Levels Of Plant Diversity Research Articles

Plant community diversity alters the response of ecosystem multifunctionality to multiple global change factors.

Biodiversity is considered important to the mitigation of global change impacts on ecosystem multifunctionality in terrestrial ecosystems. However, potential mechanisms through which biodiversity maintains ecosystem multifunctionality under global change remain unclear. We grew 132 plant communities with two levels of plant diversity, crossed with treatments based on 10 global change factors (nitrogen deposition, soil salinity, drought, plant invasion, simulated grazing, oil pollution, plastics pollution, antibiotics pollution, heavy metal pollution, and pesticide pollution). All global change factors negatively impacted ecosystem multifunctionality, but negative impacts were stronger in high compared with low diversity plant communities. We explored potential mechanisms for this unexpected result, finding that the inhibition of selection effects (i.e., selection for plant species associated with high ecosystem functioning) contributed to sensitivity of ecosystem multifunctionality to global change. Specifically, global change factors decreased the abundance of novel functional plants (i.e., legumes) in high but not low diversity plant communities. The negative impacts of global change on ecosystem multifunctionality were also mediated by increased relative abundance of fungal plant pathogens (identified from metabarcoding of soil samples) and their negative relationship with the abundance of novel functional plants. Taken together, our experiment highlights the importance of protecting high diversity plant communities and legumes, and managing fungal pathogens, to the maintenance of ecosystem multifunctionality in the face of complex global change.

Keanekaragaman Tumbuhan Bawah di Kawasan Universitas Negeri Jakarta

Understory plants are a group of plants that form a layer near the surface of the soil. One of the functions of undergrowth is as a ground cover which contributes to increasing the organic matter content in the soil. This research was conducted in November 2023 in the garden behind the KH. Hasyim Asy'ari Building, Jakarta State University. The aim of this research is to determine the diversity of understory plants found in the Jakarta State University environment. The research method used was a survey using a sampling technique with a quadratic method. There are 4 types of undergrowth in the garden behind the KH. Hasyim Asy'ari Building, namely Cyanthillium cineroum, Pilosela officinarum, Eclipta prostrata, and Cynodon dactylon. The results of the calculation of the Shannon-Wiener diversity index based on its classification show that the garden behind the KH. Hasyim Asy'ari Building, Jakarta State University has a low level of understory plant diversity.

Study on plant diversity investigation and conservation plan-ning in Yiyang City

<p>Taking the urban plants of Yiyang as the research object, the field investigation of Yiyang plants was carried out by using the method of combining route investigation and quadrat investigation, the current situation of plant diversity level in Yiyang City was analyzed, and the planning content and construction strategy of plant diversity protection in Yiyang City were studied, in order to provide reference for the effective protection of plant diversity in Yiyang City. The results showed that there were 145 families, 481 genera and 955 species of vascular plants in Yiyang urban planning area; there are 232 species of garden plant resources in the central urban area, belonging to 62 families. 105 genera; the overall level of plant diversity in Yiyang City is general. Urban landscaping relies too much on exotic species, and the utilization rate of native plants in urban gardens is low.</p>

Recruitment limitation of early‐ and late‐flowering grassland forbs can be overcome with transplanting in prairie restorations

