Synanthropization and species diversityof floodplain ecosystems of the Ob-Irtysh basin, Russia

Plant diversity plays an important role in maintaining the stability of ecosystem functioning. Based on field surveys and indoor analyses, this study investigated the relationship between species diversity and community stability at different stages of bare patch succession in degraded alpine meadow ecosystems. Results show that: (1) Using the ICV (the Inverse of the Coefficient of Variation) method to analyze changes in plant community stability, community stability was generally ranked as follows: Long-term recovered patches > Healthy alpine meadow > Degraded alpine meadow > Short-term recovered patch > Bare Patches. (2) Using factor analysis to construct an evaluation system, the stability ranking based on species diversity was as follows: Healthy alpine meadow > Long-term recovered patches > Degraded alpine meadow > Short-term recovered patches > Bare Patches. (3) The community stability index was significantly positively correlated with vegetation coverage, height, biomass, species richness, Shannon–Wiener diversity index, species evenness, and Simpson’s diversity index (p < 0.05). Therefore, a positive correlation exists between plant diversity and community stability, such that plant communities with a higher species diversity tend to be more stable. To maintain the plant diversity and community stability of alpine meadow ecosystems, it is necessary to consider the characteristics of grassland plant composition and community structure, as well as their influencing factors, and promote the positive succession process of grasslands.

荒漠草原植物群落结构及其稳定性对增水和增氮的响应

The mixed Cunninghamia lanceolata (Lamb.) Hook., Pinus massoniana Lamb., and hardwood forest in southeastern China is a major assemblage in natural secondary forests, and of national and international importance in terms of both timber and ecosystem services. However, over-harvesting has threatened its long-term sustainability, and there is a knowledge gap relating to the effect of harvesting on the ecosystem. After conifer species were selected for harvesting, the mixed Chinese fir, pine, and hardwood forest was changed into mixed evergreen broadleaf forest. In this context, we observed the restoration dynamics of plant communities over a period of 15 years (1996 to 2011) with different levels of harvesting intensity, including selective harvesting at low (13.0% removal of growing stock volume), medium (29.1%), high (45.8%), and extra-high (67.1%) intensities, as well as clear-cut harvesting (100.0%), with non-harvesting as the control, based on permanent sample plots established in a randomized block design in these forests in southeastern China. The impact on the richness, diversity, and evenness of plant species derived from descriptive statistical analyses was shown to initially increase, and then decrease, with an increase in harvesting intensity. The most critical impacts were on the richness, diversity, and evenness of shrub and herb species. Richness, diversity, and evenness of plant species recovered and increased under selective harvesting at low and medium intensities, while these parameters had not recovered and significantly decreased under selective harvesting at high and extra-high intensities, as well as with clear-cut harvesting. The impact on the plant community stability was derived from the stability test method of the improved Godron M. The plant community stability was closest to the point of stability (20/80) under selective harvesting at medium intensity, followed by selective harvesting at low intensity. The plant community stability was far from the point of stability (20/80) under selective harvesting at high and extra-high intensities, as well as with clear-cut harvesting. Of these treatments, clear-cut harvesting had the greatest effect with regard to reducing stability. Therefore, these results indicate that the selective harvesting at low and medium intensities is conducive to preserve or increase the species diversity and community stability. In order to prioritize promoting plant species diversity, clear-cut harvesting and selective harvesting at high and extra-high intensities should be avoided with regard to this type of forest in this region. This study sheds light on the practice of forest operation in the study region and subtropical forests with the same environment.

Alpine grassland degradation reduced plant species diversity and stability of plant communities in the Northern Tibet Plateau

Plant community and the influence of plant taxonomic diversity on community stability and invasibility: A case study based on Solidago canadensis L.

The relationships among species diversity, functional diversity, functional redundancy, and community stability are central to community and ecosystem ecology. In this paper, a “space substitution for time” approach is used to study the plant communities at different stages of the natural recovery process of degraded karst vegetation on the karst plateau of Guizhou. These restoration stages include the herbaceous stage, herbaceous and shrub transition stage, shrub stage, tree and shrub transition stage, and tree stage. We calculated the functional diversity and functional redundancy of the community based on functional characteristics and mediated the relationship between functional diversity, functional redundancy, and stability of the plant community through changes in functional diversity and functional redundancy. This study aims to reveal the mechanisms of changes in species diversity and community stability and thus further reveals the intrinsic reasons for maintaining the stability of karst plant communities. The most important results include the following: (1) Species diversity, functional redundancy, and stability gradually increased with restoration, and there were significant differences among the different stages; functional diversity increased at first and then decreased, and reached the highest level at the tree and shrub transition stage; (2) Plant height and specific leaf area were functional traits that influenced the diversity and stability of the plant community, with plant height being positively correlated with plant community diversity and stability, and specific leaf area being negatively correlated with plant community diversity and stability; (3) During the community's recovery, functional diversity and functional redundancy interacted to maintain stability. In the early and late stages of recovery, the effect of functional redundancy on stability was greater than that of functional diversity, but it was the opposite in the middle stages; (4) The tree and shrub transition stage is the likely point at which the functional diversity of plant communities in karst areas reaches saturation, and the growth rate of functional redundancy after functional diversity saturation is greater than that before saturation. Overall, community stability increased with species diversity; habitat heterogeneity increased functional diversity in the early stages of recovery; and habitat homogeneity increased functional redundancy.

