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Asia Center of The Academy of Natural Sciences

Forest Regeneration Study

Mookhor Khisgjargal

Taiga Forest at Hovsgol, Mongolia

Northern Mongolia represents a part of the southern boundary of the vast Siberian taiga forest. The dominant tree of the area is the Siberian Larch (Larix sibirica), composing 90 to 95% of the forest, and at Hovsgol, the larch covers ridge tops and north-facing Mountain slopes. Most of the forested area is underlain by permafrost.

The Hovsgol_GEF project is studying regeneration within and along the boundary of the forested areas. The forest regeneration study covers a long time period (at least up to 20 years) and includes some stages of immature and mature tree growth (from seed germination to the mature trees). Larch normally produces a seed “mast” year every 4th or 5th year.

Research objectives

The main objective of the study is to identify the boreal larch forest regeneration process and success.

  • How does the boreal larch forest regenerate itself, and what is the main factor influencing production of seeds and seed emergence?
  • What are the main factors for seed germination and of seedling and sapling survivorship in the larch taiga forest?
  • What is the main limiting factor regulating forest expansion rate at forest edge areas?

Methodology

Relevant data are collected with a random sample design method in plots that were selected along line transects in the forests of the Hövsgöl study valleys. The data collected were processed and statistically analyzed using one-way ANOVA and correlation using JMP IN and Sigma Plot software.

Initial Results

  • The seed source is identified in varous amounts in each valley during the last years: 2002, no seed production; 2003, moderate production; 2004, poor production.
  • Insect seed predation appears to be important but is yet to be measured.
  • In determining the growing rate of seedlings in several dominant soil cover types (moss, grass, shrub or necromass cover) the most favorable condition is the moss cover of soil. The main factor of seed growing rate in the dominant soil covers appears to be soil moisture content; maximum soil moisture content is found in areas with moss cover.
  • The larch regeneration study has shown that the forest cycle includes a key initial stage of seed predators after the seeds fall to the ground. The main seed predators are small rodents which includes Clethrionomus rufocanus and Sorex sp. The consumption of rodents does not appear to depend on seed density; there was no apparent difference in predation intensity in experimental exposures to a series of seed densities.
  • The main criteria for forest regeneration rate is the surviving number of saplings. The natural forest regeneration rate is low. But saplings and young trees diameter tree ring growth has been increasing in recent years. The distribution of the saplings and young trees is determined in relation to mountain slope and density of adult trees.

Research Outputs

  • To identify conditions and main factors for favorable larch seedling and sapling survival
  • Permafrost thaw, fire frequency, soil covers, slopes, soil and air temp-moist, grazing, climate warming and human impact.
  • Develop larch forest model as a sub-model of an ecosystem model for the Hovsgol region.
  • To prepare and publish articles about taiga larch forest regeneration.
Mookhor Khisgjargal new larch cone
old larch coneone year seedling protected from rodents germination plot seedlings

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