Changes In Phytomass Research Articles

Climate Affecting the Carbon, Phytomass and Litter Stocks in Forest Stans of the South of the European Russia

Modern global climate change manifests in an ever intensifying fashion, affecting anthropogenic and natural systems. Bioclimatic models predict significant shifts in biome boundaries, including a reduction in the forests’ proportion in the forest-steppe areas. This process can also affect carbon stocks. The aim of the work was to assess the impact of climate and its changes on the values and their changes of the phytomass’ carbon stocks of forest stands according to the data of repeated surveys of permanent sample plots. In the southern regions of the European Russia, 8 forests were selected and trial plots were set up. Repeated surveys were carried out on the test plots in 2010–2011, 2014–2015, 2019–2020. The carbon reserves of the living and the dead components of forest stands were calculated according to taxation characteristics. The litter carbon stocks were determined by the gravimetric method. The meteorological information analysis was carried out using data from the meteorological stations closest to the objects of study. Average annual temperature for 1991–2020 increased compared to 1961–1990. by 1.13°C, which is 2.5 times more than the global average. At the same time, annual precipitation decreased from 448.2 mm to 445.4 mm. The average value of the G.T. Selyaninov’s hydrothermal coefficient for May-September during the 1961–1990 period was 0.85, and 0.79 during the 1991–2020 period. The stock of the phytomass carbon in the studied forest stands varied from 38.5 ± 7.4 t C ha–1 to 270.6 ± 52.8 t C ha–1. Repeated surveys revealed both increases and decreases in phytomass carbon stocks, which ranged from –23.8 to 31.9 t C ha–1 over a five-year interval. The phytomass carbon stocks and climatic characteristics analysis revealed a statistically significant correlation with the HTC for May-September. However, comparison of changes in phytomass with changes in the average annual temperature, annual precipitation and HTC for May-September did not reveal significant dependencies. The absence of significant correlations between changes in phytomass carbon and climatic parameters’ changes can be determined by the forest ecosystems’ stability, which ensures the preservation of their functions over several years intervals.

Density of Tree Wood and Bark in Climatic Gradients of Eurasia

Under the conditions of climate changing, the biospheric role of forest cover is increasing, as well as the relevance of research on the carbon depositing capacity of the world’s forests. These studies include an assessment of the trees’ and stands’ biological productivity, which includes not only phytomass, but also the basic density (BD) of stem wood and bark. In our study, allometric models of the BD of wood and bark of 9 forest-forming tree species of Northern Eurasia have been developed, including such independent variables as the tree age, the stem diameter, as well as the average temperature of January and average annual precipitation. The structure of a mixed-effects model is applied, in which the affiliation of the source data to each of the tree species is encoded by a set of dummy variables. Based on the space-for-time substitution principle, the obtained patterns of BD changes in spatial climatic gradients are used to predict their changes in temporal gradients. The effect of Liebig’s law of limiting factor in predicting BD in spatial and temporal climatic gradients has been confirmed. The revealed patterns of changes in the BD of wood and bark in temperature and precipitation gradients completely repeat the previously established patterns of changes in phytomass and net primary production of trees and stands of Eurasia in the same gradients. This means that the climatic conditionality of the studied indicators of biological productivity has a common nature for both quantitative and qualitative indicators of trees and stands.

Hydrothermal conditions of the temporal variability of the phytoproductive functioning: case study of the Burtinskaya steppe landscape (Southern Urals)

