Community Aboveground Biomass Research Articles

Relationship Between Evolutionary Diversity and Aboveground Biomass During 150 Years of Natural Vegetation Regeneration in Temperate China.

While the link between plant species diversity and biomass has been well-studied, the impact of evolutionary diversity on community biomass across long timescales or ongoing change remains a subject of debate. We elucidated the association between evolutionary diversity and community aboveground biomass (AGB) using an ideal experimental system with over 150-year history of natural vegetation regeneration. Higher phylogenetic diversity facilitated the sampling effect under the influence of environmental filtering, and caused an increase in AGB. Phylogenetic structure varied from aggregation to dispersion during the later period of vegetation recovery (70-150 years), which was correlated with increases in niche complementarity and increasing AGB. Woody plant evolutionary diversity was used as a key to predict the relationship between vegetation recovery and AGB, with a total explanatory power of ~84.7%. Mixed forests composed of evergreen conifers and deciduous broadleaf forests had higher carbon sequestration potential than that of pure forests, which is advantageous for increasing top-stage AGB. This research expands our knowledge of the causes and effects of biodiversity and ecosystem function dynamics over time and space, which is important for accurately predicting future climate change effects.

Modelling Fresh and Dry Weight of Aboveground Biomass of Plant Community and Taxonomic Group Using Normalized Difference Vegetation Index and Climate Data in Xizang’s Grasslands

Modelling Fresh and Dry Weight of Aboveground Biomass of Plant Community and Taxonomic Group Using Normalized Difference Vegetation Index and Climate Data in Xizang’s Grasslands

Temporal stability responses to nitrogen addition in Xizang alpine grasslands: A community composition perspective

Plant community composition typically undergoes progressive changes along environmental gradients. However, most experimental studies have focused on individual communities, so it remains unclear how exogenous nutrient inputs affect the stability of plant communities along environmental gradients. Along a rainfall gradient on the northern Xizang Plateau, we conducted an 8-year nitrogen (N) addition experiment in four alpine grasslands (alpine desert steppe, ADS; alpine steppe, AS; alpine meadow steppe, AMS; and alpine meadow, AM) and used two-way ANOVA to examine the effects of N addition on the temporal stability of these different alpine grasslands. We found that community aboveground biomass showed saturation trends in AM and AMS with increasing N gradients, while there was no change in AS and a gradual increase in ADS. The temporal stability showed different patterns of gradual decreases in ADS and AM, and a unimodal trend in AMS with increasing N gradients. However, N addition had no effect on the temporal stability of AS. Dominant species stability was the controlling factor for alpine grasslands along the transect, while the effect of asynchrony gradually increased with decreasing precipitation. These findings highlight that community composition, especially the dominant species, along the environmental gradient can mediate the effects of N inputs on community temporal stability. Thus, the conservation and restoration of the dominant species are particularly important under future scenarios of increased atmospheric N deposition.

Effects of nitrogen addition and Bothriochloa ischaemum and Lespedeza davurica mixture on plant chlorophyll fluorescence and community production in semi-arid grassland.

Grass-legume mixture can effectively improve productivity and stimulate overyielding in artificial grasslands, but may be N-limited in semi-arid regions. This study investigated the effects of N addition on chlorophyll fluorescence and production in the grass-legume mixtures community. An N addition experiment was conducted in the Bothriochloa ischaemum and Lespedeza davurica mixture community, with seven mixture ratios (B0L10, B2L8, B4L6, B5L5, B6L4, B8L2, and B10L0) according to the sowing abundance of B.ischaemum and L.davurica and four N addition levels, N0, N25, N50, and N75 (0,25,50,75kgNhm-2 a-1), respectively. We analyzed the response of chlorophyll fluorescence parameters of the two species, the rapid light-response curves of chlorophyll fluorescence, as well as aboveground biomass (AGB) and overyielding. Our results showed that the two species showed different photosynthetic strategies, with L.davurica having significantly higher initial fluorescence (Fo), effective photochemical quantum yield of PSII (ΦPSII), and coefficient of photochemical fluorescence quenching (qP) than B. ischaemum, consisting with results of rapid light-response curves. N addition and mixture ratio both had significant effects on chlorophyll fluorescence and AGB (p<0.001). The ΦPSII and qP of L.davurica were significantly lowest in B5L5 and B6L4 under N addition, and the effect of N varied with mixture ratio. The photosynthetic efficiency of B. ischaemum was higher in mixture than in monoculture (B10L0), and ΦPSII was significantly higher in N50 than in N25 and N50 at mixture communities except at B5L5. The community AGB was significantly higher in mixture communities than in two monocultures and highest at B6L4. In the same mixture ratio, the AGB was highest under the N50. The overyielding effects were significantly highest under the N75 and B6L4 treatments, mainly attributed to L.davurica. The partial least squares path models demonstrated that adding N increased soil nutrient content, and complementary utilization by B.ischaemum and L.davurica increased the photosynthetic efficiency. However, as the different photosynthetic strategies of these two species, the effect on AGB was offset, and the mixture ratio's effects were larger than N. Our results proposed the B6L4 and N50 treatments were the optimal combination, with the highest AGB and overyielding, moderate grass-legume ratio, optimal community structure, and forage values.