Abstract One important goal in prairie restorations is to have forb species that flower throughout the growing season (i.e. a range of flowering phenology). We conducted an experiment to test whether three early‐ and three late‐flowering forb species are seed or recruitment limited, if mowing can influence this limitation, and if forb additions will impact overall plant diversity in ongoing restorations. The experiment was conducted at two restorations in northern Iowa and one in southern Minnesota, USA, using a split‐plot design. Whole plots tested the effect of mowing, and subplots tested the effect of target forbs being added as seeds or small transplants at varied richness levels (0, 1, 3 or 6 species added). Control plots received no forb additions. To compare establishment success, we estimated target species biomass, survivorship and per cent cover of target species across 3 years (2019–2021). Plant diversity measures (richness, inverse Simpson's diversity) were estimated within subplots to determine whether forb additions impacted diversity. Biomass and relative abundance of early‐ and late‐flowering forbs was much higher when they were added as transplants than when added as seeds. Survivorship across life stages indicated that the transition from seed to adult had lower survivorship probabilities (0.6%) than the transition from transplant (juvenile) to adult (75%). Plant diversity of these ongoing restorations was higher when target forbs were added compared to controls. Diversity was higher when target forbs were transplanted (8.4 species/plot and inverse Simpson's diversity of 4.0) than when they were seeded (7.6 species/plot and inverse Simpson's diversity of 3.8). Early‐flowering treatments increased diversity more than late‐flowering treatments, and diversity increased linearly with the number of forb species added. Mowed and unmowed plots had similar levels of target species establishment and plant diversity. Synthesis and applications: Our results indicate that early‐ and late‐flowering species are more recruitment limited than seed limited and that diversity is lower when these species are missing in restorations. We recommend transplanting a rich mix of early‐ and late‐flowering forbs to increase their biomass and ensure that flowering occurs throughout the growing season.

Analysis of Vegetation and Plant Diversity in High Conservation Value Areas in Oil Palm Plantations

The expansion of oil palm plantations is often rumored to impact the destruction of forests and other ecosystems with high conservation value (HCV). This study aimed to analyze the vegetation and plant diversity in the HCV area of oil palm plantations. The research was conducted on an oil palm plantation in Seruyan District, Central Kalimantan Province, Indonesia with an HCV area of 5379 ha. The research was carried out using the grid transect method on various types of vegetation, divided into four plots: seedlings, saplings, poles and trees. Parameters observed included the number of species, the number of individuals and the level of plant diversity. The results showed that the research location had good vegetation and plant diversity in the HCV area. There were 25 plant species from 17 families with a total of 355 plants. The number of species found in the seedling plots was 11 species (6 families) with a total of 38 plants; in the sapling plots was 16 species (12 families) with a total of 159 plants; in the pole plots was 14 species (11 families) with a total of 43 plants, and in the tree plots was 13 species (10 families) 115 plants. There was variation in the number of species and families in each plot. The overall plant diversity index was low. The diversity index of plants in the plots of seedlings, saplings, poles and trees (and the average) was in the low category.

Value of Biodiversity on Patagonian Rangeland: Estimation via a Hedonic Price Index

Plant diversity has long been linked to an increase in ecosystem productivity and function, but concrete examples in which ecosystem services are linked to diversity at the scale at which management decisions are taken are rare. We specifically tested for a correlation between plant diversity and provisioning ecosystem services estimated via the potential to produce meat and wool. We also tested whether higher levels of plant diversity conferred higher levels of ecosystem resistance to global change drivers, measured as the ability to sustain productivity across time. This was achieved by analyzing the interactive effects of a range of environmental variables on annual net primary production in a network of long-term biodiversity plots in Southern Patagonia. We found evidence of a positive correlation between plant diversity and plant productivity, which we relate to the ability to produce wool and meat from livestock. We also found evidence of a link between ecosystem resistance and diversity, though the effect was modest. The instrumental (economic) valuation presented doesn't account for the full range of values that rangeland in southern Patagonia generates. Nevertheless, these calculations do provide a starting point for broadening the discussion around the importance and value of natural capital in southern Patagonia. The results are consistent with theory and suggest that plant diversity has instrumental and monetary value as well as insurance value that may increase the resistance of rangeland ecosystems to global change drivers.

Plant diversity and soil legacy independently affect the plant metabolome and induced responses following herbivory.

