Arable Weeds Research Articles

Farming Intensity Affects Soil Seedbank Composition and Spontaneous Vegetation of Arable Weeds

Former studies carried out in the 2000s in the Lahn-Dill region located in the middle-east of the German state Hesse stated a depletion of arable weeds on the field scale and more diverse weed flora on the landscape scale. Current study, having started in 2018, aims to contribute to a better understanding of the interactions between arable weed species diversity, farming intensity, grown crops and landscape area. Moreover, the potential of organic farming methods for conservation and promotion the arable weed diversity is aimed to be assessed with the study. In total, 42 fields in two landscape regions were sampled—six seedbank samples were collected from each field; additionally, data on spontaneous arable weed flora were recorded each spring from 2019 to 2021; emerged aboveground weeds were identified in the fields and their coverage was documented. Four factors were considered in the field trial: Farming practice, landscape area, soil depth and the current crop. Effects of these factors on arable weed species diversity were calculated with a Generalized Linear Model (GLM), resulting in significant effects of the management system, the area and the current crop. Among the four organic farming systems that were sampled, the time period of organic growing had a significant effect on weed seed numbers in the soil with an increase in seed numbers. Average seedbank species numbers were around twice as high in organic farming systems (18 species) compared to conventional managed fields (nine species). Evidence of an ongoing species decline in the region on the landscape scale could be detected by comparison with a former study. Especially rare and endangered weed species are a concern due to seedbank and current vegetation depletion tendencies.

Two sides of one medal: Arable weed vegetation of Europe in phytosociological data compared to agronomical weed surveys

AbstractQuestionsTwo scientific disciplines, vegetation science and weed science, study arable weed vegetation, which has seen a strong diversity decrease in Europe over the last decades. We compared two collections of plot‐based vegetation records originating from these two disciplines. The aim was to check the suitability of the collections for joint analysis and for addressing research questions from the opposing domains. We asked: are these collections complementary? If so, how can they be used for joint analysis?LocationEurope.MethodsWe compared 13 311 phytosociological relevés and 13 328 records from weed science, concerning both data collection properties and the recorded species richness. To deal with bias in the data, we also analysed different subsets (i.e., crops, geographical regions, organic vs conventional fields, center vs edge plots).ResultsRecords from vegetation science have an average species number of 19.0 ± 10.4. Metadata on survey methodology or agronomic practices are rare in this collection. Records from weed science have an average species number of 8.5 ± 6.4. They are accompanied by extensive methodological information. Vegetation science records and the weed science records taken at field edges or from organic fields have similar species numbers. The collections cover different parts of Europe but the results are consistent in six geographical subsets and the overall data set. The difference in species numbers may be caused by differences in methodology between the disciplines, i.e., plot positioning within fields, plot sizes, or survey timing.ConclusionThis comparison of arable weed data that were originally sampled with a different purpose represents a new effort in connecting research between vegetation scientists and weed scientists. Both collections show different aspects of weed vegetation, which means the joint use of the data is valuable as it can contribute to a more complete picture of weed species diversity in European arable landscapes.

Soil Pollen Indicators of Historical Arable Horizons from the Zvenigorod Biological Station of the Moscow State University

In this work we present the results of spore and pollen analysis of forest soils from the Zvenigorod biological station of Moscow State University (Moscow Region, Russia). A comparative analysis of forest soils formed on the site of historical fields of the XVIII–XIX centuries and beyond showed that a specific complex of pollen and spores remains in the residual arable horizons, characteristic only of soils that have passed through the stages of plowing and fallow. It includes pollen from cultivated cereals and arable weeds (buckwheat, cornflower blue), spores of the mace-shaped plaunus (Lycopodium clavatum), as well as spores of the mosses Riccia glauca and Anthoceros spp. The latter are exclusive indicators of fallows, since they are practically not found in other habitats. The identified pollen indicators can be used in landscape and archaeological research to interpret the data of spore-pollen analysis of cultural layers, buried soils, gully-ravine sediments. They can also be used to define the boundaries of ancient fields under modern vegetation.

Cyhalofop-butyl resistance conferred by a novel Trp-2027-Leu mutation of acetyl-CoA carboxylase and enhanced metabolism in Leptochloa chinensis.