Plant functional traits modulate the effects of soil acidification on above- and belowground biomass

Abstract. Atmospheric sulfur (S) deposition has been increasingly recognized as a major driver of soil acidification. However, little is known about how soil acidification influences above- and belowground biomass by altering leaf and root traits. We conducted a 3-year S-addition experiment to simulate soil acidification in a meadow. Grass (Leymus chinensis (Trin.) Tzvelev) and sedge (Carex duriuscula C.A.Mey) species were chosen to evaluate the linkage between plant traits and biomass. Sulfur addition led to soil acidification and nutrient imbalances. Soil acidification decreased specific leaf area (SLA) but increased leaf dry-matter content (LDMC) in L. chinensis, showing a conservative strategy and thus suppressing aboveground instead of belowground biomass. However, in C. duriuscula, soil acidification increased plant height and root nutrients (N, P, S, and Mn), favoring competition for natural resources through enhanced above- and belowground biomass, i.e., adoption of an acquisitive strategy. Increased soil acidity resulted in an overall reduction in aboveground community biomass by 3 %–33 %, but it led to an increase in community root biomass by 11 %–22 % due to upregulation as a result of higher soil nutrient availability. Our results demonstrate that both above- and belowground plant biomass is affected by S-induced acidification. Understanding the linkage between plant biomass and functional traits contributes to a better understanding of plant–soil feedback in grassland ecosystems.

Grazing exclusion is more effective for vegetation restoration and nutrient transfer in the heavily degraded desert steppe

BackgroundGrazing exclusion is an efficient practice to restore degraded grassland ecosystems by eliminating external disturbances and improving ecosystems’ self-healing capacities, which affects the ecological processes of soil-plant systems. Grassland degradation levels play a critical role in regulating these ecological processes. However, the effects of vegetation and soil states at different degradation stages on grassland ecosystem restoration are not fully understood. To better understand this, desert steppe at three levels of degradation (light, moderate, and heavy degradation) was fenced for 6 years in Inner Mongolia, China. Community characteristics were investigated, and nutrient concentrations of the soil (0–10 cm depth) and dominant plants were measured.ResultsWe found that grazing exclusion increased shoots’ carbon (C) concentrations, C/N, and C/P, but significantly decreased shoots’ nitrogen (N) and phosphorus (P) concentrations for Stipa breviflora and Cleistogenes songorica. Interestingly, there were no significant differences in nutrient concentrations of these two species among the three degraded desert steppes after grazing exclusion. After grazing exclusion, annual accumulation rates of aboveground C, N, and P pools in the heavily degraded area were the highest, but the aboveground nutrient pools were the lowest among the three degraded grasslands. Similarly, the annual recovery rates of community height, cover, and aboveground biomass in the heavily degraded desert steppe were the highest among the three degraded steppes after grazing exclusion. These results indicate that grazing exclusion is more effective for vegetation restoration in the heavily degraded desert steppe. The soil total carbon, total nitrogen, total phosphorus, available nitrogen, and available phosphorus concentrations in the moderately and heavily degraded desert steppes were significantly decreased after six years of grazing exclusion, whereas these were no changes in the lightly degraded desert steppe. Structural equation model analysis showed that the grassland degradation level mainly altered the community aboveground biomass and aboveground nutrient pool, driving the decrease in soil nutrient concentrations and accelerating nutrient transfer from soil to plant community, especially in the heavily degraded grassland.ConclusionsOur study emphasizes the importance of grassland degradation level in ecosystem restoration and provides theoretical guidance for scientific formulation of containment policies.

