News Letter on Tree Species Research: March – 2019

Influence of Climate Variation on Growth of Tropical Tree Species in Western Kenya

Aims: Growth-climate relationships were examined in 7 tropical tree species growing in the Yala river basin of western Kenya: Acacia mearnsii, Cupressus lusitanica, Eucalyptus camaldulensis, Eucalyptus grandis, Eucalytus saligna, Mangifera indica, and Markhamia lutea.

Methodology: Standardized basal area increments were correlated with monthly and seasonal (3 month periods) climate variables (precipitation, mean temperature, Climate Moisture Index) obtained from nearby meteorological stations.

Results: A majority of the tree species (M. indica, C. lusitanica, E. camaldulensis, and E. saligna) showed positive correlations with monthly and seasonal precipitation and moisture index during periods of the long and short rainy seasons.  This study also revealed significant correlations between monthly and seasonal temperature data and radial growth of M. indica, M. lutea and E. grandis.  Growth of M. lutea was negatively affected by cool growing season conditions while M. indica and E. grandis experienced high temperature stress.

Conclusion: Associations between radial growth of tropical tree species and temperature are generally rare in warm tropical regions, and for some of the species examined in this study that are non-native (i.e., M. indica and E. grandis), strongly suggests that they may be growing outside the optimal temperature conditions of their native geographical range. [1]

Estimation of Carbon Stock in the Regenerating Tree Species of the Intact and Disturbed Forest Sites in Tanzania

Aim: Estimation of carbon in the forests located in the coast of tropics is needed to support conservation and forest monitoring strategies. This study aimed at quantifying carbon stocks in the regenerating tree species of intact forest (IFS), disturbed by agriculture (ADS) and by livestock grazing sites (LDS) to understand the importance of coastal trees in carbon stocking as part of mitigating climate change impacts.

Methodology: Thirty-three independent measurements of tree carbon stocks were carried out on 33 tree families found in the coastal zone of Tanzania. The vegetation was inventoried by means of a floristic survey of the woody component across intact, crop agriculture and livestock disturbed land use sites. The biomass was then estimated by employing the existing allometric equations for tropical forests. Thereafter, the above ground stored carbon was quantified on the sampled tree species found in each land uses.

Results: The results showed that there were significant variations (p ≤ .05) of carbon stock values across species and land uses. The average carbon (Kg/ha) stored in the regenerated adult trees was 1200 in IFS, 600 in ADS, 400 in LDS. Saplings had 0.43 in LDS, 0.07 in ADS and 0.01 in IFS. Indeed, seedlings had the average of 0.41 in IFS, 0.22 in ADS and 0.05 in LDS.

Conclusion: These findings show that crop-agriculture highly affects the regeneration potential of trees, biomass accumulation and carbon stock than livestock grazing. To restore carbon storage potential of coastal tropical forests, crop-agriculture must be discouraged, while livestock grazing can be integrated in forest management. Indeed, further studies are required to gauge the integration levels of any anthropogenic activities, so that the natural capacity of coastal tropical forests to regenerate and stock carbon is not comprised further. [2]

Air Pollution Tolerance Index (APTI) Assessment in Tree Species of Coimbatore Urban City, Tamil Nadu, India

Aims: Forest restoration in urbanized and polluted cities is paving the way for mitigation of climate change by reducing the air pollutants level and carbon content level in atmosphere. So, the study was conducted at Coimbatore urban city, Tamil Nadu by using twenty five tree species to know their air pollution tolerance index (APTI) level.

Study Design: The sample procedure used for assessing the APTI was stratified random sampling.

Place and Duration of Study: The leaf sample was collected from different zones of Coimbatore urban city and the sample analysis was carried out in Department of Silviculture, Forest College and Research Institute, Mettupalayam, Tamil Nadu between August 2015-April 2017.

Methodology: Five zones namely residential, industrial, commercial, heavy traffic and control zone were identified from Coimbatore city for estimating the air pollution tolerance index (APTI). In order to assess the air pollution tolerance index of tree species, the biochemical parameters like ascorbic acid content, total chlorophyll content, leaf extract pH and relative water content (RWC) were estimated.

Results: Among the 25 tree species tested, Thespesia populnea recorded highest APTI of 16.07, 15.76, 14.63 and 14.37 in heavy traffic zone, industrial zone, control zone and residential zone respectively. In commercial zone, Pongamia pinnata accounted highest APTI value of 13.96. On contrary, the lowest level of APTI was registered by Michelia champaca in industrial zone (10.21), Peltophorum pterocarpum in heavy traffic zone (10.93), Spathodea campanulata in residential zone (11.11) and Albizia saman in commercial zone (11.46).

Conclusion: On an overall, Thespesia populnea and Pongamia pinnata were performed well with highest APTI and they can be used for controlling the air pollution level in urban cities. [3]

Climate Change Effects on Southern Subtropical and Tropical Tree Species in Ganzhou City, China

Aims: To confirm climate warming changes that have taken place in Gannan Arboretum and Ganzhou City by the expect success of introduced tropical tree species as a response to climatic warming scenarios.
Study Design: Cross-sectional study.
Study Site and Duration: Survey and observational sites were located in 1) Gannan Arboretum and 2) Ganzhou City, Jiangxi Province, China. The survey and observations of introduced tree species were conducted from October, 2009, to November, 2010. Additional growth records were obtained for a period prior to and including the 1970s to assist in the investigation.
Methodology: 1) The meteorological data (1951–2009) record was used to analyse climatic change patterns. 2) Growth and development of introduced tree species were examined to evaluate effects of introduction. 3) Climate zone attributes of introduced tree species were determined in order to establish place of origin. Effects of introduced tree species were coupled with climatic change scenario data to analyze associative relationships.
Results: 1) A trend in climate warming has been evident in Ganzhou City since the1950s. Based on metrological records from 1951 to 2009, a steady rise in annual average temperature has occurred in the region, increasing from 0.2ºC to 0.3ºC each 20 year period. This trend has been especially evident by changes to average temperature during the coldest month (January) as well as changes in annual minimum temperatures. 2) According to observations and measurements, 39 introduced tropical tree species have successfully established themselves in the Ganzhou region through natural domestication. Among these, 24 tree species were considered basically successful with normal growth patterns while the remaining 15 species achieved preliminary success. 3) Stem analysis data on the five primary introduced tree species indicate that growth patterns were normal and vigorous, suggesting that these tropical tree species have successfully established themselves. It was therefore determined that the successful northward migration of the 39 tree species investigated was chiefly the result of a climate warming trend taking place in the region. [4]



[1] David, E. T., Chhin, S., & Skole, D. (2018). Influence of Climate Variation on Growth of Tropical Tree Species in Western Kenya. International Journal of Environment and Climate Change8(4), 295-307. Retrieved from

[2] Ligate, E., Chen, C., & Wu, C. (2018). Estimation of Carbon Stock in the Regenerating Tree Species of the Intact and Disturbed Forest Sites in Tanzania. International Journal of Environment and Climate Change8(2), 80-95. Retrieved from

[3] Balasubramanian, A., Prasath, C. N. H., Gobalakrishnan, K., & Radhakrishnan, S. (2018). Air Pollution Tolerance Index (APTI) Assessment in Tree Species of Coimbatore Urban City, Tamil Nadu, India. International Journal of Environment and Climate Change8(1), 27-38. Retrieved from

[4] Cao, F., Qi, C., Li, G., Zhong, C., Tang, D., Xu, Y., & Peng, C. (2012). Climate Change Effects on Southern Subtropical and Tropical Tree Species in Ganzhou City, China. International Journal of Environment and Climate Change2(2), 163-179.

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