Simpson Evenness Research Articles

Environmental Predictors of Diversity in Recent Planktonic Foraminifera as Recorded in Marine Sediments.

Global diversity patterns are thought to result from a combination of environmental and historical factors. This study tests the set of ecological and evolutionary hypotheses proposed to explain the global variation in present-day coretop diversity in the macroperforate planktonic foraminifera, a clade with an exceptional fossil record. Within this group, marine surface sediment assemblages are thought to represent an accurate, although centennial to millennial time-averaged, representation of recent diversity patterns. Environmental variables chosen to capture ocean temperature, structure, productivity and seasonality were used to model a range of diversity measures across the world’s oceans. Spatial autoregressive models showed that the same broad suite of environmental variables were important in shaping each of the four largely independent diversity measures (rarefied species richness, Simpson’s evenness, functional richness and mean evolutionary age). Sea-surface temperature explains the largest portion of diversity in all four diversity measures, but not in the way predicted by the metabolic theory of ecology. Vertical structure could be linked to increased diversity through the strength of stratification, but not through the depth of the mixed layer. There is limited evidence that seasonal turnover explains diversity patterns. There is evidence for functional redundancy in the low-latitude sites. The evolutionary mechanism of deep-time stability finds mixed support whilst there is relatively little evidence for an out-of-the-tropics model. These results suggest the diversity patterns of planktonic foraminifera cannot be explained by any one environmental variable or proposed mechanism, but instead reflect multiple processes acting in concert.

The influence of changes in land use and landscape patterns on soil erosion in a watershed

It is very important to have a good understanding of the relation between soil erosion and landscape patterns so that soil and water conservation in river basins can be optimized. In this study, this relationship was explored, using the Liusha River Watershed, China, as a case study. A distributed water and sediment model based on the Soil and Water Assessment Tool (SWAT) was developed to simulate soil erosion from different land use types in each sub-basin of the Liusha River Watershed. Observed runoff and sediment data from 1985 to 2005 and land use maps from 1986, 1995, and 2000 were used to calibrate and validate the model. The erosion modulus for each sub-basin was calculated from SWAT model results using the different land use maps and 12 landscape indices were chosen and calculated to describe the land use in each sub-basin for the different years. The variations in instead of the absolute amounts of the erosion modulus and the landscape indices for each sub-basin were used as the dependent and independent variables, respectively, for the regression equations derived from multiple linear regression. The results indicated that the variations in the erosion modulus were closely related to changes in the large patch index, patch cohesion index, modified Simpson's evenness index, and the aggregation index. From the regression equation and the corresponding landscape indices, it was found that watershed erosion can be reduced by decreasing the physical connectivity between patches, improving the evenness of the landscape patch types, enriching landscape types, and enhancing the degree of aggregation between the landscape patches. These findings will be useful for water and soil conservation and for optimizing the management of watershed landscapes.

Abundance and diversity of sea cucumbers in point pedro coastal waters in Jaffna peninsula of Sri Lanka

Sea cucumbers are fascinating and commercially valuable species belong to Class Holothuroidea. The present study was conducted with the aim of documenting the species composition and diversity of sea cucumber population in Point Pedro coastal area of Jaffna peninsula. The investigation was carried out from May 2014 to June 2015 at two study sites namely Viyaparimuli and Munnai. Sea cucumbers were collected within random transects areas of 4 m width and 100 m length. All the sea cucumbers were brought to the laboratory and identified up to species level based on the morphological characters and spicule preparation. Standard ecological parameters such as Simpson's Index (D), Shannon index (H) and Evenness index (J) were estimated. A total of four species belong to the Order Aspidochirotida and two each representing Family Holothuriidae and Family Stichopodidae were identified. Among them Holoturiaatra was the dominant species contributing 46.46% of the population followed by S. horrens , S. herrmanni , H. leucospilota representing 32.78%, 17.16% and 3.60%, respectively. The presence of S. horrens , S. herrmanni , H. leucospilota were recorded for the first time in Point Pedro area. According to diversity indices, maximum species diversity, richness and evenness were reported at Munnai site compared to Viyaparimoolai site. The information and observations in this study will be of use in formulating management policies for the sea cucumber fishery in the Point Pedro coastal area.

