Effects of harvester ants on seed availability and dispersal of Lavandula stoechas subsp. pedunculata in a Mediterranean grassland-scrubland mosaic

The role of harvester ants in Mediterranean grassland and scrubland has mostly focused on seed consumption. However, recent studies have reported their role as accidental dispersal agents of some of the collected seeds via refuse piles. The objective of this study is to examine the effect of the ant Messor barbarus on seed availability and dispersal of one of its major diet components, Lavandula stoechas subsp. pedunculata, in scrubland, grassland and the ecotones between them. After confirming and quantifying the Lavandula contribution to M. barbarus diet, we described the spatial and temporal patterns of pre- and post-dispersal seed predation, seed content and seedling occurrence in the refuse piles. Our results show that: (1) Lavandula propagules constitute a high proportion of the prey items collected by M. barbarus, with particularly intense collection activity in mid-summer, spring and autumn, in decreasing order. (2) Pre-dispersal predation rate was significantly higher in the ecotone than in the scrubland (76% and 13.5% of total seed production lost respectively). (3) Season and propagule type (seed vs. fruit) were the most significant variables explaining the post-dispersal predation probability, which approached 100% of seeds after 48 h in mid-summer. (4) Viable Lavandula seeds were found in refuse piles at densities of 0.06–0.2 per g of refuse pile material, or 58.8–207.2 per refuse pile. On the one hand, these results indicate that the ecotones are most affected by M. barbarus pre-dispersal consumption, which may locally limit Lavandula colonisation. On the other hand, the small proportion of consumed seeds that is dispersed to refuse piles may be relevant at the population level, as this dispersal implies arrival at potentially favourable sites for establishment.     

Lavandula stoechas L. subsp. stoechas,a New Herbal Source for Ursolic Acid: Quantitative Analysis,Purification and Bioactivity Studies

In this study, methanol, ethanol, methanol-dichloromethane (1 : 1, v/v), acetone, ethyl acetate, diethyl ether, and chloroform extracts of lavender (Lavandula stoechas L. subsp. stoechas) were prepared by maceration, and the ursolic acid contents in the extracts were determined quantitatively by HPLC analyses. The present results show that the methanol-dichloromethane (1 : 1, v/v) solvent system is the most efficient solvent system for the extraction of ursolic acid from the plant sample with the highest yield (2.22 g/100 g plant sample). In the present study, a new practical method for the isolation of ursolic acid from polar extracts was also demonstrated for the first time. The inhibition effects of the extracts and ursolic acid were also revealed on α-glycosidase, acetylcholinesterase, butyrylcholinesterase, and human carbonic anhydrase I and II enzymes by determining IC₅₀ values for the first time. The extracts and ursolic acid acted as potent antidiabetic agents by strongly inhibiting the α-glycosidase activity, whereas they were found to be very weak neuroprotective agents. In view of the present results, L. stoechas and its major metabolite, ursolic acid, can be recommended as a herbal source to control postprandial blood sugar levels and prevent diabetes by delaying the digestion of starch in food.     

The chemical constituents and biological activity of essential oil of Lavandula stoechas ssp. stoechas

The composition of essential oil of the leaves of Lavandula stoechas ssp. stoechas, was analyzed by means of capillary GC-MS. The main components of L. stoechas ssp. stoechas oil were pulegone (40.4%), menthol (18.1%), menthone (12.6%). The essential oil of the plant was evaluated for antibacterial and a panel cytotoxic activities.     

Immunolocalization of abscisic acid by monoclonal antibodies in Lavandula stoechas L. leaves

A monoclonal antibody was used to localize abscisic acid in Lavandula stoechas L. plants treated with 1 M abscisic acid. ABA localization was performed using EDC as the only fixative, which preserves antigenicity and improves the specificity of monoclonal antibodies. A relationship was observed between the effect of abscisic acid on chloroplast ultrastructure and ABA accumulation. Gold particles accumulated on swollen chloroplasts. Our findings provide cytochemical evidence that the chloroplast is a trapping compartment, and yield valuable information on the relation between chloroplast ultrastructure and ABA accumulation.Abbreviations ABA abscisic acid - BSA bovine serum albumin - EDC 1-(3-dimethyl-aminopropyl)-3 ethyl carbodiimide - IgG immunoglobulin G - mAB monoclonal antibodies - pAB polyclonal antibodies     

Changes in the canopy structure of the Mediterranean shrub Lavandula stoechas after disturbance

Abstract. This study attempts to show the dynamics of the canopy structure of the Mediterranean pioneer shrub Lavandula stoechas after man-made perturbation (i.e. grazing). The development of the vertical structure of the shrub was studied by harvesting the canopy of plants of 2–6 yr old in horizontal layers. The supportive biomass of the canopy was concentrated near the base at all ages. Leaf biomass was evenly distributed all over the vertical profile in 2- and 3-yr old plants. In 4-yr old plants it presented a maximum near the top of the canopy. For 5-yr old plants a structural transition started with leaf profiles showing a bimodal distribution. Leaf biomass predominated near the base in 6-yr old plants, suggesting that the transition was completed. Three canopy stages in the growth processes of the plant were recognized after the first year of growth: in the first one (from 2 to 3 yr old) both leaf and supportive biomass increased; in the second one (from 3 to 4 yr) leaf biomass remained stable and there was an increase in supportive biomass until the plants reached a ‘mature stage’, in 4-yr old plants; finally, in 5- and 6-yr old plants there was a decrease both in leaf and supportive biomass and plant structure showed evidence of senescence. Early transitions from seedling to 1-yr old plant and from this to 2- to 3-yr old plants were less obvious. The leaf/supportive biomass ratio always decreased with plant age, from 1.88 in seedlings to 0.01 in 6-yr old plants. Biomass density followed the pattern of supportive biomass, with an increase from 1.7 g/dm³ (2-yr old plants) to 2.4 g/dm³ (4-yr old plants). Thereafter, biomass density decreased to 0.6 g/dm³ (6-yr old plants).     

Effects of disturbance on the reproductive potential of Lavandula stoechas, a Mediterranean sclerophyllous shrub

Studies on the effects of perturbations on Mediterranean shrub vegetation have most often emphasized the role of disturbance by fire Here I report on the effects of a relatively mild (as opposed to burning) disturbance on Lavandula stoechas The study was carried out in two adjacent plots, one in which all shrub aboveground biomass had been eliminated mechanically two years before, the other with an intact layer of shrub Although the study species lacks developed underground organs, root sprouting ensued clearing and average interplant distance at the treated site was indistinguishable from that in the control area Average percent plant mass accounted for by living branches with leaves was significantly higher for rejuvenated, cleared-plot individuals, which also produced about twice as many flowering heads and seeds per head as their control-plot counterparts, along with heavier individual seeds Naturally occurring seedlings survived relatively better at the cleared plot, probably as a result of the joint effects of decreased litter cover, increased water availability, and higher growth rates The average fresh mass of one-year-old seedlings at the Open was 243 mg, vs 10 mg of shrub-plot seedlings No seedling survived the first summer drought out of ca 1000 seedlings that emerged from seed sown in a nearby, intact shrub stand It is hypothesized that mild, relatively local disturbance elicits competitive release, which has a major effect on both the fecundity of individuals and the demography of this species     

Variability of qualitative and quantitative secondary metabolites traits among wild genetic resources of Lavandula stoechas L.

Lavandula stoechas L. (Lamiaceae) is an attractive shrub native to the Mediterranean regions used for ornamental, melliferous, aromatic and medicinal purposes. Furthermore, this species presents an increasing interest in cosmetics, perfumery and pharmaceutical industries. The variability of qualitative and quantitative metabolic traits among nine wild germplasms representing the distribution area of this species in Tunisia was undertaken. A total of 45 essential oil components were identified in the aerial parts of the studied germplasms. The main essential oil components were camphor (15.32–50.63%), fenchone (6.57–34.70%), 1,8-cineole (0.05–13.45%) and γ-gurjunene (1.10–12.15%). In addition to the well known chemotypes camphor/fenchone and camphor/1.8-cineole, a new chemotype camphor/γ-gurjunene was detected in Tunisian L. stoechas L. Six phenolic acids (quinic acid, gallic acid, p-coumaric acid, 4,5-di-O-caffeoyquinic acid, salviolinic acid and trans cinnamic acid) and five flavonoids (luteolin-7-o-glucoside, naringin, apegenin-7-o-glucoside, quercetin and kampherol) were identified in the ethanolic extracts. Salviolinic acid (46.30–615.18 μg/g) and luteolin-7-o-glucoside (5.98–38.54 μg/g) were the most abundant phenolic compounds. A high significant phytochemical variability (p ˂ 0.01) in the accumulation of volatile and phenolic secondary metabolites among the studied germplasms was recorded. The conducted multivariate (PCA) and clustering (HCA) analyses revealed different classification pattern for essential oil and phenolic compounds. The detected phytochemical polymorphism among the investigated lavender ecotypes didn't show accordance with bioclimatic and geographical areas which suggests genetic background as the main explaining factor. The detected secondary metabolites polymorphism valorises Tunisian L. stoechas L. genetic resources as valuable plant material in further breeding programs. Moreover, an urgent in situ and ex situ conservation measures are required for these wild germplasms threatened by human over-harvesting practices and the occurring dramatic changes in climatic conditions.     

