Ecological Restoration Process Research Articles

Afforestation Alters the Molecular Composition of Soil Organic Matter in the Central Loess Plateau of China

Many studies have been conducted on organic carbon changes under different land use patterns, but studies and data concerning changes in the molecular composition of soil organic matter (SOM) during land use conversion are scarce. In this work, we studied the chemical composition of SOM on two Robinia pseudoacacia L. plantations and their adjacent croplands in the Loess Plateau using biomarker and nuclear magnetic resonance (NMR) techniques. Experimental data on the molecular composition of SOM showed that the soil microbial biomass carbon content initially decreased and then returned to the original level gradually after afforestation, while the SOM content and stocks increased over time. At the initial stage of afforestation, the content of total solvent extracts did not change significantly but changed slowly over time in the plantations without artificial disturbance. With an increase in restoration time, the concentrations of both the microbial- and plant-derived solvent extracts increased. Moreover, the concentrations of plant-derived solvent extracts were consistently lower than those of microbial-derived solvent extracts. Afforestation also significantly increased the lignin-derived phenol content in the surface soil layer (0–10 cm). However, no obvious change was observed in the lignin-derived phenols of the two adjacent croplands. These results indicate that the accumulation of aboveground litter and underground roots has the strongest effects on the lignin-derived phenol content. In contrast to cropland, the two plantations exhibited a high degree of degradation of lignin-derived phenols in the surface soil, but this remained almost unchanged over time. Moreover, in contrast to 20 years after the establishment of the R. pseudoacacia plantation, the low alkyl/O-alkyl carbon ratio of the 8-year R. pseudoacacia plantation indicated that more easily degradable components accumulated during the initial stage of afforestation. Therefore, the proportion of the unstable carbon pool was relatively high and the SOM content may decline in the early stage of afforestation. These results provide evidence illustrating the detailed changes in the chemical composition of SOM during the ecological restoration process.

A Bibliometric Analysis of the Impact of Ecological Restoration on Carbon Sequestration in Ecosystems

Ecological restoration, as a vital means of effectively enhancing the carbon sink function of ecosystems, is currently the subject of active research by scientists. Researchers are actively exploring how to scientifically assess the response mechanisms of ecosystem carbon reservoirs during the process of ecological restoration. In this study, CiteSpace 6.1.(R3 and R6) literature visualization software was employed to conduct data mining on 1566 research articles published from 1996 to 2022, focusing on the impact of ecological restoration on ecosystem carbon reservoirs, as recorded in the Web of Science core database. The analysis involved visualizing various aspects, including the countries involved, research institutions, publication output, research hotspots, and cutting-edge research areas. The research indicates that China holds significant influence in the study of the impact of ecological restoration on ecosystem carbon reservoirs. The literature covers a wide range of research directions and encompasses rich content on the subject matter. The current research focuses on ecological restoration, and its impact on the carbon sink function of ecosystems mainly revolves around four key themes: “the carbon sequestration potential of ecological restoration”, “technological approaches to enhancing the carbon sink function of ecological restoration”, “the importance of assessing carbon sink in terrestrial ecosystems”, and “characteristics of carbon sources/sinks in terrestrial ecosystems”. Currently, the development of research findings on the impact of ecological restoration on the carbon reservoirs of ecosystems is progressing rapidly. Novel research theories, methodologies, and scientific techniques are emerging, necessitating the continuous monitoring and investigation of scholarship in this field. It is crucial to integrate ongoing global environmental-change factors, ensuring the continuity of research and observations and, thus, furnishing robust data support for the assessment and computation of ecosystem carbon sinks.