Changes in diversity, biomass and abundance of soil macrofauna, Parrotio-Carpinetum forest at organic and semi-organic horizons

Present study evaluates diversity, abundance and biomass of soil macrofauna in organic and semi-organic horizons in P arrotia persica -C arpinus betulus forest in Shast kola area. Totally 70 sample points were randomly selected from organic and semi-organic horizons then sampling was done by a rectangle 100 cm 2 area. Soil macrofauna were separated from soil samples by hand sorting and using Berlese funnel then dried at 60°C for 72h and weighted in 0.001 gr. With using taxonomic classification key, thirteen macrofauna orders were identified. Most of abundance of soil macrofauna in both soil horizons were allocated to Millipedes order. Changes in diversity, abundance and biomass of macrofauna in both soil horizons were calculated. The results showed Shannon diversity index, Simpson evenness and Margalef richness indices in semi-organic horizon were more than organic horizon. Abundance and biomass of macrofauna in semi-organic horizon were more than organic horizon.

Arbuscular mycorrhizal and dark septate endophyte fungal associations in Asparagus

We studied the arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal associations in five species of pot-grown Asparagus (A. aethiopicus, A. densiflorus, A. setaceus, A. racemosus, and A. umbellatus). Root colonization by AM and DSE fungi and AM spore numbers in the soil were assessed. AM fungal diversity indices like species richness, Shannon-Weiner index, Simpson's index, evenness, and Jaccard's index were determined. Relationships among the fungal and soil variables were also examined. All the species of Asparagus examined were colonized by both AM and DSE fungi, and these associations have been reported for the first time in four species. Root colonization by both the fungi varied significantly among Asparagus species and was related to each other and soil factors. The AM colonization patterns reported in four Asparagus species for the first time were characterized by either intermediate or Arum-Paris type. The AM fungal community was dominated by members belonging to the Glomerales and was significantly influenced by Asparagus species and soil factors. We conclude that Asparagus species could support a diverse AM fungal community even under pot conditions; however, certain AM fungal species are sensitive to changes in soil factors and host species.

Community structure of oribatid mites (Acari: Oribatida) in rangelands of West Azerbaijan Province, Iran

In order to study the abundance, species diversity and evenness of oribatid mites in rangelands of West Azerbaijan Province (Northwestern Iran), soil samples were taken in eight different sites of rangelands, namely Ghooshchi (1600–1750 and 1750–2000 m a.s.l.), Ghasemloo (1300–1450, 1450–1600 and 1600–1750 m a.s.l.), Roze-Chai (1450–1600 m a.s.l.), Marmisho (1750–2000 m a.s.l.) and Ordooshahi (1300–1450 m a.s.l.) at three different times (mid-May, mid-August and mid-October) of the year 2012. In this study, 71 species belonging to 49 genera, 32 families and 20 superfamilies were collected and identified. Simpson and Shannon–Weiner diversity indices and Simpson evenness index were calculated for all the samples with the Ecological Methodology 6.0 software. Data analysis was performed using SPSS 19 software. One-way ANOVA revealed significant differences (P < 0.01) in abundance and diversity indices among sites (P < 0.01). Ghasemloo 2 (1450−1600 m a.s.l.) had the highest abundance and Ghasemloo 2, 3 and Marmisho had the highest diversity and Ordooshahi (1300−1450 m a.s.l.) had the lowest abundance and diversity. Also, there were significant differences (P < 0.01) in abundance and diversity at different altitudes. In this regard, the diversity of oribatid mites increased with altitude.

Impact of transgenic wheat with wheat yellow mosaic virus resistance on microbial community diversity and enzyme activity in rhizosphere soil.