Plant and soil biodiversity can have significant effects on herbivore resistance mediated by plant metabolites. Here, we disentangled the independent effects of plant diversity and soil legacy on constitutive and herbivore-induced plant metabolomes of three plant species in two complementary microcosm experiments. First, we grew plants in sterile soil with three different plant diversity levels. Second, single plant species were grown on soil with different plant diversity-induced soil legacies. We infested a subset of all plants with Spodoptera exigua larvae, a generalist leaf-chewing herbivore, and assessed foliar and root metabolomes. Neither plant diversity nor soil legacy had significant effects on overall foliar, root, or herbivore-induced metabolome composition. Herbivore-induced metabolomes, however, differed from those of control plants. We detected 139 significantly regulated metabolites by comparing plants grown in monocultures with conspecifics growing in plant or soil legacy mixtures. Moreover, plant-plant and plant-soil interactions regulated 141 metabolites in herbivore-induced plants. Taken together, plant diversity and soil legacy independently alter the concentration and induction of plant metabolites, thus affecting the plant's defensive capability. This is a first step toward disentangling plant and soil biodiversity effects on herbivore resistance, thereby improving our understanding of the mechanisms that govern ecosystem functioning.

Herbivore and native plant diversity synergistically resist alien plant invasion regardless of nutrient conditions

Alien plant invasion success can be inhibited by two key biotic factors: native herbivores and plant diversity. However, few studies have experimentally tested whether these factors interact to synergistically resist invasion success, especially factoring in changing global environments (e.g. nutrient enrichment). Here we tested how the synergy between native herbivores and plant diversity affects alien plant invasion success in various nutrient conditions. For this purpose, we exposed alien plant species in pot-mesocosms to different levels of native plant diversity (4 vs. 8 species), native generalist herbivores, and high and low soil nutrient levels. We found that generalist herbivores preferred alien plants to native plants, inhibiting invasion success in a native community. This inhibition was amplified by highly diverse native communities. Further, the amplified effect between herbivory and native plant diversity was independent of nutrient conditions. Our results suggest that a higher diversity of native communities can strengthen the resistance of native generalist herbivores to alien plant invasions by enhancing herbivory tolerance. The synergistic effect remains in force in nutrient-enriched habitats that are always invaded by alien plant species. Our results shed light on the effective control of plant invasions using multi-trophic means, even in the face of future global changes.

Diversity‐conditioned soil strengthens plant diversity–productivity relationship

Abstract How biodiversity affects terrestrial productivity is important to the maintenance of ecosystem services under global change. Although the crucial role of plant–soil feedbacks (PSF) in determining diversity–productivity relationship has been increasingly recognized in recent years, its legacy effects on subsequent diversity–productivity relationship are still unclear. We conducted a classic PSF experiment to assess how plant diversity‐conditioned soils influenced subsequent plant diversity–productivity relationships, where three plant diversity levels (1, 4 and 8 species) were planted in soils conditioned at three diversity levels (conditioned by 1, 4 and 8 species for 3 years). In addition, to test the role of soil microbial diversity in mediating the effects of soil conditioning diversity, the three plant diversity levels were planted with low, moderate and high soil biodiversity created by a soil inoculum dilution. The results showed that plant productivities were promoted by mixed‐conditioned soils (4 and 8 species) comparing to mono‐conditioned soils (1 species). Productivity was positively related to planted diversity in mixed‐conditioned soils, while showed no relation with planted diversity in mono‐conditioned soils. Productivity was promoted by soil biodiversity when 4 and 8 species were mixed planted, while did not change when 1 species was planted. Synthesis and applications . Our results highlight that PSF is crucial to strengthen the positive effects of biodiversity on productivity, implying that diversifying cropping systems should be encouraged in agroecosystem management to benefit from positive PSF effects. The importance of soil legacy for optimizing plant productivity is particularly important for conditioning soils with an intermediate number of plant species.

Keanekaragaman Tumbuhan di Kawasan Lindung Areal IUPHHK-HT PT. Wana Hijau Pesaguan Provinsi Kalimantan Barat

