How well does a botanical garden collection of a rare palm capture the genetic variation in a wild population?

Conservation is increasingly central to the botanic garden mission. Living plant collections are important components of conservation. Critical evaluation of living conservation collections with population genetic analysis can directly inform ex situ conservation strategy. Here, we quantify the degree of genetic variation captured through a population-based collection protocol, and explore optimal sampling for ex situ conservation. An extensive living collection derived from one population of Leucothrinax morrisii (Arecaceae) provided a model system. We compared 58 specimens from the ex situ collection with 100 individuals from throughout the parent population via 6 ISSR loci. Random bootstrapped resamples of the data were made to model differently structured ex situ collections. Mean diversity (He) differed little between the collection (0.204) and the population (0.216), and genetic distance (D) was very close (0.036). Very few private alleles were found between the collection and the population. Allelic capture, as measured by percent of private alleles, was greater than 94%. Resampled collections of different sizes captured from 48% to 94% of alleles. Pairwise comparison of bootstrapped resamples suggests that increasing the representation of half-sibling groups does not significantly increase allele capture. Increase in allele capture with increasing sample size is greatest at low resample sizes, and showed diminishing returns as resample size increased. No appreciable increase in allele capture was gained through maintaining different half-sibling groups. These data inform sampling for ex situ conservation purposes, and recommend sample sizes of at least 15 individuals, with the upper limit based on resources.     

Variations in the soil microbial community composition of a tropical montane forest ecosystem: Does tree species matter?

We investigated tree species effects on the soil microbial community in the tropical montane forest on Mt. Kinabalu, in Malaysian Borneo. We investigated microbial composition (lipid profile) and soil physicochemical parameters (pH, moisture, total C, N and phenolics concentration) in top 5-cm soils underneath two conifers (Dacrycarpus imbricatus and Dacrydium gracilis) and three broad-leaves (Lithocarpus clementianus, Palaquium rioence and Tristaniopsis clementis). We found that the primary difference in microbial composition was between conifer versus broad-leaves. The abundance of specific microbial biomarker lipids correlated with soil pH, total C and N. We conclude that tree species have significant impacts on the soil microbial community through their effects on soil pH, total C and N.     

How the deadwood of different tree species in various stages of decomposition affected nutrient dynamics?

Purpose

The aim of the study was to estimate how the deadwood of different tree species in various stages of decomposition affected nutrient dynamics.

Materials and methods

The deadwood of eight species (common alder, common aspen, common ash, silver fir, pedunculate oak, Norway spruce, common hornbeam and silver birch) was selected. Three logs from each species in the third, fourth and fifth decay classes were chosen for analysis. Wood in the third decay class was characterised by larger hard fragments, fragmented bark and no branches; in the fourth decay class, it was characterised by small pieces and a fragmented bark; and in the fifth decay class, it was characterised by a soft texture and no bark. The investigation was carried out in the Czarna Rózga Reserve in Central Poland. Tension lysimeters were installed under each log in the humus horizon. The water samples collected from tension lysimeters were chemically analysed in the laboratory. The water chemistry was analysed by means of ion chromatography using a DIONEX ICS 5000 unit.

Results and discussion

The leachate obtained from different tree species contained different ion concentrations. The high similarity of the concentration of total anions and statistically significant differences in the content of total cations were determined in the leachate from the wood of coniferous and deciduous species. The concentration of the cations increases with the advancement of the decomposition level. A general linear model analysis demonstrates that wood species and the decomposition classes are of equal importance in defining the ion composition of the filtrate leaching from deadwood.

Conclusions

Wood at the highest decomposition stage releases more ions to the surface soil layers than wood at the lower decay class. An exception from the rule is the wood of birch, which in the III decay class releases more ions than in its higher decay classes. When comparing the ionic composition of leachate released from wood of coniferous and deciduous tree species, the latter are characterised by higher cation concentrations in comparison with coniferous species. Among the deciduous species, wood of such species as ash, hornbeam, aspen, birch and alder has the most favourable effects on the soil surface horizons through its supply with ionic substances. The ash wood releases high amounts of calcium, hornbeam wood releases magnesium and sodium, and aspen releases calcium, potassium and nitrate anion. From the analysed coniferous species, fir wood has a more favourable effect in terms of ion release to soil than spruce wood.

     

How effectively does a single or continuous iron supply affect the phosphorus budget of aerated lakes?