The transgenic wheat line N12-1 containing the WYMV-Nib8 gene was obtained previously through particle bombardment, and it can effectively control the wheat yellow mosaic virus (WYMV) disease transmitted by Polymyxa graminis at turngreen stage. Due to insertion of an exogenous gene, the transcriptome of wheat may be altered and affect root exudates. Thus, it is important to investigate the potential environmental risk of transgenic wheat before commercial release because of potential undesirable ecological side effects. Our 2-year study at two different experimental locations was performed to analyze the impact of transgenic wheat N12-1 on bacterial and fungal community diversity in rhizosphere soil using polymerase chain reaction-denaturing gel gradient electrophoresis (PCR-DGGE) at four growth stages (seeding stage, turngreen stage, grain-filling stage, and maturing stage). We also explored the activities of urease, sucrase and dehydrogenase in rhizosphere soil. The results showed that there was little difference in bacterial and fungal community diversity in rhizosphere soil between N12-1 and its recipient Y158 by comparing Shannon's, Simpson's diversity index and evenness (except at one or two growth stages). Regarding enzyme activity, only one significant difference was found during the maturing stage at Xinxiang in 2011 for dehydrogenase. Significant growth stage variation was observed during 2 years at two experimental locations for both soil microbial community diversity and enzyme activity. Analysis of bands from the gel for fungal community diversity showed that the majority of fungi were uncultured. The results of this study suggested that virus-resistant transgenic wheat had no adverse impact on microbial community diversity and enzyme activity in rhizosphere soil during 2 continuous years at two different experimental locations. This study provides a theoretical basis for environmental impact monitoring of transgenic wheat when the introduced gene is derived from a virus.

Mapping Spatial Variations of Land Cover in a Coastal Landscape Using Pattern Metrics

The aim of this study is to analyze spatial variations of land cover using pattern metrics in the case of a Mediterranean coastal area. Various composition and configuration metrics were used to analyze characteristics of land cover and its spatial heterogeneity. Satellite images (i.e., SPOT) were used to classify land cover. Pattern analyses were conducted in Erdemli district of Mersin, Turkey, from coastline to about 200m ASL. Landscape patterns were quantified and mapped on the basis of number of patches (NP), edge density (ED), largest patch index (LPI), aggregation index (AI), Shannon's and Simpson's diversity and evenness indices (SHDI, SIDI, SHEI, SIEI). A relationship between observed patterns/calculated indices and current land uses were investigated. Results showed that many of the pattern features differed between the coast and upper lands due to varying composition and configuration characteristics of land cover types under investigation.

Edge effect on vascular epiphytes in a subtropical Atlantic Forest

Forest fragmentation affects biological communities by reducing habitat and increasing edges, thus reducing the effective size of the habitable zones. The subtropical atlantic Araucaria forest, typical on the southern Brazil, in some regions has been reduced to less than 1% of its original size lasting only in small isolated fragments. This study aimed to analyse the impact the edge has on vascular epiphyte ensemble in a remnant of Araucaria forest. We surveyed 40 host trees in four transects: one at the edge; and three at 15, 30 and 60 m from the edge. On each host tree we estimated the epiphyte biomass, using four size classes. We compared the transects using Jackknife estimator of absolute species number, diversity indices, non-metric multi-dimensional scaling and multi-response permutation procedure analysis. We recorded 85 epiphytes species. Absolute species richness and diversity were lower at the edge and higher at 60 m in from the edge. Shannon's evenness did not differ significantly among transects and Simpson's evenness values were inconsistent. The vascular epiphyte community under study was significantly altered by the edge.