The interpretation of a geographic landscape as a geosystem requires evidence that, under certain conditions, an external signal has a similar response in its spatial elements. The article examines the similarities and differences in the response of units in the steppe landscape of the Southern Urals (Burtinskaya steppe) to varying hydrothermal conditions. The Normalized Difference Vegetation Index (NDVI) is used as an indicator of intra-seasonal variability in phytoproduction performance. 110 standardized increments of NDVI during the growing seasons in 2010–2020 were ranked and interpreted as types of dynamics in comparison with background modal values. The occurrence and diversity of types of phytomass dynamics within the model units (gullies, ridges, and interfluve flat surfaces) vary depending on hydrothermal conditions and the length of the time interval between measurements. The integrity of the unified response in the landscape is enhanced during dry periods, when changes in phytomass in gullies and on ridges differ little from those on spatially dominant slopes and flat surfaces. Strong deviations from the background dynamics often appear at intervals of up to 2 months, but are compensated for within 4–5 months. The dynamics of hydrothermal conditions over the entire growing season manifests itself in phytomass changes in a similar way over the landscape, which proves the connection between the spatial and temporal parameters of landscape organization. Depending on the landform, phytocenoses adapt to the late summer moisture deficit either by transitioning to another stable state of structure while maintaining the intensity of functioning (self-organization), or by maintaining the structure while reducing the intensity of functioning (self-regulation).

Use of the Earth Remote Sensing Data to assess the state of recreational forests in the Kokshetau National Park

Currently, modern satellite systems are increasingly used in various areas of studying natural resources and the dynamics of natural phenomena, and in carrying out an ecological assessment of the state of the environment. At the same time, remote sensing data provide greater visibility, data acquisition in dynamics, high speed of image acquisition, and transmission. The article presents the results of spatio-temporal changes in the vegetation biomass of the Kokshetau National Park based on the calculation and analysis of the vegetation index. Based on the analysis of the NDVI values, the tendencies of changes in phytomass were estimated and correlations with the main climatic characteristics of the territory for the studied period were revealed. For the research, we used Landsat satellite images and geoinformation mapping in the ArcGIS software package. In general, there is a negative trend in the values of the indices for the forests of all functional zones over a 10-year period. For the preservation and further renewal of forests, the National Park of Kokshetau needs to carry out a number of regulatory measures.

Review of studies of production and destruction processes in the mires of West Siberia: methods and results

The review discusses the results of research of production and destruction processes involved in the carbon cycle, which were carried out by the Institute of Soil Science and Agrochemistry of the Siberian Branch of the Russian Academy of Sciences the bog and palsa complexes of West Siberia. Some characteristic of the carbon cycle in mires, the methods used, and the geographical coverage of the investigations are described. Based on the published results, specific patterns of changes in phytomass, its primary production and destruction along the latitudinal gradient are characterized, and the productivity of bogs and other biogeocenoses of the region is compared.

Моделювання динаміки біопродуктивності деревостанів сосни звичайної в умовах Байрачного Степу України

Dynamic changes in forest ecosystems, which can be both short-term and long-term, are assessed on the scale of long-term biologically determined stages, through the determi-nation of age parameters. In this context, the results on the dynamic changes of the components of the aboveground phytomass of Scots pine in the northern steppe zone of Ukraine are presented. Based on the simulated growth tables of the studied modal artificial pine stands, standards for the dynamics of their bioproductivity have been developed for such components of aboveground phytomass as trunk in bark, branches in bark and needles. Modeling and statistical evaluation to determine the phytomass of the aboveground part of the pine stand: wood and bark of the trunk, branches and needles of the crown in a completely dry state. Tables of theoretical distribution of indicators of components of phytomass of pines for an age category from 10 to 80 years are con-structed. Regularities of phytomass changes of trunk components in bark and crown for stands of I–IV classes of quality were found. It is established that the dynamics of changes in the components of both the stem part and the components of the crown is characterized by a gradual increase in phytomass with age. The trend of dynamic changes is similar for all studied rating classes. It is ob-vious that stands of the first quality have the highest productivity of the studied classes. Decreased creditworthiness is accompanied by a gradual decline in productivity. It is investigated that the most significant differences in the phytomass parameters of different qualities are characteristic of older stands. It is calculated that the phytomass of the trunk in the bark varies from 5.4 t/ha (10 years) to 144 t/ha (80 years), and the nature of changes in the phytomass of the crown with age actually reflects the trend of phytomass dynamics of branches compared to pine. A comparative assessment of the dynamic changes of phytomass components of pine stands of the northern steppe part with the results of bioproductivity of pines of Ukrainian Polissya and Forest-Steppe, forest-steppe and northern-steppe regions of the European part, Kazakhstan and Siberia is given. On the basis of the received tables of dynamic changes of bioproductive processes in pines of the Northern Steppe the theoretical substantiation of practical use of normative-reference material for conditions of steppe part of Ukraine is made. The obtained results provide an opportunity to assess the current state of pine forests in the study region and predict the dynamics of their changes, which will allow the objective implementation of forestry measures, taking into account the regional peculiarities of pine formation.

