The genus Racomitrium (Grimmiaceae) in Brazil, with the first report of R. subsecundum in South America

Four species of the moss genusRacomitrium Brid. are reported from Brazil:R. subsecundum (Harv.) Wils,R. didymum (Mont.) Lorentz,R. crispipilum (Taylor) A. Jaeger, andR. visnadiae W. R. Buck.Racomitrium subsecundum is reported for the first time from South America in Brazil and Colombia. The species is fully described and illustrated.Racomitrium didymum is recorded for the first time from Brazil; the specimens previously assigned toR. crispulum (Hook.f. & Wils.) Hook.f. & Wils. represent this species.Racomitrium cucullatifolium Hampe andR. crispulum (Hook. f. & Wils.) Hook.f. & Wils. are excluded from the Brazilian bryophyte flora. All Brazilian species ofRacomitrium are briefly assessed taxonomically and bryogeographically and illustrated, and a key to their determination is given. A lectotype is selected forGrimmia didyma Mont.     

Waterlogging duration: Interspecific comparison of Leptospermum scoparium (Forst et Forst.f.), Acacia melanoxylon (R. Br.), Nothofagus cunninghamii (Hook.) and Eucalyptus obliqua (L’Herit)

Abstract The effect of the duration of waterlogging on the pre‐dawn water potential, gas exchange, biomass accumulation and survival was investigated on four species, Leptospermum scoparium (Forst et Forst.f.), Acacia melanoxylon (R. Br.), Eucalyptus obliqua (L’Herit) and Nothofagus cunninghamii (Hook.). These species co‐occur, but are restricted to particular microsites. The three waterlogging treatments applied to potted seedlings were: four cycles of 15 days, two cycles of 30 days or one 60‐day cycle, followed by an equal period in freely drained conditions. Water potential, gas exchange, biomass accumulation and survival were not significantly affected by the duration of waterlogging in L. scoparium or A. melanoxylon. With increased waterlogging duration, N. cunninghamii had progressively decreased survival, had less biomass accumulation in all waterlogging treatments and more negative water potential after the 60‐day waterlogging cycle. In contrast, E. obliqua had low survival under the 15‐day waterlogging cycle treatment, although survival, biomass accumulation and maximum net photosynthesis were decreased by all waterlogging cycle treatments. Water potential was significantly lower (more negative) in E. obliqua than other species after the 30‐ and 60‐day waterlogging cycle treatments only. When exposed to oxygen deficit in hypoxic nutrient culture for 5 days, L. scoparium had 100% survival and maximum net photosynthesis was not affected. Acacia melanoxylon had 80% survival and decreased photosynthesis from 2 days of exposure onwards. Nothofagus cunninghamii and E. obliqua had 70% and 30% survival, respectively, and their photosynthesis was significantly depressed after 1 day of exposure to hypoxic conditions. Relative tolerance of the species examined to waterlogging and hypoxia was consistent with adaptation to conditions of seasonal variation in water table height and soil oxygenation concentration observed at the microsites occupied by the respective species. The results indicate that duration of waterlogging may be a major determinant in the microsite distribution of the co‐occurring species investigated.     

HEAVY METAL ACCUMULATION AND THE NATURE OF EDAPHIC ENDEMISM IN THE GENUS CALOCHORTUS (LILIACEAE)

Bulb and leaf tissues from five species in the genus Calochortus and the soils from collection sites were analyzed for cation and trace element concentrations. All five species, only three of which are considered ultramafic endemics, possessed high concentrations of nickel and copper in both the bulbs and leaves, but not at levels high enough (> 1% dry wt) to be considered hyperaccumulators. Only moderate to trace amounts of cobalt and chromium were detected in both plant tissues. Calcium-magnesium ratios, typically low in ultramafic soils and plants, were low in bulb tissue, but two to 10 times higher in leaf tissue. The ability to tolerate excessively high levels of nickel and other heavy metals may be a physiological exaptation of the genus Calochortus and not necessarily an evolutionary response by several species to life on an ultramafic substrate. The nature of “serpentine” endemism is discussed in the context of heavy metal accumulation by various plant species.     