Soil Quality Evaluation and Driving Factor Analysis of Hippophae rhamnoides Plantations in Coal Mine Reclamation Areas Based on Different Restoration Durations

The driving factors affecting soil quality were identified to evaluate the effect of vegetation on soil quality in coal mine reclamation areas with various restoration durations. This study used Hippophae rhamnoides subsp.sinensis Rousi with different reclamation durations (3, 4, 5, 6, and 7 years) in the abandoned land area of the Juxinlong coal mine in Ordos as the research subject. Artificial and abandoned grasslands were selected as the study’s controls. A soil quality evaluation model was constructed to assess the soil quality in the reclamation area. A structural equation model was used to thoroughly analyze the driving factors affecting soil quality in the study area. The findings show that: (1) Reclamation duration significantly affected the physicochemical characteristics of the soil. As the reclamation duration increased, soil nutrients such as organic carbon accumulated while the bulk density index (BD) decreased. (2) The soil quality index of Hippophae rhamnoides forest land in China was the highest after 6 years of reclamation. The Hippophae rhamnoides forest land with the lowest soil quality index after 4 years of reclamation differed significantly from that after 6 years (p < 0.05). The soil quality index (SQI) of 6a (years) significantly increased by 67.44% compared to 4a. (3) By constructing a structural equation model, it was found that physical indicators (saturated water content and silt) and reclamation durations were the main drivers of soil quality. SQI had a strong interaction with organic matter (OM) and different restoration durations. The findings of this study will serve as important guidelines for future quantitative evaluation of soil quality following land reclamation and management during the ecological restoration process.

Effects of soil conservation on the spatial heterogeneity of vegetation carbon sequestration in the Yellow River Basin, China

AbstractAn improved understanding of the potential controls on vegetation carbon sequestration (VCS) is essential for the prediction of VCS in response to global change. Ecosystem restoration can provide remarkable contributions to VCS. However, attention to the impact of soil conservation (SC) on VCS is lacking. Therefore, the Yellow River Basin, a typical area of soil erosion in the world, was chosen as the study area. The VCS and SC trends from 2000 to 2020 were analyzed and the potential response of VCS to SC was explored by adopting correlation analysis, elastic coefficient method, geographically weighted regression model, and geographical detector model. The influence of SC drivers on the spatial heterogeneity of VCS was also revealed. Results showed the following: (1) VCS and SC had a significant upward trend, especially in the eastern monsoonal ecoregion. (2) The area with a significant positive correlation between VCS and SC accounted for 31.74% of the total, mainly concentrated in the key areas of SC, wherein a 100% increase in SC would lead to a 25%–100% increase in VCS. (3) Among the SC drivers, vegetation cover and management (C) factor and rainfall erosion force (R) factor mainly influenced spatial heterogeneity in VCS, and their interaction considerably enhances this effect. Therefore, the interaction between precipitation and vegetation should be considered when evaluating the impact of water erosion management on VCS. The results of the study have important implications for the enhancement of VCS capacity of degraded land in the ecological restoration process.

Characteristics of Soil Microbial Community in Different Habitats in the Process of Ecological Restoration of Haifeng Wetland in Guangdong

Soil microorganisms can respond to changes in wetland ecosystem quality and functional evolution sensitively. To explore the changes and response mechanisms of soil microorganisms under ecological restoration measures, the characteristics of the soil microbial community and their influencing factors were analyzed using high-throughput sequencing technology in four different habitats (revegetation area, native vegetation area, tidal creek, and tidal flat) during the ecological restoration process in Haifeng wetland in Guangdong. The results showed that:soil physicochemical properties of the four different habitats were significantly different; the contents of TC, TN, TOC, and TK in the tidal creek were significantly higher than those in the other habitats; and the contents of TC, TN, and TP in the revegetation restoration area were significantly higher than those in the tidal flat. The EC values in the tidal creeks and tidal flat were significantly higher than those in the revegetation area and the native vegetation area. The diversity index and abundance of soil bacteria in the tidal creek were the highest, and those in the vegetation restoration area were significantly higher than those in the bare flat. The archaea in the tidal creek were significantly more complex than those in the other three habitats, and the fungal community diversity index and abundance in the native vegetation area were significantly higher than those in the other areas, which had the most complex community structure. TN and TC were the main factors affecting the bacterial community, whereas TN and EC were the main factors affecting the archaea community, and pH, TN, and TP were the key factors affecting the fungal community. In conclusion, the planting of vegetation on the tidal flat increased the diversity and richness of the soil microbial community during the process of ecological restoration, indicating that it has resulted in positive feedback on ecological restoration so far. The results of this study can provide a theoretical basis for the selection of ecological restoration strategies for the tidal flat.

