Age structure and trends in annual stem increment of Larix sibirica in two neighboring Mongolian forest–steppe regions differing in land use history

Khansaritoreh, E., et al., 2017. Trees - Structure and Function

Original research (primary data)
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Abstract

Climate warming increasingly limits the productivity of boreal forests via increased drought stress, especially at the southern fringe of the biome. The southernmost boreal forests are exposed to more intensive human disturbance than most forests at more northern latitudes. We asked the question of how forest use through logging and moderate forest grazing interferes with the climate response of the annual radial stem increment. We conducted a case study in Larix sibirica stands of the Mongolian forest–steppe involving two neighboring forest regions (20 km distance) differing in logging and grazing intensity. One site was subjected to heavy logging until 25 years ago and low intensity of livestock grazing; another site was exposed to moderate selective logging and higher, but still moderate livestock numbers. While the differences in grazing had no detectable effect, former heavy logging led to younger and more even-aged forest stands. Forests at both sites showed recent increases in missing-ring frequency, which probably indicated increased drought vulnerability. Climate-response analysis indicated that heavy logging 25 years ago was associated with high sensitivity of stemwood formation to high summer (especially June) temperatures. These findings suggest that: (1) recent logging under the conditions of climate warming has increased the sensitivity of tree growth to temperature in these southern boreal forests; (2) high replication at the stand level is needed to avoid bias in dendrochronological analyses in regions exposed to spatially heterogeneous logging intensities.

Case studies

Basic information

  • Case ID: INT-058-1
  • Intervention type: Management
  • Intervention description:

    unplanned occasional selective logging by the local population; livestock grazing by pastoral nomads

  • Landscape/sea scape ecosystem management: No
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Biomass cover loss  Positive sensitivity of tree ring index to climate; cumulative radial stem increment
  • Approach implemented in the field: Yes
  • Specific location:

    Zavkhan province of Mongolia ca. 70–90km southwest of the city of Tosontsengel (48°450 N, 98°160 E, 1700 m a.s.l.) at the border of the Tosontsengel and Ider administrative subunits of the Zavkhan province. in the northern Khangai Mountains, a large mountain range of central and western Mongolia

  • Country: Mongolia
  • Habitat/Biome type: Montane/Alpine |
  • Issue specific term: Not applicable

Evidence

  • Notes on intervention effectivness: effectiveness compared to a non-adaptive, non-NbS form of management (high logging intensity (selective logging and clear-cuts) prior to 1990 followed by Low-intensity selective logging after 1990)
  • Is the assessment original?: Yes
  • Broadtype of intervention considered: Not applicable
  • Compare effectivness?: No
  • Compared to the non-NBS approach: Not applicable
  • Report greenhouse gas mitigation?: No
  • Impacts on GHG: Not applicable
  • Assess outcomes of the intervention on natural ecosystems: No
  • Impacts for the ecosystem: Not reported
  • Ecosystem measures:
  • Assess outcomes of the intervention on people: No
  • Impacts for people: Not reported
  • People measures:
  • Considers economic costs: No
  • Economic appraisal conducted: No
  • Economic appraisal described:
  • Economic costs of alternative considered: No
  • Compared to an alternative: Not reported

Evaluation methodology

  • Type of data: Quantitative
  • Is it experimental: No
  • Experimental evalution done: In-situ/field
  • Non-experimental evalution done: Not applicable
  • Study is systematic: