Reviewer Comments on the manuscript ‘Hydrological soil properties control tree regrowth after forest disturbance in the forest-steppe of central Mongolia‘ submitted by Schneider et al.

Abstract. The central Mongolian forest-steppe is a sensitive ecotone, commonly affected by disturbances such as logging and forest fires. In addition, intensified drought events aggravate stress on the trees that are anyway at their drier limit in the forest-steppe. Climate change increases evapotranspiration and reduces the distribution of discontinuous permafrost. The motivation for this study came about through our previous observation that forest stands show great differences with respect to their recovery after disturbance by fire or logging. Sometimes, no regrowth of trees takes place at all. As water availability is the main limiting factor of forest growth in this region, we hypothesized that differences in hydrological soil properties control the forest-recovery pattern. To test this hypothesis, we analysed soil properties under forests, predominantly consisting of Siberian larch (Larix sibirica Ledeb.), in the forest-steppe of the northern Khangai Mountains in central Mongolia. We distinguished four vegetation categories: 1. near-natural forest (FOR), 2. steppe close to the forest (STE), 3. disturbed forest with regrowth of trees (DWIR), and 4. disturbed forest showing no regrowth of trees (DNOR). 54 soil profiles were described in the field and sampled for soil chemical, physical, and hydrological analysis. We found a significant difference in soil texture between soils under DWIR and DNOR. Sand generally dominated the soil texture, but soils under DWIR had more silt and clay compared to soils under DNOR. Soil pF curves showed that soils under DWIR had higher plant-available field capacity than soils under DNOR. In addition, hydraulic conductivity was higher in the uppermost horizons of soils under DWIR compared to soils under DNOR. Chemical properties of the soils under DWIR and DNOR showed no significant differences. We conclude that the differences in post-disturbance tree regrowth are mainly caused by soil hydrological properties. High plant-available field capacity is the key factor for forest recovery under semi-arid conditions. High hydraulic conductivity in the uppermost soil horizons can further support tree regrowth, because it reduces evaporation loss and competition of larch saplings with grasses and herbs for water. Another important factor is human impact, particularly grazing on cleared forest sites, which often keeps seedlings from growing and thus inhibits forest recovery. Permafrost was absent at all studied disturbed sites (DWIR, DNOR). We thus conclude that it is not a major factor for the post-disturbance tree-regrowth pattern, although it does contribute to water availability in summer.

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Hydrological soil properties control tree regrowth after forest disturbance in the forest steppe of central Mongolia

SOIL ◽

10.5194/soil-7-563-2021 ◽

2021 ◽

Vol 7 (2) ◽

pp. 563-584

Author(s):

Florian Schneider ◽

Michael Klinge ◽

Jannik Brodthuhn ◽

Tino Peplau ◽

Daniela Sauer

Keyword(s):

Hydraulic Conductivity ◽

Soil Properties ◽

Soil Texture ◽

Field Capacity ◽

Forest Growth ◽

Forest Recovery ◽

Forest Steppe ◽

Soil Hydrology ◽

Central Mongolia ◽

Disturbed Forest

Abstract. The central Mongolian forest steppe forms a transition between different ecozones and is as such particularly sensitive to environmental changes. It is commonly affected by disturbances such as logging and forest fires. Intensified drought events aggravate stress on the trees that are anyway at their drier limit in the forest steppe. Climate change increases evapotranspiration and reduces the distribution of discontinuous permafrost, which leads to drier soil conditions. The motivation for this study came about through our previous observation that forest stands show great differences with respect to their recovery after disturbance by fire or logging. Sometimes, no regrowth of trees takes place at all. As water availability is the main limiting factor of forest growth in this region, we hypothesised that differences in soil hydrology control the forest recovery pattern. To test this hypothesis, we analysed soil properties under forests, predominantly consisting of Siberian larch (Larix sibirica Ledeb.), in the forest steppe of the northern Khangai Mountains, central Mongolia. We distinguished the following four vegetation categories: (1) near-natural forest (FOR), (2) steppe close to the forest (STE), (3) disturbed forest with regrowth of trees (DWIR), and (4) disturbed forest showing no regrowth of trees (DNOR). A total of 54 soil profiles were described in the field and sampled for soil chemical, physical, and hydrological analysis. We found a significant difference in soil texture between soils under DWIR and DNOR. Sand generally dominated the soil texture, but soils under DWIR had more silt and clay compared to soils under DNOR. Soil pF curves showed that soils under DWIR had higher plant-available field capacity in their uppermost parts than soils under DNOR. In addition, hydraulic conductivity tended to be higher in the uppermost horizons of soils under DWIR compared to their counterparts under DNOR. Chemical properties of the soils under DWIR and DNOR showed no significant differences. We conclude that the differences in post-disturbance tree regrowth are mainly caused by different soil hydrology. High plant-available field capacity is the key factor for forest recovery under semi-arid conditions. High hydraulic conductivity in the uppermost soil horizons can further support tree regrowth because it reduces the evaporation loss and the competition of larch saplings with grasses and herbs for water. Another important factor is human impact, particularly grazing livestock on cleared forest sites, which often keeps seedlings from growing and, thus, inhibits forest recovery. None of the disturbed sites (DWIR and DNOR) had permafrost. We, thus, conclude that permafrost is no major factor for the post-disturbance tree regrowth pattern, although it generally supports tree growth in the forest steppe by preventing meltwater from seasonal ice from seeping below the root zone, thus increasing the water supply in summer.

