Management intensity and temporary conversion to other land‐use types affect plant diversity and species composition of subtropical grasslands in southern Brazil

Passive restoration of subtropical grasslands leads to incomplete recovery of ant communities in early successional stages

Decline of grassland diversity throughout Europe within the last decades is threatening biological diversity and is a major conservation problem. There is an urgent need to determine the underlying factors that control vascular plant species richness and composition in managed grasslands. In this study, 117 grasslands were sampled using standardised methods. Explanatory variables were recorded for each grassland site, reflecting the local field management, site-specific environmental conditions and large-scale spatial trends. Using variation partitioning methods, we determined the pure and shared effects of these three sets of explanatory variables on the plant species richness and composition in grasslands. Most of the explained variation in plant species richness was related to the joint effect of local field management and environmental variables. However, the applied variation partitioning approach revealed that the pure effect of spatial variables contributed relatively little to explaining variation in both the plant species richness and species composition. The largest fractions of explained variation in plant species composition were accounted for by the pure effects of environmental and local field management variables. Moreover, the results revealed that the main mechanisms by which these sets of explanatory variables affect plant species vary according to the type of management regime under study. From our findings we could conclude that particularly a reduction of nitrogen fertilisation on meadows and grazing at a low stocking rate on pastures can help to conserve biodiversity.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 224:55-67 (2001) - doi:10.3354/meps224055 Plant species diversity and composition: experimental effects on marine epifaunal assemblages John D. Parker*, J. Emmett Duffy, Robert J. Orth College of William and Mary, School of Marine Science, Virginia Institute of Marine Science, PO Box 1346, Gloucester Point, Virginia 23062, USA *Present address: Georgia Institute of Technology, School of Biology, Atlanta, Georgia 30332, USA. E-mail: gte782w@prism.gatech.edu ABSTRACT: Plant diversity is believed to govern animal community structure, yet few studies have tested this relationship. We manipulated plant species diversity and composition (2 seagrasses and 3 seaweeds) and measured the abundance, diversity, and biomass of plant-associated macroinvertebrates in a temperate, estuarine seagrass community. Animal diversity was weakly but positively related to plant diversity (Simpson¹s 1 - λ). Most indices of animal diversity, however, were more strongly related to total plant surface area than to plant diversity. Epifaunal abundance and biomass increased, whereas epifaunal diversity and evenness decreased with total plant surface area. Both food and habitat covary with plant surface area, providing potential mechanistic explanations for these patterns. Plant species composition had strong effects on epifaunal community structure. After statistically controlling for effects of plant surface area, epifaunal abundance and biomass remained higher, and evenness remained lower, among assemblages composed of branched (mostly seaweeds) relative to unbranched (mostly seagrasses) macrophytes. Multiple regression analyses also revealed differential use of particular plant species by epifauna. For example, amphipods responded particularly strongly to the coarsely branched red alga Gracilaria verrucosa. Thus, our experimental results support a strong effect of plant species composition, and little effect of plant diversity per se, on the motile macrofauna that we studied. This conclusion is consistent with results of a concurrent field survey; epifaunal community structure differed among plant species and seasons, with no host-plant specialists. These results support evidence from both terrestrial and aquatic communities; ecosystem structural and functional properties are often more strongly influenced by particular attributes, rather than number of species, in a community. KEY WORDS: Biodiversity · Community structure · Epifauna · Macroalgae · Zostera marina Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 224. Online publication date: December 18, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