Assessment of biological productivity of modal spruce forests in the taiga zone based on modeling the growth of stands

The article provides information on the biological productivity of spruce stands of the Siberian green-moss group of forest types in the taiga zone (Southern ecoregions), which reflects the dynamics of the phytomass fractional composition and the carbon stock in them. The normative reference tables are developed on the basis of mathematical modeling of growth processes in combination with the conversion-volume method for determining the volume of phytomass and its fractional composition based on deposited carbon. Tables of biological productivity of spruce forests in the taiga zone are proposed, which give a quantitative characteristic of the age dynamics of changes in phytomass and the carbon contained in it. The range of phytomass changes in stands of spruce of the green-moss group of forest types over the entire age range in the conditions of the III bonitet class is from 11 to 166.5 t m−3, for the IV bonitet class is from 8.6 to 142.5 t m−3. Carbon pools in quantitative equivalent in spruce forests of the III bonitet class concentrate from 4.0 to 72.5 tC·ha−1, for conditions of the IV bonitet class is from 5.6 to 60.8 tC·ha−1. The obtained results complement the existing database on the biological productivity of taiga forests and can be used in the organization of forest monitoring, implementation of environmental programs at the regional level, including calculations of the carbon cycle.

Macrophytes in the littoral of Lake Arakhley in different states of water regime

Abstract The study of aquatic vegetation in the littoral of the dimictic water bodies of taiga is of particular interest in case of long-term observations carried out under conditions of climate fluctuations. During the low-water period, drying of the littoral with a decrease in the water level leads to the changes in phytomass of macrophytes, as well as in the composition of species and their distribution by depth. The area of littoral covered with ice in winter is also large in the low-water period; it affects the growth of perennial plants. When the water level decreases, the sand beach replaces the sand and pebble beach; it leads to the disappearance of epilithon and the predominance of rooting plants. The features of vegetation were determined for each period of water content. The low-water period is characterised mostly by grass-type vegetation; the high-water period is characterised by vegetation of mixed type.

SOME MATHEMATICAL MODELS OF COMPONENTS OF ABOVE-GROUND PHYTOMASS OF BEECH TREES DEPENDING ON THEIR ASSESSMENTS INDEXES IN THE PREVAILING FOREST VEGETATION TYPES OF POLONYNSKY RANGE OF THE UKRAINIAN CARPATHIANS

SOME MATHEMATICAL MODELS OF COMPONENTS OF ABOVE-GROUND PHYTOMASS OF BEECH TREES DEPENDING ON THEIR ASSESSMENTS INDEXES IN THE PREVAILING FOREST VEGETATION TYPES OF POLONYNSKY RANGE OF THE UKRAINIAN CARPATHIANS

Assessment of phytomass changes in an alpine Geranium-Hedysarum meadow after the removal of dominants: The results of a ten-year experiment

Changes in the aboveground phytomass of a Geranium-Hedysarum meadow community and its constituent species after the removal of dominants, Geranium gymnocaulon and Hedysarum caucasicum, over ten years have been studied in the Northwestern Caucasus. Responses of individual species to this intervention have been revealed. It has been shown that the phytomass of nondominant species increases under such conditions, but this cannot fully counterbalance the loss of phytomass resulting from the removal of dominants. Dominant species of Geranium-Hedysarum meadows exert different influences on the community structure and also compete with each other. However, this competition is fairly weak, which is probably due to considerable divergence of these species with respect to resource consumption.