Response of Sphagnum Peatland Testate Amoebae to a 1-Year Transplantation Experiment Along an Artificial Hydrological Gradient

Peatland testate amoebae (TA) are well-established bioindicators for depth to water table (DWT), but effects of hydrological changes on TA communities have never been tested experimentally. We tested this in a field experiment by placing Sphagnum carpets (15 cm diameter) collected in hummock, lawn and pool microsites (origin) at three local conditions (dry, moist and wet) using trenches dug in a peatland. One series of samples was seeded with microorganism extract from all microsites. TA community were analysed at T0: 8–2008, T1: 5–2009 and T2: 8–2009. We analysed the data using conditional inference trees, principal response curves (PRC) and DWT inferred from TA communities using a transfer function used for paleoecological reconstruction. Density declined from T0 to T1 and then increased sharply by T2. Species richness, Simpson diversity and Simpson evenness were lower at T2 than at T0 and T1. Seeded communities had higher species richness in pool samples at T0. Pool samples tended to have higher density, lower species richness, Simpson diversity and Simpson Evenness than hummock and/or lawn samples until T1. In the PRC, the effect of origin was significant at T0 and T1, but the effect faded away by T2. Seeding effect was strongest at T1 and lowest vanished by T2. Local condition effect was strong but not in line with the wetness gradient at T1 but started to reflect it by T2. Likewise, TA-inferred DWT started to match the experimental conditions by T2, but more so in hummock and lawn samples than in pool samples. This study confirmed that TA responds to hydrological changes over a 1-year period. However, sensitivity of TA to hydrological fluctuations, and thus the accuracy of inferred DWT changes, was habitat specific, pool TA communities being least responsive to environmental changes. Lawns and hummocks may be thus better suited than pools for paleoecological reconstructions. This, however, contrasts with the higher prediction error and species’ tolerance for DWT with increasing dryness observed in transfer function models.Electronic supplementary materialThe online version of this article (doi:10.1007/s00248-014-0367-8) contains supplementary material, which is available to authorized users.

Impacts of Transportation Routes on Landscape Diversity: A Comparison of Different Route Types and Their Combined Effects

A comparison of different transportation route types and their combined effects on landscape diversity was conducted within Tiaoxi watershed (China) between 1994 and 2005. Buffer analysis and Mann-Kendall's test were used to quantify the relationships between distance from transportation routes (railway, highway, national, and provincial road) and a family of landscape diversity parameters (Simpson's diversity index, Simpson's evenness index, Shannon's diversity index, and Shannon's evenness index). One-way ANOVA was further applied to compare influences from different route types and their combined effects. Five other landscape metrics (patch density, edge density, area-weighted mean shape index, connectance index, and Euclidean nearest neighbor distance) were also calculated to analyze the associations between landscape diversity and landscape pattern characteristics. Results showed that transportation routes exerted significant impacts on landscape diversity. Impact from railway was comparable to that from highway and national road but was more significant than that from provincial road. The spatial influential range of railway and national road was wider than that of highway and provincial road. Combined effects of routes were nonlinear, and impacts from different route types were more complex than those from the same type. The four landscape diversity metrics were comparably effective at the buffer zone scale. In addition, landscape diversity can be alternatively used to indicate fragmentation, connectivity, and isolation at route buffer scale. This study demonstrates an applicable approach to quantitatively characterize the impacts from transportation routes on landscape patterns and has potential to facilitate route network planning.

Farmland Heterogeneity Benefits Birds in American Mid-west Watersheds

It is now well known that biodiversity in agricultural landscapes can be increased by converting production lands (i.e., farmland) into more natural habitat. However, it remains relatively unknown to what extent biodiversity can also be enhanced by changing the composition and configuration of farmland per se. We examined relationships between farmland structure and avian biodiversity in six watersheds representing a gradient in rowcrop intensity in the American Mid-west. We used canonical correspondence analysis (CCA) to model relationships at the site (0.8 ha), field (21 ha), section (165 ha) and watershed (4000–18,000 ha) extents to explore these questions: (1) At what spatial extent do birds respond most strongly to farmland structure? (2) Which farmland variables are most important? (3) Does avian biodiversity increase with increasing farmland heterogeneity? Most variation in bird assemblages was explained at the field versus the site or section extents. Of the top 20 field-extent variables in CCA, most important were: % woodland, an index of compositional heterogeneity (the modified Simpson's evenness index, MSIEI), % rowcrop, % core pasture (i.e., away from an edge), and edge density. Eighteen species were associated with woodland; their richness increased with woodland from 0% to 10%. Nine species were associated with rowcrop; their richness decreased two-fold with a change in rowcrop from 80% to 3%. Twelve species were associated with farmland heterogeneity; their richness increased four-fold with more field cover heterogeneity (MSIEI) and decreased three-fold with increasing mean field size from 1.2 to 7 ha. Field-extent α and β species richness were significantly higher than expected in the null model in the two most heterogeneous watersheds and lower in the two most intensely farmed watersheds. Differences among watersheds were significant and evident in the CCA ordination plot. Our results show empirically that policies to influence farmland heterogeneity could provide a conservation benefit to avian biodiversity.