Climate and soil stressed elevation patterns of plant species to determine the aboveground biomass distributions in a valley-type Savanna.

Extreme environments such as prolonged high temperatures and droughts can cause vulnerability of vegetation ecosystems. The dry-hot valleys of Southwestern China, known for their extremely high annual temperature, lack of water, and unique non-zonal "hot island" habitat in the global temperate zone, provide exceptional sites for studying how plant adapts to the prolonged dry and hot environment. However, the specific local biotic-environment relationships in these regions remain incompletely elucidated. The study aims to evaluate how valley-type Savanna vegetation species and their communities adapt to long-term drought and high-temperature stress environments. The study investigated the changes in species diversity and communities' aboveground biomass of a valley-type Savanna vegetation along an elevation gradient of Yuanmou dry-hot valley in Jinsha River basin, southwest China. Subsequently, a general linear model was utilized to simulate the distribution pattern of species diversities and their constituent biomass along theelevation gradient. Finally, the RDA and VPH mothed were used to evaluate the impacts and contributions of environmental factors or variables on the patterns. The field survey reveals an altitudinal gradient effect on the valley-type Savanna, with a dominant species of shrubs and herbs plants distribution below an elevation of 1700m, and a significant positive relationship between the SR, Shannon-Wiener, Simpson, and Pielou indices and altitudes. Relatively, the community aboveground biomass did not increase significantly with elevation, which was mainly due to a decreased biomass of herbaceous plants along the elevation. Different regulators of shrub-herbaceous plant species and their functional groups made different elevation patterns of species diversity and aboveground biomass in valley-type Savannas. Herbaceous plants are responsible for maintaining species diversity and ensuring stability in the aboveground biomass of the vegetation. However, the influence of shrubs on aboveground biomass became more pronounced as environmental conditions varied along the altitudinal gradient. Furthermore, species diversity was mainly influenced by soil and climatic environmental factors, whereas community biomass was mainly regulated by plant species or functional groups. The study demonstrates that the spatial pattern of valley-type Savanna was formed as a result of different environmental responses and the productive capacity of retained plant species or functional groups to climate-soil factors, highlighting the value of the Yuanmou dry-hot Valley as a microcosm for exploring the intricate interactions between vegetation evolution and changes in environmental factors.

Nitrogen supply neutralizes the nanoplastic-plant interaction in a coastal wetland

The presence of nanoplastics posed a potential threat to coastal saline-alkaline wetlands where nitrogen (N) fertilizer is being implemented as an important ecological restoration measure. Notwithstanding, the effects of N inputs on plant community in polypropylene-nanoplastics (PP-NPs) coexistence environments are largely unknown. To address this, we investigated the effects of PP-NPs addition alone or combined N supply on community aboveground biomass, morphological traits, diversity, composition, niche differentiation, interspecific interactions, and assembly. Our results showed that the PP-NPs addition alone reduced community aboveground biomass and morphological traits. However, the addition of high concentration (0.5%) PP-NPs alone favored community α-diversity and reduced community stability, which could be weakened through combined N supply. Overall, the effect of PP-NPs addition alone on plant community composition was greater than that of combined N supply. We also demonstrated PP-NPs addition alone and combined N supply reduced the niche breadth of the plant community and affected the niche overlap of dominant species. In the assembly of plant communities, stochastic processes played a dominant role. We conclude that N fertilization can amend the terrestrial nanoplastics pollution, thus mitigating the effects of PP-NPs on the plant community.

The plant root economics space in relation to nutrient limitation in Eurasian herbaceous plant communities.