The self-thinning process in mangrove Kandelia obovata stands

The self-thinning process was monitored in crowded Kandelia obovata Sheue, Liu & Yong stands over four years. The frequency distribution of tree phytomass was an L-shape, which was kept over the experimental period. Spearman's rank correlation coefficient for phytomass decreased as the time span of the comparison became longer, a result which indicates that the rank of phytomass changes as stands grow. Death of trees resulted from one-sided competition, i.e., death occurred in lower-rank trees. Surviving trees continued to grow. Whatever the current spatial distribution of the trees, death occurred randomly and the spatial distribution gradually became close to random as stands grew. The self-thinning exponent was 1.46, which can be regarded as evidence in favor of the 3/2 power law of self-thinning. Relative growth rate, RGR, decreased in proportion to decreasing relative mortality rate, RMR, with a proportionality constant of 1.57, which was not significantly different from the slope of the self-thinning exponent. This experimental result probably justifies the assumption that the ratio of RGR to RMR in the mean phytomass-density trajectory for any self-thinning population with different densities becomes constant as the growth stage progresses.

Plant Phytomass Changes in a Larch Forest of the Lake Hövsgöl Area, Northern Mongolia

In the present study we related the decrease of the vegetation productivity in a larch forest with an increase of the air temperature over a 20-year period (1987-2007). During the years of the study the data from nearby weather stations showed warming and drying trends in climatic conditions: a 1.6 0 C increase of mean annual temperature, increase in maximum and minimum temperature extremes, and delay of summer rains. Plant community changes include the shift in species dominance from mesophytes to xerophytes, decrease in vegetation cover and plant height, and transformation of a single July blooming peak to the more diffuse blooming season. We also showed the plant phytomass of the larch forest of the Hovsgol region is decreasing in response to the climate changes.

Vegetation, phytomass and carbon storage in Northern Eurasia during the last glacial–interglacial cycle and the Holocene

The phytomass (the biomass of terrestrial vegetation) is one of the main reservoirs of carbon, as carbon makes up approximately 0.45 of the phytomass by weight [Ajtay, G.L., Ketner, P., Duvigneaud, P., 1979. Terrestrial primary production and phytomass. In: Bolin, B., Degens, E.T., Kempe, S., Ketner, P. (Eds.), The Global Carbon Cycle, SCOPE 13, Wiley, Chichester, pp. 123–181.]. During the glacial–interglacial climatic rhythm both composition and geographical distribution of vegetation over Northern Eurasia have been repeatedly subjected to major changes, accompanied by corresponding changes of phytomass and carbon storage. Of special interest are three key intervals within the last 125,000 years: the Mikulino (Eem) Interglacial optimum, about 125 ka BP; the Last Glacial maximum, 18–20 ka BP and the Holocene optimum, 5.5–6 ka BP. These intervals correspond to the extreme states of the environment. Vegetation which existed in Northern Eurasia 125, 18–20 and 5.5–6 ka BP, accumulated 377.1 Gt, 66.1 Gt and 292.1 Gt of phytomass, which corresponds to 169.7 Gt, 29.9 Gt and 131.4 Gt of carbon, respectively. Compared to present-day carbon storage in the phytomass of potential vegetation (taken as 100%), these values are 155%, 27% and 120%, respectively.