ABSTRACTGrasslands represent a major biome on Earth and play a vital role in ecosystem functioning and dynamics. However, owing to the variations among grassland types, the impact of grazing on plant community diversity and stability remains unclear. This study is based on the typical steppe of the Mongolian Plateau. Field sampling and data analysis were combined to qualitatively and quantitatively investigate the structural characteristics, species diversity, and stability of plant communities under varying grazing intensities, that is, four‐season nomadic, two‐season rotational, and sedentary grazing (FSNG, TSRG, and SG, respectively). The results indicated that FSNG pastures exhibited the largest number of plant species while FSNG and TSRG pastures exhibited relatively high importance values for the primary dominant species. Carex duriuscula, Chenopodium glaucum, and Cleistogenes squarrosa were prominent in SG pastures, with C. duriuscula having the largest importance value. The mean height, cover, and aboveground biomass of plant communities in FSNG were significantly higher than those in SG (p &lt; 0.05), with no significant difference observed between FSNG and TSRG. FSNG also demonstrated the highest Shannon–Wiener, Simpson, and Pielou indexes. The Shannon–Wiener and Simpson indexes between the FSNG, TSRG, and SG pastures showed significant differences (p &lt; 0.05). Nomadic plant communities displayed positive loosely interspecific traits, suggesting independence and positive succession. Conversely, communities in TSRG and SG exhibited negative correlations and higher instability. The stability analysis ranked community stability as FSNG &gt; TSRG &gt; SG, suggesting that judicious grazing practices could enhance grassland stability. The findings reveal that grazing patterns influence plant community composition and function and that FSNG pastures promote higher species diversity, perennial dominance, and overall stability compared with TSRG and SG pastures.

The four-eyed fir bark beetle Polygraphus proximus Blandf. from the Russian Far East has led to the decline of Siberian fir in significant areas across several Russian regions. Presently, the four-eyed fir bark beetle is a primary factor contributing to the degradation of fir forests and the occurrence of various changes in the flat part of Western Siberia. The study was conducted in stands with varying compositions, with a mandatory inclusion of a specific proportion of Siberian fir. Reference stands were located in Central Siberia, along the border of the forest-steppe (Krasnoyarsk forest-steppe) and taiga zones (mountain-taiga region of the Eastern Sayan). A comprehensive field study was conducted on research plots (a total of 10). The stands and outbreak areas presented here serve as a reference for the study area in terms of species composition, stand characteristics, and the degree of infestation of fir trees by the pest. The analysis yielded a scale that differentiated forest stands according to species composition and the extent of damage. The four-eyed fir bark beetle’s infection and damage to stands were found to be influenced by species composition. The intensity of damage was found to vary among species, with fir forests experiencing the most significant damage, followed by Siberian pine forests, birch forests, Scots pine forests, and aspen forests. Consequently, from a forestry perspective, forests dominated by aspen and Scots pine exhibit the greatest resistance to the invasive impact of the four-eyed fir bark beetle in the Krasnoyarsk forest-steppe zone.

In a changing climate, phenological observations are gaining new importance. They can tell what changes are taking place in certain environmental conditions. The studies were conducted in 2019 within the territory of the Republic of Mordovia (the center of the European part of Russia). Beer traps (beer as a bait) were used to collect Diptera. The material was collected in the period from April to October in different forest biotopes (pine forest, lime forest, aspen forest, birch forest and oak forest) and the air temperature was recorded at the same time. In total, more than 14.000 specimens of Diptera were recorded. Overall, 29 families were recorded. The largest number of families was observed for birch (23 families) and pine (24 families) forests, the smallest number – in aspen forest (16 families). The families Muscidae, Drosophilidae, Calliphoridae had the largest number of captured individuals (44.5%, 35.2%, 7.6% of the total number of individuals respectively). The highest number of individuals was captured in oak forest. The dynamics of abundance in all biotopes were similar and were characterized by the same number of declines and rises. The first small significant peak in the number of Diptera occurred in the first half of summer. A slight increase in the number of specimenі occurred in mid-June. In the second half of September, there was a gradual increase in the number and the maximum peak was recorded in mid-October, then there was a decline. The autumn increase in the number of Diptera in all five biotopes exceeded the summer peak by several times. This dynamic was typical for most families. However, species from the family Lonchaeidae had the peak in July. For our better understanding of the changes in the seasonal dynamics of the number of Diptera, long-term observations in different climatic zones are needed.