Protected area in plantation forest should be managed properly in order to sustainable development. One of the initial steps of the protected area management is by knowing the level of plant diversity which composing the community of its vegetation. The aim of this research is to measure plant diversity in protected area of IUPHHK-HT PT. Wana Hijau Pesaguan in Province West Kalimantan. Vegetation analysis is done at riverbanks, slope area more than 40% and conservation area of biodiversity. The result is that there are found 295 species of plants consisting 222 trees, 32 under storey plants, 38 lianas and 3 epiphytes. Shannon-Wiener diversity index (H’) values of trees with anystage of growth are about 3.02–4.41, which classified as high level of diversity. Under storey plants and lianas have H’ values about 1.00-3.22 which classified as mid level diversity. The diversity level of epiphytes are low to mid, with H’ values 0-1.04. Similarity Index value between all locations are low (less than 75%) except for epiphytes, which only in conservation area of biodiversity had different epiphytes composition comparing to the other sites.
 Key words: plant diversity, plantation forest, protected area, West Kalimantan

Associations of soil bacterial diversity and function with plant diversity in Carex tussock wetland.

Some species of Carex can form tussocks, which are usually distributed in valleys and flood plains. The soil microbial community diversity and function of micro-habitats formed by tussocks are associated with plant diversity, and research on these associations can guide Carex tussock wetland restoration. In this study, we selected tussock wetlands dominated by Carex appendiculata, including natural wetlands (NW), artificially restored wetlands (ARW), and naturally restored wetlands (NRW), and investigated plant diversity. Soil samples were collected from the quadrats of each sample plot with the maximum (ma), median (me), and minimum (mi) plant Shannon index values, and high-throughput sequencing was used to analyze the bacterial community composition, diversity, and functions. The plant diversity indexes of neither ARW nor NRW significantly differed from that of NW, but the companion species in NRW were hygrophytes and mesophytes, in contrast to only hygrophytes serving as companion species in NW and ARW. The soil bacterial communities at the operational taxonomic unit level of the nine quadrats with different plant Shannon index values significantly (p < 0.01) differed. The relative abundances of the dominant phyla (Proteobacteria, Chloroflexi, and Bacteroidetes) and the dominant genera (Geobacter, Sideroxydans, and Clostridium except for unassigned genera) significantly (p < 0.05) differed under the different levels of plant diversity. The plant Shannon index, soil moisture content, total organic carbon, N, and P were significantly (p < 0.05 or p < 0.01) correlated with the bacterial Shannon index. The phylogenetic diversity of the bacterial community in NW was significantly (p < 0.0001) different from those in ARW and NRW, and that in ARW was also significantly (p < 0.05) different from that in NRW. The functional groups of bacterial communities associated with plant diversity. In the NWme, ARWme, and NRWme bacterial communities, the relative proportions of functional groups related to soil N cycle were higher, but those related to soil S and C cycles were lower. Considering the rehabilitation of both plant and microbial communities, the methods used for establishing the ARW are recommended for Carex tussock wetland restoration.

Functional traits of soil nematodes define their response to nitrogen fertilization

Abstract Nitrogen (N) fertilization and warming are two crucial global change factors affecting the soil nematode communities. The effects of N fertilization and warming, however, on nematode communities in soils are inconsistent across ecosystems and maybe be even opposite. One key reason is that the commonly used taxonomic diversity is less sensitive to environmental changes than the seldom‐used trait‐based indicators. To verify this, we performed an 8‐year field experiment with four N fertilization levels with and without soil warming and collected an extensive dataset consisting of (i) six traits related to the nematode performance, that is, body size, maximum body length, maximum body width, stylet length, oesophagus length and intestinal length; (ii) the taxonomic alpha (richness and abundance) and beta diversity (Bray–Curtis dissimilarities) of the whole nematode community and each nematode functional group, (iii) soil food web resources (the total taxonomic richness and abundance of plant, bacterial and fungal communities) and (iv) soil properties (pH, total, ammonium and nitrate N, microbial N and C, total and available P and soil water content). We found that N fertilization altered plant diversity and soil nitrate levels, which in turn decreased taxonomic alpha diversity of two nematode functional groups (phytophagous nematodes and predators), but taxonomic diversity for the whole nematode community remained stable. The decreased taxonomic alpha diversity of phytophagous nematodes resulted in increased maximum body width, but decreased stylet length and oesophageal length. Mild warming (~ 0.7°C) had no effects on soil properties and soil food web resources, and the taxonomic diversity or nematode traits remained unchanged. Our results reveal that nematode functional traits show strong responses to N fertilization as individual nematode groups adapted quickly to changed soil properties and food web resources. Taxonomic diversity indices, however, were more stable under these changes showing that the functional composition of nematode communities may respond in the short term despite little effects on species diversity. Thus, the trait‐based indicators not only reveal how nematodes respond to N fertilization, but also how nematodes mediate the effects of N fertilization on ecosystem functioning (i.e. soil nutrient cycling). Read the free Plain Language Summary for this article on the Journal blog.