Chinese sprangletop (Leptochloa chinensis (L.) Nees) is an invasive grass weed severely infesting rice fields across China. In October 2020, a suspected resistant Leptochloa chinensis population HFFD3 that survived the acetyl-CoA carboxylase (ACCase)-inhibiting herbicide cyhalofop-butyl applied at its field-recommended rate was collected from a rice field in Feidong County, Anhui Province, China. This study aimed to determine the resistance profile of HFFD3 to ACCase inhibitors and to investigate its mechanisms of resistance to cyhalofop-butyl. Single-dose testing confirmed that HFFD3 had evolved resistance to cyhalofop-butyl. Two loci encoding plastidic ACCase were each amplified from the susceptible (S) and resistant (R, HFFD3) individual plants. Target gene sequencing and derived cleaved amplified polymorphic sequence assay revealed all the R plants carried a Trp-2027-Leu substitution in their ACCase1,2 copies. Dose-response bioassays revealed that HFFD3 was highly resistant to cyhalofop-butyl and exhibited cross-resistance to metamifop, fenoxaprop-P-ethyl, quizalofop-P-ethyl, and clethodim. Pre-treatment with piperonyl butoxide and 4-chloro-7-nitrobenzoxadiazole considerably reversed the resistance of the R plants to cyhalofop-butyl, by 23% and 43%, respectively. Liquid chromatography-tandem mass spectrometry analysis suggested the metabolic rates of cyhalofop-butyl were significantly faster in the R than in the S plants. This study confirmed the first case of an arable weed species featuring cross-resistance to ACCase-inhibiting herbicides due to a novel Trp-2027-Leu mutation of ACCase. Target gene mutation and cytochrome P450s- and glutathione-S-transferases-involved enhanced metabolism may have simultaneously participated in the resistance of HFFD3 population to cyhalofop-butyl.

Phytosociological study of arable weed communities across small scale agricultural landscape in Swaziland

Phytosociological study of arable weed communities across small scale agricultural landscape in Swaziland

Toward an Investigation of Diversity and Cultivation of Rye (Secale cereale ssp. cereale L.) in Germany: Methodological Insights and First Results from Early Modern Plant Material

Rye (Secale cereale ssp. cereale L.) is a secondary domesticate, considered to have originated as a weed in wheat fields and to have developed traits of domestication by evolving similar physiological and morphological characteristics to those of wheat. Although it migrated into Europe as a weed possessing domestication traits, it became one of the most significant crops grown in large parts of Europe from the medieval period onward. Within the modern borders of Germany, rye was grown using at least two divergent cultivation practices: eternal rye monoculture and three-field rotation. The straw of rye was used to produce Wellerhölzer, which are construction components in traditional half-timbered houses that have enabled a desiccated preservation of the plant remains. In order to assess the impact of cultivation practices, local environmental conditions and genetic variation on the genetic diversification of rye, we seek to integrate well-established archaeobotanical methods with aDNA sequencing of desiccated plant remains obtained from Wellerhölzer from Germany. In the current contribution, we present a proof of concept, based on the analysis of plant remains from a Wellerholz from the Old Town Hall of Göttingen. We use arable weed ecology to reconstruct cultivation practices and local environmental conditions and present a phylogenetic analysis based on targeted loci of the chloroplast and nuclear genome. Our results emphasise that the study of desiccated remains of plants from Wellerhölzer offer a unique opportunity for an integration of archaeobotanical reconstructions of cultivation practices and local environment and the sequencing of aDNA.

Genetic Variability of Acetolactate Synthase (ALS) Sequence in Centaurea cyanus Plants Resistant and Susceptible to Tribenuron-Methyl

Centaurea cyanus, belonging to the Asteraceae family, is an arable weed species encountered mainly in fields with cereals, sugar beet, and maize. The high genetic variability of C. cyanus has been recently reported; however, little is known about its sequence variability in the context of its herbicide resistance. C. cyanus resistance was found mainly against acetolactate synthase (ALS) inhibitors, but no ALS sequence information concerning the herbicide resistance mechanism has been published yet. The aim of this study was to determine the ALS sequences for biotypes susceptible and resistant to tribenuron-methyl in order to identify mutations that may be associated with the resistance emergence. DNA isolation from susceptible and resistant plants was followed by PCR amplification and ALS sequencing. As a result, different lengths of DNA products were obtained. Moreover, both nucleotide and amino acid sequence analysis revealed high sequence variability within one plant as well as between plants from the same biotype. In a few resistant plants, four changes in the amino acid sequence were identified in comparison to those in the susceptible ones. However, these preliminary studies require further investigation toward confirming the significance of these mutations in herbicide resistance development. This study provides preliminary information contributing to the research on the C. cyanus target-site resistance mechanism.

A framework to estimate the contribution of weeds to the delivery of ecosystem (dis)services in agricultural landscapes

There is a pressing need for indicators and methods to quantify the provision of ecosystem services as a prerequisite to identify management options that optimize trade-offs between services. Arable weeds provide multiple services and are thus a good model to evaluate such trade–offs. This flora provides trophic resources (flowers or seeds) that support pollinators and pest natural enemies (pollination and pest control services) but can also be harmful for crop production (disservice). To date, few indicators are available to quantify the contribution of weeds to ecosystem services or their harmfulness, and no indicators account for intraspecific variability in weed traits that result from contrasting growing conditions, notably the location of weeds within fields (field edge vs field core) and crop type. Here, we developed nine proxies for potential weed harmfulness (competition, harvest difficulties and future weed infestations) and weed contributions to resources provision to pollinators (bees, bumblebees and hoverflies) and pest natural enemies (carabid beetles, birds and parasitoid wasps). These nine proxies accounted for individual weed plant response to growing conditions (combination of within-field location by crop type) for 155 weed species, resulting in 967 unique situations (combinations of species by within-field locations by crop types). Apart from harvest difficulties, all proxies were positively correlated, i.e. harmfulness increased when services increased. Weed plants located on field edges had greater contributions to all proxies than those located in field cores, especially in cereal crops. We identified that small weed species with short life cycles and low competitiveness, presented the optimum proxy combination, i.e. high services and low harmfulness. The development of these proxies and the proposed framework provide new avenues for assessing trade-offs between multiple ecosystem services at different temporal (crop sequence) and spatial scales (landscape).

Quantifying seed and establishment limitation to seedling recruitment of arable weeds: an example of barnyardgrass (Echinochloa crus-galli)

AbstractThe establishment of plants in an ecosystem is limited by the availability of seeds and the availability of suitable sites for establishment. Describing plant population dynamics through the relative strength of seed and establishment limitation is an important concept in the study of natural ecosystems. To date, it is unclear whether this concept can be applied to describe populations of annual weeds in agricultural fields. Using a recruitment function, we show that limitation parameters prove valuable in describing seedling recruitment in weed populations. We conducted a seed addition experiment in three cornfields (Zea maysL.) and recorded seedling recruitment in populations of the economically important weed barnyardgrass [Echinochloa crus-galli(L.) P. Beauv.]. Seed predation, competition with other weeds, and seed burial were prevented. We estimated the strength of seed and establishment limitation in the population with two parameters:n, which is the number of microsites, andb, which is the suitability of those sites to support a seedling. We further estimated the relative proportions of density-dependent and density-independent establishment limitation in the seedling population. Recruitment rates ofE. crus-galliranged from 31% to 36% across all evaluated seed densities and fields, which is high compared with results from other seed addition studies. Two of the three monitored populations were predominantly establishment limited at the highest evaluated seed density of 2,400 added seeds m−2. Further knowledge about the relative strength of limitations in other weed populations will provide important information on how effective different weed management strategies can be.

A high diversity of mechanisms endows ALS-inhibiting herbicide resistance in the invasive common ragweed (Ambrosia artemisiifolia L.)

