This study aimed to identify the effects of oxidized brown coal humic acid fertilizer on the relative growth rate of several tree species intended for reforestation. Field experiments were carried out during 2011–2014 at the Research and Experimental Center for Combating Desertification located at the Elsen Tasarkhai station in central Mongolia. The trees studied were Populus sibirica Tausch., Salix ledebouriana Trautv., and Acer tataricum L. The experiment was conducted with concentrations of 2000, 10,000, and 20,000 mg L⁻¹ of humic acid fertilization treatment. Measurement of the relative height growth rate (RHGR) was undertaken for a period of four years. The results demonstrated significant differences between the humic fertilizer concentrations, which varied depending on the species. Compared to monthly RHGR over the study period, the treatment using fertilizers yielded significantly better tree growth. P. sibirica, when treated with 2000 mg L⁻¹ and 10,000 mg L⁻¹ humic acid fertilizers, had significant height growth rates. S. ledebouriana with 20,000 mg L⁻¹ of humic acid fertilzers treatments showed the highest RHGR. In addition, when the humic acid treatments were compared to the control, results showed that oxidized brown coal humic acid fertilizers as an organic fertilizer can have a significant effect on the growth of A. tataricum. The results equally showed that the soil chemical properties EC, CO₂, NO₃, and K₂O were significant among all the treatments compared to control. The effect on P₂O₅ significantly increased in all the treatments; however, there was no significant effect on pH and Mg among all treatments. Combining the results obtained with reforestation and sustainable land-management practices can help to improve soil organics in degraded sandy soil regions.

Field experiments were carried out during 2011-2014 at the Research and Experimental Center to Combating Desertification located in the Elsen Tasarkhai station of central Mongolia. The study was aimed to identify the effects of oxidized brown coal humic acid fertilizer on the relative growth rate of several trees for forest rehabilitation. The trees used were Populus sibirica, Salix ledebouriana and Acer tataricum. The experiment was carried out with the concentrations of 2,000, 10,000 and 20,000 mg L-1 of humic acid fertilization treatments. The measurement of relative height growth rate (RHGR) was conducted for a period of 4 years. The treatments showed significant differences within humic fertilizer concentrations which differed depending on the species. Compared to the monthly RHGR over the study, the treatment of fertilizers were significantly better for tree growth. P. sibirica in the 10,000 and 20,000 mg L-1 humic acid fertilizers had significant height growth rates. In addition, when the humic acid treatments were compared to control, A. tataricum decreased over the years which were statistically significant for high growth rate and a positive effect of humic acid fertilization treatments was observed. Furthermore, results showed that oxidized brown coal humic acid fertilizers as organic fertilizer can have a positive effect for the growth of A. tataricum during the study years. The results showed that the soil chemical properties EC, CO2, NO3, and K2O were significant among all the treatments compared to the control. The effect on P2O5 statistically significantly increased among all the treatments. However, pH and Mg were not significant effect among all the treatments. Combining the results obtained from the oxidized brown coal humic acid fertilization with sustainable land management practices can help improve soil organics for environmental issues in degraded sandy soil regions.