Artificial reseeding improves multiple ecosystem functions in an alpine sandy meadow of the eastern Tibetan Plateau

AbstractDesertification in alpine grasslands is exacerbated by rapid climate change and intensive anthropogenic activity, which will substantially threaten the structure and function of alpine grassland ecosystems. Artificial reseeding was a widely used strategy for the restoration of alpine sandy grasslands. However, it is still unclear whether reseeding restoration can improve multiple ecosystem functions of sandy meadows. To narrow these knowledge gaps, we evaluated the changes in plant communities, soil conditions, and ecosystem multifunctionality (EMF) across native meadow, sandy meadow, and restored meadow on the eastern Tibetan Plateau, and further identified the links between individual and multiple ecosystem functions. Artificial reseeding had contributed to the promotion of plant diversity, productivity, soil fertility, and soil carbon and nitrogen sequestrations. However, the recovery levels of plant diversity, productivity, and soil fertility in the restored meadow were still far lower than that in the native meadow. The results revealed that the EMF index of the restored meadow increased greatly compared with the sandy meadow, but it did not recover to that of the native meadow level. In addition, short‐term reseeding improved the aboveground EMF index more than the belowground EMF index. The EMF indexes and most individual ecosystem functions showed positive correlations with plant diversity and productivity. These findings indicated an important role of artificial reseeding in the restoration of ecosystem functions in the alpine sandy meadow, and it had critical implications for the regional ecological security and sustainable development of alpine grasslands.

The effects of external forcing agents on the biodiversity and species richness associated with the environmental history of Louisiana's wetlands over the late Holocene

This study evaluates plant diversity and species richness levels and reconstructs the environmental history of a site near Little Lake in southeast Louisiana, USA over the past 3200 years. Six successive ecosystems occurred as a result of changing environmental conditions, ranging from the local (anthropogenic activities), regional (delta lobe switching), and to global (sea level rise): interdistributary bay (3.2–2.3 cal kyr BP), hydrophytic freshwater marsh (2.3–1.42 cal kyr BP), mesophyte coastal prairie (1.42–0.92 cal kyr BP), Typha marsh (0.92–0.33 cal kyr BP), intermediate marsh (0.33 cal kyr Bp – ad, 1972 CE), brackish marsh (197 CE2-present). Biodiversity was evaluated for each ecosystem, with maximum diversity occurring during the period of maximum delta-growth as the river dynamics increased landscape heterogeneity by creating diverse habitats, including marsh, swamps, oxbow lakes, and natural levees, while the transgressive phase presents the lowest biodiversity due to increasing salinity. Multivariate analysis is used to identify the primary depositional processes for each stage and infer the proximate forcing agents(s). Early ecosystem shifts were controlled by the stages of the delta cycle, while more recent shifts are associated with anthropogenic activities and the effects of global climate change such as sea-level rise, and more intense tropical cyclones.

Understanding the drivers of woody plant diversity in urban parks in a snow climate city of China