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Interrelations between relief, vegetation, disturbances, and permafrost in the forest‐steppe of central Mongolia

Earth Surface Processes and Landforms ◽

10.1002/esp.5116 ◽

2021 ◽

Author(s):

Michael Klinge ◽

Florian Schneider ◽

Choimaa Dulamsuren ◽

Kim Arndt ◽

Uudus Bayarsaikhan ◽

...

Keyword(s):

Forest Steppe ◽

Central Mongolia

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Comments to “Modelled potential forest area in the forest-steppe of central Mongolia is about three times of actual forest area”

10.5194/bg-2020-13-rc1 ◽

2020 ◽

Author(s):

Anonymous

Keyword(s):

Forest Area ◽

Forest Steppe ◽

Central Mongolia

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The degree of restoration of the soil properties developed under the fallows in the early stages of succession

E3S Web of Conferences ◽

10.1051/e3sconf/202022404025 ◽

2020 ◽

Vol 224 ◽

pp. 04025

Author(s):

D. A. Filimonova ◽

S V Solovev ◽

A N Bezborodova ◽

G F Miller

Keyword(s):

Soil Properties ◽

Humus Content ◽

Steppe Zone ◽

Forest Steppe ◽

General Tendency ◽

Middle Aged ◽

Initial State ◽

Plant Matter ◽

Fallow Lands ◽

Two Stages

At present, the return of fallow lands to agricultural circulation is an important and one of the topical issues of the whole world. Research related to the restoration of soil properties of fallows is of particular value. Therefore, it is necessary to know what processes occur in the vegetation and soil cover of fallows at the different stages of their development, taking into account local natural features. The paper presents the results of a survey of young (up to four years) and middle-aged (up to ten years) fallows of the forest-steppe zone of Western Siberia within the Novosibirsk region. It is established that in the first decade of succession in fallow areas there are two stages of overgrowth, and when analyzing the structure of plant matter, it is shown that the ratio of their fractional composition reflects the general tendency to restore the ecosystem that preceded plowing. Restoration of soil properties under young and middle-aged fallows is much slower. Data of humus content analysis allow us to conclude that its content is somewhat higher in the upper parts of the profile in middle-aged fallows compared to young fallows. The research on soil-physical characteristics and vegetation cover allowed us to note the trends of restoration of the initial state of soils.

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Geoecological parameters indicate discrepancies between potential and actual forest area in the forest-steppe of Central Mongolia

Forest Ecosystems ◽

10.1186/s40663-021-00333-9 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Michael Klinge ◽

Choimaa Dulamsuren ◽

Florian Schneider ◽

Stefan Erasmi ◽

Uudus Bayarsaikhan ◽

...