Facilitation between plants and the use of facilitating species as an ecological restoration strategy

Ecosystems subject to extreme abiotic factors are privileged places for studies of positive interactions between plants, such as facilitation mechanisms, which, from biotic or abiotic modifications, generate benefits to the environment. Due to the increase in the number of articles on facilitation in recent decades and the indication of the use of facilitating species in recovery and ecological restoration projects, the present study presents a literature review on facilitation between plant-plant and its applicability between the years 2011 and 2020. A total of 64 studies were considered that encompass the facilitation theme, and the text was composed of an introduction and two sections: i) studies on the facilitation mechanism – advances in the last decade and ii) facilitation as a strategy for ecological restoration. This review indicates that the best understanding of facilitation mechanisms occurs from the combination of knowledge at different levels, such as knowledge of species, ecological organization, phylogenetics and environmental conditions. Thus, this approach enables a better understanding of the community dynamics and demonstrates how the use of facilitating species in restoration areas, especially in regions with severe environmental conditions and/or more vulnerable to climate change, has been considered an effective strategy in the ecological restoration process.

Estimation of soil losses due to water erosion in the Dagua River Basin, Colombia

The Dagua river basin, in Colombia, is the most important source of water for the Valle del Cauca ecosystem, however, due to poor agricultural practices, it has been affected by water erosion. This study aimed at estimating soil erosion in the Dagua river basin, using the universal soil loss equation (USLE). The results show that most of the area presents erosivities that are between 1000-5000 MJ.mm.ha-1, corresponding to low and very low categories. On the other hand, erodibility ranged from 0.143 to 0.842 t. ha.h. MJ-1 mm-1 ha-1, which is framed in the categories from weak to extremely erodable, where the low to medium category predominates. Regarding soil losses due to erosion, it was found that more than 20% of each of the municipalities of Dagua, Restrepo, La Cumbre, and Vijes, showed high and very high erosion, particularly in the areas with bare soils and crops such as pineapple, contribute strongly, sometimes reaching over 1000 t ha-1 yr-1. Therefore, it is important to promote practices such as contour or contour planting, integrated crop cover management, land uses that integrate trees, and in more critical cases to consider ecological restoration processes.

Landsenses Ecology: A New Idea for Watershed Ecology Restoration

Watershed ecology restoration is the key to solving the ecological and environmental problems of watersheds and achieving sustainable development. As one direction of the frontiers of ecology, landsenses ecology is supported by science and technology and cares for humans. It has a great significance for enhancing the human habitat and achieving sustainable development. Combining landsenses ecology and the technical process of watershed ecology restoration allows the integration of people's visions into the system of strategies and applied technologies for watershed ecology restoration while ensuring the restoration of the ecological functions of watersheds. It is a complement to the traditional ecosystem restoration model. This study establishes the connection between landsenses ecology and watershed ecology restoration in terms of goals, models and focus of attention. It aims to construct an indicator system of restoration with the application of landsenses ecology, form a complete process of ecological restoration with the integration of landsenses ecology and apply it to the ecological restoration of watershed elements with relatively intensive human activity such as urban green areas, buildings and wetlands (rivers and lakes). Rather than just always emphasizing natural ecology, landsenses ecology treats human beings as part of nature. It tries to establish a more comprehensive, humanized ideal restoration model by taking "human perceptions" into consideration. Through a restoration process based on long-term and continuous coordination, feedback and improvement, it can improve the ecological benefits of the watershed and improve residents' well-being, so as to ultimately realize the establishment of a "community of life between man and nature".

An approach to quantify heavy metals and their source apportionment in coal mine soil: a study through PMF model.

Mining activities in the opencast coal mines contaminate the surrounding soil by releasing coal dust containing heavy metals (HMs). The objective of the present study was to quantify the concentration of HMs like Fe, Cu, Mn, Ni, Cr, Zn, and Co in soil on profile and distance basis in the vicinity of the coal mines. This research also proposed the synthesis application of positive matrix factorization (PMF) model for the quantitative assessment of pollution sources. The results showed that the soil was more affected due to the presence of Cr in mining areas., and the contamination factor (Cf)of Cr was high at the edge of coal mine. It was observed from the study thatCfof the HMs was decreased with the increase indistance from the mine edge. The application ofPMF model demonstratedthat the contributions of Zn (4.2%), Ni (16.8%), and Mn (100%) were maximum in the pollution. The study concluded that soil contamination is inexorable due to opencast coal mining activities, and it can be mitigated by developing a green belt or through the process of ecological restoration and phytoremediation.

Ecological Health Assessment with the Combination Weight Method for the River Reach after the Retirement and Renovation of Small Hydropower Stations

This study aimed to effectively evaluate the ecological restoration of the river reach where a small hydropower station was retired or renovated. An ecological health index system was constructed based on the environmental characteristics of the upstream and downstream of the small hydropower station after its retirement and renovation. Based on the combination weighting concept of game theory, the combination weights were obtained by the comprehensive analytic hierarchy process (subjective weight) and entropy method (objective weight). This ecological health assessment with fuzzy comprehensive evaluation was applied to assess the health status of Shimen (dam removal) and Changqiao (renovation in ecological flow) reaches of the Tufang River in Changting County, China. The results showed that the ecological health assessment index system proposed in this study was comprehensive and reasonable, and the revision degree of the hydropower station obviously influenced the process of ecological river restoration. The findings from this study would benefit for the rational utilization of water resources and the river ecological health maintenance in mountainous areas.

Differential Analysis of Biochar Effects on Soil Physicochemical Properties

For a long time, because of China’s large population and small per capita resource occupancy, the use of natural resources is unreasonable. Soil degradation problem due to the long-term irrational utilization of land resources is becoming more and more serious, which seriously damaging the ecological environment and hindering China’s modernization process. Facing the problem of soil remediation, biochar technology has become a research hotspot because of its advantages of green environmental protection, low cost, high efficiency, and wide application. And black soil in northeast China and southern region of red soil as important soil types of agroforestry in China, over the years have experienced serious soil degradation crisis. In this paper, black soil and red soil are selected as research objects to explore the impact of biochar on the physical and chemical properties of the two soils. This paper intends to use the methods of investigation and analysis, and comparison in many aspects. Through the study, it was found that the application of biochar had the same trend of influence on the organic carbon content and C/N ratio of the two soils, but the index of black soil increased more significantly. The change trend of soil bulk density and pH was also consistent with the application of biochar, and the difference was not significant. The effects of biochar applied to the two soils on greenhouse gas emissions were quite different. The soil health of black soil and red soil is of great significance in China’s agricultural production and life. This paper expects to bring reference value to the improvement of the overall soil function and the promotion of ecological restoration process of China’s biochar modification work for different soil types in the north and south, by comparing the impact of biochar on the physical and chemical properties of the two soils. A better soil improvement program can be obtained after comparative analysis, so as to provide suggestions on sustainable development and comprehensively promote ecological construction.

Dynamic Effects of Climate and Land Use Policies on Water Yield in Drylands—A Case Study in the Northwest of China

Water yield as an important ecosystem service for mitigating water scarcity in drylands, is quite sensitive to land use and climate change. Evaluating the response of water yield to land use policies in drylands under climate change is conducive to sustainable water resource management. Taking the Hohhot-Baotou-Ordous-Yulin region in the northwest of China as an example, this study used the methods of the InVEST model, trend analysis, comparative experiment, PLUS model to explore the spatial-temporal trends and driving factors of water yield variation, as well as to simulate the future water yield under different land use policy scenarios. The results showed that (1) water yield in the study area fluctuated and increased from 14.14 mm to 46.59 mm during 2000 to 2020, the places with a significant increasing trend of water yield were mainly distributed in the southeast loess hilly area; (2) climate change is the major driving factor of water yield variation with a contribution rate of 85.8–99.6%, but land use change played an increasingly important role in affecting water yield; (3) the Grain-Security-Dominated (GSD) land use policy scenario would generate the highest water yield in 2030 under climate conditions of SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5, while the Regional-Greening-Dominated (RGD) land use policy scenario has the lowest water yield in the future. The results could provide reference for the decision-making process of ecological restoration and land use planning in drylands.

Differential Response of Soil Microbial Community Structure in Coal Mining Areas during Different Ecological Restoration Processes

Micro-organisms play important roles in promoting soil ecosystem restoration, but much of the current research has been limited to changes in microbial community structure in general, and little is known regarding the more sensitive and indicative microbial structures or the responses of microbial diversity to environmental change. In this study, based on high-throughput sequencing and molecular ecological network analyses, the structural characteristics of bacterial communities were investigated in response to four different ecological restoration modes in a coal mining subsidence area located in northwest China. The results showed that among soil nutrients, nitrate-nitrogen and fast-acting potassium were the most strongly associated with microbial community structure under different ecological restoration types. Proteobacteria, Actinobacteria, and Acidobacteria were identified as important phyla regarding network connectivity and structural composition. The central natural recovery zone was found to have the smallest network size and low complexity, but high modularity and good microbial community stability. Contrastingly, a highly complex molecular ecological network of soils in the photovoltaic economic zone existed beneath the photovoltaic modules, although no key species, strong bacterial competition, poor resistance to disturbance, and a significant increase in the relative abundance of Gemmatimonadetes were found. Furthermore, the reclamation zone had the highest soil nutrient content, the most complex network structure, and the most key and indicator species; however, the ecological network was less stable and readily disturbed.

Assessing the success of forest restoration based on landscape analysis

Recognition of landscape configuration is essential to define priority sites most likely to succeed in forest restoration. The research aimed to reduce uncertainties regarding the feasibility of ecological restoration processes by applying landscape metrics to support priority areas for restoration in three watersheds located in the northwest region of the state of Paraná, Brazil. A temporal analysis of the landscape was performed for the years 1985, 1996, 2007, and 2018. Seven land use and land coverage categories were proposed and seven landscape metrics were calculated to assess the configuration using the Fragstats® software, and an assessment of restoration success using GoFor® software. The studied area was divided into four priority levels: low, medium, high, and very high probability of restoration success. The landscape matrix was composed of pastures and agriculture, which corresponded to almost 90% of the area. There has been a considerable increase in forest coverage over the years due to commercial plantations and the recovery of Permanent Preservation Areas (APP). Approximately 12.6 percent of the landscape has the potential to be restored if restoration efforts are allocated to areas with the highest potential for restoration success.

Ecological Stoichiometric Changes and the Synergistic Restoration of Vegetation Concrete Restoration Systems under Different Precipitation Conditions

Based on vegetation-soil nutrient monitoring data under different precipitation conditions, this study investigated the impact of precipitation changes on the ecological restoration process of disturbed slopes. Precipitation change, to a certain extent, changed the carbon (C), nitrogen (N) and phosphorus (P) content and the stoichiometric ratio of the soil–plant system. With the increase of the weekly precipitation from 10 to 20 mm, the C content of Cynodon and Indigofera Amblyantha Craib on each slope gradually increased, increased by 8.69% and 4.28%, respectively, compared with the initial recovery period, and the N/P of Cynodon increased from 3.81 to 4.94, and the N limit gradually decreased, while the limit of P increased continuously. The efficiency of the coordinated utilization of N and P of the Indigofera Amblyantha Craib increased, which had a certain adaptability to changes in precipitation. The C/N and C/P in the soil first increased and then decreased, and reached the peak at the slope of 15 mm precipitation, while the N/P fluctuated around 0.35 overall. N was an important element restricting the growth of grass, while P was an important influencing element limiting the growth of shrubs. This also showed that soil C, N and P had a good promoting effect on plant growth, and the self-regulating nutrient utilization strategies of different growth forms of plants under different precipitation conditions differed. There was a coupling effect in the contents of C, N, P and their stoichiometric ratio in the soil–plant system, and stoichiometry and elastic ecological interactions jointly controlled the supply and demand of elements in the plants, but there was no consistent temporal pattern of nutrient ecological stoichiometric ratio in the plant–soil system during the recovery process, thus requiring further research and evaluation.

How does tree mortality caused by bark beetle (Trypophloeus klimeschi) outbreaks affect changes in soil fungal communities?

Forest disturbances such as fires, windthrows, and insect outbreaks have a serious influence on how these ecosystems function. In recent years, an outbreak of an endemic bark beetle species (Trypophloeus klimeschi Eggers) has caused a major disturbance in the Populus alba var. pyramidalis northwest shelter forest in China. The rapid and widespread death of P. alba var. pyramidalis caused by this beetle has cascading effects on the soil properties and fungal communities’ diversity that remain uncertain. We evaluated the mortality of P. alba var. pyramidalis forest attacked by T. klimeschi in this area and set four different levels of tree mortality: T1 level (0–10%), T2 level (11–40%), T3 level (41–70%) and T4 level (71–100%). We simultaneously measured rhizosphere soil properties and fungal community composition (using high-throughput sequencing) at different tree mortality levels. The increase in tree mortality resulted in a steep increase in the soil concentrations of ammonium nitrogen (NH4+), nitrate nitrogen (NO3–) and available phosphorus, as well as a reduction in soil pH. Meanwhile, the fungal communities showed profound changes, the relative abundance of ectomycorrhizal fungi decreased significantly by 71%, and the relative abundance of pathogenic fungi increased significantly by 73%. The combined effects of the changes in the soil fungal communities’ composition and available nitrogen content resulted in a significant 26% reduction in the richness of soil fungi. Our findings suggest that the mortality of poplar species due to the rapid range expansion of T. klimeschi will have significant impacts on crucial soil fungal communities, which may have sustained and potentially important implications for the future restoration of forest ecology in this area. The composition and changes of soil fungal communities should be considered in the subsequent forest ecological restoration process in this area.

Taxonomic and functional diversity of bird communities in mining areas undergoing passive and active restoration in eastern Amazon

The advance of land-use change processes in the Amazon rainforest has modified its natural landscape, resulting in losses of biodiversity and ecological functions. Under this scenario, some reforestation methods have been proposed and tested in degraded areas aiming to reverse environmental damage. We assess the efficiency of three reforestation methods by investigating the taxonomic and functional diversity of birds in a post-mining landscape located in the eastern Brazilian Amazon. We counted birds in 56 sites located in both forest and areas under the process of ecological restoration through natural regeneration, planting seedlings, and nucleation. Species composition and richness differed significantly between forests and areas under recovery. Nucleation showed distinct species composition from planting seedlings or natural regeneration areas, which can be explained by the difference in environmental structure in the areas recovering by this method. Although age did not influence species richness, we observed different species composition between old and young areas that received planting of seedlings. In general, we found no differences in functional diversity and functional richness between the methods of recovery. We conclude that the three recovery strategies evaluated herein showed a similar efficiency. However, it is necessary to consider that perhaps eight years is a short period to observe significant differences in the structure of the areas recovered by the different methods and, consequently, the structure of bird communities. Also, the diversity patterns of the current bird communities located in the post-mining areas were far from those found in forest areas, indicating the need for maintaining long-term recovery programs.

Spatial indicator of priority areas for the implementation of agroforestry systems: An optimization strategy for agricultural landscapes restoration

The ecological functions restoration in agricultural areas is a major challenge on a landscape scale. In the specific case of active restoration through Agroforestry Systems (AFS), the absence of a specific direction hinders ecological restoration processes, especially in regions that prefer intensive agriculture. Thus, this study aims to develop a Spatial Indicator of Priority Areas to guide Agroforestry Systems implementation in agricultural landscapes. A spatial multicriteria decision analysis (MDCA) was carried out based on environmental factors: soil, geology and slope (which determine the natural vulnerability of the land) and anthropogenic factors: land use and land cover, forest fragments, potential land use capacity and legal protected areas in rural properties (which reflects human pressure and land use suitability). Subsequently, four priority levels were classified for agroforestry interventions: (1) Low priority; (2) Average priority; (3) High priority; (4) Extreme priority. A final map was made to identify priority areas for landscape recovery in 9 cities located at the mouth of the Mogi Guaçu River Hydrographic Basin, State of São Paulo, Brazil. Considering the natural vulnerability of the land and the multifunctional aspects of the landscape, the scenarios projection allowed a consensus for forest conservation and agricultural suitability perspectives. A final combination of the explored aspects culminated in the spatial indicator, which model foresees 22,300 ha available for urgent actions for restoration, reforestation and sustainable exploitation through agroforestry systems. We emphasize the challenges in reconciling the socioeconomic and ecological functions in the agroecosystem, however, the metric provides a more inclusive and assertive management strategy for natural resources and advances towards the goal of reforestation and implementation of payment for environmental services (PES) schemes.