Agroforestry practices (AFPs) have the potential to improve species composition and the ecological integrity of various landscapes. However, site-specific studies on the role of AFPs in enhancing plant species composition, richness, and diversity are scarce. This study aimed to determine variations in useful plant species composition and diversity across five agroforestry practices: Boundary Planting Agroforestry Practice (BAP), Multiple Woody Perennial Agroforestry Practice (MWPAP), Agrosilvopastoral Practice (ASP), Coffee Intercropped Agroforestry Practice (CIAP), and Mixed Intercropping Agroforestry Practice (MAP). A 10 × 10 m plot size was used to assess plant species composition and richness. Four plant species life forms were identified: trees, shrubs, climbers, and herbs. Variations in plant species composition and diversity among the AFPs were statistically analysed using ANOVA in R software, while correlations between plant life forms were determined using Pearson product-moment analysis. A total of 58 tree species (61.6%), 20 shrub species (21.3%), 10 climber species (10.5%), and 6 herb species (6.6%) belonging to 40 families and 72 genera were identified. Fabaceae and Euphorbiaceae were the most represented families, with 13 and 9 species, respectively. The highest mean species richness for trees (39), shrubs (19), and herbs (6) was recorded in ASP, while the highest mean climber species richness (10) was observed in CIAP. MAP exhibited the highest mean diversity for tree and herb species, whereas shrub and climber species diversity was highest in MWPAP and CIAP, respectively. Tree, shrub, climber, and herb species richness and diversity differed significantly (p < 0.001) across all AFPs. A significant positive correlation was observed between the species richness in trees, shrubs, and climbers in all practices (p < 0.05). The ASP and MAP demonstrated higher potential for supporting plant species richness and diversity, as well as a greater number of plant life forms. These two systems should be prioritized for their ecological and socio-economic benefits.   Key words: Plant life forms, agroforestry practices, useful, species diversity, species richness.

How micro-topography affecting plant communities classification and species composition at one stand-level was investigated through the plant communities and species composition varied across fine-scale environmental heterogeneity at the 25-ha Lienhuachih broad-leaved forest dynamics plot (FDP). All free-standing woody plants with diameter at breast height ≧ 1 cm were identified, measured, tagged and mapped. Four plant communities were identified and represented with dominant and indicating species based on two-way indicator species analysis (TWINSPAN). Type I, Pasania nantoensis - Randia cochinchinensis, locating on the ridge and the highest elevation was with the highest stem density; Type II, Mallotus paniculatus - Engelhardtia roxburghiana, locating on the upper slope was an ecotone between type I and type III, with the middle stem density and basal area among four plant community types; Type III, Diospyros morrisiana - Cryptocarya chinensis, locating on the lower slope and stream side was with lower stem density but the highest species heterogeneity; and Type IV, Machilus japonica var. kusanoi - Helicia formosana locating on west stream side was with the lowest stem density and basal area. Detrended Correspondence Analysis (DCA) results showed nearly 27.11% of the plant species composition was attributable to micro-topographic variables. Ridge distance, stream distance and convexity were the most important factors effected the changes of plant community and species composition. Classification and regression tree (CART) method was also used to examine the relationship between each single specie and micro-topographic variables. Over 70% species had more than 27.11 % variations which explained by DCA results. To conclude, our results support the existence of habitat association and niche divergence related to micro-topography in a subtropical evergreen broad-leaved forest.