Interpreting recruitment limitation in forests

Studies of tree recruitment are many, but they provide few general insights into the role of recruitment limitation for population dynamics. That role depends on the vital rates (transitions) from seed production to sapling stages and on overall population growth. To determine the state of our understanding of recruitment limitation we examined how well we can estimate parameters corresponding to these vital rates. Our two-part analysis consists of (1) a survey of published literature to determine the spatial and temporal scale of sampling that is basis for parameter estimates, and (2) an analysis of extensive data sets to evaluate sampling intensity found in the literature. We find that published studies focus on fine spatial scales, emphasizing large numbers of small samples within a single stand, and tend not to sample multiple stands or variability across landscapes. Where multiple stands are sampled, sampling is often inconsistent. Sampling of seed rain, seed banks, and seedlings typically span <1 yr and rarely last 5 yr. Most studies of seeding establishment and growth consider effects of a single variable and a single life history stage. By examining how parameter estimates are affected by the spatial and temporal extent of sampling we find that few published studies are sufficiently extensive to capture the variability in recruitment stages. Early recruitment stages are especially variable and require samples across multiple years and multiple stands. Ironically, the longest duration data sets are used to estimate mortality rates, which are less variable (in time) than are early life history stages. Because variables that affect recruitment rates interact, studies of these interactions are needed to assess their full impacts. We conclude that greater attention to spatially extensive and longer duration sampling for early life history stages is needed to assess the role of recruitment limitation in forests.     

Essential oils from wild populations of Algerian Lavandula stoechas L.: composition, chemical variability, and in vitro biological properties

In an effort to develop local productions of aromatic and medicinal plants, a comprehensive assessment of the composition and biological activities of the essential oils (EOs) extracted from the aerial flowering parts of wild growing Lavandula stoechas L. collected from eleven different locations in northern Algeria was performed. The oils were characterized by GC‐FID and GC/MS analyses, and 121 compounds were identified, accounting for 69.88–91.2% of the total oil compositions. The eleven oils greatly differed in their compositions, since only 66 compounds were common to all oils. Major EO components were fenchone ( 2 ; 11.27–37.48%), camphor ( 3 , 1.94–21.8%), 1,8‐cineole ( 1 ; 0.16–8.71%), and viridiflorol ( 10 ; 2.89–7.38%). The assessed in vitro biological properties demonstrated that the DPPH‐based radical‐scavenging activities and the inhibition of the β‐carotene/linoleic acid‐based lipid oxidation differed by an eight‐fold factor between the most and the least active oils and were linked to different sets of molecules in the different EOs. The eleven EOs exhibited good antimicrobial activities against most of the 16 tested strains of bacteria, filamentous fungi, and yeasts, with minimum inhibitory concentrations (MICs) ranging from 0.16 to 11.90 mg/ml.     

Chemical Composition and Antifungal Activity of the Essential Oils of Lavandula pedunculata (Miller) Cav.

The chemical composition and antifungal activity of the essential oils of Lavandula pedunculata (Miller ) Cav. , harvested in North and Central Portugal, were investigated. The essential oils were isolated by hydrodistillation and analyzed by GC and GC/MS. The minimal‐inhibitory concentration (MIC) and the minimal‐lethal concentration (MLC) of the essential oils and of their major constituents were used to evaluate the antifungal activity against different strains of fungi involved in candidosis, dematophytosis, and aspergillosis. The oils were characterized by a high percentage of oxygenated monoterpenes, the main compounds being 1,8‐cineole (2.4–55.5%), fenchone (1.3–59.7%), and camphor (3.6–48.0%). Statistical analysis differentiated the essential oils into two main types, one characterized by the predominance of fenchone and the other one by the predominance of 1,8‐cineole. Within the 1,8‐cineole chemotype, two subgroups were well‐defined taking into account the percentages of camphor. A significant antifungal activity of the oils was found against dermatophyte strains. The essential oil with the highest content of camphor was the most active with MIC and MLC values ranging from 0.32–0.64 μl/ml.     

