Бидний тухай
Багш ажилтан
Хуш модны физиологийн судлах нь энэ модны төрөл зүйл уур амьсгалын өөрчлөлтөд хэрхэн хариу үйлдэл үзүүлэхийг ойлгоход модны жилийн цагирагийн өсөлт болон физиологийн судалгаа хийсэн зарим үр дүнгээс танилцуулж байна.
Climate change is increasing the intensity and frequency of extreme heat events. Ecological responses to extreme heat will depend on vegetation physiology and thermal tolerance. Here we report that Larix sibirica, a foundation species across boreal Eurasia, is vulnerable to extreme heat at its southern range margin due to its low thermal tolerance (Tcrit of photosynthesis: ~ 37–48 °C). Projections from CMIP6 Earth System Models (ESMs) suggest that leaf temperatures might exceed the 25th percentile of Larix sibirica’s Tcrit by two to three days per year within the next two to three decades (by 2050) under high emission scenarios (SSP3-7.0 and SSP5-8.5). This degree of warming will threaten the biome’s continued ability to assimilate and sequester carbon. This work highlights that under high emission trajectories we may approach an abrupt ecological tipping point in southern boreal Eurasian forests substantially sooner than ESM estimates that do not consider plant thermal tolerance traits.
Extreme heat is becoming increasingly common across the boreal biome. Better quantification of vegetation physiology and thermal tolerance is needed to predict ecological responses to these extreme heat events. Here we report that Larix sibirica, a foundation species across boreal Eurasia, has a low thermal tolerance of photosynthesis (Tcrit: ~37-48°C) at its southern range margin. Projections from Earth System Models (ESMs) participating in CMIP6 suggest that leaf temperatures might exceed the 25th percentile of Larix sibirica’s Tcrit by 2 to 3 days per year under high emission scenarios (SSP5-8.5 and SSP3-7.0) by 2050. Such exceedances would cause sustained damage to Larix sibirica’s photosynthetic apparatus and its ability to assimilate carbon. This work highlights that we may be rapidly approaching an ecological tipping point in boreal Eurasia within the next two to three decades. It also demonstrates the need to consider thermal tolerance information to forecast the terrestrial carbon cycle and presents a framework to do so.
Монгол орны хувьд хот суурин газруудад хүн ам суурьших үйл явц ХХ зууны сүүлийн хагаст явагдаж эхэлсэн хэдий ч 1990 оны нийгмийн өөрчлөлттэй холбоотой зөв зохистой суурьшил, хүн амын нягтшилын бодлого алдагдсан. Олон хүн бөөгнөрөн суурьших байгалийн нөхцөл, нөөц багатай манай орны хувьд томоохон хот суурин газрууд ихэвчилэн томоохон голын хөндий, уулын ам хөндийн системд төвлөрсөн шинжтэй байгаа нь хүн амын төвлөрөлтэй уялдан техноген нөлөөлөлд хялбар өртөх, байгаль орчны тэнцэл алдагдах үндсэн шалтгаан болж байна. Энэ судалгааны ажлын хүрээнд баруун бүсийн хөгжлийн томоохон төв болох Завхан аймгийн Улиастай хотын орчны бохирдол, антропогени нөлөөллийг тодорхойлох зорилгын хүрээнд хөрсний хүнд металлаас хүрээлэн буй орчин болон хүний эрүүл мэндэд үзүүлэх эрсдлиийн үнэлгээг тооцоолох, Улаанбаатар хотын хөрсний судалгааны үр дүнг харьцуулсан судалгааг хийж гүйцэтгэсэн. Улиастай сумын төвийн бүсд газар ашиглалтын эрчим, төрөл, нягтшилтай уялдуулан хөрсний 38 цэгээс холбогдох стандартын дагуу өнгөн хөрсний дээжлэлт гүйцэтгэсэн бөгөөд хэмжилтийн үр дүнгийн үнэмшилийг нэмэгдүүлэх зорилгоор Завхан аймгийн Ус, цаг уур орчны шинжилгээний газрын Улиастай төвийн мониторингийн цэгүүдийг хамруулсан. Лабораторийн задлан шинжилгээг МУИС-ийн Хүрээлэн буй орчны лаборатори болон Япон улсын Каназава их сургуулийн Байгаль орчны технологийн хүрээлэнгийн Геохимийн лабораторид хөрсний хүнд элементийн агууламжыг ICP-MS болон ICP-OES аргазүйгээр хэмжилт гүйцэтгэсэн. Судалгааны үр дүнгийн урьдчилсан боловсруулалтаас үзэхэд