Purpose

In lake restoration, the redox sensitivity of iron (Fe)?Cphosphorus (P) compounds has been regarded as detrimental for a sustainable increase in sedimentary P retention since developing low redox potentials release Fe-bound P. Thus, Fe salts alone have rarely been used successfully to inactivate sediment P, and there are no studies on the long-term effects of in-lake Fe applications on P retention. Here, we analyzed for how long, and how efficiently, a single and continuous Fe application can affect the P budget of lakes.

Materials and methods

Two aerated lakes in Berlin, Germany were compared: Lake Tegel (TEG) experienced a continuous Fe supply via its tributaries, while Lake Gro?-Glienicke (GGS) was treated once with Fe in the winter of 1992/1993. By controlling the operation of aerators, their effectiveness on P exchange at the sediment?Cwater interface (non-aerated vs. aerated) was directly compared in spring and autumn between 2008 and 2010. The amount of P controllable by aeration (P _control) was experimentally determined by non-aerated vs. aerated sediment cores (at 10 and 16?°C). Core stratigraphy of Fe was observed by high-resolution ??X-ray fluorescence analysis.

Results and discussion

In TEG, the mobility of Fe was limited due to its sulfidic fixation, and thus Fe only accumulated slightly at the sediment surface (Fe/P ratio, ??3). P _control corresponded to only 4?% of the P content of the lake and 18?% of P loading. Hence, aeration only slightly influenced trophy-relevant epilimnetic P. In GGS, the single Fe application still ensures a high P binding ability of sediment since Fe relocated towards the surface (Fe/P ratio, ??7). P _control corresponded to 38?% of the P content of the lake and 74?% of annual P loading. Thus, the P release is not relevant for the P supply to the epilimnion since with the lake??s overturn P is co-precipitated by the hypolimnetically accumulated Fe.

Conclusions

When external P loading is sufficiently reduced, as in GGS, amendments to Fe precipitants can increase sediment P retention in a redox-dependent manner over the long term. Thus, the redox-dependent mobility of Fe should no longer be regarded as a disadvantage of Fe-containing precipitants. To compensate for co-precipitation and complexation of Fe with sediment organic matter, a high Fe dosage (??200?g?m^?2) is needed.     

How do AMF-inoculation and supplemental irrigation affect the productivity of rainfed yellow sweet clover in agrisilviculture systems?

ABSTRACT

Yellow sweet clover (Melilotus officinalis L.) was assessed for its yield in an agri-silvicultural model of the plum (Prunus domestica (L.) cv. Opal). The treatments included two sun light exposures (morning light and afternoon light) as main plots and species of arbuscular mycorrhizal fungi (AMF) (Funneliformis mosseae, Rhizophagus irregularis and no-AMF-inoculated control) as subplots. The treatments were separately arranged for two irrigations (rainfed and supplemental irrigation) during 2016–2017. In irrigated and AMF-inoculated plants, a significant increase was observed in the performance of yellow sweet clover (dry weight and biological yield), seed nutrients (phosphorus and potassium) and weight of aerial parts in morning light conditions as much as rainfed conditions, identically for two species of fungi. In both rainfed and supplemental irrigations, the biological yield of F. mosseae inoculated plants increased by up to 23%. In supplemental irrigation, the maximum growth of plant height and relative water content were obtained from AMF-inoculated plants (R. irregularis) in afternoon light area as much as rainfed condition. In conclusion, the identical beneficial effects of mycorrhizal fungi species were enhanced by single supplemental irrigation. However, plant performance, including the quality and quantity of yield, was superior in the morning light part of each treatment.     

Are the declining trends in forest grouse populations due to changes in the forest age structure? A case study of Capercaillie in Finland

In Finland, Capercaillie (Tetrao urogallus) populations have a history of serious decrease starting from the mid-20th century. The decline is temporally in line with the expansion of modern forestry practices that created major changes in the landscape. We used tetraonid route-censuses from 18 forestry board districts and Finnish forest inventories (data on forest stand structure) to analyze the decline in 1965-1988. We used information theoretical model selection to evaluate a set of log-linear second order autoregressive models, allowing for spatially correlated process errors. The average trend throughout the country corresponded to an annual decline of 4.01% (mean of local trends) ± 0.24% (SEM), parallel to a half-life of 17 years. The decline was surprisingly uniform throughout the country (SD = 1.01%) and most parsimoniously explained by a geographically constant log-linear trend. At the large scale of observation applied here, population trends could not be explained by the proportional increase of younger forest age classes (<40 years old and <80 years old, respectively). Our analysis does not support the hypothesis that the decline in Capercaillie numbers is due to changes in the forest age structure, but we cannot exclude the possibility that other factors behind the decline may have interacted with forestry in general. From a conservation point of view, we caution against over-emphasizing the role of forest age especially at large spatial scales, but leaning also on other research, we recommend that more management efforts would go into the preservation of the overall forest cover and the original physiognomy in single forest patches.     