Plant species occupy distinct niches along a nitrogen-to-phosphorus (N:P) gradient, yet there is no general framework for belowground nutrient acquisition traits in relation to N or P limitation. We retrieved several belowground traits from databases, placed them in the "root economics space" framework, and linked these to a dataset of 991 plots in Eurasian herbaceous plant communities, containing plant species composition, aboveground community biomass and tissue N and P concentrations. Our results support that under increasing N:P ratio, belowground nutrient acquisition strategies shift from "fast" to "slow" and from "do-it-yourself" to "outsourcing", with alternative "do-it-yourself" to "outsourcing" strategies at both ends of the spectrum. Species' mycorrhizal capacity patterns conflicted with root economics space predictions based on root diameter, suggesting evolutionary development of alternative strategies under P limitation. Further insight into belowground strategies along nutrient stoichiometry is crucial for understanding the high abundance of threatened plant species under P limitation.

Grazing exclusion alters denitrification N2O/(N2O + N2) ratio in alpine meadow of Qinghai–Tibet Plateau

Grazing exclusion has been implemented worldwide as a nature-based solution for restoring degraded grassland ecosystems that arise from overgrazing. However, the effect of grazing exclusion on soil nitrogen cycle processes, subsequent greenhouse gas emissions and underlying mechanisms remain unclear. Here, we investigated the effect of four-year grazing exclusion on plant communities, soil properties, and soil nitrogen cycle-related functional gene abundance in an alpine meadow on the Qinghai–Tibet Plateau. Using an automated continuous-flow incubation system, we performed an incubation experiment and measured soil-borne N2O, N2, and CO2 fluxes to three successive “hot moment” events (precipitation, N deposition, and oxic-to-anoxic transition) between grazing-excluded and grazing soil. Higher soil N contents (total nitrogen, NH4+, NO3−) and extracellular enzyme activities (β-1,4-glucosidase, β-1,4-N-acetyl-glucosaminidase, cellobiohydrolase) are observed under grazing exclusion. The aboveground and litter biomass of plant community was significantly increased by grazing exclusion, but grazing exclusion decreased the average number of plant species and microbial diversity. The N2O + N2 fluxes observed under grazing exclusion were higher than those observed under free grazing. The N2 emissions and N2O/(N2O + N2) ratios observed under grazing exclusion were higher than those observed under free grazing in oxic conditions. Instead, higher N2O fluxes and lower denitrification functional gene abundances (nirS, nirK, nosZ, and nirK + nirS) under anoxia were found under grazing exclusion than under free grazing. The N2O site-preference value indicates that under grazing exclusion, bacterial denitrification contributes more to higher N2O production compared with under free grazing (81.6 % vs. 59.9 %). We conclude that grazing exclusion could improve soil fertility and plant biomass, nevertheless it may lower plant and microbial diversity and increase potential N2O emission risk via the alteration of the denitrification end-product ratio. This indicates that not all grassland management options result in a mutually beneficial situation among wider environmental goals such as greenhouse gas mitigation, biodiversity, and social welfare.

Snow and vegetation seasonality influence seasonal trends of leaf nitrogen and biomass in Arctic tundra

AbstractClimate change, including both increasing temperatures and changing snow regimes, is progressing rapidly in the Arctic, leading to changes in plant phenology and in the seasonal patterns of plant properties, such as tissue nitrogen (N) content and community aboveground biomass. However, significant knowledge gaps remain over how these seasonal patterns vary among Arctic plant functional groups (i.e., shrubs, grasses, and forbs) and across large geographical areas. We used three years of in situ field vegetation sampling from an 80,000‐km2 area in Arctic Alaska, remotely sensed vegetation data (daily normalized difference vegetation index [NDVI]), and modeled output of snow‐free date to determine and model the seasonal trends and primary controls on leaf percent nitrogen and biomass (in grams per square meter) among Arctic vegetation functional groups. We determined relative vegetation phenology stage at a 500‐m spatial scale resolution, defined as the number of days between the date of the seasonal maximum NDVI and the vegetation field sampling date, and relative snow phenology stage (90‐m spatial scale) was determined as the number of days between the date of snow‐free ground and the sampling date. Models including relative phenology stage were particularly important for explaining seasonal variability of %N in shrubs, graminoids, and forbs. Similarly, vegetation and snow phenology stages were also important for modeling seasonal biomass of shrubs and graminoids; however, for all functional groups, the models explained only a small amount of seasonal variability in biomass. Relative phenology stage was a stronger predictor of %N and biomass than geographic position, indicating that localized controls on phenology, acting at spatial scales of 500 m and smaller, are critical to understanding %N and biomass.