Essential Oil Compositions and Antibacterial and Antioxidant Activities of Five Lavandula stoechas Cultivars Grown in Thailand

The essential oils of five Lavandula stoechas cultivars grown in Thailand were characterized for their volatile compounds using GC‐FID and GC/MS methods as well as screened for antibacterial and antioxidant activities. Dried aerial parts, including flowers and stems from each cultivar, were subjected to hydrodistillation for 4 h. The essential oil yields were 0.18 %–0.82 % w/w. Of the 95 compounds detected and identified, 1,8‐cineole, fenchone, and camphor were considered the major compounds. Essential oil from each cultivar demonstrated different patterns of antibacterial activity and a variety of antioxidant properties. The highest antibacterial activity, MIC=0.39 mg mL^?1, was observed from the essential oil of L. stoechas ‘major’ (against Klebsiella pneumoniae and Salmonella typhimurium) and the essential oil of L. stoechas ‘white lavender’ (against S. typhimurium). The essential oil of L. stoechas×viridis ‘St. Brelade’ possessed the highest antioxidant capacity, as determined by the DPPH and ABTS assays (IC₅₀ of 67.65 and 89.26 mg mL^?1, respectively). The results indicated that some of these essential oils could be used as key ingredients in lavender oil products in Thailand to increase their therapeutic efficacy, depending on their intended application.     

Resource limitation and recruitment patterns in a coral reef fish assemblage

The potential effects of food and shelter availability on the recruitment and early survivorship of coral reef fishes were studied on St. Croix, U.S. Virgin Islands. The faunal assemblage studied included diurnally active fishes found in the “rubble/sand” habitat. The most abundant members were: beaugregory, Stegastes leucostictus (Muller & Troschel), goldspotted goby, Gnatholepis thompsoni Jordan, bridled goby, Coryphopterus glaucofraenum Gill, surgeonfishes, Acanthurus bahianus Castelnau and A. chirurgus (Bloch), and French grunt, Haemulon flavolineatum (Desmarest). Comparisons of recruitment to reefs constructed from substrata that varied in morphological characteristics showed that there were differences in the relative abundances of recruits attracted to and/or surviving on the different reef types. Juveniles of most species appeared to prefer the branching coral Porites porites (Pallas), which provided a large number of small crevices between the branches.Manipulations of the availability of shelter sites for fishes demonstrated that recruitment and/or early survivorship were strongly limited by the number of refuges. This result was found in six separate carried out during different years and in different seasons. Shelter site availability presumably limits fish populations through its effects on prédation rates.Experimental manipulations of food availability indicated that food does not directly influence settlement or early survivorship of coral reef fishes. However, it is probable that correlations between habitat characteristics and food availability have influenced the evolution of settling preferences.     

The xanthophyll cycle is induced by light irrespective of water status in field-grown lavender (Lavandula stoechas) plants

The water relations, the photosynthetic capacity and the pigment content of leaves, i.e. chlorophylls, carotenes and xanthophylls, were analysed during the summer drought and recovery after autumn rainfalls in lavender ( Lavandula stoechas L.) plants grown in Mediterranean field conditions. Summer drought caused photoinhibition of photosynthesis and significant decreases in chlorophylls (by ca 75%), β -carotene (by ca 65%), and lutein and neoxanthin (by ca 50%), although their contents remained unaltered between predawn and midday, suggesting a progressive decrease in response to drought. In contrast, the levels of violaxanthin decreased from predawn to midday, giving rise to enhanced formation of zeaxanthin and antheraxanthin in high light. Zeaxanthin and antheraxanthin formation was not induced by water deficit. Although the levels of photosynthetic pigments were severely affected by water deficit, carotenoids decreased less than chlorophylls, which resulted in increased levels of carotenoids per unit of chlorophyll. We conclude that the enhanced formation of zeaxanthin in high light and the increased levels of carotenoids per unit of chlorophyll observed in water-stressed plants may help to avoid photoinhibitory damage to the photosynthetic apparatus.     

Salt stress limitation of seedling recruitment in a salt marsh plant community

Summary Seedling recruitment in salt marsh plant communities is generally precluded in dense vegetation by competition from adults, but is also relatively rare in disturbance-generated bare space. We examined the constraints on seedling recruitment in New England salt marsh bare patches. Under typical bare patch conditions seed germination is severely limited by high substrate salinities. We examined the germination requirements of common high marsh plants and found that except for one notably patch-dependent fugitive species, the germination of high marsh plants is strongly inhibited by the high soil salinities routinely encountered in natural bare patches. Watering high marsh soil in the greenhouse to alleviate salt stress resulted in the emergence of up to 600 seedlings/225 cm². The vast majority of this seed bank consisted of Juncus gerardi, the only common high marsh plant with high seed set. We tested the hypothesis that salt stress limits seedling contributions to marsh patch secondary succession in the field. Watering bare patches with fresh water partially alleviated patch soil salinities and dramatically increased both the emergence and survival of seedlings. Our results show that seedling recruitment by high marsh perennial turfs is limited by high soil salinities and that consequently their population dynamics are determined primarily by clonal growth processes. In contrast, populations of patch-dependent fugitive marsh plants which cannot colonize vegetatively are likely governed by spatially and temporally unpredictable windows of low salinities in bare patches.     

Seed and microsite limitation of recruitment in plant populations

Summary Availability of seed and microsites, respectively, are two factors that potentially may limit recruitment in plant populations. Microsites are small-scale sites suitable for germination and survival of seedlings. We discuss this dichotomy of recruitment limitation both from a theoretical and empirical point of view. Investigations of recruitment in 14 woodland species showed that 3 species were seed limited, 6 species were limited by a combination of seed and microsite availability, and 5 species were found not to be seed limited, but the limiting factor was not identified. A combination of seed and microsite limitation implies that recruitment is promoted by increasing both seed and microsite availability. We suggest that the importance of seed limitation in plant populations has been underestimated, and that the operating limiting factors may be dependent on spatial and temporal scale. We expect that many species, if adequately studied, will turn out to be both seed and microsite limited. Experimental field studies that incorporate a range of seed and microsite densities in various spatial and temporal scales are needed to examine the extent to which plant populations are seed and microsite limited.     

Topsoil properties and seedling recruitment in Lavandula latifolia: stage-dependence and spatial decoupling of influential parameters

This paper investigates the influence of topsoil texture and chemistry on long‐term patterns of seedling recruitment in Lavandula latifolia (Labiatae), an evergreen Mediterranean shrub. The questions addressed are: (1) Are spatial patterns of seedling emergence and survival probabilities related to spatial variation in soil properties? (2) Are the two components of recruitment similarly influenced by the same soil parameters or, alternatively, are they influenced in different ways and/or by different soil parameters? (3) If the latter applies, then do the sets of soil parameters influencing emergence and survival show congruent patterns of spatial variation? Seed progenies from fourteen maternal families were sown at ten widely spaced field sites (between‐site distances in the scale of a few kilometers). Sites differed in average soil characteristics. There was also considerable variation in some soil parameters within sowing sites (distances between soil sampling points in the scale of meters). The seedling recruitment process was monitored for six years. Both the probability of one seed of L. latifolia giving rise to an emerged seedling, and the probability of an emerged seedling remaining alive six years past emergence and entering the juvenile age class, were significantly related to topsoil properties. Seedling emergence and survival tended to be influenced by largely non‐overlapping sets of soil properties that were related, respectively, to texture‐ and fertility‐related gradients. These two soil gradients tended to be uncorrelated at the scale of the study, and differed in the apportionment of variance among small (within sites) and large (between sites) spatial scales. While most variance in the emergence‐influencing, texture‐related gradient occurred at the between‐site scale, a considerably greater fraction of variance in the survival‐influencing, fertility‐related gradient occurred at the within‐site scale. It is suggested that, because of fine scale variability in soil fertility, local adaptations of L. latifolia to soil textural properties enhancing seedling emergence will be easier to evolve than adaptations to fertility‐related features enhancing seedling survival.     