Улиастай хотын хүрээнд хүнцэлийн агууламж анхаарал татахуйц өндөр агууламтай байгаа бол хүлцэх агууламжаас кобальт, хром зэрэг элементүүд давсан утгатай байгаа бөгөөд бохирдлын гол тархалт нь голын арал орчмын бүс, цахилгаан станц, сургуулийн халаалтын уурын зуух зэрэг газрууд багтаж байна. Улиастай хот нь орчим жилийн хугацаанд баруун бүсийн засаг захиргаа, эдийн засгийн бүс болж байсан газар ашиглалтын түүхтэй бүс нутгийн хувьд хөрсний бохирдол анхаарал татах хэмжээнд хүрсэн байна. Улаанбаатар хот нь нийгэм-эдийн засгийн голлох төв ач холбогдол бүхий суурин газрын хувьд хөрсний бохирдолд хүчтэй өртөн, хар тугалга, хром, азот зэрэг элементүүд цагаан хаалга, баянбүрд, 100-н айлын худалдааны төв, Нарантуул ОУХТ зэрэг газруудад бүртгэгдсэн байна. иймд хөрсний бохирдолоос хүний эрүүл мэндэд үзүүлэх нөлөөллийн эрсдэлийн үнэлгээг USEPA-ийн аргыг ашиглан хүүхэд том хүн дээр тооцоолсон. Үр дүнд бидний Улаанбаатар хотын гэр хороололд хийгдсэн тооцоотой харьцуулахад Улиастай сумын хөрсний бохирдол хүний эрүүл мэндэд үзүүлэх эрсдлийн үнэлгээний үр дүн эрсдэл өндөр гарсан нь суурийн газрын хөрсний хүнд металлын бохирдол хот хөдөөд нүүрснээс шалтгаалан ижилхэн өндөр байгааг харуулж байна.
The Scots pine (Pinus sylvestris L.) forest is one of major forest types in Mongolia, and overharvesting has threatened its natural regeneration and forest ecosystem sustainability. In present study we examined the effect of different logging intensity on natural regeneration and soil properties 20 year after logging using the experimental research plots established with a randomized block design. Here, we considered four treatments, including low (27.5% removal of growing stock volume), medium (51.6%), high (74.3%) intensities of selective cutting with non-cutting as the reference stand. Our findings revealed that logging under low and medium intensities ensures a successful natural regeneration of Scots pine, and high intensity logging and clear-cuts showed a limiting effect to the regeneration for Scots pine and created more suitable preconditions for broad-life tree regeneration, and development of abundant herbal and shrub coverage.
The amount of carbon stored in deadwood is equivalent to about 8 per cent of the global forest carbon stocks1. The decomposition of deadwood is largely governed by climate2,3,4,5 with decomposer groups—such as microorganisms and insects—contributing to variations in the decomposition rates2,6,7. At the global scale, the contribution of insects to the decomposition of deadwood and carbon release remains poorly understood7. Here we present a field experiment of wood decomposition across 55 forest sites and 6 continents. We find that the deadwood decomposition rates increase with temperature, and the strongest temperature effect is found at high precipitation levels. Precipitation affects the decomposition rates negatively at low temperatures and positively at high temperatures. As a net effect—including the direct consumption by insects and indirect effects through interactions with microorganisms—insects accelerate the decomposition in tropical forests (3.9% median mass loss per year). In temperate and boreal forests, we find weak positive and negative effects with a median mass loss of 0.9 per cent and −0.1 per cent per year, respectively. Furthermore, we apply the experimentally derived decomposition function to a global map of deadwood carbon synthesized from empirical and remote-sensing data, obtaining an estimate of 10.9 ± 3.2 petagram of carbon per year released from deadwood globally, with 93 per cent originating from tropical forests. Globally, the net effect of insects may account for 29 per cent of the carbon flux from deadwood, which suggests a functional importance of insects in the decomposition of deadwood and the carbon cycle.