Effects of intra-annual precipitation patterns on grassland productivity moderated by the dominant species phenology.

Phenology and productivity are important functional indicators of grassland ecosystems. However, our understanding of how intra-annual precipitation patterns affect plant phenology and productivity in grasslands is still limited. Here, we conducted a two-year precipitation manipulation experiment to explore the responses of plant phenology and productivity to intra-annual precipitation patterns at the community and dominant species levels in a temperate grassland. We found that increased early growing season precipitation enhanced the above-ground biomass of the dominant rhizome grass, Leymus chinensis, by advancing its flowering date, while increased late growing season precipitation increased the above-ground biomass of the dominant bunchgrass, Stipa grandis, by delaying senescence. The complementary effects in phenology and biomass of the dominant species, L. chinensis and S. grandis, maintained stable dynamics of the community above-ground biomass under intra-annual precipitation pattern variations. Our results highlight the critical role that intra-annual precipitation and soil moisture patterns play in the phenology of temperate grasslands. By understanding the response of phenology to intra-annual precipitation patterns, we can more accurately predict the productivity of temperate grasslands under future climate change.

Carbon Stock and Carbon Dioxide Sequestration Potential in a Multi-species Forestry Plot of the Kagyu Nalanda Monastery, Bylakuppe, Mysore District, Karnataka, India

In the Kagyu Nalanda Monastery in Bylakuppe, Karnataka, India, during 2010-2011 has established the multi-species forestry plots in the degraded land of the monastery and nurtured them. In one of these plots (2.5 ha in size) aboveground biomass, carbon stock and the potential of carbon dioxide sequestration in the aboveground biomass were assessed. In the study plot, 927 trees belonging to 45 species were recorded. The Gini Index obtained for different species indicated that within a species the inequality is low for tree height when compared to that for tree basal area. The estimated total basal area and total tree volume in the study plot is 33.34 m 2 and 315.73 m 3 respectively. The total aboveground biomass for the plot was 326.39 tonnes with the total carbon stock of 163.18 tonnes. A positive correlation was observed between the carbon stock and total tree volume of the top five species ( Cassia fistula , Swietenia macrophylla, Mangifera indica , Moringa oleifera and Spathodea campanulata), which contributed predominantly (54%) of the total carbon stock (r=0.812, p&lt;0.05). The study plot sequestrated 598.13 tonnes of carbon dioxide with mean annual rate of 59.81 tonnes. the potential annual economic value of carbon dioxide sequestrated in the aboveground biomass of tree community in the study area ranges from US$ 239.3 to 2,990.7 (Indian Rupees 17,872 to 2,23,402; US$ 1= Rs.74.7). The scope for selling the carbon credits generated in this multi-species forestry plot to buyers to support further environmental priorities are discussed.

Nitrogen and Phosphorus Fertilizer Increases the Uptake of Soil Heavy Metal Pollutants by Plant Community.

Soil heavy metal pollution is widespread around the world. Compared with hyperaccumulation plants, non-hyperaccumulator plant communities have many advantages in the remediation of heavy metals pollution in soil. The application of nitrogen (N) and phosphorus (P) is inexpensive and convenient, which can promote the growth of plant. N and P fertilizer might increase plant community remediation of heavy metal polluted soils. In our study, the effects of N and P fertilizer on remediation of soil Cd, Cu, Pb pollution by plant community were studied through a greenhouse experiment. Our results indicated that addition of N, P and N + P fertilizer increased plant community aboveground biomass. Simultaneously, addition of N and P fertilizer increased the accumulation of heavy metals in aboveground of the plant community and accelerated plants absorption soil heavy metals. Among them, N fertilizer had the best effect. Our results provide an inexpensive method for remediation heavy metal pollution of contaminated farmland, abandoned land and mine tailings, etc.