Plant recruitment bottlenecks in temperate forest fragments: seed limitation and insect herbivory

Numerous studies have documented declines in plant diversity in response to habitat loss in fragmented landscapes. However, determining the mechanisms that lead to species loss is challenging using solely a correlative approach. Here we link correlative assessments of plant community composition with seed additions for a focal species to test the hypothesis that distributions of forests plants within a fragmented landscape are limited by seed dispersal. Woody plant species richness of fragments declined as fragments (n=26) became more isolated by agricultural fields. We predicted that if these isolation effects were driven by poor dispersal rather than other effects associated with habitat loss, then plants should vary in their response to isolation in relation to their seed size (i.e., stronger effects for plants with larger seeds). As predicted under this dispersal limitation hypothesis, sensitivity of bird-dispersed shrubs to isolation was related to their seed mass, with species with heavy seeds (e.g., Lindera benzoin) exhibiting stronger declines in presence across isolation gradients than species with light seeds. Seed addition experiments were performed for Lindera benzoin in two high isolation forest fragments (nearest neighbor mean distance=803 m) where Lindera was naturally absent, and two low isolation fragments (nearest neighbor mean distance=218 m) with naturally occurring Lindera populations. Seed addition and control plots (n=50 1 m² plots per fragment) were monitored for 13 censuses over 3 years. Across all four fragments, seed additions resulted in significant increases in Lindera seedling recruitment with no differences in final seedling establishment among fragments. However, insect herbivory was higher on Lindera seedlings in high isolation compared to low isolation fragments and was negatively correlated with seedling survival over some years. Consistent with prior work, our results confirm that seed dispersal plays a significant role in affecting plant diversity in fragmented landscapes. However, results also suggest the need for a better understanding of how additional processes, such as herbivory, may be altered as habitat is lost and what effects such changes have for forest plants.     

A comparative exploration of the phytochemical profiles and bio-pharmaceutical potential of Helichrysum stoechas subsp. barrelieri extracts obtained via five extraction techniques

We endeavoured to probe into and compare the possible effect(s) of different extraction techniques (accelerated solvent extraction (ASE), microwave-assisted extraction (MAE), ultrasonication-assisted extraction (UAE), maceration, and Soxhlet extraction (SE)) on the bioactivity (antioxidant and enzyme inhibitory activities) of the aerial parts of Helichrysum stoechas subsp. barrelieri (Ten.) Nyman. Total phenolic and flavonoid contents of the extracts obtained by different extraction methods followed the order of ASE > MAE > UAE > maceration > SE. Extract obtained by ASE was the most potent radical scavenger (219.92 and 313.12 mg Trolox equivalent [TE]/g, against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), respectively) and reducing agent (927.39 and 662.87 mg TE/g, for cupric reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP), respectively). Helichrysum stoechas extract obtained by UAE (18.67 mg ethylenediaminetetraacetic equivalent [EDTAE]/g) was the most active metal chelator and inhibitor of acetylcholinesterase (4.23 mg galantamine equivalent [GALAE]/g) and butyrylcholinesterase (6.05 mg GALAE/g) cholinesterase. Extract from maceration (183.32 mg kojic acid equivalent [KAE]/g) was most active against tyrosinase while ASE extract (1.66 mmol acarbose equivalent [ACAE]/g) effectively inhibited α-glucosidase. In conclusion, data amassed herein tend to advocate for the use of non-conventional extraction techniques, namely ASE and UAE, for the extraction of bioactive secondary metabolites from H. stoechas aerial parts.     

Diversity loss, recruitment limitation, and ecosystem functioning: lessons learned from a removal experiment

A five-year removal experiment in which plant functional group diversity was manipulated found strong limitation of ecosystem functioning caused by the differing abilities of remaining functional groups to recruit into space left unoccupied by the plants removed. We manipulated functional group diversity and composition by removing all possible combinations of zero, one, or two plant functional groups (forbs, C₃ graminoids, and C₄ graminoids), as well as randomly chosen biomass at levels corresponding to the functional group removals, from a prairie grassland community. Although random biomass removal treatments showed no significant effect of removing biomass in general on ecosystem functions measured ( P >0.05), the loss of particular functional groups led to significant differences in above- ( P <0.001) and belowground ( P <0.001) biomass, rooting-zone ( P =0.001) and leached ( P =0.01) nitrogen, nitrogen mineralization ( P <0.001), and community drought resistance ( P =0.002). Many of these differences stemmed from the marked difference in the ways remaining functional groups responded to the experimental removals. Strong recruitment limitation of C₄ graminoids resulted in large areas of open ground, high nutrient leaching, and high community drought resistance in plots containing just this functional group. In contrast, rhizomatous C₃ graminoids quickly colonized space and used soil resources made available by the removal of other groups, leading to lower soil nitrate in plots containing C₃ graminoids. These effects of recruitment limitation on ecosystem functioning illustrate possible effects of diversity loss not captured by synthetic experiments in which diversity gradients are created by adding high densities of seeds to bare soil.