Ambrosia artemisiifolia L. (common ragweed) is a globally invasive, allergenic, troublesome arable weed. ALS-inhibiting herbicides are broadly used in Europe to control ragweed in agricultural fields. Recently, ineffective treatments were reported in France. Target site resistance (TSR), the only resistance mechanism described so far for ragweed, was sought using high-throughput genotyping-by-sequencing in 213 field populations randomly sampled based on ragweed presence. Additionally, non-target site resistance (NTSR) was sought and its prevalence compared with that of TSR in 43 additional field populations where ALS inhibitor failure was reported, using herbicide sensitivity bioassay coupled with ALS gene Sanger sequencing. Resistance was identified in 46 populations and multiple, independent resistance evolution demonstrated across France. We revealed an unsuspected diversity of ALS alleles underlying resistance (9 amino-acid substitutions involved in TSR detected across 24 populations). Remarkably, NTSR was ragweed major type of resistance to ALS inhibitors. NTSR was present in 70.5% of the resistant plants and 74.1% of the fields harbouring resistance. A variety of NTSR mechanisms endowing different resistance patterns evolved across populations. Our study provides novel data on ragweed resistance to herbicides, and emphasises that local resistance management is as important as mitigating gene flow from populations where resistance has arisen.

Rye (<em>Secale cereale</em> L.) and squarrose clover (<em>Trifolium squarrosum</em> L.) cover crops can increase their allelopathic potential for weed control when used mixed as dead mulch

Cover crops are essential tools in agro-ecosystems for reducing the reliance on synthetic inputs and associated environmental risks. Alongside their benefits to soil fertility, cover crops can control weeds by their competitive and allelopathic attributes. Laboratory and field experiments were conducted to assess the allelopathic potential of two cover crop species, rye (Secale cereale L.) and squarrose clover (Trifolium squarrosum L.), alone or in a mixture, on seed germination and growth of arable weeds. Aqueous extracts of the two cover crops and their mixture were tested in a bioassay on Conyza canadensis (L). Cronq., Amaranthus retroflexus L. and Digitaria sanguinalis (L.) Scop. In vitro effects of aqueous extracts varied in a dose-dependent manner, with cover crops and weed species. All three extracts were able to reduce the germination of A. retroflexus (–87%) considerably. Inhibitory effects by rye and mixture extracts on radicle growth of all weed species ranged between 51 and 82%. Rye extract was the best at reducing shoot length of C. canadensis and D. sanguinalis (–39 to 44%), while squarrose clover was more effective on A. retroflexus (–79%). Plant extracts also delayed the germination time of weed species with a substantial effect of the mixture on C. canadensis seeds. In the field experiment, no significant weed suppression was provided by cover crop residues incorporated as green manure compared to control plots, despite tillage being more effective in reducing weed density than no-till. Still, the mulch of the mixture controlled weed emergence significantly better than single cover crop mulches. The chemical characterization of cover crop residues, both shoots and roots, revealed a notable richness of allelopathic phenolic acids and flavonoids, which may constitute potential natural herbicides through slow decomposition. From the analysis of the aqueous extracts, other non-analysed and/or unidentified water-soluble allelopathic compounds should underlie the phytotoxicity observed in vitro, at least for rye. For cover crop mixture, positive interactions among plant materials leading to a better release of allelochemicals and weeding effectiveness are discussed according to chemical profiles and field data. Our study demonstrated the allelopathic activity of the cover crops and their potential to be included in weed management strategies according to cropping system needs. Additional trials are needed to confirm the performance of cover crop residues under field conditions. Highlights - Rye and squarrose clover are cover crops with potential allelopathic effects. - Aqueous extracts of residues of rye, squarrose clover, and their mixture reduced and/or slowed weed germination of A. retroflexus and C. canadensis in the in vitro bioassays. - Depending on the concentration of residues, the aqueous extracts had inhibitory effects on radicle and shoot growth of A. retroflexus, C. canadensis, and D. sanguinalis. - The mulch of a mix of rye and squarrose clover under field conditions suppressed weeds better than the single species.

Arable weeds of the Scottish Borders

Many years of fieldwork have led the authors to hypothesise that there is a single relatively species-rich arable weed community present across the Scottish Borders that is best expressed in broad-leaved root crops and in set-aside on imperfectly-drained soils, while the species-poor communities typically found in cereal crops are a degraded form of this. 102 samples have been studied to test this hypothesis and to search for a community typical of slightly calcareous well-drained soils. The community typical of imperfectly-drained soils has been defined and is considered to be a species-rich variant of the NVC OV13 Stellaria media-Capsella bursa-pectoris open habitat community. Species typical of well-drained soils have been shown to be scarce and not to form a distinct community, though they may well have done so in the past.