We conducted a complex investigation of anthropogenic roadside phytocoenoses. For the study, 8 plots (birch and pine forests) were selected, close to roads in the south of Tyumen region within the five administrative districts: Uporovsky, Zavodoukovsky, Yalutorovskiy, Yarkovsky, and Tobolsk. As a result of the studies, 75 species of vascular plants from 21 families were noted in the plant communities. It was found that the majority of the total projective cover of the plant communities was provided by synanthropic species. In the synanthropic fraction of the flora, 33 species belonging to 11 families were identified, those with the most species being: Scrophulariaceae, Compositeae, Rubiaceae, Poaceae, Fabaceae, Polygonaceae, Umbellíferae. The index of synanthropization of the flora of the studied phytocenoses is in the range from 43% to 64%. Among the identified pollutants accumulated in the phytocenoses, the group of heavy metals was identified (Cr, Cu, Ni, Pb, Sr, Zn). Needles of Pinus sylvestris L. mainly accumulate Cr, Cu, Ni, Sr. The greatest concentration of Pb and Zn was found in the leaves of Betula pendula Roth. The content of other heavy metals in the leaves of Betula pendula Roth. during the growing season was relatively stable. Accumulation of heavy metals in the studied components of forest ecosystems can be displayed structurally: soil &gt; leaves &lt; phytomass (birch forests), soil &lt; needles &gt; phytomass (pine forests). Methodological approaches to conducting a complex of long-term observations of natural ecosystems have been formulated, substantiated and justified. To evaluate the absorption efficiency of heavy metals, the biological absorption coefficient was calculated. The obtained results can be used as a control in the study of migration and accumulation of heavy metals and for assessing the degree of anthropogenic load on phytocenoses of roadside ecosystems and predict the extent of probable changes in them. The forecast of the results will facilitate the elaboration of a necessary system of measures aimed at increasing the stability of plant communities.

Températe forests are distributed over very extensivo areas in North America but in tropical Middle America are limited to montane zones, and at the present time these montane forests are threatened by man because of overpopulation. I studied the structure and use of foliage of bird communities in montane températe forests of , the Valley of México. In August and September of 1981 I censused bird communities in six températe forest study areas one each in oak woodland and pine-alder forest, and two each in pine forest and firforest using the variable circular-plot method. Overall bird densities were greater in broad-leaved forests than in coniferous forests. Species richness was similar between broad-leaved and pine forests but generally lower in fir forests. A similar trend was shown by bird species diversity (BSD). The oak woodland bird community was the most distinctive, whereas the pine-alder one was similar to the fir forests. Bird communities of the two pine forests had low similarity indices, whereas communities of fir forests had the highest índices. Qranivorous birds were very important in pine forests, whereas insectivores were the most important in broad-leaved and fir forests. Profiles of foliage stratification were used selectively by all the bird communities, and profiles of utiiization were significantly different between August and September for all the communities except that of the pine-alder forest. Among dietary categories and guilds, all but the seed-eaters used the profile of foliage stratification very selectively; this selectivity was especially marked for the salliers and the foliage gelaners. In a latitudinal gradient of températe forests over western North America and México, there were not big differences in species richness of bird communities from broad-leaved and mixed-conifer forests, but there was a decrease in the number of species from pine forests as latitude decreased. BSD decreased southwards in the broad-leaved forests and only slightly in mixed-conifer forests, whereas in pine forests BSD increased. Seed-eaters were relatively more abundant in the northem forests, whereas foliage gleaners were the most important in Southern forests, but not in the pine forests.

Studying the effects of different degrees of exotic plant invasion on native plants' community structure and plant diversity is essential for evaluating the harm caused to ecosystems by plant invasion. In this study, we investigated the effects of Xanthium spinosum, a widespread invasive species, on plant community species diversity and community stability in the Ili River Valley area of Xinjiang, China, under three invasion levels (no invasion and low, moderate, and heavy invasion), and the competitive advantage index, invasion intensity, and contribution of plant community species diversity to community stability and invasibility were determined for the prickly fungus under different degrees of invasion. The results show that there were significant differences (p < 0.05) in the species diversity and community stability of plant communities caused by different degrees of invasion of X. spinosum. The species diversity and stability of plant communities were negatively correlated with the community invasibility, competitive advantage, and invasion intensity of X. spinosum (p < 0.05); therefore, the competitive advantage and invasion intensity of X. spinosum increase with the increase of its invasion degree. On the contrary, community species diversity and stability decreased with the increase of its invasion degree, ultimately leading to differences in community invasibility under different invasion degrees. The Shannon-Wiener and Simpson's indices were the greatest contributors to community stability and invasibility, respectively. Moderate and heavy levels of invasion by X. spinosum reduced the diversity and stability of local plant communities, increased the invasibility of communities, and substantially affected the structures of plant communities. Therefore, the continued invasion by X. spinosum will have an immeasurable impact on the fragile ecosystems and diversity of indigenous species in Xinjiang. We recommend that this invasive species be controlled and eradicated at the early stages of invasion to prevent further harm.