Different responses of community temporal stability to nitrogen and phosphorus addition in a non-degraded alpine grassland

Fertilization has been widely used in grassland management, but different types of fertilizers may have inconsistent impacts on grassland productivity and stability. However, less is known about the responses of plant community stability and the shifts of driving mechanisms under different fertilizers. We conducted a long-term nitrogen (N) and/or phosphorus (P) addition experiment in an alpine steppe meadow, using two N levels (5 (N5), 10 (N10) g N/m−2(−|-) year−1), one P level (5 g N m−2 year−1, P5) and the combined treatments (N5P5 and N10P5), to examine their effects on community temporal stability and the underlying mechanisms. Both N addition alone and the combined addition significantly increased community aboveground biomass, while P5 did not affect community aboveground biomass. However, only N10, N5P5, and N10P5 decreased annual average species richness, while other treatments showed no pronounced effect. Except for N5, community stability decreased under both N and P additions. The most remarkable finding is that the driving mechanisms underlying community stability shifted with nutrient types. The decrease in species richness induced by N addition decreased community stability. However, the decrease in dominant species asynchrony induced by P addition affected community asynchrony, which contributed to the decrease in community stability. N and P combined addition could additively affect community stability both by species richness and dominant species asynchrony and further community asynchrony. Our results indicate that fertilizer types can alter the regulatory effect of plant diversity on community stability. This study reveals that attention should be paid to the different mechanisms driving community stability under different nutrient types, which provides a scientific basis for alpine grassland management.

Using Trait-Based Methods to Study the Response of Grassland to Fertilization in the Grassland in Semiarid Areas in the Loess Plateau of China.

Grassland is the dominant vegetation type in the Loess Plateau, and grassland productivity and processes are limited by nitrogen (N) and phosphorus (P). Studies have shown that productivity would change following fertilization in the grassland. The response of productivity to fertilization mainly depends on the dominant species traits. Trait-based methods provide a useful tool for explaining the variations in grassland productivity following fertilization. However, the relative contribution of plant functional traits to grassland productivity under N and P addition in the Loess Plateau is not clear. We measured aboveground biomass (AGB) and leaf N content (LN), leaf P content (LP), leaf N/P ratio (LN/P), specific leaf area (SLA), leaf tissue density (LTD), leaf dry matter content (LDMC), and maximum plant height (Hmax) to study how these plant functional traits regulate the relative biomass of different species and grassland productivity following fertilization. Our results showed, that under different nutrient addition levels, the linkages between plant functional traits and the relative biomass of different species were different. Community AGB was positively related to community−weighted mean LN (CWM_LN), CWM_LN/P, CWM_SLA, and CWM_Hmax, but negatively related to CWM_LTD and CWM_LDMC. Dominant species traits largely determined grassland productivity, in line with the mass ratio hypothesis. These findings further highlight the close linkages between community-level functional traits and grassland productivity. Our study contributes to the mechanisms underlying biodiversity–ecosystem function relationships and has significance for guiding semiarid grassland management.

Effects of mowing regime on community characteristics and forage yield and quality in Hulun Buir, China

In order to select a best mowing regime for natural grassland in Hulun Buir with highly efficient hay-making and sustainable utilization, we conducted an experiment to examine the effects of mowing time (July 31, August 10, August 20, August 30, and September 9), stubble height (3, 9, and 15 cm), and their interaction on grassland community characteristics and forage yield and quality in a grassland of Hulun Buir from 2019 to 2021. The results showed that late mowing and low stubble-height mowing significantly reduced community-level height and coverage in the next year. Low stubble-height mowing reduced community aboveground biomass in the following year, but the effect of mowing time was not significant. The relative biomass of grasses and sedges first increased and then decreased with the delay of mowing time, forbs showed an opposite pattern, and legumes showed no signi-ficant change. Low stubble-height mowing could enable higher hay yield in the same year, but resulted in substantial reduction in the next year. When mowing on August 30 with 3 cm high stubble left, the hay yield reached maximum value of 469 g·m-2, which was 361.5% of the minimum value. The crude protein content of forage reached the maximum at the mowing time of August 30, which was higher than the minimum value by 6.5%, and the content was higher at high stubble-height mowing. The contents of acid and neutral detergent fiber increased gradually over the growing season, with those from mowing on September 9 being 8.0% and 5.9% higher than those from mowing on July 31 respectively, and were decreased with the increases of stubble height. We found that the reasonable mowing regime of Hulun Buir grassland as the mowing implemented from August 20 to 30 with about 9 cm high stubble left. Long-term mowing experiments are needed to draw a more reliable and objective conclusion.

