Search Results (29)

In order to investigate the characteristics and driving factors of keystone species change in vegetation communities, we conducted a network analysis to analyze the complexity of grassland plant communities and keystone species. We conducted a study with six plots of degraded grassland, intact grassland, and various ages of artificial grassland. We systematically analyzed the characteristics of vegetation community and soil physical–chemical properties under different treatments. Our findings revealed that the 5-year-old artificial grassland exhibited lower biodiversity, as indicated by a Shannon–Weiner index of 1.70 and a Pielou’s evenness index of 0.72. In comparison to the degraded grassland, soil organic carbon and nitrate nitrogen levels in the 5-year-old artificial grassland increased by 22% and 13%, respectively, while soil density decreased by 9%. However, despite the relatively stable plant community in the 21-year-old artificial grassland, it had not fully recovered to the level of natural grassland due to the complexity of the plant community and the shift in keystone species. Therefore, it is crucial to consider the impact of soil bulk density and nutrient levels on the complexity of the plant community when restoring degraded alpine meadows through the establishment of artificial grassland. Full article

Over a comprehensive 5-year assessment, and extrapolating it prospectively until 2025, a thorough examination was conducted of productive agrobiodiversity in nine rural agricultural districts across Peru. The present study involved in-depth interviews with 180 representative farmers of the Coast, Highlands, and Jungle natural regions. Employing the Shannon–Weiner diversity index and the Margalef species richness index, the dynamics within years and across different zones were analyzed. Utilizing quadratic trend models, we assessed the frequency of each crop, aiming for the optimal fit concerning absolute deviation from the mean, mean squared deviation, and mean absolute percentage error. These findings revealed five distinct crop types—tuberous, fruits, cereals, legumes, and roots—distributed across 25 diverse families. Looking ahead to 2025, our projections indicated positive trends in 15 families and negative trends in 9 crop families. The nuanced mathematical distinctions observed in crop management decisions varied significantly depending on the specific area and year, underscoring the importance of localized considerations in agricultural planning. Full article

To assess the effects of reforestation on ecosystem carbon storage, a long-term Forest Restoration Experimental Project (FREP) was established in 1991 on southern degraded red soil in Taihe County, Jiangxi Province, China. In this study, we selected five types of plantations: Schima superba plantation (SS), Liquidambar formosana plantation (LF), Pinus massoniana plantation (PM), Pinus elliottii plantation (PE), and P. elliottii and broadleaf mixed plantation (MEB). The unforested land was used as an experimental control check (CK). We aimed to assess the changes in carbon storage in plantations and the factors affecting them. Thirty years after reforestation, the ecosystem carbon storage of the five types of plantations was significantly higher than that of the control site, and there were also significant differences in the ecosystem carbon storage between the different plantation types (p < 0.05). The ecosystem carbon storage of SS, MEB, LF, PM, and PE were 211.71 Mg ha⁻¹, 199.02 Mg ha⁻¹, 160.96 Mg ha⁻¹, 155.01 Mg ha⁻¹, and 142.88 Mg ha⁻¹, respectively. Compared to the CK, these values were increased by 436.8%, 404.6%, 308.1%, 293.1%, and 262.3%, respectively. The ecosystem carbon storage was significantly positively correlated with soil porosity, total nitrogen (TN), and stand density, and was significantly negatively correlated with pH, Pielou’s evenness index (PEI), and the Shannon–Weiner diversity index (SWDI). The soil water content (SWC), bulk density (BD), SWDI, and stand density can be used as indicators of the impact of reforestation plantings on ecosystem carbon storage. The research results has shown that reforestation plantings significantly increase ecosystem carbon storage, and that afforestation should be encouraged on degraded land. Full article

The Sierra Madre Mountain Range (SMMR) is the backbone of the Luzon Islands that contains a high concentration of highly important ecological resources distributed among the 68 protected areas therewith. The present study aimed to assess the composition and diversity of tree species in a secondary forest within the SMMR. A 2.25 km transect with 10 900-m² plots were established to record tree species with a diameter at breast height of at least 10 cm. The findings revealed 148 individuals of trees from 38 morphospecies, 28 genera, and 20 families. Importance values unveiled the Aurora endemic Macaranga stonei Whitmore as the most important species in terms of the relative values of its abundance, frequency, and dominance. The area was also found to be home to 33 natives, 12 endemics, five IUCN threatened species, and nine Philippine threatened trees. Furthermore, the study site was also found to have considerably high diversity, with a Shannon–Weiner Index value of 3.269 and a relatively even distribution of individuals among species, as supported by the Simpson’s Evenness index value of 0.9453. Significant correlational relationships were also found among species richness, Shannon–Weiner index, and Simpson’s Evenness index, with correlation coefficients ranging from 0.881 to 0.934, with all significant at p < 0.001. Lastly, the study was able to produce a distribution map, which is necessary for implementing targeted conservation strategies. These findings provided valuable implications for future research and implementation of targeted and participatory biodiversity conservation and protection strategies. Full article

Plant biodiversity data are prerequisites for the sustainable management of a forest. We used quantitative ecological tools to determine the species composition, diversity (richness and evenness), population structure, distribution patterns, and regeneration status of trees in a Tropical Moist Sal Forest of Eastern Ghats, India. For this purpose, a field inventory was conducted during 2020–2022 in sixteen 1.0 ha forest stands along a human-induced disturbance gradient. A total of 161 species (61 trees, 40 shrubs, 60 herbs) belonging to 77 families and 143 genera were recorded in the 16.0 ha of forest area. The results revealed a significant (p < 0.01) decrease in the tree and shrub species density, basal area, species richness, and diversity along the gradient of disturbance. However, in the case of herbs, the Shannon–Weiner diversity index increased significantly (p < 0.01) with increasing disturbance levels. Irrespective of forest types and disturbance levels, the tree diameter class (10–30 cm) accounted for the highest stem density in the forest. A mixed trend was found in the case of the basal area; the >41 cm diameter class constituted the highest basal area in the Pure Sal Forest while the 10–30 cm class was in the Moist Deciduous Forest without Sal. Tree species richness was found higher in lower diameter classes. Disturbances impacted the distribution pattern of trees; in the Pure Sal Forest, the contagious distribution of trees were 61.54%, 40%, and 12.5% in undisturbed, low-disturbed, and moderately disturbed sites, respectively. The percent of trees showing random and regular distribution increased with the increased level of disturbance in all forest types. The number of tree species having good regeneration decreased with the increased disturbance intensity in all forest types. Frequent grazing, repeated forest fires, and poor soil seed banks at the Moderately Disturbed site were the main reasons for the poor/no regeneration of Pterocarpus marsupium, Adina cordifolia, Terminalia bellerica, and some other economical species. Significant changes in structural attributes of the tree community revealed the impact of human-induced disturbances in the Moist Sal Forests of Eastern Ghats. The disturbance mosaics promoted the growth of many invasive weed species and lianas, depleting the number of valuable species in the forest. This study suggests the adaption of sustainable biodiversity conservation approaches through the active participation of the tribal so that the remnants the Moist Sal Forests of Eastern Ghats can be controlled to prevent further degradation. Full article

Wheat is grown in an area totalling 31.1 million hectares in India. The North-western Indo-Gangetic Plains (IGP) constitutes the major share of area and production of wheat in India and is known as the wheat belt of India. However, sustaining wheat production under declining/lower resource-use efficiency in the existing rice–wheat cropping system has led to considerations about diversifying this system with a pigeon pea–wheat system (PWS) in the IGP of India. However, little or no information is available on the impact of CA-based PWS on weed dynamics, productivity, profitability, and resource-use efficiencies. Therefore, we studied these aspects in wheat under a long-term (~12 years) conservation agriculture (CA)-based PWS. Treatments were conventional till flatbed (CT), ZT permanent narrow beds (PNBR & PNB), broad beds (PBBR & PBB), and flat beds (PFBR & PFB) with and without residue (R) retention and different N levels (75% and 100% of the recommended N). The results showed that the Shannon–Weiner index and the Simpson dominance index were higher under the CA system in 2021–2022 than in 2010–2011 and 2015–2016, indicating a change in weed diversity over the period. Furthermore, the Sorensen similarity index showed that there was not much difference in weed diversity for 2010–2011. However, in 2015–2016 and 2021–2022 respectively, only 89% (0.89) and 62% (0.62) of weed species were common to both CT and CA systems, indicating a shift in weed species in the long-term CA system in 2021–2022. Residue retention and N dose decreased weed density at 30 days after sowing (DAS). All the CA-based (PFBR100N, PBBR100N, PNBR100N, PFBR75N, PBBR75N, and PNBR75N) treatments reduced the weed density and dry weight compared to CT at 30 DAS. Wheat grain yield and net returns increased by 11.6–14.9% and 19.4–23.8% over CT in CA treatments, of which PFBR100N and PBBR100N were superior. The PBBR100N and PBBR75N systems had water productivity significantly higher than CT. Residue retention in ZT permanent beds reduced energy productivity in CA than CT and no residue treatments. In the 12th year, CA with 75% N (PFBR75N, PBBR75N, PNBR75N) resulted in a higher partial factor productivity of N and total NPK applied. Contrast analysis showed that 75% N was comparable with 100% N on crop, water, and energy productivities and 75% N was superior to 100% N on partial factor productivity of N and total NPK. Thus, the permanent broad bed with residue and 100% N in the initial years and 75% N in later years can be adopted in the north-western IGP for better weed suppression, higher yield, profitability, and resource-use efficiency. Full article

Small-scale livestock farmers in the drylands of South Africa are highly exposed to agricultural drought-related food insecurity. Research has used descriptive analyses and missed the need to index the diversity of coping strategies used for managing agricultural drought-induced food insecurity. This study was conducted to bridge this gap using a two-step procedure. Initially, the study identified the farmers’ coping strategies and food security status. A coping strategy diversity index was computed using the Shannon–Weiner method and its relationship with the food security status was determined. Secondly, the determinants of the coping strategy diversity index were explored using an ordered logit regression model after testing for the proportional odds assumption. A mixed methods approach was utilized and a standardized questionnaire was administered to 217 smallholder livestock farmers in the Northern Cape province of South Africa. The household food insecurity mean score (8.429 ± 7.105) from the household food insecurity scale (HFIAS) was significantly related to a higher diversity of coping strategies. Similar results were reported for the household food insecurity access prevalence (HFIAP) status. The different forms of support (e.g., cash, food, training and assets) had a significant (p < 0.05) and positive effect on the coping strategy diversity index among the households. Education, access to credit and insurance facilities and the frequency of droughts significantly (p < 0.05) influenced the diversity of coping strategies under drought conditions. The utilization of cash reserves and investment stocks also significantly (p < 0.05) influenced the extent of coping strategy diversity. The study recommended strengthening the functional and technical capacity pillars of dealing with agricultural drought through strategic partnerships between the government and livestock value chain players. This collaboration should target affordable credit lines tailor-made for farmers to cope with agricultural drought. If well-coordinated, these interventions should reduce food insecurity prevalence, especially during drought conditions among vulnerable smallholder livestock farmers. Lessons from this study could also inform future research on the effectiveness of the current agricultural drought coping strategies while expanding the diversity clusters over space and time. Full article

Artificial pruning is an important silvicultural practice that can produce clear wood in poplar plantations. This study focused on the growth of poplar, understory vegetation diversity and soil properties in response to different pruning intensities in poplar plantations. We implemented three different pruning treatments based on the height-to-crown base (HCB) to tree height (H) ratio in Populus deltoides ‘Nanlin 3804′ plantations: CK (no pruning), a 1/3 pruning treatment and a 1/2 pruning treatment. The poplar growth conditions, understory vegetation biodiversity and soil properties were investigated for one year after pruning. Compared with CK, the 1/2 pruning treatment significantly decreased the increment of diameter at breast height (DBHi) and stem volume increment (Vi) by 16.4% and 12.8%, respectively. Meanwhile, pruning significantly promoted understory vegetation biomass and increased the Shannon–Weiner diversity index of understory vegetation, and these variables were positively correlated with pruning intensity. The 1/2 pruning treatment significantly reduced the contents of soil nitrate nitrogen (NO₃-N), total inorganic nitrogen (IN) and microbial biomass nitrogen (MBN) by 21.9%, 13.9% and 22.4%, respectively. However, the 1/3 pruning treatment had no significant influence. Pruning mainlyaffectedthe soil enzyme activity in the surface (0–10 cm) layer. The 1/3 and 1/2 pruning treatments significantly decreased soil urease activity by 20.1% and 15.0%, respectively. Furthermore, nonmetric multidimensional scaling analysis showed that the seasonal variation in soil properties was significant, and significant differences among pruning treatments were mainly observed in July and October. Redundancy analysis showed that the growth of aboveground vegetation was significantly correlated with soil properties, particularly soil IN content and urease activity. Therefore, the results highlighted that pruning could promote the growth of understory vegetation and accelerate the transformation of soil nutrients. The 1/2 pruning treatment significantly inhibited the growth of poplar in terms of DBH and V, while the 1/3 pruning treatment promoted the growth of poplar in the short term. Overall, we think that the 1/3 pruning intensity is more suitable for pruning practice. Full article