Hyperaccumulation of nickel by Geissois species

Summary Herbarium specimens of 17 species of Geissois were analysed for nickel, cobalt, chromium and iron with a view to discovering further hyperaccumulators of nickel (>1000 g/g on a dry mass basis) in addition to the previously recordedG. pruinosa. A further six hyperaccumulators were discovered, all from New Caledonia. Unlike 90% of hyperaccumulators, Geissois is in Subclass Rosidae of the Magnioliate which it shares with three other hyperaccumulators (two species ofArgophyllum andPearsonia metallifera. The work highlights the remarkable concentration of hyperaccumulators in New Caledonia.     

Effetti del cobalto,nichel e cromo sulla germinazione di Alyssum,durante il ciclo di postmaturazione e invecchiamento

Abstract

Cobalt, nickel and chromium effects on germination of Alyssum, during after-ripening and aging. Cobalt (2.5–20mM), nickel (2.5–25mM) and chromium (0.2-1mM) effects have been studied in seeds of three species of Alyssum, of which two, A. bertolonii and A. argenteum, endemics to serpentine soils and one, A. nebrodense, closely related to the others but endemic to the Madonie (Sicily) where it grows on limestone.

The results, expressed as percentage of germinated seeds (p), Kotowski coefficient of velocity (v) and germination average ratio (pτ), have been subjected to statistical analysis.

The effect per mM is generally inhibitory, not significant for cobalt, weak but significant for nickel, more marked and significant for chromium, linearly correlated to concentration. The inhibition reaches its highest level when seeds are ripe, being significantly related to the control germination capacity (pτ).

The values of the specific inhibition (effect/mM modditppτ) for all the three species are higher for chromium, which is more toxic than nickel, and increase from A. nebrodense to A. argenteum, showing that of the two serpentine endemics A. bertolonii is more tolerant both to nickel and chromium.     

1064. Agapetes grandiflora Hook.f.: Ericaceae

A specimen of Agapetes from Myanmar is described and illustrated as Agapetes grandiflora Hook.f., as a result of comparison with A. burmanica W.E.Evans, A. macrantha (Hook.) Hook.f. and A. variegata (Roxb.) D.Don ex G.Don. This species has extrafloral nectaries on the margins of young leaves and at the apex of calyx lobes.     

A nickel-accumulating plant from Western Australia

Summary A small shrub Hybanthus floribundus (Lindl.) F. Muell. Violaceae growing in Western Australia accumulates nickel and cobalt to a very high degree. Values of up to 23% nickel in leaf ash may represent the highest relative accumulation of a metal on record. The high accumulation of nickel poses interesting problems in plant physiology and plant biochemistry.     

Response of mitochondria to light intensity in the leaves of sun and shade species

The present authors have shown previously that both respiration rates and in vivo activities of the alternative oxidase (AOX) of leaves of Alocasia odora, a shade species, are lower than those in sun species, thereby optimizing energy production under limited light conditions (Noguchi et al., Australian Journal of Plant Physiology 28, 27–35, 2001). In the present study, mitochondria isolated from A. odora leaves were examined in order to investigate the biochemical basis for the differences in respiratory parameters. Alocasia odora and spinach plants were cultivated under both high and low light intensities, mitochondria were isolated from their leaves, and their respiratory properties compared. Mitochondrial content of leaf extracts from the two species was estimated using fumarase activities and antibody detection of porin (the voltage-dependent anion channel of the outer mitochondrial membrane). On a mitochondrial protein basis, spinach leaves showed higher capacities of the cytochrome pathway and cytochrome c oxidase (COX) than A. odora leaves. However, on a mitochondrial protein basis, A. odora showed higher capacities of AOX, which had a high affinity for ubiquinone when activated by pyruvate. Alocasia odora also had larger amounts of mitochondrial protein per leaf dry weight, even under severely shaded conditions, than spinach. Lower growth light intensity led to lower activities of most pathways and proteins tested in both species, especially glycine-dependent oxygen uptake. In the low light environment, most of the AOX protein in A. odora leaves was in its inactive, oxidized dimer form, but was converted to its reduced active form when plants were grown under high light. This shift may prevent over-reduction of the respiratory chain under photo-oxidative conditions.     

