1 Faculty of Environment and Resource Studies, Mahidol University, Nakhon Pathom 73170, Thailand. Abstract. The research determined the cambial activity of ...
Supaporn Buajan1, , Nathsuda Pumijumnong1, 1 Faculty of Environment and Resource Studies, Mahidol University, Nakhon Pathom 73170, Thailand
Mahidol University Abstract
The research determined the cambial activity of five dominant species; Tetrameles nudiflora, Magnolia baillonii, Canarium euphyllum Kur, Toona Ciliata and Spondias axillans at Khao Yai National Park, Thailand. The result was archived from the first six months (July - December 2010). The most number of cell layers was found in Canarium euphyllum (7.52 cell layer in November). Spondias axillans showed the average cells of the highest-activity month were 7.35 layers in August. Magnolia baillonii revealed the average cells of the highest-activity month were 7.02 layers in November. Tetrameles nudiflora presented the average cells of the highest-activity month were 6.75 layers in July and Toona Ciliata showed the average cells of the highest-activity month were 9.70 layers in December. Growth dynamic of five species were quite different. Cambial activity of Toona Ciliata strongly responded with monthly total precipitation. The amount of rain fall may influence to those species. On the other hand, cambial activity of Spondias axillans and Tetrameles nudiflora did not respond with monthly total precipitation but it significant with monthly mean temperature. Canarium euphyllum was significant with monthly mean minimum temperature. Magnolia baillonii was not significant with climate factor. It might be explained that another factor could affect on their cambial activity with amount of rain fall. However, this study is still carry on collecting samples.
Study site and sample collection Cambial samples were collected on the 30ha Mo-singto permanent forest plot, Khao Yai National Park, Nakhon Nayok Province, Thailand (14° 26’ N, 101° 22’ E) (Fig. 1). The plot was situated in mature, seasonally-wet evergreen forest at 723–817 m in elevation (Brockelman 1998).The sampling took place in monthly intervals since July 2010 (Fig 2). Data on monthly mean temperature, monthly total rainfall and relative humidity were obtained from Khao Keaw station (12° 21’ N, 101° 22’ E) (RTAF, 2011). The cambium samples (25 x 10 x 10 mm) were taken from living trees with a chisel and knife. They contained phloem, cambium and outer xylem. After sampling, blocks of tissue were immediately fixed in glutaraldehyde solution of 3 % and, dehydrated through a graded series of ethanol and embedded in polyethlene glycol (PEG 1500). Thereafter, microsection of 15-30 µm thicknese were cut with rotary microtome. Sections were finally stained for light microscopy with safranine and fastgreen dissolved in xylene and mounted in permount.
Fig 1 Map of study area, showing the location of the study station.
Results and discussion
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Cambial activities from five species in Khao Yai National Park were quite different, as show in Fig 3 A-J. Pearson’s correlation was used to estimate the relationship between cambial activities of five species and climatic factors. For the Tetrameles nudiflora, we found a significant positive correlation between cambial cell layers and monthly mean temperature (r = 0.902, p = 0.01) and it was also significant with monthly mean maximum temperature (r = 0.761, p = Fig 2 Impression of study site and sampling collection 0.05). We conclude that the temperature must be the main climatic factor influence with this species. For the Magnolia baillonii, we found no significant correlation between cambial activity and climatic factor. It can be assume that this species growth depend on other factor. Result of this species similar with the study of seasonal variation in cambial activity of Podocarpus neriifolius at Khao Yai National Park, Thailand (Suwanpatra, 2006). For Toona ciliata, we found a significant negative correlation with monthly total precipitation (r = -0.730, p = 0.05). So we conclude that the onset of cambial activity must be related to amount of rainfall. The result related with study of Toona ciliate at the Curtain Fig (Tracey, 1982). For the cambial activity of Canarium euphyllum, we found a significant negative correlation with monthly minimum temperature (r = -0.769, p = 0.05). Nevertheless, it showed high correlation with monthly total precipitation (r = -0.641) and monthly mean relative humidity (r = 0.712). Considering correlation between climatic factor and cambial activity of both species (Toona ciliate and Canarium euphyllum) were similar. We can assume that both of growth species respond to assimilative climate. Responding of cambial activity of Spondias axillans and Tetrameles nudiflora to precipitation and relative humidity were similar. In other words, responding to temperature was contrary.
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Fig 3 Transverse section of cambial zone, A-B: cambial cell layer of Tetrameles nudiflora in August and July, C-D : cambial cell layer of Spondias axillans in July and August, E-F: cambial cell layer of Toona Ciliata in August and December, G-H: cambial cell layer of Canarium euphyllum in July and November, I-J: cambial cell layer of Magnolia baillonii in July and November.
Conclusion Reference : Brockelman, W. Y. 1998. Long term ecological research plot for the study of animal diets in Khao Yai National Park. Pages 307– 310 in The Asian hornbills: ecology and conservation (P. Poonswad, Ed.). Thai Studies in Biodiversity, no. 2. Biodiversity Research and Training Program, Bangkok, Thailand. Royal Thai Air Force. 2011. [ Meteorological data from Khao Keaw control and report center]. Unpublished raw data. Suwanpatra, K. 2006. Seasonal variation in cambial activity of Podocarpus neriifolius at Khao Yai National Park. Unpublished master’s thesis, Mahidol University, Nakhonphathom, Thailand. Tracey, J.G., 1982. The Humid Tropical Region of North Queensland. CSIRO, Melbourne.
We studies of seasonal cambial activity of five species in tropical forest at Khao Yai National Park. The result showed that the cambial activity of four species, Tetrameles nudiflora, Magnolia baillonii, Canarium euphyllum and Spondias axillans were not significant correlation with rainfall and relative humidity. The temperature has more influent to their cambial activity than rainfall. One species has different from other is Toona ciliate, it was high significant correlation with rainfall.