Weed vegetation in conventional and organic farming in West Bohemia (Czech Republic)

The paper presents species richness and composition of arable weed vegetation in the region of West Bohemia (Czech Republic) in different types of farming (conventional and organic) and grown crops (winter and spring cereals, wide-row crops). During the field survey in the years 2007 to 2017, 105 phytocoenological relevés were recorded. The average species richness in one relevé was significantly higher in organic farming, as well as total weed cover. The lowest species richness was found in wide-row crops. Recently widespread species belonged to the most frequent species in our study. Based on multivariate statistics, the effects of variables on the occurrence of weed species were found as statistically significant. Most of the variability in data was explained by crop, following by type of farming. Weed species of Fabaceae Lindl. family (especially Vicia L.) and many perennial species positively correlated with the organic type of farming. Endangered species were found mainly in organic farming and cereals. Less intensive cultivation with a higher weed cover is beneficial for the promotion of biodiversity.

Harvest Techniques: Hand-Pulling and Its Potential Impact on the Archaeobotanical Record Vis a Vis Near Eastern Plant Domestication

A “cultivation prior to domestication”, or a “pre-domestication cultivation” phase features in many reconstructions of Near Eastern plant domestication. Archaeobotanists who accept this notion search for evidence to support the assumption regarding a wild plant’s cultivation phase, which in their view, preceded and eventually led to plant domestication. The presence of non-crop plant remains in the archaeobotanical record interpreted as arable weeds, i.e., weeds of cultivation, is viewed as a strong argument in support of the pre-domestication cultivation phase. Herein, we show that the simple practice of harvest by hand-pulling (uprooting) has the potential to secure an almost weed-free harvest. Indeed, rather clean (weed-free) Neolithic seed caches from a range of relevant sites were documented in archaeobotanical reports. These reports, alongside ethnographic observations suggest that (in certain cases) ancient harvest may have been carried out by selective hand-pulling. Hence, one has no reason to view archaeobotanical assemblages from occupation sites as fully representative of cultivated fields. Therefore, the concept of “arable—pre-domestication weeds”, its logic, and its potential contribution to the prevailing reconstructions of Near Eastern plant domestication need be reconsidered.

Developing hierarchical density‐structured models to study the national‐scale dynamics of an arable weed

AbstractPopulation dynamics can be highly variable in the face of environmental heterogeneity, and understanding this variation is central in the study of ecology. Robust management decisions require that we understand how populations respond to management at a range of scales, and under a broad suite of conditions. Population models are potentially valuable tools in addressing this challenge. However, without adequate data, models can fail to produce useful results. Populations of arable weeds are particularly problematic in this respect, as they are widespread and their dynamics are extremely variable. Owing to the inherent cost of collecting data, most studies of plant population dynamics are derived from localized experiments under a small range of environmental conditions, limiting the extent to which variance in population dynamics can be measured. Density‐structured models provide a route to rapid, large‐scale analysis of population dynamics, and can expand the scale of ecological models that are directly tied to data. Here we extend previous density‐structured models to include environmental heterogeneity, variation in management, and to account for inter‐population variation. We develop, parameterize, and test hierarchical density‐structured models for a common agricultural weed, black‐grass (Alopecurus myosuroides). We model the dynamics of this species in response to crop management, using survey data gathered over 4 yr from 364 fields across a network of 45 UK farms. We show that hierarchical density‐structured models provide a substantial improvement over their nonhierarchical counterparts. Using these models, we demonstrate that several alternative crop rotations are effective in reducing weed densities. Rotations with high wheat prevalence exhibit the most severe infestations, and diverse rotations generally have lower weed densities. However, a key outcome is that in many cases the effect of crop rotation is small compared to the high variability arising from spatiotemporal heterogeneity. This result highlights the need to monitor and model population dynamics across large spatial and temporal scales in order to account for variation in the drivers of plant dynamics. Our framework for data collection and modeling provides a means to achieve this.