Do secondary forests act as refuges for old growth forest animals? Recovery of ant diversity in the Atlantic forest of Brazil

The extent to which secondary forests occupying degraded and abandoned lands provide suitable habitat for forest-adapted species is an important conservation issue in times of vanishing old growth forests. We used ants (Hymenoptera: Formicidae), a functionally important and diverse group of invertebrates, to investigate the recovery of soil taxa during secondary forest succession in the Atlantic Forest of Southern Brazil. We compared the resilience of epigeic vs. hypogeic ant assemblages. For this purpose we established 27 sites that encompassed a chronosequence from pastures to old growth forests on two contrasting soil types. Our results are based on a collection of 35 508 individuals in 40 genera.Richness and composition of ant assemblages in secondary forests have recovered slowly and have not approached conditions typical of old growth forests. The distribution of genera along the successional stages was arranged in a nested pattern where ant genera of younger successional stages were a subset of genera present in older stages. Edaphic conditions had no influence on the recovery process. Overall, richness of ants was lower at study sites with water-logged soils than at sites where soils did not exhibit hydromorphic properties. The hypogeic ant assemblage recovered more slowly than the epigeic assemblage.Our results show that secondary forests do not act as refuges for many forest-adapted animals which are currently restricted to discontinuous patches of old growth forest in the highly endangered Atlantic Forest of Brazil. Moreover, estimated recovery times of 50 to several hundred years suggest it would take much longer than previously presumed for complete recolonization.     

How does the application of different nitrification inhibitors affect nitrous oxide emissions and nitrate leaching from cow urine in grazed pastures?

Nitrous oxide (N₂O) is a potent greenhouse gas, and nitrate () is a water contaminant. In grazed grassland, the major source of both leaching and N₂O emissions is nitrogen (N) deposited in animal excreta, particularly in the urine. The objective of this study was to determine the effectiveness of two nitrification inhibitors: (i) a solution of dicyandiamide (DCD) and (ii) a liquid formulation of 3,4‐dimethylpyrazole phosphate (DMPP) for reducing N₂O emissions and leaching from urine patch areas in two grazed pasture soils under different environmental conditions. In the Canterbury Templeton soil, the nitrification rate of ammonium from the animal urine applied at 1000 kg N/ha was significantly decreased by the application of DCD (10 kg/ha) and DMPP (5 kg/ha). N₂O emissions, measured over a 3‐month period, from dairy cow urine applied to the Canterbury Templeton soil were 1.14 kg N₂O‐N/ha, and this was reduced to 0.43 and 0.39 kg N₂O‐N/ha by DCD and the liquid DMPP, respectively. These are equivalent to 62–66% reductions in the total N₂O emissions. Nitrate leaching losses from dairy cow urine applied to the Waikato Horotiu soil lysimeters were reduced from 628.6 kg ‐N/ha to 400.6 and 451.5 kg ‐N/ha by the application of DCD (10 kg/ha) or DMPP (1 kg/ha), respectively. There was no significant difference between the DCD solution and the liquid DMPP in terms of their effectiveness in reducing N₂O emissions or leaching under the experimental conditions of this study. These results suggest that both the liquid formulations of DCD and DMPP have the potential to be used as nitrification inhibitors to reduce N₂O emissions and leaching in grazed pasture soils.     

Nitrogen availability and leaching during the terrestrial phase in a várzea forest of the Central Amazon floodplain

Availability and leaching of dissolved inorganic N (DIN = NH₄⁺ + NO₃^-) in soil were measured in a periodically flooded forest of the Central Amazon floodplain (várzea) during one terrestrial phase. Special emphasis was on the effects of a legume and a non-legume tree species. NH₄⁺-N accounted for more than 85% of DIN even at the end of the terrestrial phase although it decreased throughout the experimental period. While extractable NO₃^–-N was always low in the soil (less than 15% of DIN), the amount of leached NO₃^–-N was in the same range as NH₄⁺-N. Under the legume trees mean DIN contents of the topsoil were higher than under the non-legume trees. DIN leaching from the topsoil (0–20 cm) was significantly higher under the legume trees than at the other sites, also indicating a higher N availability. Therefore, despite considerable leaching legume trees may be an important source of N supporting a high biomass production of the várzea forest.     