The rapid development of urbanization has changed landscape patterns and biological habitats severely and, therefore, affected biodiversity. In this study, we selected 75 townships in Lishui, a mountainous area in eastern China, to conduct bird surveys for two years. We analyzed the birds’ composition characters in townships with different levels of development in order to identify the effects on bird diversity of the urban development level, land cover pattern, landscape pattern, and other factors. In total, 296 bird species from 18 orders and 67 families were recorded between December 2019 and January 2021. A total of 166 species of birds belonged to Passeriformes (56.08%). The seventy-five townships were divided into three grades by K-means cluster analysis. The average number of bird species, richness index, and diversity index were higher in G-H (highest urban development level) compared with the other grades. At the township level, landscape diversity and landscape fragmentation were the key factors that positively affected the bird species number, diversity index, and richness index. Landscape diversity had a greater effect than landscape fragmentation, particularly on the Shannon–Weiner diversity index. The diversity and heterogeneity of urban landscapes could be improved by constructing biological habitats in future urban development planning to maintain and increase biodiversity. The results obtained in this study provide a theoretical basis for urban planning in mountainous areas, and a reference for policymakers to formulate biodiversity conservation strategies, construct reasonable biodiversity patterns, and solve practical biodiversity conservation problems. Full article

Sundarban is the world’s largest mangrove wetland. This study, conducted in 2016, to compare blue carbon sequestration with different natural metapopulations and a four-year-old Avicennia marina (30% area)-Rhizophora mucronata (70% area)-mixed mangrove plantation under anthropoganic stress. The aims of the study is to find out the variations in soil ecological function indicators (pH, electrical conductivity, bulk density, soil texture, available nitrogn, phosphorus and soil organic carbon) and key ecological service indicator (soil blue carbon pool) between sites. Simpson’s Index of dominance, diversity and Shannon-Weiner Index revealed that all the sites are under ecological stress, with the Suaeda maritima-dominated mudflat having the least biodiversity. It is also revealed that pH and electrical conductivity were highest in Suaeda maritima and Phoenix padulosa-dominated metapopulations, whereas organic carbon was the highest under the mangrove plantation and Avicennia marina-dominated site. Available nitrogen was recorded highest in the community with the Sonneretia sp.-Avicennia marina association. The mixed mangrove plantation had the highest blue carbon pool. The species diversity was not found to be related with the distance from the nearby conserved mangrove forest, contrary to the island biogeography theory. This study concludes with a recommendation of mixed mangrove plantations to restore the degraded saline mudflats along the human settlements across the globe. Full article

Climate is critical for plant altitudinal distribution patterns. Non-climatic factors also have important effects on vegetation altitudinal distribution in mountain regions. The purpose of this study was to explore the current distribution of plant diversity along the altitudinal gradient in the Taihang Mountain range of northern China and to estimate the effects of climatic and non-climatic factors on the elevational pattern. Through a field survey, a total of 480 sampling plots were established in the central Taihang Mountain range. Alpha diversities (the Shannon–Weiner index and Simpson index) and beta diversities (the Jaccard index and Cody index) were measured based on the survey data. Plant community structure change based on the altitudinal gradient was explored by measuring the diversity indices. Canonical correspondence analysis was carried out to determine the factors influencing plant altitudinal distribution. The contributions of climatic and non-climatic factors on plant distribution were determined by partial methods. The results showed that the plant diversity of the elevational gradient complied with a “hump-shaped” pattern, in which communities in the medium altitude area with higher plant diversity had a higher species turnover rate, and non-climatic factors, particularly the anthropogenic factors, had an important influence on the plant altitudinal pattern. In conclusion, climatic and non-climatic factors both had important effects on the plant altitudinal pattern. It is strongly recommended to reduce human interference in mountain vegetation protection and management. Full article

Sundarban is the world’s largest contiguous mangrove forest but is under threat from anthropogenic interventions. Plantations are the favored method to restore degraded mudflats. In this study, ecological functional soil indicators (available N, soil organic C, available P, salinity) and service (Blue carbon pool) of the iteroparous tree Avicennia marina (Forssk.) Vierh. (Acanthaceae family), plantation has been compared with a natural mudflat dominated by mangrove semelparous grass Proteresia coarctata (Roxb.) Tateoka (Poacease family). Both sites were under anthropogenic pressure. It was observed that the P. coarctata dominated natural site has gone through fluctuations in species population between 2012 and 2016 with higher Simpson’s dominance, and lower value of the Shannon–Weiner Index. A one-way Analysis of Variance (ANOVA), Principal Component Analysis (PCA), indicated that soil indicators have significantly varied and linearly increased across the years at the A. marina plantation site. Blue carbon pool increased by four times (10 cm soil depth) at the plantation site since 2012 compared to only one time in the mangrove grass dominated community within the study period (2012–2016). This study concludes that plantation with iteroparous mangrove species can improve ecosystem function and services at degraded mudflats dominated by semelparous grass and aid in achieving the Sustainable Development Goal 13 (Climate action). Full article