Background/Question/Methods. Ponds are among the most diverse and yet threatened components of freshwater biodiversity. The conservation of ponds would greatly benefit from the identification of surrogate taxa in preliminary assessments aimed at detecting ponds of potentially high biodiversity value. Vascular plants and water beetles have often been used in pond conservation assessments. To evaluate whether wetland plants are a suitable surrogate group to evaluate pond biodiversity, we used plant, beetle, and environmental data collected from 54 ponds located in two farmed regions in Ireland. Specifically, we aimed at assessing cross-taxon congruence between water beetles and plants; quantifying and comparing the capacity of vegetation data and environmental variables to predict beetle species composition; assessing and comparing the response of plant and beetle communities to environmental conditions. The predictive strength of vegetation data was evaluated at the levels of species and community type composition, and species diversity. To identify the best predictor data-set for beetle species composition, we used predictive co-correspondence analysis (Co-CA) and predictive canonical correspondence analysis (CCA-PLS). Congruence in species richness was calculated using simple regression analysis, while a generalized linear model was developed to quantify the effect of environmental variables on patterns of beetle and plant diversity. Results/Conclusions. The study ponds supported over 30% of the Irish water beetle fauna (76 species), with five species having some form of IUCN Red List Status in Ireland, and 67 wetland plant species, including a nationally rare one. Co-CA showed that plant species composition had a positive predictive accuracy, which was significantly higher compared to that of data at the plant community type level. Although environmental variables showed a higher predictive capacity compared to that of plant species composition, the difference was not significant. Explanatory CCA analyses showed that plants and beetles both responded to the same subset of environmental conditions, explaining ca.18% of the variation in both plant and beetle species composition. Regional differences, permanency, substratum, and grazing intensity affected the composition of both plant and beetle assemblages. The relationship between plant and beetle diversity was rather weak, reflecting the contribution of few plant species in supporting diverse beetle assemblages. These findings have important implications in conservation planning. First, the composition of wetland plants can be effectively used as a surrogate taxon in the identification of conservation-priority ponds. Second, conservation strategies aimed at maintaining and enhancing pond biodiversity should be based on considerations on the vegetation.

Abandonment of coppicing is one of the main reasons of diversity decline in European temperate forests. To reverse this trend, coppicing has been reintroduced in several forests, especially in areas of high conservation value. However, empirical information on the effects of coppicing on plant diversity and composition is still scarce. By comparing vegetation data from active coppices and beech-dominated high forests in the Banat region in Romania, we tested the hypothesis that coppices have a higher plant diversity and different plant species composition than high forests. Data were collected in 60 randomly placed phytosociological releves and were analysed using linear models and multivariate methods. As expected, we found differences in understorey plant composition. Herb species with various environmental demands–sciophytes-(hemi)-heliophytes and grassland species–were more frequent in coppices whereas high forests had more vernal species and sciophytes. Coppices also had slightly greater plant diversity but did not differ in herb species richness. Our results demonstrate that coppicing has a small positive effect on plant diversity but a large effect on species composition. Coppice restoration may be especially beneficial for populations of thermophilous and non-forest species.

Plant diversity in groundwater-fed wetland ecosystems is typically extraordinarily high, yet the biogeochemical controls of this diversity are still incompletely understood. We hypothesized that fine-scale variation in sulfide would influence plant community composition via direct phytotoxicity and indirect mediation of phosphorus release from iron, coupled with gradients in other chemicals such as calcium. We measured porewater chemistry and plant species composition at 400 locations within a calcareous rich fen in central New York State. Groundwater-derived calcium (Ca2+) and sulfate and redox-sensitive sulfide and ferrous iron (Fe2+) showed high heterogeneity. Phosphorus availability was limited and not readily traceable to toxic sulfide, whereas nitrogen (TDN) was more abundant than expected. Using the corrected Akaike information criterion to select between competing models of toxic, nutrient, and mixed-chemistry influences on vegetation, we found that hydrogen sulfide explained decreases in total plant cover, cover of the three most frequently occurring species, dicot species density, plant height, and litter accumulation. Furthermore, sulfide coupled with calcium and phosphorus to explain plant species density and composition. Sulfide was more likely to explain decreased cover of dominant species than rare species. The presence and cover of uncommon species was often unexpectedly explained best by Fe2+ and sulfate, but all models of plant responses with environmental predictor variables were better than the “null” model of mean plant response that lacked environmental variables. An integrated geochemical assessment of coupled groundwater chemistry, redox-sensitive chemistry, and nutrient influences on plants demonstrated the importance of phytotoxic sulfide in explaining plant species density and composition.

