Habitat distribution modelling for reintroduction of Ilex khasiana Purk., a critically endangered tree species of northeastern India

Aquilaria malaccensis, a critically endangered tree species of India, is cultivated in homegardens of Assam. We studied the population structure and regeneration status of this species in homegardens of Upper Assam, northeast India. Population structure of the species was studied in 135 homegardens and regeneration status was studied in eight selected homegardens of Jorhat and Golaghat districts of Upper Assam. In the studied homegardens, population density (individuals ha -1 ) of A. malaccensis was 1,443, 4,060 and 33,917 for trees (> 3.18 cm diameter at breast height = DBH), saplings and seedlings, respectively. This pattern of density distribution (seedlings > saplings > trees) indicates good regeneration status of the species in homegardens. On the other hand, out of the eight selected homegardens, seven showed good regeneration status, whereas, one showed fair regeneration status for the species. Seasonal survival rate of A. malaccensis saplings was significantly different among the eight selected homegardens during all the four seasons (each season of three months) of the year but that of seedlings and trees did not differ significantly. Average seasonal growth rate of A. malaccensis (in terms of collar diameter for seedlings and saplings, and DBH for trees) varied significantly among the eight selected homegardens as well as between the four seasons. The findings of the present study suggest that homegardens can save the species from the risk of extinction.

Population structure and regeneration status of Aquilaria malaccensis Lam. in homegardens of Upper Assam, northeast India

Background and aims Ilex khasiana is a rare and critically endangered holly endemic to the Khasi Hills of Meghalaya, India, and confined to a small number of pocket areas. In addition to conventional methods of propagation, endemic and threatened plants such as this could be more effectively multiplied and conserved using in vitro methods. Such techniques have the additional advantage of having a low impact on wild populations because they require a minimum of starting material. Our objective was to develop methodologies for the successful in vitro mass propagation of I. khasiana. Methodology Seedlings were germinated in vitro under sterile conditions and nodal explants from these were transferred to Murashige and Skoog (MS) medium supplemented with 8.88 mM 6-benzyladenine and 4.64 mM kinetin. Principal results This generated � 10 shoots per explant. In a second approach, callus was obtained from seedling-derived leaf discs cultured on MS medium supplemented with 2,4-dichlorophenoxyacetic acid and 6-benzyladenine. Approximately 12 adventitious shoots per callus were regenerated from 83.33 % of the calli after transfer to MS medium supplemented with 6.63 mM 6-benzyladenine. The most effective treatment for inducing root formation on the shoots was transfer of shoots to half-strength MS medium with 9.84 mM indole-3-butyric acid. Regenerated plantlets with well-developed shoots and roots were hardened and transferred to open soil with 70 % survival after 4 weeks. Conclusions Both the methods described here are well suited for the mass multiplication of this critically endangered tree species.

Micropropagation of Ilex khasiana, a critically endangered and endemic holly of Northeast India

Rare tropical tree species are endangered due to the disappearance of old-growth forests. Although some undisturbed old-growth and formerly logged forests are protected today, the extent to which r...

https://journals.sagepub.com/doi/pdf/10.1177/194008291400700211

The fate of five rare tree species after logging in a tropical limestone forest (Xuan Son National Park, northern Vietnam)

The reproductive phenology and germination behavior of 15 important tree species (Acer laevigatum, Adinandra griffithii, Citrus latipes, Elaeocarpus prunifolius, Engelhardtia spicata, Ilex embelioides, Ilex khasiana, Ilex venulosa, Illicium griffithii, Magnolia lanuginosa, Magnolia punduana, Photinia cuspidata, Photinia integrifolia, Quercus glauca and Schima khasiana) were monitored at monthly intervals for two calendar years in subtropical broad-leaved humid forests of Northeast India. These species are either endemic or threatened to the region. The investigated species showed peak flowering during the spring- while fruiting peak was observed in the autumn-season. Of the fruit types, drupes and follicles were produced by many of these species. Majority of the species adopted zoochoric mode of dispersal. The germination phenology revealed that most of the species (Acer laevigatum, Elaeocarpus prunifolius, Illicium griffithii, Magnolia lanuginosa, Magnolia punduana and Quercus glauca) undergo a period of dormancy during winter season (December–February) and germination collides with the onset of rain indicating that moisture aids in germination. The prevailing environmental condition coupled with human disturbance seems to be of potential importance in influencing the recruitment of the selected species. Such studies would help in formulating effective strategies for conservation of these species.

Reproductive Phenology and Germination Behavior of Some Important Tree Species of Northeast India

Detailed studies on population structure and regeneration ecology of Ilex khasiana were carried out at five representative natural populations i.e. Mylliem (Population - I), Upper Shillong (Population - II), Shillong Peak (Population - III), Laitkor (Population - IV) and Nongpiyur (Population - V) to probe into the responsible affecting factors for its population structure and regeneration ability in these populations. Experimental observation under three controlled light conditions (full sunlight (100%), intermediate sunlight (50%) and low sunlight (30%)) showed that the growth status and survival rates of seedlings under intermediate and low light were better than those under the high light condition. The density-diameter distribution in population of adult trees (≥5cm dbh) exhibited a typical character of a regenerating population. A higher seedling mortality rate in natural populations of I. khasiana was most probably due to increase in light intensity following vegetation destruction and other anthropogenic disturbances that cause opening of forest canopy. The findings of the present study would be of immense value in formulating appropriate conservation measures for the species.

http://dspace.nehu.ac.in/bitstream/1/2723/1/REGENERATION%20ECOLOGY.pdf

Upadhaya Krishna

Papers

Regeneration ecology and population status of a critically endangered and endemic tree species ( Ilex khasiana Purk.) in north-eastern India