林下引入耐阴树种功能性状特征及其与生长的关系

植物功能性状之间的协调性揭示了其适应特定生境的主要策略,而植物早期生长与功能性状可能具有很大关联性。为探讨林下引入耐阴树种的根、茎、叶功能性状协调性及其与生长的关系,研究了杉木人工林林下引入5种常绿阔叶树种（洒金叶珊瑚、杨桐、蚊母树、栀子和海桐）的生长率（树高和地径相对增长率）以及27个根茎叶形态、生理性状指标。结果表明：（1）由主成分分析（Principal component analysis,PCA）可知耐阴树种种间根茎功能性状关联更紧密。此外,种间根、茎性状的变异系数均小于叶面积;（2）耐阴树种种间和种内关键性状与生长率网络关联性差异较大。在种间水平上,生长率与大部分叶性状显著正相关,与根茎性状多为显著负相关;在种内水平上,关键性状与生长率关系网更加复杂;（3）树高相对增长率是种间和种内关系网中心性最高的生长率指标。种间中心性最高的性状指标是叶面积;叶、茎生物量占比和根干物质含量是种内中心性最高的性状指标。但只有叶面积与树高相对增长率在种间和种内均显著正相关,因此,叶面积更适合作为指示林下耐阴树种生长率变化的性状。总体上,耐阴树种叶性状对生长率的调控要强于根茎性状,其中引入较大叶面积的常绿阔叶树种可能更有利于杉木纯林的人促更新和高效复层林的构建。     

Changes in growth of two C4 grasses (Schizachyrium scoparium and Paspalum plicatulum) in monoculture and mixture: influence of soil depth

The growth of Schizachyrium scoparium (Michx.) Nash (little bluestem) and Paspalum plicatulum Michx. (brownseed paspalum), two C₄ grasses, was examined in monoculture and in mixed culture in three soil depths. Effects of soil depth and competition were both significant. Growth of both species increased as soil depth increased from 30 to 180 cm in pot experiments. However, P. plicatulum dry mass increased approximately four times more than S. scoparium as soil depth increased. Schizachyrium scoparium dry mass was always greater in monoculture while P. plicatulum dry mass was always greater in mixture. Significant interspecific competition was not measured in the shallow soil treatment (30 cm) suggesting equal competition. Significant interspecific competition was measured in the deeper soil treatments (90 and 180 cm), and P. plicatulum dry mass was clearly greater in mixtures in the two deeper soils. Paspalum plicatulum does not appear to prevent the growth of S. scoparium roots in the deeper soil, but seems able to exploit deeper soil resources by proliferating roots at depths where S. scoparium roots do not seem capable of growth.     

西藏墨脱悬钩子属植物小志

该文在野外调查、标本采集、标本查阅与鉴定及文献考证的基础上,对西藏墨脱县产的蔷薇科悬钩子属植物进行了系统整理。结果表明:目前发现该区共有悬钩子属植物28种4变种,其中Rubus lineatus Reinw. var. glabrior Hook. f.为中国分布新记录植物,小柱悬钩子(R. columellaris Tutcher)、红毛悬钩子(R. wallichianus Wight et Arn.)、独龙悬钩子(R. taronensis C. Y. Wu ex T. T. Yu et L. T. Lu)和疏松悬钩子(R. efferatus Craib)为西藏分布新记录植物。该文还对《中国植物志》和Flora of China中该属部分学名的不恰当使用进行了探讨。     

Land‐use legacies and present fire regimes interact to mediate herbivory by altering the neighboring plant community

Past and present human activities, such as historic agriculture and fire suppression, are widespread and can create depauperate plant communities. Although many studies show that herbivory on focal plants depends on the density of herbivores or the composition of the surrounding plant community, it is unclear whether anthropogenic changes to plant communities alter herbivory. We tested the hypothesis that human activities that alter the plant community lead to subsequent changes in herbivory. At 20 sites distributed across 80 300 hectares, we conducted a field experiment that manipulated insect herbivore access (full exclosures and pseudo‐exclosures) to four focal plant species in longleaf pine woodlands with different land‐use histories (post‐agricultural sites or non‐agricultural sites) and degrees of fire frequency (frequent and infrequent). Plant cover, particularly herbaceous cover, was lower in post‐agricultural and fire suppressed woodlands. Density of the dominant insect herbivore at our site (grasshoppers) was positively related to plant cover. Herbivore access reduced biomass of the palatable forb Solidago odora in frequently burned post‐agricultural sites and in infrequently burned non‐agricultural woodlands and increased mortality of another forb (Pityopsis graminifolia), but did not affect two other less palatable species (Schizachyrium scoparium and Tephrosia virginiana). Herbivory on S. odora exhibited a hump‐shaped response to plant cover, with low herbivory at low and high levels of plant cover. Herbivore density had a weak negative effect on herbivory. These findings suggest that changes in plant cover related to past and present human activities can modify damage rates on focal S. odora plants by altering grasshopper foraging behavior rather than by altering local grasshopper density. The resulting changes in herbivory may have the potential to limit natural recovery or restoration efforts by reducing the establishment or performance of palatable plant species.     