Plant community diversity and composition provide little resistance to <i>Juniperus</i> encroachment

QuestionFire and grazing, and their interaction, are the main drivers of vegetation structure and plant species composition in many grasslands globally. However, for subtropical grasslands in southern Brazil, the interactive effects of fire and grazing on plant community composition characteristics remain relatively understudied, even though this ecosystem is recognized as fire‐dependent with critical importance for livestock grazing.LocationSubtropical grassland in southern Brazil (Santiago, Rio Grande do Sul state).MethodsBeginning in 2017, we established an experiment with three treatments: fire only (F), grazing only (G), and fire and grazing (F + G). Grazing was continuous with ca 1.1 animal unit per hectare annually and prescribed fires were applied annually in winter. We assessed vegetation structure (via percentage of bare soil, height of canopy, and available forage) and plant species composition during spring (November) and summer (March) of 2017, 2018, 2019 and 2020 (only summer season).ResultsDifferences in vegetation structure were found among treatments, wherein bare soil, height of canopy and available forage were higher in F, and lower but similar in F + G and G. Plant species richness was equal among treatments, but cover of C3 grasses was higher in F than in other treatments, and shrub cover was lower in F and F + G in comparison to G. In F + G treatment, available biomass for subsequent burning was limited, resulting in lower amounts of fuel, reduced fire spread, and ultimately less total area burned in the subsequent years.ConclusionsOur findings suggest that interaction of fire and grazing can be a useful vegetation management tool for conserving native plant species, increasing availability of more desirable forage plants, and decreasing shrubs (including toxic Senecio species which contain hepatotoxic pyrrolizidine alkaloids). The singular and interactive effects of fire and grazing suggest the subhumid Río de la Plata grasslands are a fire‐adapted ecosystem with variable plant functional trait responses facilitating differential dominance. There is a need for future work to address spatio‐temporal variability and vegetation heterogeneity.

The aim of this paper is to investigate differences in plant species composition between managed and unmanaged forests, and to assess if these difference give rise to a higher plant diversity in the unmanaged forest. Furthermore our aim is to relate forest structure to differences in plant species composition, identifying the structural attributes more strongly related to the unmanaged forest vegetation. We compared an old-growth forest and a managed highforest in the Abruzzo Lazio and Molise National Park (Central Italy). Plant species composition and diversity, deadwood components and live structure have been analyzed. We used permutational multivariate analysis of variance to test the response of species composition to management factor; furthermore, we compared species richness and beta diversity. Redundancy analysis has been used to relate plant species abundances to structural variables; the importance of dead and living wood components has been compared through variation partitioning. Plant species composition proved to be significantly different in the two sites, and the old-growth stand showed a higher plant diversity. From a structural point of view, we found differences especially in the amount and quality of deadwood, and in the diameter class distribution. These variables are also the most important in determining the old-growth stand plant species composition according to redundancy analysis. Variation partitioning confirmed the greater importance of the deadwood variables. Our results suggest that including deadwood surveys in traditional forest inventories could help in finding forests with both structural and floristic old-growth properties to be considered in conservation programmes. The imitation of natural dynamics, through the creation of gaps avoiding deadwood removal, could be an effective strategy for restoring old-growth conditions, also in terms of plant diversity.

Reduced precipitation as well as warming may result in less snow accumulation in seasonally snow-covered areas, leading to lower minimum soil temperatures and more frequent and severe soil frosts. Therefore, plant stress is increased not only by drought in warmer months, but also by increased exposure to frost in cooler periods. We conducted a 4-year field experiment to evaluate the effects of diminished snowpack accumulation (through snow removal) and rainfall reduction (through rain-out shelters) on aboveground plant productivity, diversity and species composition of two subalpine grassland plant communities from the central region of the Spanish Pyrenees. We found that the snow removal treatment decreased minimum soil temperature by 0.5°C. Plant diversity decreased by 16 percent, although this effect was only observed in one of the grasslands studied. Aboveground primary productivity seemed to be unaffected. In contrast, we found that the rainfall reduction treatment negatively affected aboveground productivity of leguminous forb species, yet no effect on plant diversity was observed. Both treatments were important drivers of changes in plant species composition. Overall, our results suggest that the resilience of subalpine grasslands to snow cover removal and rainfall reduction treatments may depend on the specific community composition and dominant plant groups.

