 1 22.2 6 Melastoma candidum MELASTOMATACEAE Shrub 38.1 4 28.4 4 Possible indicator species RIF Erythrophleum fordii CAESALPINIACEAE L-tree 45.8 2 – – Parashorea stellata DIPTEROCARPACEAE L-tree 42.4 3 – – SLF Scaphium lychnophorum STERCULIACEAE M-tree – – 61.2 1 Knema pierrei MYRISTICACEAE L-tree – – 54.4 2 Croton cascarilloides EUPHORBIACEAE Shrub – – 50.6 3 Ampelocalamus patellaris POACEAE Bamboo 16.1 2 – – SWF Scleria levis POACEAE Grass – – 66.1 3 Imperata cylindrica POACEAE Grass 52.5 3 – – Respondent values (ResVal) and indicator values (IndVal) were listed from local interview data and plot survey data, respectively. L-tree: large tree (>30 m high); M-tree: medium tree (15–30 m high); S-tree: small tree (<15 m high). ecological indicators 8 (2008) 767–770768 Index of Viet Nam (IEBR and CRES, 2003). From plot data, the indicator value (IndVal) of each species was calculated using the method of Dufreˆne and Legendre (1997). This method combined information on the concentration of species abundance in a particular forest type (specificity) and the faithfulness of occurrence of a species in a particular forest type (fidelity). The IndVal may range from zero (no indication) to 100 (perfect indication). PC-ORD software (version 4.41, McCune and Mefford, 1999) was used to calculate the IndVal for each species. We constructed two final lists of indicator species based on (1) the overlap between interview-derived and plot-derived data for each species, and (2) the rank of that species in each data type. A ‘probable indicator species’ was one that appeared in both sources of data for that forest type and had high IndVal or ResVal for at least one data set. A ‘possible indicator species’ appeared in only one source of data but had an IndVal or ResVal rank in the top three for that forest type. 3. Results Thirty-two species were identified by local people as indica- tors, with 15 for RIF, 9 for SLF, and 8 for SWF. The top locally known indicator species for RIF were Hopea pierrei, Erythroph- leum fordii, and Parashorea stellata. Local indicators for SLF were Horsfieldia amygdalina, Ampelocalamus patellaris, and Gardenia annamensis. Top local indicator species for SWF were Thysa- nolaena maxima, Mallotus paniculatus and Imperata cylindrica. Analysis of plot data yielded 21 indicator species for RIF, 30 for SLF and 15 for SWF. The top plot-derived indicators for RIF were Gironniera subaequalis and Palaquium annamense. Top indicator species for SLF were Scaphium lychnophorum, Knema pierrei and Croton cascarilloides. In SWF, indicator species were M. paniculatus, Macaranga denticulata and Sclera levis. Comparing the interview data with the plot data returned 13 probable indicators and eight possible indicators (Table 1). H. pierrei, G. subaequalis, and P. annamense appeared to be the strongest probable indicators for RIF because they had both high ResVals and high IndVals. Probable indicator species for SLF included H. amygdalina, G. annamensis, and Garcinia cochinchinensis. SWF probable indicators were M. paniculatus, M. denticulata, T. maxima, and Melastoma candidum. Seven species were possible indicators across the three forest types including E. fordii (RIF), S. lychnophorum, K. pierrei, C. cascar- illoides and A. patellaris (SLF). Two possible indicator species for SWF were Scleria levis and I. cylindrica. 4. Discussion There are two indicandum for which indicator species can be used in monitoring levels of forest condition. First, early warning of forest degradation can occur over time if the abundance of SWF or SLF indicators increases while the abundance of RIF indicators declines. In contrast, recovery of degraded forest can be interpreted over time if the abundance of RIF indicators increases and the abundance of SWF or SLF indicators decreases. While a wide range of species may regenerate (establish) across forest types owing to dispersal (e.g. M. denticulata in RIF, G. subaequalis in SLF), when data are aggregated across a sufficient sample size and collected repeatedly over time, significant changes in frequencies of indicator species should indicate changing overall forest conditions. This could be even more powerful if individuals of indicator species are tagged and monitored to calculate survival and size class transition rates. Seedlings and saplings could be included in the data set if favorable conditions for their growth are known. Various factors could influence the amount of overlap or mismatch between locally derived and plot-derived indicator lists. First, some species listed by local people as important indicators for a particular forest type may be ecologically transient and present only for a short period of time, and thus rarely encountered in quantitative plots. Examples in this study were Crassocephalum crepidioides and Eupatorium odor- atum (both local SWF indicators). Second, humans may alter the populations of potential indicator species, such that present and future capacity of that species to indicate trends in forest condition is compromised. E. fordii and P. stellata are large, commercially valuable timber species that were listed as indicators by local people, but had been heavily logged in the study area and were nearly absent from quantitative plots. Third, local use of a species may influence people’s listing of it as an indicator, with more valuable or commonly utilized species attaining higher prominence than more ecologically responsive species, in local observations of abundance in the forest. These three factors may have affected the amount of agreement in locally derived and plot-derived indicator species lists. The results of this study suggest that indicator species may represen t a cost-effective method for monitoring by local people. Care must be taken when interpreting reasons for mismatching of indicator lists. Despite possible sources of confusion and imprecision, we encourage the useofmultipledatasetswhenworkingwithruralcomm- unities that are i nvolved in the monitoring process. Local people can propose t imely and appropriate measures of forest conservation and improvement, and can definitely integrate indicator species into community forest monitor- ing activities. Acknowledgements We thank Tran Nam Thang, Ho Dinh Tuan, and Tran The Nhan at the Faculty of Forestry, Hue University of Agriculture and Forestry for their contribution in collecting data and discus- sion. This study was supported by a grant from the John D. and Catherine T. MacArthur Foundation to the Asian Institute of Technology. references Dufreˆne, M., Legendre, P., 1997. Species assemblages and indicator species: the need for a flexible asymmetrical approach. Ecol. Monogr. 67 (3), 345–366. Faith, D.P., Walker, P.A., 1996. How do indicator groups provide information about the relative biodiversity of different sets ecological indicators 8 (2008) 767–770 769 of areas? on hotspots, complementary and pattern-based approaches. Biodivers. Lett. 3, 18–25. Ho, P.H., 2000. Cay Co Viet Nam. An Illustrated Flora of Viet Nam, 3 volumes. Youth Publishing House, Ho Chi Minh City (in Vietnamese). 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Report No. 1, WWF Indochina, Hanoi, Viet Nam. ecological indicators 8 (2008) 767–770770 . indicator species for relatively intact forest (RIF), selectively logged forest (SLF), and Swidden forest (SWF) in Nam Dong district of Central Viet Nam Forest type Species name Family Life form. monitoring levels of forest condition. First, early warning of forest degradation can occur over time if the abundance of SWF or SLF indicators increases while the abundance of RIF indicators declines 2007 Keywords: Degradation Disturbance Participation Regeneration Succession Tropical forest Tree community abstract In tropical central Viet Nam, as part of a forest allocation program, forest condition should be monitored by local