How do grassland management history and bacterial micro-localisation affect the response of bacterial community structure to changes in aboveground grazing regime?

In a context of frequent intensification or de-intensification of management in grasslands, a better understanding of how quickly soil microbiota responds to changes in management is required. The kinetics of changes in the structure of the bacterial community (using ribosomal intergenic spacer analysis) was studied in grassland mesocosms after changes of aboveground grazing regime, taking into account bacteria micro-localisation by separating the bacteria located inside stable aggregates (inner soil fraction) and the bacteria easily washed out, i.e. mainly located in macropores (outer soil fraction). Four treatments were used: (i) control grazed mesocosms, (ii) control ungrazed mesocosms, (iii) application of grazing on previously ungrazed mesocosms, (iv) cessation of grazing on previously grazed mesocosms. Each grazing event was simulated by application of synthetic sheep urine and plant clipping. Application of grazing led to a change in the structure of the whole soil bacterial community within 5 months, whereas changes were observed only 12 months after cessation of grazing. Changes in plant species composition and soil organic carbon content observed after cessation of grazing were found to be possible drivers of the changes in the bacterial community structure. However, after application of grazing, changes of the bacterial community structure occurred prior to changes in plant species composition and soil organic carbon content, suggesting that supply of urine and/or impact of labile carbon were likely the main drivers of changes. After 12 months, the application of grazing significantly affected the bacterial community structure in both inner and outer soil fractions. Conversely, 12 months after cessation of grazing, community structure was affected only for bacteria located in the outer fraction. This study shows that the bacterial community structure responded faster and more deeply after application than after cessation of grazing, and may be driven by different environmental factors between both scenarios. This study also shows that, 2 years after the changes in grazing regime, the bacterial community structure was determined by both the past and new grazing regimes.     

How relevant is recalcitrance for the stabilization of organic matter in soils?

Traditionally, the selective preservation of certain recalcitrant organic compounds and the formation of recalcitrant humic substances have been regarded as an important mechanism for soil organic matter (SOM) stabilization. Based on a critical overview of available methods and on results from a cooperative research program, this paper evaluates how relevant recalcitrance is for the long‐term stabilization of SOM or its fractions. Methodologically, recalcitrance is difficult to assess, since the persistence of certain SOM fractions or specific compounds may also be caused by other stabilization mechanisms, such as physical protection or chemical interactions with mineral surfaces. If only free particulate SOM obtained from density fractionation is considered, it rarely reaches ages exceeding 50 y. Older light particles have often been identified as charred plant residues or as fossil C. The degradability of the readily bioavailable dissolved or water‐extractable OM fraction is often negatively correlated with its content in aromatic compounds, which therefore has been associated with recalcitrance. But in subsoils, dissolved organic matter aromaticity and biodegradability both are very low, indicating that other factors or compounds limit its degradation. Among the investigated specific compounds, lignin, lipids, and their derivatives have mean turnover times faster or similar as that of bulk SOM. Only a small fraction of the lignin inputs seems to persist in soils and is mainly found in the fine textural size fraction (<20 µm), indicating physico‐chemical stabilization. Compound‐specific analysis of ¹³C : ¹²C ratios of SOM pyrolysis products in soils with C3‐C4 crop changes revealed no compounds with mean residence times of > 40–50 y, unless fossil C was present in substantial amounts, as at a site exposed to lignite inputs in the past. Here, turnover of pyrolysis products seemed to be much longer, even for those attributed to carbohydrates or proteins. Apparently, fossil C from lignite coal is also utilized by soil organisms, which is further evidenced by low ¹⁴C concentrations in microbial phospholipid fatty acids from this site. Also, black C from charred plant materials was susceptible to microbial degradation in a short‐term (60 d) and a long‐term (2 y) incubation experiment. This degradation was enhanced, when glucose was supplied as an easily available microbial substrate. Similarly, SOM mineralization in many soils generally increased after addition of carbohydrates, amino acids, or simple organic acids, thus indicating that stability may also be caused by substrate limitations. It is concluded that the presented results do not provide much evidence that the selective preservation of recalcitrant primary biogenic compounds is a major SOM‐stabilization mechanism. Old SOM fractions with slow turnover rates were generally only found in association with soil minerals. The only not mineral‐associated SOM components that may be persistent in soils appear to be black and fossil C.     