Urban parks are an important part of urban ecosystems and play an important role in biodiversity conservation. However, it is still unclear how park characteristics affect plant diversity which could hinder the conservation of urban biodiversity due to the ineffective design of urban parks. The diversity of woody plants in 33 parks of Changchun, China, was measured with plot measurements and linked with urban park characteristics (e.g., size and age of the park) to uncover the relationship between them. The results show that urban woody plant species were abundant, with 98 species belonging to 51 genera and 26 families in the snow climate city of Changchun. The variation in woody plant diversity was largely explained by internal patch characteristics (e.g., size, age, shape), and external factors surrounding the park (e.g., land use type and socioeconomic level) accounted for only 16.0% in our study. For internal patch characteristics, older urban parks with larger areas demonstrated a richer level of plant diversity and increased nonlinearly with increasing park area. The threshold size significantly affecting plant diversity variation was approximately 30 ha. Plant diversity had positive linear relationships with the ages of urban parks, supporting the legacy effect. In addition, woody plant diversity nonlinearly decreased with increasing park shape index, which suggested that the plant diversity could also be increased by optimizing the park shape. Regarding the external factors surrounding parks, the spatial distribution of woody plant diversity varied greatly from the urban center to the suburbs. House prices around the park had positive linear relationships with woody plant diversity in parks, supporting the luxury effect. However, building and road proportions, and green space proportion had no relationship with plant diversity in parks. This study can provide a robust reference for enriching plant diversity in urban parks, thus improving the development of urban sustainable cities.

Late Cenozoic environmental changes drove the diversification of a weevil genus endemic to the Cape Floristic Region

AbstractThe Cape Floristic Region in the Republic of South Africa is a well‐recognized hotspot of biodiversity. Although this region is mostly known for its high level of plant diversity and endemicity, it also hosts an understudied and likely diverse arthropod fauna. Here we investigate the evolutionary history and timing of diversification of the apterous weevil genus Phlyctinus (Curculionidae: Entiminae), which is endemic to the coastal area and adjacent mountain ranges of the Cape floristic region and generally associated with sunflower plants (Asteraceae). We use a diverse array of molecular analyses (phylogenetic inference, molecular species delimitation and dating analyses) to analyse a novel molecular dataset of 202 weevil specimens (including 170 Phlyctinus sampled in 60 sites), and sequenced for two mitochondrial and four nuclear gene fragments. Phylogenetic and dating analyses indicate that the genus started diversifying in the late Miocene, with contrasting diversification dynamics for the three inferred clades, which present disjunct distributions. Host plant records and the lack of relatedness of species living in sympatry indicate that the diversification of Phlyctinus was predominantly driven by allopatric (geographic) speciation. We hypothesize that the interplay between topography and recurring cycles of coastline‐habitat fragmentation resulting from sea level oscillations spurred the diversification of the most speciose clade, whereas in the two remaining clades populations likely remained connected thus hampering allopatric speciation. Interestingly, this pattern echoes with the role of sea level oscillations as an important driver of the radiation of several lineages in the coastline ecosystems of the Cape Floristic Region.

Plant Diversity and Fungal Richness Regulate the Changes in Soil Multifunctionality in a Semi-Arid Grassland.

Simple SummaryUnderstanding relationships between biodiversity and ecosystem functions is important in the context of global plant diversity loss. We evaluated the relationships between soil bacterial and fungal diversity, rare microbial taxa, and soil multifunctionality in a semi-arid grassland with varied plant diversity levels. The fungal richness rather than bacterial richness was positively related to soil multifunctionality. The relative abundance of saprotrophs was positively correlated with soil multifunctionality, and the relative abundance of pathogens was negatively correlated with soil multifunctionality. Furthermore, the rare fungal taxa played a disproportionate role in regulating soil multifunctionality. The shift of plant biomass allocation patterns increased plant below-ground biomass in the high diversity plant assemblages, which can alleviate soil microbial carbon limitations and enhance the fungal richness, thus promoting soil multifunctionality. This study provides a new perspective for evaluating the relative roles of fungal and bacterial diversity in maintaining multiple soil functions under global plant diversity loss scenarios.Loss in plant diversity is expected to impact biodiversity and ecosystem functioning (BEF) in terrestrial ecosystems. Soil microbes play essential roles in regulating ecosystem functions. However, the important roles and differences in bacterial and fungal diversity and rare microbial taxa in driving soil multifunctionality based on plant diversity remain poorly understood in grassland ecosystems. Here, we carried out an experiment in six study sites with varied plant diversity levels to evaluate the relationships between soil bacterial and fungal diversity, rare taxa, and soil multifunctionality in a semi-arid grassland. We used Illumina HiSeq sequencing to determine soil bacterial and fungal diversity and evaluated soil functions associated with the nutrient cycle. We found that high diversity plant assemblages had a higher ratio of below-ground biomass to above-ground biomass, soil multifunctionality, and lower microbial carbon limitation than those with low diversity. Moreover, the fungal richness was negatively and significantly associated with microbial carbon limitations. The fungal richness was positively related to soil multifunctionality, but the bacterial richness was not. We also found that the relative abundance of saprotrophs was positively correlated with soil multifunctionality, and the relative abundance of pathogens was negatively correlated with soil multifunctionality. In addition, the rare fungal taxa played a disproportionate role in regulating soil multifunctionality. Structural equation modeling showed that the shift of plant biomass allocation patterns increased plant below-ground biomass in the highly diverse plant plots, which can alleviate soil microbial carbon limitations and enhance the fungal richness, thus promoting soil multifunctionality. Overall, these findings expand our comprehensive understanding of the critical role of soil fungal diversity and rare taxa in regulating soil multifunctionality under global plant diversity loss scenarios.