Changes in phytomass and nutrient partitioning in young conifers in extreme alkaline growth conditions

The impact of long-term dust pollution emitted from a cement works on the growth, nutrients content and allocation in conifers was investigated. It was found that alkaline cement dust (pH 12.3–12.6) and the resulting alkalization of the environment inhibit the height growth of trees, reduce the length of needles and shoots and the biomass of all organs. Based on the difference of morphological parameters from the control the following order of tolerance of conifers to dust was established: Pseudotsuga menziesii> Picea abies>Pinus sylvestris>Picea glauca>Picea mariana. An important reason for the reduced biomass of conifers is a disbalanced content of nutrients in tissues and changes in their partitioning. In the influence zone of the cement works at a distance up to 0.5 km, shortage of N, Mn and P develops, especially in roots, stem and shoots. Regression analysis revealed a dependence of the biomass of organs on N and K content in trees, and in the case of those growing in a polluted area, also on the content of Ca, Mg and P.

Change in phytomass and net primary productivity for Siberia from the Mid‐Holocene to the Present

Phytomass (live plant mass) and net primary productivity are major components of the terrestrial carbon balance. A major location for phytomass storage is the subcontinent of Siberia, which is dominated by extensive reaches of taiga (boreal forest). The responsiveness of the phytomass component of the carbon pool is examined by comparing vegetation in the mid‐Holocene (4600–6000 years before present) to modern potential vegetation. The mid‐Holocene was warmer and moister in middle and northern Siberia than today, producing conditions ideal for boreal forest growth. As a result, both northern and middle taiga were dominated by shade‐tolerant dark‐needled species that thrive in moist climates. Today, shade‐tolerant dark‐needled taiga is restricted to western Siberia and the highlands of central Siberia, with its central and eastern components in the mid‐Holocene replaced today by light‐demanding light‐needled species with lower productivity and phytomass. Total phytomass in Siberia in the mid‐Holocene was 105.0 ± 3.1 Pg, compared to 85.9 ± 3.2 Pg in modern times, a loss of 19.1 ± 3.1 Pg of phytomass. The reduction in dark‐needled northern and middle taiga classes results in a loss of 28.8 Pg, while the expansion of the corresponding light‐needled taiga results in a gain of 13.5 Pg, a net loss of 15.3 Pg. The loss is actually greater, because the modern figures are for potential vegetation and not adjusted for agriculture and other anthropogenic disturbances. Given long periods for vegetation to approach equilibrium with climate, the phytomass component of the carbon pool is responsive to climate change. Changes in net primary productivity (NPP) for Siberia between the mid‐Holocene and the present were not as large as changes in phytomass. A minor decrease in NPP (0.6 Pg yr−1, 10%) has occurred under our cooler modern climate, primarily due to the shift from dark‐needled taiga in the mid‐Holocene to light‐needled taiga today.

Effects of Interannual Climate Variation on Aboveground Phytomass in Alpine Vegetation

Relationships between peak annual vascular aboveground phytomass and annual climate variation in alpine plant communities located on Niwot Ridge, Colorado, were analyzed using path analysis. The five community types, fellfield, dry meadow, moist meadow, wet meadow, and snowbed, represent a snow depth—soil moisture gradient and broadly represent the most common vegetation types on east—facing slopes of the Front Range alpine zone. Using nine successive years of data, this is the first longer term analysis of alpine phytomass and climate and one of the longest nonagricultural production records available. Live phytomass ranged from 97 g/m2 (snowbed) to 237 g/m2 (fellfield). Among—community differences in phytomass were greater than differences among years, but there was also significant phytomass variation among years. Path analysis indicated that climate accounted for 15—40% of the variation in phytomass. The dry communities, fellfield (exposed rocky summit areas dominated by cushion and mat plants) and dry meadow, were most sensitive to previous year precipitation, the moist and wet meadow communities were most sensitive to current growth season soil moisture, and the snowbed community was most sensitive to date of snow release. Because of the relatively high amount of variation attributable to variables related to precipitation, changes in precipitation regimes that may occur in alpine ecosystems will likely result in changes in phytomass that are detectable with clip—harvest methods.