Background/Question/Methods In arid ecosystems, grazing by livestock and wild ungulates affect vegetation. The study aimed to identify grazing effects on herbaceous and shrub communities' diversity, species richness, and some morphological variables (height, canopy, basal covers, and horizontal annual growth) of the dominant shrub; Amygdalus pedunculata Pall (A. pedunculata), in Ikh Nart Nature Reserve located at semi-desert steppe of Mongolia. Results/Conclusions Our findings revealed that high grazing intensity negatively affects the species richness, diversity, and evenness of herbaceous plants, more profoundly in shrub communities. Few annuals and A. pedunculata dominate in grazed communities. As part of grazing avoidance, the height and canopy cover of A. pedunculata decreases along the grazing gradient. Significant relationships between growing season rainfall, air temperature, and ring-width of A. pedunculata were not observed. It might indicate this shrubs' adaptation to use deep soil water, which is not easily affected by rainfall and temperature. The average age of the individuals of A. pedunculata does not differ along the grazing gradient. The density of A. pedunculata diminishes with grazing. The results suggested a need for well-managed pasture management, which covers the conservation of shrub communities alongside other species in the semi-desert region.
Warming in Central Asia has been accelerating over the past three decades and is expected to intensify through the end of this century. Here, we develop a summer temperature reconstruction for western Mongolia spanning eight centuries (1269–2004 C.E.) using delta blue intensity measurements from annual rings of Siberian larch. A significant cooling response is observed in the year following major volcanic events and up to five years post-eruption. Observed summer temperatures since the 1990s are the warmest over the past eight centuries, an observation that is also well captured in Coupled Model Intercomparison Project (CMIP5) climate model simulations. Projections for summer temperature relative to observations suggest further warming of between ∼3°C and 6°C by the end of the century (2075–2099 cf. 1950–2004) under the representative concentration pathways 4.5 and 8.5 (RCP4.5 and RCP8.5) emission scenarios. We conclude that projected future warming lies beyond the range of natural climate variability for the past millennium as estimated by our reconstruction. (1) (PDF) Accelerated Recent Warming and Temperature Variability Over the Past Eight Centuries in the Central Asian Altai From Blue Intensity in Tree Rings. Available from: https://www.researchgate.net/publication/353486939_Accelerated_Recent_Warming_and_Temperature_Variability_Over_the_Past_Eight_Centuries_in_the_Central_Asian_Altai_From_Blue_Intensity_in_Tree_Rings [accessed Aug 27 2021].
Shrub expansion has been widely documented in Northern Hemisphere due to the climate change and land use impacts. The findings of some studies show that shrub expansion greatly corresponds with changes in temperature and precipitation in Arctic, whereas studies in Tibetan Plateau show that shrub expansion is more dependent on soil moisture. However, there has not been sufficient studies of shrub expansion in Central Asia, including our country. We carried out studies on 12 shrub species present in Khar Yamaat Natural Reserve Area (N47.645727, E112.043829) to determine the response of several shrub species to climate factors and disturbances. We were able to distinguish diverse pore arrangements, various growth patterns, climate-growth relationships and finally, pointer years were recorded as well. That being the case, shrubs in Mongolia have successfully been proven to have a high dendrochronological potential and it is practicable to apply it for rangeland and ecological assessments.
This study was carried out in Scots pine (Pinus sylvestris L.) plantations that were previously established in West Khentii Mountains of Northern Mongolia. In this study, species composition, richness, diversity and plant cover changes among planted forests with different plantation ages were analyzed. We found an obvious difference of species composition between natural stands and plantations. Our findings revealed continuous changes in vascular plant composition among plantations by increasing light demanding species. A number of species from forest and forest-meadow mesophytes were replaced with xerophytes from forest-steppe and steppe. Current profound changes in species composition and a stable existence of invasive plant species from different ecological groups have a tendency to be stored during the initial stage of forest plantation establishment. The strong effect of planted trees on the growing environment appeared rather late, and has intensified since 15 years after the plantation establishment