Assessing the extent and causes of forest degradation in India: Where do we stand?

In India, conservation of biodiversity goes hand in hand with human welfare, as millions of people live adjacent or within protected areas and depend upon forests products. The high density and biomass requirements of these households could result in the degradation of forests and loss of biodiversity. We assessed the collection of forest products among households in five sites in the Western and Eastern Ghats of peninsular India: the Kogar region of the Central Western Ghats, the Bandipur and Sigur regions of the Nilgiri Biosphere Reserve, the Kalakad-Mundanthurai Tiger Reserve of the southern Western Ghats and Similipal Tiger Reserve of the northern Eastern Ghats, and tested whether extraction pressure on forests was associated with the proportion of agricultural households, wage labour and population density. We also examined whether data on loss of cover as stated by the State of the Forest Reports was supported by field data. The regions differed in land use: Kogar, KMTR and Similipal were primarily agricultural regions, whereas households engaged in wage labour or in running small businesses were predominant in Sigur and Bandipur. Fuel-wood was collected ubiquitously for household use in all sites, used mainly for domestic requirements and secondarily for generating income. Green leaves for making fertilizer and fodder were collected for household use and did not enter the market. Cattle manure for the global organic coffee industry was a major forest product in Bandipur and Sigur. Extraction pressure on forests was positively associated with the availability of wage labour and was negatively with the proportion of agricultural households. Data from official sources seem inadequate to measure forest degradation in protected forests. Accurate estimation of forest condition through field assessments and remote sensing, and understanding the socio-economic variables associated with forest loss and degradation are needed for the sustainable management of Indian protected areas.     

How Much Does the Presence of a Competitor Modify the Within-Canopy Distribution of Ozone-Induced Senescence and Visible Injury?

Many natural vegetation species have been shown to be negatively affected by ozone. This study has investigated how the presence of competing species in a community affects two common responses to ozone: visible injury and senescence. Monocultures and mixtures of Trifolium repens and Lolium perenne were grown in large containers and were exposed in solardomes to either a rural episodic ozone profile (AOT40 of 12.86 ppm h) or control conditions (AOT40 of 0.02 ppm h) for 12 weeks. The proportion of ozone-injured or senesced leaves was different in the different regions of the canopy. The highest proportions of injured/senesced leaves were in the plant material growing at the edge of the canopy and the upper canopy, with a significantly lower proportion of injured leaves in the inner canopy. The presence of L. perenne increased the proportion of ozone-injured leaves in T. repens at the final harvest, whilst the presence of T. repens decreased the proportion of senesced leaves in L. perenne. In L. perenne, the proportion of injured leaves at the edge and inner canopy decreased significantly when grown in competition, whilst for T. repens the reverse effect occurred in the inner canopy only. Different mechanisms appeared to influence the interaction between response to ozone and competitors in these two species. In L. perenne the response to ozone may have been related to nitrogen supply, whereas in T. repens canopy structure was more important.     

Do boundaries of soil animal and plant communities coincide? A case study of a Mediterranean forest in Russia

We studied the relationship between plant and soil animal communities by geostatistical analysis in a piedmont forest close to Novorossiysk (Southern Russia). Vegetation on the slope of a hill was an oak-ash-hornbeam forest, while the vegetation on the foot of the hill was a maple-ash-hornbeam forest. Two plots were studied each including both slope and foot habitats. On every plot samples collected formed a grid of 10 × 5 units with a 5 m distance between them. Soil macroinvertebrates were hand-sorted from the samples, and several soil parameters (soil, pebble, and litter mass, soil moisture) were measured.The analysis did not reveal coincidence between the boundaries of plant and soil animal communities on the bend of the hill. Soil animal communities of the plots were dominated by woodlice, diplopods, and insect larvae, reaching an abundance of 680–990 individuals m⁻² throughout the plots. Number of taxonomic groups per sample and overall animal abundance in the bend were the highest in both plots, whilst these parameters on the slope were the lowest. Variograms and maps of spatial distribution indicated that the boundary between soil animal communities was situated further up on the slope than the vegetation boundary. The size of the animal community was smaller than the size of plots sampled, what probably explained the lack of coincidence between the boundaries. There was a significant correlation between distribution of litter mass and parameters of soil animal communities, which was modulated by depth of soil layer and soil moisture. Soil parameters were more important for explaining boundaries between soil animal communities than plant communities in the forest considered.     