Large herbivores and topo-edaphic gradients are well-documented, major determinants of grassland plant production and species composition. In contrast, there is limited information about how these factors together may influence the composition of the arbuscular mycorrhizal fungus (AMF) communities associated with plants. AMF are a common component of grassland ecosystems where they can influence plant productivity, diversity, and soil stability. In this study, AMF community composition was analyzed in paired plots located inside and outside 40-44-year-old ungulate exclosures at six grassland sites in Yellowstone National Park (YNP), USA, that varied in soil moisture and the availability of soil nitrogen (N) and phosphorus (P). AMF spore abundance, species richness, and the relative abundance of AMF species were determined from soil samples collected (1) randomly (n = 5 samples) within each of the 12 plots and (2) from beneath the dominant grass (n = 5 samples per plot) at each site. Randomly collected soil samples explored the effects of ungulates and topographic position on AMF composition at the plant community level, subsuming potential effects of ungulates on plant species composition. Dominant plant samples examined how grazers, in particular, influenced AMF communities, while controlling for host-plant identity. Grazing decreased AMF spore abundance across the landscape (examined by random sampling) but increased the AMF species richness associated with dominant plants. Grazing influenced the AMF species composition at the plant community level and at the host-plant level by shifting the relative abundances of individual AMF species. Individual AMF species responded differently to grazing and N and P availability. Our results demonstrate how soil moisture and N and P availability across the landscape interact with grazing to influence AMF species composition.

The study was conducted to assess the effect of conventional, integrated and organic management on differences in plant species composition, richness and diversity. The plants were studied in triads of orchards situated in three regions of the Czech Republic. Data about species occurrences were collected on 15 permanent plots in the tree rows and 15 plots between tree rows in each of the apple orchards during 2009. A total of 201 vascular plant species (127 native species, 65 archaeophytes, and 9 neophytes) were found. Management type and also different regional conditions had a significant effect on plant species composition and on diversity parameters of orchard spontaneous vegetation. Species richness and species pool was significantly higher in the organic orchards than in the differently managed orchards. Management type had significant effect on proportions of archaeophytes, and also neophytes in apple orchards. The results showed that a change from conventional to integrated and organic management in apple orchards lead to higher plant species diversity and to changes in plant species composition.

Insects and spiders comprise more than two-thirds of the Earth's total species diversity. There is wide concern, however, that the global diversity of arthropods may be declining even more rapidly than the diversity of vertebrates and plants. For adequate conservation planning, ecologists need to understand the driving factors for arthropod communities and devise methods, that provide reliable predictions when resources do not permit exhaustive ground surveys. Which factor most successfully predicts arthropod community structure is still a matter of debate, however. The purpose of this study was to identify the factor best predicting arthropod assemblage composition. We investigated the species composition of seven functionally different arthropod groups (epigeic spiders, grasshoppers, ground beetles, weevils, hoppers, hoverflies, and bees) at 47 sites in The Netherlands comprising a range of seminatural grassland types and one heathland type. We then compared the actual arthropod composition with predictions based on plant species composition, vegetation structure, environmental data, flower richness, and landscape composition. For this we used the recently published method of predictive co-correspondence analysis, and a predictive variant of canonical correspondence analysis, depending on the type of predictor data. Our results demonstrate that local plant species composition is the most effective predictor of arthropod assemblage composition, for all investigated groups. In predicting arthropod assemblages, plant community composition consistently outperforms both vegetation structure and environmental conditions (even when the two are combined), and also performs better than the surrounding landscape. These results run against a common expectation of vegetation structure as the decisive factor. Such expectations, however, have always been biased by the fact that until recently no methods existed that could use an entire (plant) species composition in the explanatory role. Although more recent experimental diversity work has reawakened interest in the role of plant species, these studies still have not used (or have not been able to use) entire species compositions. They only consider diversity measures, both for plant and insect assemblages, which may obscure relationships. The present study demonstrates that the species compositions of insect and plant communities are clearly linked.