Productivity and Subordinate Species Response to Dominant Grass Species and Seed Source during Restoration

Grasses can be important regulators of species diversity and ecosystem processes in prairie systems. Although C₄ grasses are usually assumed to be ecologically similar because they are in the same functional group, there may be important differences among species or between seed sources that could impact restorations. I tested whether C₄ grass species identity, seed source, or grass species richness scales to influence aboveground net primary productivity (ANPP), resistance to weed invasion, or establishment of subordinate prairie species during restoration. Plots in western Iowa, United States, were planted with equal‐sized transplants of one of five common grass species (Panicum virgatum L., Sorghastrum nutans (L.) Nash, Andropogon gerardii Vitman, Schizachyrium scoparium (Michx.) Nash, and Bouteloua curtipendula (Michx.) Torrey) either from local seed or from cultivar seed sources. These plots were compared to plots containing all five species in mixture and to nonplanted plots. Differences in ANPP were found among species but not between cultivars and noncultivars or between monocultures and mixtures. Panicum virgatum, S. nutans, and S. scoparium were more productive than A. gerardii and B. curtipendula. Weed invasion was much higher when plots were not planted with grasses. Schizachyrium scoparium allowed greater establishment of subordinant prairie species than all other focal grass species. There were two separate mechanisms by which grasses suppressed prairie species establishment either (1) by growing tall and capturing light or (2) by quickly filling in bare space by spreading horizontally through rhizome growth in short species. These results suggest that high ANPP can be found with noncultivar plantings during the first 2 years after planting and that subordinate species establishment is most likely when shorter bunchgrasses such as S. scoparium are dominant.     

Phytoextraction of Soil Cobalt Using Hyperaccumulator Plants

A greenhouse study was conducted on phytoextraction of cobalt by nickel hyperaccumulators Alyssum murale and Alyssum corsicum and by two varieties of cobalt accumulator Nyssa sylvatica compared with the nonmetal accumulator crop plant Brassica juncea. The plants were grown on Sassafras sandy loam soil (<2 mg Co and 5 mg Ni/kg dry soil), amended with 1 mmol Co/kg dry soil (58.9 mg/kg), and two Ni smelter-contaminated soils, Quarry muck with 24 mg Co and 1720 mg Ni/kg dry soil and Welland loam with 37 mg Co and 2570 mg Ni/kg dry soil. All soils were adjusted to pH 6.5 to prevent Ni phytotoxicity. Of the five plant entries tested in the study, the two Alyssum species demonstrated the most promising Co phytoextraction results. In Co-amended Sassafras soil, the maximum concentration accumulated by Alyssum murale was 1320 mg Co/kg dry weight, which was almost 60 times higher than accumulation by crop plant Brassica juncea. At a single harvest after 60 days of growth, A. murale was able to extract more than 3% of Co from Co-amended soil. As expected, both Alyssum species accumulated up to 1% Ni on dry weight basis when grown on Ni-contaminated soils.

Nyssa sylvatica showed considerable Co accumulation; foliar Co concentration in the second harvest was as high as 800 mg/kg dry weight. The first few leaves that emerged were chlorotic, both in the Co-amended soil and Ni-contaminated soils, but with growth the signs of toxicity disappeared. In the Co amended soil, Co concentration in Nyssa sylvatica leaves was 30% of that found in shoots of Alyssum species, but an order of magnitude higher than that of Brassica juncea. The leaves accumulated a higher concentration compared with the stems.

Both Alyssum species and Nyssa sylvatica offer promise for phytoextraction of Co and ⁶⁰Co from contaminated or mineralized soils.     