Marchalina hellenica (Gennadius) (Hemiptera: Margarodidae) is a scale insect, endemic in pine (Pinus halepensis) forests of Greece and other Mediterranean countries, which plays a major role in the production of honeydew honey. We investigated the morphological and the biological characteristics of M. hellenica in the pine forests of Mt. Parnis in comparison with those in the high-altitude fir (Abies cephalonica) forest of Mt. Helmos where it has been recently established, after anthropogenic intervention. Morphologically, the final body size of the 1st instar and the adult stages of M. hellenica in the fir forest were equal to those in the pine forest. Biologically, in the fir forest, the insect exhibited a long 1st instar’s period, which was the stage of its overwintering. In the pine forest, the 1st instar period was short and the insect overwinters in the stage of 2nd instar. The number of eggs per female in the fir forest was quite low (25–145) compared with the number of eggs in the pine forest (200–300). Concerning the qualitative parameters of the resulting honeydew-honey, statistically significant differences were found in Diastase and HMF (p < 0.0001). No difference was found in sucrose, fructose + glucose and water content, neither to electrical conductivity and total acidity. All values were within the EU limits (EU Directive 2001).

The stability, diversity, and biomass of grassland plant communities directly impact the functionality and resilience of ecosystems, making them a focal point for ecological research. This three-year study (2021–2023) in the Habahe pastoral area of Xinjiang, China, aimed to investigate the long-term effects of grazing on grassland vegetation structure, community stability, species diversity, and productivity. The results indicate the following. (1) The Habahe pastoral area hosts a relatively rich plant species diversity, with 40 species distributed across 17 families and 37 genera, predominantly comprising perennial and annual herbs. (2) Grazing significantly affected grassland structure and function, resulting in a 4.35% decrease in plant community stability, a 40.74% decrease in species richness, a 21.55% decrease in species dominance, a 5.08% decrease in species diversity, a 46.79% decrease in aboveground biomass, a 61.86% decrease in coverage, and a 72.12% decrease in height. (3) Grazing alters the relationship between species diversity and community stability, shifting it from a positive correlation to a negative one (p &lt; 0.01) or rendering it non-significant after grazing. (4) Grazing affects the correlation between aboveground biomass and both species diversity and community stability. While the positive correlation between aboveground biomass and species diversity persists, it is not statistically significant (p &gt; 0.05) after grazing. Conversely, the correlation between aboveground biomass and community stability shifts from positive to negative (p &lt; 0.01). These results emphasize the need for integrated management strategies that consider both grazing intensity and plant community composition to maintain the health of grassland ecosystems.

Nutrient enrichment can reduce ecosystem stability, typically measured as temporal stability of a single function, e.g. plant productivity. Moreover, nutrient enrichment can alter plant–soil interactions (e.g. mycorrhizal symbiosis) that determine plant community composition and productivity. Thus, it is likely that nutrient enrichment and interactions between plants and their soil communities co‐determine the stability in plant community composition and productivity. Yet our understanding as to how nutrient enrichment affects multiple facets of ecosystem stability, such as functional and compositional stability, and the role of above–belowground interactions are still lacking. We tested how mycorrhizal suppression and phosphorus (P) addition influenced multiple facets of ecosystem stability in a three‐year field study in a temperate steppe. Here we focused on the functional and compositional stability of plant community; functional stability is the temporal community variance in primary productivity; compositional stability is represented by compositional resistance, turnover, species extinction and invasion. Community variance was partitioned into population variance defined as community productivity weighted average of the species temporal variance in performance, and species synchrony defined as the degree of temporal positive covariation among species. Compared to treatments with mycorrhizal suppression, the intact AM fungal communities reduced community variance in primary productivity by reducing species synchrony at high levels of P addition. Species synchrony and population variance were linearly associated with community variance with the intact AM fungal communities, while these relationships were decoupled or weakened by mycorrhizal suppression. The intact AM fungal communities promoted the compositional resistance of plant communities by reducing compositional turnover, but this effect was suppressed by P addition. P addition increased the number of species extinctions and thus promoted compositional turnover. Our study shows P addition and AM fungal communities can jointly and independently modify the various components of ecosystem stability in terms of plant community productivity and composition.