Interactions between sea urchin grazing and prey diversity on temperate rocky reef communities.

While we frequently observe that increasing species richness within a trophic level can increase the rates of predation or herbivory on lower trophic levels, the general impacts of prey diversity on consumption rates by their predators or herbivores remains unclear. Here we report the results of two field experiments that examined how subcanopy sessile species richness affects rates of consumption by sea urchins. We crossed a natural gradient of species richness in a benthic subtidal community of understory macroalgae and sessile invertebrates against two experimental gradients of urchin density (0-50 and 0-14 individuals) in 0.5-m2 fenced plots. We found that the percent cover of macroalgae and invertebrates consumed by urchins was greater at higher levels of sessile prey species richness. However, this positive association between prey richness and sea urchin consumption was only apparent at low urchin densities; at high urchin densities nearly all algal and invertebrate biomass was consumed irrespective of sessile species richness. The positive relationship between prey richness and urchin consumption was also stronger when the abundance of prey species was more even (i.e., higher Simpson's evenness). Collectively, our results show that the consumptive impacts of urchins on kelp forest understory communities increases as a function of species diversity (both prey richness and evenness), but that prey diversity becomes irrelevant when urchins reach high densities.

Elevated nitrogen effects on Bromus tectorum dominance and native plant diversity in an arid montane ecosystem

AbstractQuestionsDominance of the widespread fire‐altering invasive grass, Bromus tectorum, is markedly reduced at upper elevations in the Great Basin Desert. Here, we evaluated whether increased anthropogenic nitrogen (N) deposition would have an effect on species composition and ecosystem invasibility by B. tectorum at high elevations, and whether B. tectorum cover was associated with decreased native plant diversity.LocationSagebrush steppe of the eastern Sierra Nevada, CA, US, at the western edge of the Great Basin Desert.MethodsWe set up 54 paired plots, half of which were exposed to elevated N deposition (50 kg·ha−1·yr−1 at the time of snowmelt for 4 yr) and half acted as controls, in areas differing in disturbance history (grazed, burned and grazed–burned). We monitored species composition each summer from 2008 to 2011 and then compared species richness, Shannon's diversity (H'), Simpson's dominance (D'), Simpson's evenness (E1/D), B. tectorum dominance and community similarity (with ANOSIM and SIMPER analyses) by N treatment and disturbance history.ResultsSpecies composition differed by disturbance history in all years (ANOSIM, P &lt; 0.05), and the grazed–burned plots consistently had the highest levels of B. tectorum dominance (P ≤ 0.0003) and cover (P ≤ 0.0001). Bromus tectorum cover was inversely related to native forb species richness (r = −0.44, P &lt; 0.0001), H'(rs = −0.73, P &lt; 0.0001), ‐ln(D') (rs = −0.75, P &lt; 0.0001) and E1/D'(rs = −0.49, P &lt; 0.0001). We found no evidence that increased N deposition would affect native plant diversity after 4 yr in this arid montane ecosystem, but the possibility of longer‐term effects cannot be eliminated.ConclusionsResults suggest that high‐elevation plant communities are already experiencing invasion impacts even though changes to the fire cycle have not yet occurred. In the most disturbed areas, B. tectorum cover is approaching the threshold for increased fire risk, which could result in more severe impacts at high elevations.