After more than ten years of offshore wind farm (OWF) construction, the total installed capacity of China ranks first in the world. The effect of OWF on fish communities—to attract or banish—differs among fish species and wind farms. Studies on the effects of OWFs are limited in China and results from other regions may not be transferable due to different environmental and biological conditions. In October 2019, an acoustic survey was conducted in Jinwan OWF, outside the Pearl River Estuary, northern South China Sea, China, to assess the fish resources (biomass and abundance), community diversity, and distribution information of this area. According to the Index of Relative Importance (IRI), Harpadon nehereus and Brionobutis koilomatodon were the dominant fish species in the study area. The mean Shannon–Weiner diversity index was 1.74. The mean Margalef richness index and Pielou uniformity index were 2.51 and 0.84, respectively. The ABC curve indicated that the fish community was undisturbed. The mean acoustically-derived biomass and abundance densities were 195.40 ± 254.32 kg/km² and 6506.83 ± 11,098.96 individuals/km², respectively. The fishery resources had evident aggregate distribution patterns, and the southern part of the study area had more biomass than the northern part. Seven environmental factors were selected by canonical correspondence analysis (CCA) analysis to reveal the correlation between fish assemblages and environmental factors, including nitrate (NO₃⁻), ammonium (NH₄⁺), dissolved oxygen (DO), water depth, pH, Chlorophyll a (Chl a), and phosphate (PO₄⁺). However, the CCA only accounted for 45.49% of the total variation, indicating that other unexplained stresses affect the fish assemblage in Jinwan OWF. This is the first study to examine the fish distribution patterns and community structures of the Jinwan OWF area. In addition, it will help all sectors of society to more scientifically and objectively understand offshore wind farm projects. In future studies, control areas with more trawl samples can be set up to explore the long-term impact of OWF facilities on local fish communities. Full article

In temperate forested regions, historical agricultural production and value have been characterized by booms and busts. Agricultural diversification can encourage more stable agricultural development in the future. Agricultural Census and Survey data from 1840 to 2017 were used to estimate crop and livestock species’ product production and value for Maine, USA. These data were also used to calculate agricultural diversity indicators over time such as species richness, relative abundance, effective number of species, species diversification index, evenness, Shannon-Weiner index, and composite entropy index. Maine’s historical grass-based livestock systems included crops raised to feed livestock from the state’s establishment until the 1950’s. Since the 1950’s, production and value of livestock commodity products (e.g., meat chicken, eggs) have busted after initial booms. Three categories where diversity indicators have become more favorable since the 1950’s in Maine include livestock, livestock forage/feed, and potatoes and potato rotation crops. Mixed vegetables, fruits, nuts, and specialty crops as a category have had diversity increases during the 1970’s back-to-the-land movement and over the past two decades. Floriculture, propagation, and X-Mas trees as a category have witnessed volatile diversity indicator changes over time. Past diversification strategies can inspire farmers to go “back to the future” to improve sustainability. Full article

The South China Sea (SCS) plays an important role in global marine ecology. Studies of phytoplankton diversity promote the sustainable utilization of resources in the SCS. From July to August 2020, the phytoplankton community structure at 47 stations in the northern SCS was investigated. Species composition and distribution of phytoplankton, water quality, diversity index, main influencing factors, and succession characteristics of the community structure were analyzed in combination with the survey results from previous years. A total of 332 separate taxa from 83 genera and three phyla were identified, including 142 species and 45 genera of Bacillariophyta, 188 species and 36 genera of Dinophyta, and two species and two genera of Chrysophyta. Average phytoplankton cell abundance was 649.97 cells/L. Nitzschia spp., Thalassionema nitzschioides, and Scrippsiella spp. were the dominant species. Scrippsiella spp. was found for the first time as a dominant species in the northern SCS. Meanwhile, Nitzschia spp. was associated with organic-polluted water. The high-value areas of Nitzschia spp. also indicated eutrophication, and water was slightly polluted. The Shannon–Weiner diversity index of the surface layer was 0.99–4.56 (with a mean of 3.57), and the evenness index was 0.23–0.96 (with a mean of 0.83). The phytoplankton community structure in the northern SCS was deemed to be stable. Pearson correlation analysis showed that the sum of nitrate and nitrite was significantly negatively correlated with the abundance of dinoflagellate, which indicated restrictions as a result of the sum of nitrate and nitrite, with no significant correlation between ammonium salt and various groups. Small- and medium-sized phytoplankton are usually dominant in the SCS, where nitrogen is limited. Full article