Old timber plantations and secondary forests attain levels of plant diversity and structure similar to primary forests in the West African humid tropics

Considering the high rate of primary forest degradation and loss in the tropics, the ability to conserve plant diversity within alternative forest landscape components is critical to biodiversity conservation. This study compares the restoration potential of old forest plantations and secondary forests. We assessed and compared the floristics, plant species diversity, conservation value, and structure of old (42–47 years) timber plantations ofAucoumea klaineana Pierre,Cedrela odorata L.,Tarrietia utilis Sprague, andTerminalia ivorensis A. Chev. and similar-aged secondary forests with nearby primary (old-growth) forests in the moist and wet forest zones of Ghana.We established a systematic sampling set-up of ninety-three 20 m × 20 m plots in total on 11 sites, with smaller nested subplots for saplings and ground vegetation.The floristic composition of the plantation and secondary forest stands were similar to that of the primary forests, with many rare and restricted-range species shared by the three forest types. Approximately 77% and 60% of primary forest plant species also occurred in plantation and secondary forests, respectively. Species diversity, measured by the Shannon-Wiener Diversity Index (H’) and Simpson Index (S), for the primary forest (H’=3.07, S = 0.91) was not statistically different from the plantation (H’=2.85, S = 0.87) or secondary (H’=2.95, S = 0.88) forests. Overall, species richness was higher in the primary and secondary forests compared to the plantations. At the tree stratum (≥10 cm DBH), the assessed diversity indices were significantly different between the primary forest and the plantations. However, such differences did not exist among the saplings (10 cm > DBH ≥ 2 cm) and ground vegetation (<2cm DBH). The plantations and secondary forests were similar to the primary forests for all the structural characteristics assessed. However, basal area and bole volume were significantly higher in the plantations compared with secondary forests. Conservation value (using Genetic Heat Index as an indicator) was highest in one of the C. odorata plantations (W-CO).Our study demonstrates that plantation and secondary forests can develop into structurally complex and floristically diverse self-organized stands similar to primary forests. Passive conversion of plantations to more natural ecosystems is an effective and low-cost forest restoration strategy leading to diverse ecosystems with high conservation value.

Diversified crop rotations increase the yield and economic efficiency of grain production systems