Comparison of Soil Macro Fauna Biodiversity in Broad Leaf and Needle Leaf Afforested Stands

This study evaluated the macro fauna diversity in 20 years Cypress, Poplar, Maple and Alder plantation and also adjacent Natural forest likewise relation with some soil characteristics in shast kela forest that is located in golestan province, northern Iran. Soil sampling performed using core soil sampler 81 cm 2 areas in bottom from 0~10 and 10~20 cm soil depth in May 2012. 5 samples randomly selected in each plantation and totally 50 samples were taken then soil macro fauna segregated with hand and were collected in bags. Then number and fresh weight were measured with 0.01 g accuracy in laboratory. Shannon diversity, Simpson evenness and margalef richness indices were used for comparing diversity. Data showed that afforested stands significantly affected macrofauna biodiversity and soil characteristics. The average of soil macrofauna abundance and biomass were consistently higher in Alder stand than in the other tree plantations, while they were lowest in Cypress plantation. In general, soil macrofauna biodiversity (for both of abundance and biomass) were decreased in Alder, Maple, Natural forest, Poplar and Cypress, respectively. Most of biodiversity indices were significantly higher in 0~10 cm than in 10~20 cm depth for abundance and biomass of soil macrofauna. The Principal Component Analysis (PCA) results suggest that the macrofauna distribution is regulated by total nitrogen and bulk density. In general, it can be pointed out that soil habitants play a significant role in reviving and rebuilding destructed forests and accelerating and reinforcing growth in natural forests. This interacts with the genus type and, hence, species must be planted and reinforced in forest habitats which positively affect biomass and activity of soil habitants and improve habitat conditions and productivity.

Floristic Diversity and Indigenous Uses of Dominated Weeds in Maize Crop of Chinthapalli mandal, Visakhapatnam district, Andhra Pradesh, India

The weed flora of maize crop in Chinthapalli mandal Visakhapatnam district was assessed to identify the weeds and evaluate their abundance. The comprehensive stock of weeds obtained was analyzed to determine the relative abundance of taxa and life forms. Forty five weed species belonging to 15 dicot families, 4 monocot families were identified. In terms of abundance and distribution, weeds of Asteraceae and Amaranthaceae were found to be far more invasive. The diversity of weed species represented by Shannon's and Simpson's and species evenness were calculated in the maize crop. Out of 45 weeds 35 weeds are Ethnomedicinal use along with local name, botanical name, family, parts used, ailments for which the drug is administered and mode of administration are presented.

The role of landscape structure in determining palynological and floristic richness

The associations between floristic and palynological richness and landscape structure were studied based on modern pollen–vegetation data from a patchy cultural landscape in southern Estonia (northern temperate vegetation zone). Nine study sites (small lakes and their surrounding vegetation) represent land cover gradient from closed forest to semi-open vegetation. Floristic richness (number of species) and floristic richness of pollen types (number of pollen-equivalent taxa) were used to describe the vegetation within the radius of 250 m from the pollen sampling sites. Palynological richness was calculated to describe the modern pollen samples diversity. Landscape structure was estimated on the basis of landscape openness and three landscape diversity measures: richness of community patches, Simpson evenness of community patches and Simpson diversity of community patches. To study the effect of the spatial scale of landscapes on the vegetation–landscape and pollen–landscape associations, landscape structure was estimated within eight radii (250–2,000 m) around each lake. The results showed that landscape openness was the most important determinant of both floristic richness and palynological richness in southern Estonia and that landscape diversity estimated by Simpson diversity index was also significantly associated with the richness estimates. Floristic and palynological richness were significantly positively correlated with landscape structure within the radii greater than 1,000 m from the pollen sampling sites, which is similar to the estimated Relevant Source Area of Pollen in southern Estonia. We conclude that within one floristic or climatic region, palynological richness gives reliable estimates about the variation in floristic richness and landscape structure; however, caution must be taken when comparing pollen-inferred vegetation diversities from different regions or when interpreting fossil pollen records from times with highly different vegetation associations.