The purpose of this research was to estimate the wind force reduction effects of different types of tree species in windbreak, based on monitoring results. Field experiments were carried out during 2010–2017 at the Research and Experimental Center for Combating Desertification (47°27′N, 103°68′E; 1967 m a.s.l) in Elsen Tasarkhai, Khugnu-Tarna National Park in Rashaant soum of Bulgan province, central Mongolia. The studied tree species included Acer tataricum, Populus sibirica, Malus Pallasiana, Ulmus pumila, Salix ledebouriana and Caragana arborescens. The wind data collected by the Hobo loggers were downloaded using Onset HOBOware® Lite Software Version 2.2.1 (Onset Computer Corporation, Pocasset, MA). The estimation procedure incorporated the 1999 version of the windbreak sub-model of the Wind Erosion Prediction System (WEPS). Windbreak effects were estimated in terms of friction velocity reduction, which is a function of wind speed and direction, distance from the barrier, tree height, porosity, width and orientation. Windbreak characteristics (windbreak type, height, width, porosity, and location) were recorded. A significant effect of windbreak on airflow reduction was proven on the leeward side of windbreak in a belt corresponding to approximately 15-30 times the height of the windbreaks and it depended on the optical porosity. During the monitoring period, the impacts were varied, but all species had reduced the wind speed to a certain distance. As a result, the annual growth rate of tree species showed the significant importance of wind protection. By identifying the effect of shelterbelts on living windbreaks and wind data using long-term monitoring in sandy soil regions of central Mongolia, advanced tree planting and forest strip establishing methods would be developed. Монгол орны ой, тайгын хөрсний урвалын орчин (pH)-ы шинж чанар ба онцлог ХУРААНГУЙ: Монгол орны хөрсний судалгаануудад ой, тайгын хөрсний урвалын орчны тухай дурдагдсан байдаг боловч хөрсний хэв шинжээр нь урвалын орчныг харьцуулан судалсан судалгааны ажлууд дутмаг байна. Энэхүү судалгааны ажлын зорилго нь Хангай, Хэнтий, Хөвсгөлийн уулсын ой, тайгын хөрсний урвалын орчны онцлог шинж чанар, ялгаатай байдлыг судлахыг зорьсон. Монгол оронд 2024 оноос өмнө хийгдэж байсан ойн хөрсний 301 зүсэлтийн 1558 ширхэг дээжийн дүн мэдээллийг ашиглав. Хөрсний урвалын орчныг хөрс усны 1:2.5 харьцаагаар Thermo scientific Orion 5 star багаж ашиглаж тодорхойлсон. Монгол орны ойд Тайгын цэвдэг, Тайгын ширэгт, Чандруулаг, Ойн бараан, Нугархаг ойн бараан, Сул чандруулаг элсэн, Татмын ойн зэрэг хэв шинжийн хөрс голчлон тархсан байдаг. Эдгээр хөрсний хэв шинж бүрийн урвалын орчныг хооронд нь харьцуулах аргаар энэхүү судалгааны үр дүнг боловсруулав. Мөн хөрсний дээд (topsoil) үе давхарга дахь урвалын орчныг доод (subsoil) үе давхарга дахь урвалын орчны агууламжтай харьцуулахаас гадна хөрсний генетик үе давхаргууд дах урвалын орчныг судалсан. R studio Тукей (Tukey) тест ашиглан ойн хөрсний хэв шинж, төрөл хооронд урвалын орчин ялгаатай эсэхийг шалгасан. Монгол орны ойн хөрсний урвалын орчин 3.50-8.55 хооронд байх бөгөөд дунджаар 6.39 буюу сул хүчиллэг шинж чанартай байна. Тукей тестийн үр дүнгээр хөрсний урвалын орчин ойн хэв шинж бүрд ялгаатай байсан (p < 0.05). Тайгын чандруулаг хөрс хамгийн хүчиллэг буюу pH=4.9 байхад Нарсан ойн сул чандруулаг элсэн хөрс хамгийн шүлтлэг буюу pH= 6.96 байна. Хөрсний дээд үе давхарга буюу О органик үе давхаргад илүү хүчиллэг (pH 6.0) байх бөгөөд доошлох тусам ойн хөрс илүү шүлтлэг (pH 7.32) шинж чанартай болж байна. Газарзүйн тархалтаар ойн хөрсний урвалын орчныг харахад Хөвсгөл нуурын баруун тал, дархадын хотгор орчмын ойн хөрсний урвалын орчин (pH) дунджаар 7.51-8.09 байна. Энэ нь бусад ойн хөрсний урвалын орчинтой харьцуулахад маш шүлтлэг бөгөөд Монгол орны зарим ой, мод илүү шүлтлэг орчинд ургадаг онцлогтойг харуулж байна. Түлхүүр үгс: Хөрсний урвалын орчин, pH, Ойн хөрс, Хөрс, Хангай, Хэнтий, Хөвсгөл, Монгол

Desertification is recognised as land degradation in arid, semi-arid, and dry subhumid regions, typically resulting from climatic fluctuations and human activities, and essentially translates to a reduction in land productivity. Therefore, dynamic shifts in vegetation cover can be viewed as indicators of this land degradation and desertification. This study attempted to illuminate the dynamics of vegetation within Govi-Sumber province, a crucial ecotone zone highly vulnerable to land degradation, over the period 2010-2020 using remote sensing techniques. The normalised difference vegetation index (NDVI) was calculated using Landsat 7 and 8 satellite images to determine changes in vegetation cover. Our findings revealed a tendency towards an increase in vegetation cover in recent years, with a mean NDVI of 0.34 observed from 2010 to 2020. In previous years, sparse vegetated areas were prevalent throughout the province, but showed a steady decrease by 2020. On the contrary, densely vegetated areas progressively expanded, while ranges of 0-0.1, 0.3-0.4 and above 0.7 showed no discernible changes. The northern territory, characterised by wet depressions, exhibited the most significant transformations, with NDVI values increasing in recent years. However, the southern and northwest regions recorded significant changes, showing a downward trend in their NDVI values.