Crop rotations with high plant diversity and biomass input have been recognized worldwide as a crucial practice for increasing the sustainability of grain production systems, particularly in regions under no-tillage (NT) management. Nonetheless, low-diversity grain production systems based on double cropping (two crops in the same agricultural year) repeated over time, including soybean followed by maize (known in Brazil as “second crop maize”) or wheat, remain prevalent in Brazil. The continuous use of these systems can impair soil yield capacity, farmers’ profits, and environmental sustainability. Therefore, this study aimed to verify the grain yield and profitability of different production systems with different levels of plant diversity. This study was based on results obtained during the 2009–2017 cropping seasons through a long-term field trial conducted under NT since 1985 in southern Brazil. The trial covered two 4-year agricultural cycles with two crops per year, resulting in eight crops per cycle and 16 crops over the entire period. The experiment followed a randomized complete block design, with five treatments and four replicates. The treatments involved three diversified crop rotations, comprising different cover crops and two double-crop systems (wheat-soybean and maize-soybean). For a given agricultural year, wheat and cover crops (white oats, black oats, and forage radish) were grown from May to September, and the second crop maize was grown from March to August. Soybean and first crop maize were grown during the summer from October to February. The grain yield, gross revenue, production cost, and cumulative profit were analyzed for each production system. Gross revenue and profit were primarily estimated based on the actual annual average commodity prices received by farmers, and two additional price scenarios (pessimistic and optimistic) were proposed considering the average prices from 2010 to 2017. Regardless of the cropping season, first crop maize and wheat grain yields were higher in diversified crop rotations. The production system only affected the second crop maize yield in 2010/2011, with a higher value obtained in a diversified crop rotation system. The soybean yield in diversified crop rotations was higher than that in double-crop systems. Considering each cash crop separately, soybean produced the highest average profit (US$ 472.50 ha−1), followed by the first crop maize (US$ 245.31 ha−1) and wheat (US$ 77.71 ha−1), whereas the second crop maize led to economic losses (−US$ 121.73 ha−1). All diversified crop rotations produced a higher 8-year cumulative profit and gross margin than the maize–soybean in double-crop system. The relative economic performance of production systems remained unchanged under alternative price scenarios (pessimistic and optimistic) compared with that under the observed (actual) price scenario. However, the cumulative profit of maize and soybean in double-crop system was the most negatively impacted in the pessimistic scenario (−45.9%), indicating greater economic risk. Overall, lack of direct revenues from cover crops were compensated by increased grain yield in the spring-summer season and profitability of diversified crop rotation systems. Therefore, diversified crop rotation systems are economically competitive with double crop systems, rendering them feasible management options for conserving natural resources and increasing crop resilience to adverse climatic conditions.

Species-Enriched Grass-Clover Mixtures Can Promote Bumblebee Abundance Compared with Intensively Managed Conventional Pastures

(1) Land use intensification has led to serious declines in biodiversity, including in forage production systems for dairy cows. Agri-environmental schemes, such as enriching grasslands in floral species, were shown to be an effective tool to promote biodiversity in higher trophic levels. Here, we studied an innovative pasture-based dairy production system with floral-species-enhanced temporary grasslands, with respect to the effect on wild bee abundance and species richness. (2) We studied three grass-clover mixtures with perennial ryegrass and clover species with different levels of plant diversity for flower cover and wild bees. The grass-clover pastures were rotationally stocked with cattle and parts of the pastures were excluded from grazing. Intensively managed conventional permanent grasslands were studied as the common land use type. Wild bees were caught by sweep netting. Wild bee diversity was analysed with a general linear mixed model. For species richness, an incidence-based coverage estimator was calculated. (3) In total, 541 wild bees from 10 species were found. No wild bees were caught on the conventional grasslands. Wild bee abundance and species richness did not differ among the three grass-clover mixtures, but with increasing flower cover of white clover (Trifolium repens), wild bee abundance increased. Except for one solitary wild bee individual, the recorded community exclusively consisted of bumblebees. While generalist species that are commonly found on farmland dominated, rare long-tongued bumblebees made up 10% on the grazed sites of the multispecies mixture and made up 20% on the ungrazed strips of the binary mixture and multispecies mixture. (4) We conclude that multispecies mixtures can provide resources for generalist bumblebee species, especially when compared with conventional grasslands that offer no resources. Considering that the multispecies mixture has been also shown to reduce greenhouse gas emissions and nitrate leaching, while maintaining high forage yields, our findings add to the potential to promote a wide range of ecosystem services. Yet, should their full potential be enfolded, grazing should partially be excluded, and the mixture should be extended by plant species with more open flowers, suitable for solitary wild bees.