From October 2014 to April 2015, we completed the data collection in fieldwork and data analysis. The results are as follows:
We analysed the status of red-listed tree species across differently protected zones in the Ta Xua Nature Reserve in north-western Vietnam, a rarely studied region located within a biodiversity hotspot. The study area covered an altitudinal range of 1000 to 1700 m asl and comprised: an undisturbed core zone; a low intensity traditional forest use buffer zone; and a forest restoration zone.
In total, 18 red-listed tree species were recorded, of which 10 species are listed in different threatened degrees of the IUCN Red List and 16 species are listed in high conservation concern in the Vietnam Red List. Red-listed tree species richness (IUCN and Vietnamese Red Lists combined) amounted to 16 in the core zone, 10 in the buffer zone and five in the restoration zone. Most red-listed species, such as Fokienia hodginsii, reached their highest densities in the core zone, but one species (Quercus platycalyx) was quite abundant in the restoration zone.
The multivariate analysis (canonical correspondence analysis (CCA)) was used to determine which ecology and human disturbance factors have strong effect on the appearance of threatened tree species. We found that for some red-listed tree species, canonical correspondence analysis suggested relationships between the presence of footpaths, canopy closure and basal area, which points to reduced abundance of red-listed tree species as a consequence of human activities.
In the present study, the high number of red-listed tree species in the core zone illustrates the merits of strict protection measures, while the low number of red-listed tree species in the buffer and restoration zones indicates that these species are sensitive to selective logging and shifting cultivation. From a conservation point of view, low selective logging intensity seems to represent a better protection measure for threatened species than shifting cultivation. Future time and work schedule
The results from this study will be presented and discussed with management committee of Ta Xua Nature Reserve, local rangers and local people.
We are going to write a manuscript about the red-listed tree species abundance in differing levels of protection in the Ta Xua Nature Reserve in north-western Vietnam.
Table 1: Number of individual trees with DBH ≥ 6cm and conservation status of red-listed tree species. The results from 40 sample plots (20x20m) per each conservation zone.
Figure 1: Canonical correspondence analysis (CCA) shows the correlations betweenenvironmental and human disturbance variables and density red-listed tree species which were encountered more than once in the core and buffer zones. The first and the second axes explained 7.3%, and 5.8% of the variance of present data, respectively. Correlation threshold r2= 0.26. (BA = basal area, Fpath = footpath, abbreviation for species code as in Table 1).