Light Intensity and Soil Compaction as Influenced by Ecotourism Activities in Pahang National Park, Malaysia

Pahang National Park provides a diversity of flora and fauna, which is popular for ecotourism activities within Malaysia. The ecotourism activities such as trekking and camping may result in some degree of changes to the forest condition in the protected areas. Therefore, a study was conducted to investigate the influences of ecotourism activities on the light intensity and soil compaction in Pahang National Park. A total of 40 plots measuring at 20 × 25 m were established in camping area, trekking trail and natural area of the park. The light intensity and soil compaction were measured using hemispherical photography at nine points and a hand penetrometer at five points, respectively, randomly selected in each plot. The Analysis of Variance shows there was a significant difference in the means of light intensity and soil compaction in three study sites (p < 0.05). The light intensity in the trekking trail is significantly greater than in natural area (18.87% vs. 13.13%). The soil compaction in the trekking trail is significantly greater than in natural area and camping area (p < 0.05). This may suggest that ecotourism activities especially trekking activity has significantly influenced the trend of forest light intensity and soil compaction in Pahang National Park

A preliminary study on the influences of ecotourism activities to the stand structure of protected forests of Taman Negara Pahang

A preliminary study on the influences of ecotourism activities on forest stand structure was carried out in the protected forests of Taman Negara Pahang. Forest stand attributes data were collected from Kuala Keniam and Lata Berkoh areas which comprised of two different conditions (known as natural and disturbed areas) with the size of plots of 20 m × 25 m. All trees greater than 1 cm in diameter at breast height (DBH) were measured and identified. A total of 1,398 stems were enumerated in study areas. Basal area of sampled trees was determined. From the analysis of variance, it was found that the difference in the means of the basal area of trees between study sites were not statistically significant at P≤0.05. The forest stand structure described by diameter distribution was inverse J-shaped which indicates the stands are developing and regeneration in the forest is present in the study areas. Information from this study may provide a valuable reference for forest assessment as well as ecotourism planning and management

Pathogenicity of Aeromonas hydrophila in high-value native Pangasius catfish, Pangasius nasutus (Bleeker)

Pangasius catfish, Pangasius nasutus, is a promising candidate for aquaculture due to its high market value. However, the presence of pathogenic bacteria in Aeromonas hydrophila is a major concern in P. nasutus farming in this country. This study determines the pathogenicity of A. hydrophila in P. nasutus. A total of 80 P. nasutus juveniles were intraperitoneally injected with 0, 103 , 105 , and 107 CFU mL-1 of A. hydrophila and monitored until 240 hr. The infected moribund fish’s kidneys, livers, and spleens were collected for histopathological analysis. The LD50-240hr value was found at 0.8 × 104 CFU/ml of A. hydrophila. The percentage of mortality in 0, 103 , 105 , and 107 CFU/ml infected groups were found to be at 0, 40, 60, and 90, respectively. The infected fish showed congestion at the base of the fin, ascites, enlarged gall bladder, and swollen spleen. It is the earliest report on A. hydrophila’s pathogenicity in high-value native fish, P. nasutus

Influence of ecotourism activities on the forest structure and light intensity in forests of Taman Negara Pahang

Ecotourism activities in protected area such as in Taman Negara (i.e., hiking and camping) may result in canopy opening which increases light transmission to the forests floor and influencing the variation in forest structure. Thus, this study was conducted to evaluate the effects of ecotourism activities on the light intensity and examine its influence to the forest structure in the protected forests of Taman Negara Pahang. Information on light intensity and forest stand attributes were collected in a total of 16, 20 m × 25 m plots which consists of camping sites, forest trails and natural areas. All trees ≥ 1 cm in diameter-at-breast height (DBH) were measured, tagged and numbered. The light intensity was measured using hemispherical photography at nine points randomly sampled in each plot. The diffuse light intensity recorded in hemispherical photographs was analysed (in percent) using RGBFisheye software. From the field measurements, there is a significant difference (P≤0.05) in basal area between two conditions (i.e., disturbed and undisturbed). The means of light intensity as recorded in hemispherical photographs of forest trails, camping sites and natural areas were 11.37%, 10.05% and 8.32%, respectively. Results from the analysis of variance indicated that there was a significant difference in the means of light intensity among study conditions (P≤0.05). Moreover, all study areas showed an inverse J-shaped DBH distribution which indicates the presence of abundance regeneration in the forest and the stands are still at the stage of development. Therefore, the study showed that the increase in light intensity in disturbed areas may result in the variation of forest structure beneath canopy. This could be because of the lesser stratification of canopy layers and the tolerance between some tree species and light in the disturbed areas

Distribution of biomass dynamics in relation to tree size in forests across the world

•Tree size shapes forest carbon dynamics and determines how trees interact with their environment, including a changing climate. Here, we conduct the first global analysis of among-site differences in how aboveground biomass stocks and fluxes are distributed with tree size. •We analyzed repeat tree censuses from 25 large-scale (4–52 ha) forest plots spanning a broad climatic range over five continents to characterize how aboveground biomass, woody productivity, and woody mortality vary with tree diameter. We examined how the median, dispersion, and skewness of these size-related distributions vary with mean annual temperature and precipitation. •In warmer forests, aboveground biomass, woody productivity, and woody mortality were more broadly distributed with respect to tree size. In warmer and wetter forests, aboveground biomass and woody productivity were more right skewed, with a long tail towards large trees. Small trees (1–10 cm diameter) contributed more to productivity and mortality than to biomass, highlighting the importance of including these trees in analyses of forest dynamics. •Our findings provide an improved characterization of climate-driven forest differences in the size structure of aboveground biomass and dynamics of that biomass, as well as refined benchmarks for capturing climate influences in vegetation demographic models