Keyword(s):

Forest Fires ◽

Forest Area ◽

Mean Annual Precipitation ◽

Forest Steppe ◽

Forest Stands ◽

Tree Biomass ◽

Living Tree ◽

Central Mongolia ◽

Forest Distribution ◽

Topographic Parameters

Abstract Background Forest distribution in the forest-steppe of Mongolia depends on relief, permafrost, and climate, and is highly sensitive to climate change and anthropogenic disturbance. Forest fires and logging decreased the forest area in the forest-steppe of Mongolia. The intention of this study was to identify the geoecological parameters that control forest distribution and living-tree biomass in this semi-arid environment. Based on these parameters, we aimed to delineate the area that forest might potentially occupy and to analyse the spatial patterns of actual and potential tree biomass. Methods We used a combination of various geographic methods in conjunction with statistical analyses to identify the key parameters controlling forest distribution. In several field campaigns, we mapped tree biomass and ecological parameters in a study area within the Tarvagatai Nuruu National Park (central Mongolia). Forest areas, topographic parameters and vegetation indices were obtained from remote sensing data. Significant correlations between forest distribution and living-tree biomass on one hand, and topographic parameters, climate data, and environmental conditions on the other hand, were used to delineate the area of potential forest distribution and to estimate total living-tree biomass for this area. Results Presence of forest on slopes was controlled by the factors elevation, aspect, slope, mean annual precipitation, and mean growing-season temperature. Combining these factors allowed for estimation of potential forest area but was less suitable for tree-biomass delineation. No significant differences in mean living-tree biomass existed between sites exposed to different local conditions with respect to forest fire, exploitation, and soil properties. Tree biomass was reduced at forest edges (defined as 30 m wide belt), in small fragmented and in large forest stands. Tree biomass in the study area was 20 × 109 g (1,086 km2 forest area), whereas the potential tree biomass would reach up to 65 × 109 g (> 3168 km2). Conclusions The obtained projection suggests that the potential forest area and tree biomass under the present climatic and geoecological conditions is three times that of the present forest area and biomass. Forest fires, which mostly affected large forest stands in the upper mountains, destroyed 43% of the forest area and 45% of the living-tree biomass in the study area over the period 1986–2017.

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Modelled potential forest area in the forest-steppe of central Mongolia is about three times of actual forest area

10.5194/bg-2020-13 ◽

2020 ◽

Author(s):

Michael Klinge ◽

Choimaa Dulamsuren ◽

Florian Schneider ◽

Stefan Erasmi ◽

Markus Hauck ◽

...

Keyword(s):

Vegetation Index ◽

Arid Environment ◽

Forest Area ◽

Forest Steppe ◽

Forest Edges ◽

Climate Data ◽

Forest Stands ◽

Tree Biomass ◽

Central Mongolia ◽

The Mean

Abstract. The Mongolian forest-steppe is highly sensitive to climate change and environmental impact. The intention of this study was to identify, which geoecological parameters control forest distribution and tree growth in this semi-arid environment, and to evaluate the actual and potential tree biomass. For this purpose, we applied a combination of tree biomass and soil mapping, remote sensing and climate data analysis to a study area in the northern Khangai Mountains, central Mongolia. Forests of different landscape units and site conditions generally showed minor differences in tree biomass. We found no significant correlation between tree biomass and NDVI (normalized differentiated vegetation index). Tree biomass was reduced at forest edges, in small fragmented forest stands of the steppe-dominated area, and in large forest stands, compared to all other forest units. The tree biomass of forests on slopes ranged between 25 and 380 Mg ha−1. The mean tree biomass in forests of 10–500 ha was 199–220 Mg ha−1, whereby tree biomass at the forest edges was 50–63 Mg ha−1 less than in the interior parts of the forests. The mean tree biomass of forests > 500 ha was 182 Mg ha−1, whereas that of forests

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Changes in carbonate state and other properties of fallow soils in the forest-steppe and steppe zones of Russia

10.5194/egusphere-egu21-8037 ◽

2021 ◽

Author(s):

Anna Bulysheva ◽

Olga Khokhlova ◽

Nikita Bakunovich ◽

Alexey Rusakov ◽

Tatyana Myakshina

Keyword(s):