中国算盘子属(叶下珠科)一些种的分类学处理

算盘子属(Glochidion J.R.G.Forst.)是叶下珠科(Phyllanthaceae)叶下珠族(Phyllantheae)中一个分类极为困难的类群。基于广泛野外考察与馆藏标本查阅,对中国该属部分物种进行分类学处理。其中,长柱算盘子[G.khasicum(Müll.Arg.)Hook.f.]与倒卵叶算盘子(G.obovatum SieboldZucc.)在中国的分布予以排除,菲岛算盘子[G.philippicum(Cav.)C.B.Rob.]在中国被发现仅分布于台湾地区;G.bodinieri H.Lév.,G.pseudo-obscurum var.glabrum Pamp.与G.pseudo-obscurum var.lanceolatum Pamp.这三个名称被处理为湖北算盘子(G.wilsonii Hutch.)的新异名;G.vaniotii H.Lév.被排除在算盘子属外,并接受为芸香科臭常春(Orixa japonica Thunb.)的异名。另外,对G.khasicum(Müll.Arg.)Hook.f.,G.obovatum SieboldZucc.,G.philippicum(Cav.)C.B.Rob.,G.pseudo-obscurum var.lanceolatum Pamp.及G.wilsonii Hutch.这五个名称进行了后选模式的指定。     

Re-examination of the elemental composition of some Caryophyllaceae on North American ultramafic soils

A paper of Kruckeberg et al. (1993) reported the hyperaccumulation of nickel by Arenaria rubella at an ultramafic site at Olivine Bridge in the state of Washington, USA. Several aspects of the publication led the present authors to doubt the reliability of the data, leading to a reinvestigation of the behaviour of this species at this site. Extensive sampling of two species of the Caryophyllaceae, A. rubella and Cerastium arvense, was then carried out at Olivine Bridge in two different years, together with the collection of soil samples. The plant samples were treated in various ways in an attempt to reduce the potential influence of soil contamination. The results of this work indicate that A. rubella and C. arvense both behave in a normal way in respect of their nickel uptake from ultramafic soil. The elements nickel, iron, cobalt, chromium and magnesium have been found at levels only 1/10–1/100 of those reported in the earlier work. The weaknesses in the earlier study have led to a consideration of several aspects of putative nickel hyperaccumulation, especially as applied to species in the Caryophyllaceae. Particularly important are washing procedures, selection of material for analysis, and the use of various criteria for assessing the likelihood of soil contamination of plant samples. A careful re-examination of several other reported cases of nickel hyperaccumulation by members of the Caryophyllaceae is now recommended.     

Distribution of low molecular weight carbohydrates in the subgenusCeratotropis of the genusVigna (Leguminosae)

The seeds of 9 members of the subgenusCeratotropis (Piper) Verdc., namelyVigna aconitifolia (Jacq.) Maréchal,V. angularis (Willd.) Ohwi et Ohashi,V. minima (Roxb.) Ohwi et Ohashi,V. nakashimae (Ohwi) Ohwi et Ohashi,V. reflexo-pilosa Hayata,V. umbellata (Thumb.) Ohwi et Ohashi,V. mungo (L.) Hepper,V. radiata (L.) Wilczek andV. sp., have been examined. On their low molecular weight carbohydrate compositions, this subgenus has been divided into 2 subgroups, mungo-radiata group and angularis group. Four other species referred to the subgeneraPlectotropis (Schumach.) Bak.,Lasiospron (Benth. emend Piper) Maréchal, Mascherpa et Stainier andVigna, V. vexillata (L.) A. Rich.,V. lasiocarpa (Benth.) Verdc.,V. marina (Burm.) Merr. andV. unguiculata (L.) Walp., were also analyzed and they had distinctive carbohydrate compositions. 1d-4-O-methyl-myo-inositol and 1d-5-O-(α-d-galactopyranosyl)-4-O-methyl-myo-inositol were detected in all species examined exceptV. vexillata, V. mungo andV. radiata.     

Assessment of cytogenetic damage in lymphocytes and in exfoliated nasal cells of dental laboratory technicians exposed to chromium, cobalt, and nickel