Quantitative estimation of reclamation status of a dry secondary forest using “measure of climax”: A novel approach

Determination of reclamation status of secondary forests is particularly urgent in human impacted landscapes for conservation of biodiversity and other ecosystem services. However, there is a lack of a quantitative method to estimate the recovery status of secondary forest globally. In the present work, the authors have attempted to estimate the recovery status of a dry secondary forest of Similipal Biosphere Reserve (SBR), India quantitatively with a nearby primary forest. We have formulated an equation (measure of climax stage) to estimate the secondary forest for its possible climax stage (early climax stage/mid climax stage/stable climax stage/non climax stage) based on species richness. For this study, the value of “measure of climax stage” between 0 and 0.2 is considered as stable climax stage, 0.2–0.6 as mid climax stage and 0.6–1 as early climax stage. On the other hand, the value >1 was considered as a non-climax stage of the forest. Accordingly, the studied secondary forest was estimated as to be in mid climax stage (measure of climax stage = 0.4230) even after c. 25 years of successional stage. We have also estimated the recovery stage of a secondary dry forest in SBR by fitting it with a suitable equation and found that the time frame for the stable climax stage is more than 50 years. ANOVA analysis indicates that there is no significant difference observed in the case of soil nutrient contents (except Electrical Conductivity) between primary and secondary forest sites. This developed equation may be implicated in the evaluation of reclamation status of secondary and degraded forest lands globally. Further, in-depth study is encouraged for the development of a modern climax concept to understand the ecological restoration process in a better way.

Species Diversity and Carbon Sequestration Oxygen Release Capacity of Dominant Communities in the Hancang River Basin, China

Plants play an important role in the storage of organic carbon as a carbon reservoir, mainly reflected in the absorption of carbon dioxide and the release of oxygen by plants through photosynthesis, which plays an important role in regulating regional carbon balance. This study aimed to explore the pattern of dominant vegetation species diversity in small basin ecosystems, analyze the photosynthetic carbon sequestration characteristics of dominant vegetation and its carbon sink potential, and use the Hancang River Basin as the research area to obtain species abundance data using the sampling method. The community characteristics were analyzed from the aspects of species richness, α diversity index, dominant population spatial pattern, and interspecific correlation. Fifteen typical plants were selected; the photosynthetic carbon sequestration capacity of the plants was measured and quantified, and the correlation of the nitrogen ecological measurement characteristics of the leaves were analyzed. The results showed that all 15 dominant vegetation types were clustered, and the aggregation intensity and interspecific correlation were closely related. Spearman’s analysis showed that the dominant vegetation community structure and diversity in the Hancang River Basin were unstable, and there may be strong interspecies competition and frequent species replacement in the future succession process. The daily trend of the net photosynthetic rate of dominant vegetation tended to be bimodal or nearly bimodal, and the peak generally appeared at 10:00 or 14:00. The leaf area index of the dominant species was greater than 3.0, of which the largest was Platanus acerifolia at 5.31. The smallest was Hemerocallis fulva (L.) L., which was 1.16. The average carbon sequestration per unit leaf area and unit land area of the dominant species was 10.02 g·m−2·d−1 and 42.35 g·m−2·d−1, respectively, and the average oxygen release was 7.29 g·m−2·d−1 and 30.8 g·m−2·d−1, respectively. The average maintenance breathing volume of the leaves was 2.94 μmol CO2 m−2s−1. Comprehensive analysis of the ecological restoration process of the Hancang River Basin should focus on Platanus acerifolia, Prunus serrulata var. lannesiana, Prunus cerasifera, Ligustrum lucidum, and other highly efficient carbon sequestration plants, to carry out rational planting and to build a multilayer composite configuration of forest shrub and grass models to improve the ecological problems of the basin.