Is land-use change a cause of loss of pedodiversity? The case of the Mazzarrone study area, Sicily

Anthropogenic soils created ex novo by land-use change in large scale farming are, from a pedogenetic point of view, catastrophic events that bring the soils to time zero and change the natural pattern of the soilscape, remarkably, in some cases. The quantitative aspects of pedodiversity of a soilscape in South-East Sicily, where some types of soils, in recent decades, have suffered a consistent reduction due to the transformations by large scale farming, are considered. The evolution of pedodiversity over a 53-year period (1955 to 2008) is examined using a dedicated statistical method and a space–time model based on Markov analysis and cellular automata in order to predict the evolution of the soilscape pattern in the next 42 years (i.e. until 2050). Soil subgroups, using the USDA Soil Taxonomy and a classification proposal, were considered and the following indices were used: richness; Shannon's diversity index; Simpson diversity index; modified Simpson's diversity index; Shannon's evenness index; Simpson's evenness index and modified Simpson's evenness index. These indices measured over time, show, quantitatively, a decrease in pedodiversity that highlights the effect of the human intervention in modifying the natural order of the soilscape.

Recovery of Native Plant Community Characteristics on a Chronosequence of Restored Prairies Seeded into Pastures in West‐Central Iowa

Restored grasslands comprise an ever‐increasing proportion of grasslands in North America and elsewhere. However, floristic studies of restored grasslands indicate that our ability to restore plant communities is limited. Our goal was to assess the effectiveness of restoration seeding for recovery of key plant community components on former exotic, cool‐season pastures using a chronosequence of six restoration sites and three nearby remnant tallgrass prairie sites in West‐Central Iowa. We assessed trends in Simpson's diversity and evenness, richness and abundance of selected native and exotic plant guilds, and mean coefficient of conservatism (mean C). Simpson's diversity and evenness and perennial invasive species abundance all declined with restoration site age. As a group, restoration sites had greater richness of native C3 species with late phenology, but lower richness and abundance of species with early phenology relative to remnant sites. Total native richness, total native abundance (cover), mean C, and abundance of late phenology C3 plants were similar between restoration and remnant sites. Observed declines in diversity and evenness with restoration age reflect increases in C4 grass abundance rather than absolute decreases in the abundance of perennial C3 species. In contrast to other studies, restoration seeding appears to have led to successful establishment of tallgrass prairie species that were likely to be included in seeding mixtures. While several floristic measures indicate convergence of restoration and remnant sites, biodiversity may be further enhanced by including early phenology species in seeding mixes in proportion to their abundance on remnant prairies.

Relationship Between Aboveground Biomass and Multiple Measures of Biodiversity in Subtropical Forest of Puerto Rico

ABSTRACTAnthropogenic activities have accelerated the rate of global loss of biodiversity, making it more important than ever to understand the structure of biodiversity hotspots. One current focus is the relationship between species richness and aboveground biomass (AGB) in a variety of ecosystems. Nonetheless, species diversity, evenness, rarity, or dominance represent other critical attributes of biodiversity and may have associations with AGB that are markedly different than that of species richness. Using data from large trees in four environmentally similar sites in the Luquillo Experimental Forest of Puerto Rico, we determined the shape and strength of relationships between each of five measures of biodiversity (i.e., species richness, Simpson's diversity, Simpson's evenness, rarity, and dominance) and AGB. We quantified these measures of biodiversity using either proportional biomass or proportional abundance as weighting factors. Three of the four sites had a unimodal relationship between species richness and AGB, with only the most mature site evincing a positive, linear relationship. The differences between the mature site and the other sites, as well as the differences between our richness–AGB relationships and those found at other forest sites, highlight the crucial role that prior land use and severe storms have on this forest community. Although the shape and strength of relationships differed greatly among measures of biodiversity and among sites, the strongest relationships within each site were always those involving richness or evenness.