Dental laboratory technicians may be exposed to metal alloys that are used in the production of crowns, bridges and removable partial dentures. These alloys consist of 35–65% cobalt, 20–30% chromium, 0–30% nickel, and small amounts of molybdenum, silica, beryllium, boron and carbon. The aim of this study was to assess whether dental technicians are occupationally exposed to chromium, cobalt and nickel, by analyzing urinary excretion levels of these metals and to investigate the genotoxic effects of occupational exposure associated with dental prostheses production operations by analyzing cytokinesis-blocked micronucleus (CB-MN) frequencies in peripheral lymphocytes and micronucleus (MN) frequencies in exfoliated nasal cells from 27 dental laboratory technicians and 15 control subjects. The differences in the urinary excretion of metals between technicians and controls were statistically significant. The mean (±S.D.) CB-MN frequencies (‰) in peripheral lymphocytes were 4.00 (±2.98) among the dental technicians and 1.40 (±1.30) among the controls, a statistically significant difference (P<0.005). The mean (±S.D.) MN frequencies (‰) in nasal cells were 3.50 (±1.80) among the dental technicians and 1.19 (±0.53) among the controls, which was also a statistically significant difference (P<0.005). There was a significant correlation between duration of exposure and MN frequencies in lymphocytes (r=0.642, P<0.01), but not in nasal cells of technicians. Our data reveal that in vivo exposure to chromium, nickel and cobalt metals is evident and that this occupational exposure may contribute to the observed genotoxic damage in two types of cells, e.g. lymphocytes and exfoliated nasal cells. However, it cannot be determined which compound(s) are responsible for the genotoxic damage observed in this study.     

Microbial biomass,respiration and diversity in ultramafic soils of West Dome,New Zealand

Ultramafic soils are colonised by plant communities adapted to naturally elevated heavy metal content but it is not known whether soil microbial communities are similarly adapted to heavy metals. We measured microbial properties of six ultramafic soils that ranged in heavy metal content to test whether microbial diversity would decrease and respiratory quotient (microbial respiration:biomass) increase due to the stress imposed by increasing metal content. Soil samples were collected from beneath Nothofagus solandri var. cliffortioides tall forest, tall Leptospermum scoparium shrubland, open Leptospermum scoparium shrubland, an open Leptospermum scoparium shrubland with the rare ultramafic endemic Celmisia spedenii, a mixed divaricate shrubland, and a red tussock (Chionochloa rubra) grassland on the Dun Mountain Ophiolite belt, New Zealand. Samples were analysed for catabolic evenness using the catabolic response profile technique, microbial biomass, microbial respiration, and soil properties (pH, total carbon, total nitrogen, magnesium and total or extractable chromium and nickel). The sites differed in base saturation, pH and concentrations of metals, particularly magnesium, chromium and nickel, properties that are a major determinant of the plant communities that develop. Microbial biomass and respiration, catabolic evenness (range of 19.1 to 22.7) and the respiratory quotient were not correlated to any of the measured soil chemical properties. Factor analysis of the respiratory responses showed that the microbial communities under each vegetation type were distinct. The second factor extracted was correlated to total carbon (r ²=0.62, P<0.01), basal respiration (r ²=0.55, P<0.01) and microbial biomass (r ²=0.65, P<0.01). Increasing metals concentrations had no direct impact on microbial diversity, biomass, respiration or community energetics. However, we suggest that metal concentrations may have exerted an indirect effect on the structure of the microbial communities through control of the vegetation community and litter inputs of carbon to the soil.     

Woody plant encroachment reduces species richness of herb‐rich woodlands in southern Australia

Abstract Woody plants have been increasing in many woodland and savanna ecosystems owing to land use changes in recent decades. We examined the effects of encroachment by the indigenous shrub Leptospermum scoparium (Myrtaceae) on herb‐rich Eucalyptus camaldulensis woodlands in southern Australia. Species richness and compositional patterns were examined under the canopy of L. scoparium and in surrounding open areas to determine the species most susceptible to structural changes. Richness was significantly lower in areas of moderate to high L. scoparium cover (>15%), suggesting that a threshold shrub cover caused major change in this ecosystem. Shrubs were associated with a significant reduction in above‐ground biomass of the ground‐layer flora and a significant shift in community composition. The few species that were positively associated with high L. scoparium cover were also common in the woodland flora; no new species were recorded under the shrub canopy. Important environmental changes associated with L. scoparium cover were decreased light availability and increased litter cover, which were likely a consequence of encroachment. Leptospermum scoparium cover was also associated with greater surface soil moisture, which may be a consequence of increased shading under the shrub canopy or indicate favourable soil conditions for L. scoparium establishment. Reductions in species richness and abundance of the germinable seed bank were found in soil samples taken from under L. scoparium. With ongoing recruitment of L. scoparium and consequent increases in shrub cover, ground‐layer diversity in these species‐rich woodlands should continue to decline over time.