How does sonication affect the mineral and organic constituents of soil aggregates?—A review

Application of ultrasound to disperse soil aggregates has been critical in enabling researchers to separate and analyze aggregate building blocks that include organic and mineral particles as well as mineral associated organic matter. But the forces generated in the process may also alter the dispersion products and, thus, potentially interfere with the interpretation of experimental results. This review summarizes present knowledge on experimental conditions that may lead to physical damage and chemical modifications of aggregate building blocks. The energy level at which physical disintegration of organic particles could be detected was as low as 60 J mL^–1. Physical damage of sand‐ and silt‐sized mineral particles was observed to commence at energy levels exceeding 700 J cm^–3. No evidence was found for the disintegration of particles within the clay‐size fraction of soils even though studies analyzing pure minerals such as kaolinite revealed particle breakage after application of energy amounts > 12,000 J cm^–3. Here we outline a strategy to minimize artifacts such as physical damage of mineral or organic particles resulting from ultrasonication by adopting a stepwise dispersion protocol involving successively higher energy levels, accompanied by a sequential separation of organic and mineral compounds.     

Is ‘grey literature’ a reliable source of data to characterize soils at the scale of a region? A case study in a maritime pine forest in southwestern France

Soil scientists are receiving increasing numbers of requests for expert advice on soil over large areas, but at a high resolution. We tested the use of the soil data contained in sources of information that are not directly accessible (referred to as ‘grey’ data) to accomplish this task. We collected grey data about a pine forest, which is currently the subject of drastic, and questionable, changes in management, including a rapid rate of biomass removal. These grey data (from 266 sites) were compared with soil data obtained directly from our field sampling (83 sites). Our comparisons showed that the two sources of data were consistent when the variables concerned had been sampled and analysed by using methods shared by the soil scientists such as particle‐size distribution. Conversely, significant discrepancies appeared for variables for which different methods existed, such as for CEC. For the latter, using corrective equations gave contrasting results, depending on the soil variable. The final database was used to characterize the soils of the study region. Results showed that soils of the study region (mainly sandy podzols and arenosols) were acidic and particularly oligotrophic. Several important properties (CEC, phosphorus cycling, pH, bulk density) were related to the organic fraction or carbon (C) content of soils. For instance, CEC values were linearly and exclusively dependent on C content. The most oligotrophic sites of the study region were clearly not suitable for the new intensive management of the forest in the long term. For the other sites, the question remains open because some specific data are still needed before drawing conclusions. We conclude that as a complement to conventional soil studies, the grey literature is a useful source of data and information to characterize soils at a regional scale.     

Do metal contamination and plant species affect microbial abundance and bacterial diversity in the rhizosphere of metallophytes growing in mining areas in a semiarid climate?

Journal of Soils and Sediments - Mining areas are low-quality habitats for macro- and microorganisms’ development, mainly due to the degradation of the soil quality by metal pollution. The...     

Do elevated soil concentrations of metals affect the diversity and activity of soil invertebrates in the long‐term?

This study aimed to elucidate the response of diversity and activity of soil invertebrates to elevated soil metal concentrations that were a result of sewage sludge application. Field sampling of soil invertebrates was carried out from 2002 to 2004 at an experimental site established in 1982 to test the effects on crop production of metal contamination from sewage sludge applications with elevated concentrations of zinc (Zn), copper (Cu) and nickel (Ni) with certain treatments exceeding the current UK statutory limits for the safe use of sludge on land. At metal concentrations within the limits, none of the invertebrates sampled showed adverse effects on their abundance or overall community diversity (from Shannon–Weiner index). At concentrations above the limits, individual taxa showed sensitivity to different metals, but overall diversity was not affected. Earthworm abundance was significantly reduced at total Cu concentrations at and above 176 mg kg^?1, while nematode and enchytraeid abundances were sensitive to Cu and high Zn concentrations. Correspondingly, litter decomposition was lower in Zn and Cu treatments although there was no direct relationship between decomposition and soil invertebrate abundance or diversity. Such enduring changes in both soil biodiversity and biological activity around the current UK regulatory limits warrant further investigation to determine whether they indicate detrimental damage to soil functioning over the long‐term.