Land Use ◽

Organic Carbon ◽

Soil Properties ◽

Water Regime ◽

Arable Land ◽

Natural Soil ◽

Forest Steppe ◽

Main Role ◽

14C Age ◽

Abandoned Land

In the forest-steppe and steppe zones of Russia, soils are subject to prolonged agricultural impact which affected their properties and processes. Therefore, the study of soil transformation under different land-use regimes is an urgent task. The aim of the study is to examine the general patterns of changes in the carbonate state and other properties of soils of the steppe and forest-steppe in Russia of land-use changes from arable to abandoned land (fallow).The objects of research are &#1089;hronosequences of fallow Chernozems and Phaeozems. The first &#1089;hronosequence is located in the Belgorod region, Russian Federation. It consists of a virgin, arable Phaeozems, and Phaeozems being in the fallow for 40-45 years. The second &#1089;hronosequence is located in the Rostov region. It consists of arable Chernozem and abandoned during 14, 20, 30, and 86 years Chernozems. The third &#1089;hronosequence is located in the Lipetsk region. It consists of arable Chernozems and abandoned during 15, 25 years Chernozems. The fourth &#1089;hronosequence is located in the Kursk region. It consists of a virgin, arable Chernozems and abandoned during 10, 25, and 50 years Chernozems.It is noted that all soils in the abandoned land tend to restore virgin properties. Restoration of vegetation and water regime plays the main role in the acquisition of natural soil properties. For 25-30 years, the structural state is restored in Chernozems and Phaeozems. Overconsolidation of the subsurface horizon disappears in Chernozems in 10-15 years, and in Phaeozems it persists up to 40 years. The restoration of the organic carbon in Chernozems and Phaeozems proceeds in different ways. If in &#1057;hernozems, in general, there is an increase in the content and reserves of organic carbon, then in Phaeozems, in the opposite, their decrease is observed. In the transition from arable to fallow soils, there is a decrease in the content and reserves of carbonate carbon due to a change in the water regime: the intensity of the ascending water flows decreases and descending - increases.In fallow soils, the radiocarbon age of pedogenic carbonates decreases. In arable land "ancient" carbonates are pulled up closer to the day surface. And when plowing stops, they are gradually washed out into the depth of a profile. The greatest 14C age of carbonates is observed in fallow soils with large herbaceous vegetation, which sucks the moisture out from the depth with powerful roots.The recovery time of the natural soil properties depends on the initial state of the soil, the intensity of the agrogenic impact, the use of soil-saving technologies under plowing, and fertilizers use. In general, Chernozems restore faster than Phaeozems. The carbonate state in all &#1089;hronosequences acquires the virgin (before plowing) features after about 30 years.

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Which Selective Logging Intensity is Most Suitable for the Maintenance of Soil Properties and the Promotion of Natural Regeneration in Highly Continental Scots Pine Forests?–Results 19 Years after Harvest Operations in Mongolia

Forests ◽

10.3390/f10020141 ◽

2019 ◽

Vol 10 (2) ◽

pp. 141 ◽

Cited By ~ 4

Author(s):

Gerelbaatar Sukhbaatar ◽

Baatarbileg Nachin ◽

Battulga Purevragchaa ◽

Batsaikhan Ganbaatar ◽

Khishigjargal Mookhor ◽

...

Keyword(s):

Organic Matter ◽

Soil Properties ◽

Total Nitrogen ◽

Scots Pine ◽

Natural Regeneration ◽

Pine Forest ◽

Selective Logging ◽

Forest Steppe ◽

Scots Pine Forest

Scots pine (Pinus sylvestris L.) forests are one of the main vegetation types in the Asian forest-steppe zone. However, over-harvesting currently threatens the natural regeneration and sustainability of these forests. In this study, we examine the long-term effects of different logging intensities on soil properties and natural regeneration in a natural Scots pine forest in the West Khentii Mountains (Mongolia), 19 years after selective logging. Our experimental design included five treatments: clear cut (CC), treatments with high (HI), medium (MI), low (LI) intensities, and a reference parcel with no logging impact at all (RE). We described and quantified the harvest events and applied ANOVA and LMM modeling to analyze and explain the long-term impacts of the logging intensities on soil properties and natural regeneration. We found that logging has a significant negative influence on the physical and chemical properties of the soil because it increases soil compaction and reduces soil nutrients. The most critical impacts of logging were on soil bulk density, total porosity, organic matter, and total nitrogen and phosphorus. The LMM modeling showed that organic matter (OgM), total nitrogen (TN), available K (AK) and pH values are especially impacted by logging. Our study revealed that the values for all of these variables show a linear decrease with increasing selective logging intensity and have a level of significance of p < 0.05. Another finding of this study is that selective logging with low and medium intensities can promote natural regeneration of Scots pine to numbers above those of the reference site (RE). High intensity logging and clear-cuts, however, limit the regeneration of Scots pine, reduce overall seedling numbers (p < 0.05), and create conditions that are suitable only for the regeneration of deciduous tree species. This underlines the risk of Scots pine forest degradation, either by replacement by broad-leaf trees or by conversion into non-forest ecosystems.

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