Shrub encroachment impaired the structure and functioning of alpine meadow communities on the Qinghai–Tibetan Plateau

AbstractShrub encroachment has been rapidly occurring due to climate change, with profound ecological consequences for the alpine meadows of the Qinghai–Tibetan Plateau. Here, we conducted field surveys along a shrub coverage gradient to examine the effects of shrub encroachment on the structure and functioning of alpine meadows' plant communities. Our results showed that the overall coverage, density, aboveground biomass, species richness, and diversity of meadow community gradually declined with increasing levels of shrub encroachment, especially when shrub coverage exceeded 60%. Aboveground ecosystem multifunctionality also decreased along the shrub coverage gradient. With 90% shrub coverage, the relative importance value of the forbs functional group significantly increased while the Cyperaceae functional group showed the opposite trend: the originally dominant sedges Carex moorcroftii and Kobresia myosuroides were replaced by the forbs Androsace umbellate and Polygonum sparsipilosum. Additionally, shrub encroachment had a strong effect on nonrandom herb species extinction and colonization. At shrub coverages higher than 60%, there were 9 herb species absent and 18 new species colonizing—7 of which were only observed in meadows with 90% shrub coverage. Rare species and those with lower stature were more likely to go extinct, while taller and shade‐tolerant species tended to colonize areas with increasing shrub coverage. Overall, our results indicate that shrub encroachment negatively affects herbaceous community structure and functioning, which has important implications for the management of alpine meadows of the Qinghai–Tibetan Plateau under ongoing climate change.

Target species rather than plant community tell the success of ecological restoration for degraded alpine meadows

Ecological conservation and restoration projects in Three-river Headwater Region (TRHR) have been implemented to respond to the serious degradation of alpine meadow ecosystem. Compared with the substantial amount of studies on the recovery of plant communities, soil quality and ecosystem services, few studies have focused on the restoration performance of target species. Therefore, we conducted this study to analyze the dynamics and underlying mechanisms of species richness and aboveground biomass of plant communities and target species. The results showed that restoration actions (grassland cultivation and fencing) did not significantly improve the community aboveground biomass of the degraded alpine meadows, while the actions did significantly promote community species richness, target species richness and target species aboveground biomass. Community species richness (20%-45%) was significantly impacted by the restoration strategies, and community aboveground biomass (31%-53%) was impacted by the mean annual precipitation and mean annual temperature. The species richness (57%) and aboveground biomass (63%) of the target species were directly and indirectly impacted by restoration actions, climatic factors, biotic factors and soil factors. The implications of this study stress that target species should be highlighted in assessing the restoration success of degraded alpine meadows. Integrating climatic factors, target species and other biotic and abiotic indicators could help us better understand and evaluate restoration actions for degraded alpine meadows in the TRHR or other similar regions worldwide.

Structure, Biomass and Diversity of a Late-Successional Subtropical Atlantic Forest in Brazil

The highly biodiverse Atlantic Forest has been heavily exploited and its remnant areas, which are mostly composed of secondary forests, cover less than 20% of its original extension. This study analyzed the structure, aboveground biomass (AGB) and species diversity of a secondary evergreen rainforest in the state of Santa Catarina, southern Brazil. Individuals with diameter at breast height ≥ 5 cm on 22 sample plots were measured, totalizing 3.49 hectares of sampled area. A mean AGB of 201.6 Mg ha-1 (standard deviation = 35.5) was found; Hyeronima alchorneoides and Miconia cinnamomifolia represented 29.1% and 7.6% of the community AGB ha-1, respectively. A total of 153 species distributed in 107 genera and 55 families was observed; it was estimated that 121 species (95% confidence interval: [117, 125]) occurred in one hectare. These results highlight the importance of secondary forests for biodiversity restoration/conservation and carbon sequestration.