Occurrence of native weed species on arable land - Effect of different environmental factors

Native species form a substantial part of arable weed communities. The objective of this survey was to study the occurrence of native species in arable fields in the Czech Republic related to applied management systems (conventional and organic farming), crops (winter cereals, spring cereals, wide-row crops) and environmental conditions at different altitudes. In 2006–2018, a phytocoenological survey (320 relevés) was performed across the Czech Republic. In total, 180 weed species were recorded, of which 43.33% were considered as native (78 species). The net effects of all the studied variables on the occurrence of native species were found as statistically significant. Most of the variability was explained by the altitude, followed by the crop and type of farming. The highest occurrence of native weeds was noticed in organic farming and cereals and increased with an increasing altitude. The higher incidence in higher elevations can be connected to the more intensive agriculture in the lowlands.

Functional biogeography of weeds reveals how anthropogenic management blurs trait–climate relationships

AbstractQuestionsStudies in functional biogeography have mostly focused on unmanaged ecosystems, and neglected testing how management intensity affects community‐level response of plant traits to bioclimatic gradients. We hypothesize that trait–climate relationships for arable weeds spontaneously establishing in croplands subject to intensive management should differ from the relationships characterizing less intensively managed grassland ecosystems.LocationFrance.MethodsWe computed community‐weighted means (CWM) and variances (CWV) of 954 and 5,619 cropland and grassland plant assemblages, respectively, for three fundamental leaf traits (specific leaf area, SLA; leaf dry matter content, LDMC; leaf nitrogen content, LNC). Based on growing season length accounting for both temperature and soil water limitations (GSLtw), we compared trait–climate relationships between herbicide‐free croplands and grasslands, and between herbicide‐free and herbicide‐sprayed cropland assemblages. The contribution of beta‐diversity to the trait–climate relationships was then evaluated using multiple regression on distance matrices.ResultsDistinct trait–climate relationships characterized herbicide‐free cropland and grassland plant assemblages. CWM of all traits showed weaker relations with GSLtw in cropland relative to grassland assemblages. CWV of LDMC and LNC responded more sharply in croplands. Furthermore, no herbicide effect on trait–climate relationships was detected within cropland assemblages. These results seem to be explained by a greater taxonomic beta‐diversity along the GSLtw gradient for grasslands.ConclusionsSpecific trait–environment relationships characterize croplands, underlining that management intensity greatly affects trait–climate relationships for plant assemblages. Deciphering the interplay between land use intensification and climate is critical to accurately forecast functional vegetation changes in response to global changes, and hence to foster actions enhancing ecosystem resilience.

Characterizing the environmental drivers of the abundance and distribution of Alopecurus myosuroides on a national scale.

Arable weeds threaten farming and food production, impacting on productivity. Large-scale data on weed populations are typically lacking, and changes are frequently undocumented until they reach problem levels. Managing the future spread of weeds requires that we understand the factors that influence current densities and distributions. In doing so, one of the challenges is to measure populations at a large enough scale to be able to accurately measure changes in densities and distributions. Here we analyse the density and distribution of a major weed (Alopecurus myosuroides) on a large scale. Our objectives were to (i) develop a methodology for rapid measurement of occurrence and abundance, (ii) test hypotheses about the roles of soils and climate variation in determining densities, and (iii) use this information to identify areas in which occurrence could increase in the future. Populations were mapped through England over 4 years in 4631 locations. We also analysed UK atlas data published over the past 50 years. Densities of populations show significant interannual variability, but historical data show that the species has spread. We find significant impacts of soil and rainfall on densities, which increase with the proportion of heavy soils, but decrease with increasing rainfall. Compared with independent atlas data we found that our statistical models provide good predictions of large-scale occupancy and we provide maps of current and potential densities. Models of spread highlight the localised nature of colonisation, and this emphasises the need for management to limit dispersal. Comparisons of current, historical and potential distributions suggest sizeable habitable areas in which increases in abundance are still possible. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The Association of Arable Weeds with Modern Wild Cereal Habitats: Implications for Reconstructing the Origins of Plant Cultivation in the Levant

ABSTRACT Reconstructing the origins of plant cultivation in southwest Asia is crucial for understanding associated processes such as the emergence of sedentary communities and domesticated crops. Among the criteria archaeobotanists developed for identifying the earliest plant cultivation, the presence of potential arable weeds found in association with wild cereal and legume remains has been used as a basis for supporting models of prolonged wild plant cultivation before domesticated crops appear. However, the proposed weed floras mainly consist of genus-level identifications that do not differentiate between arable weeds and related species that characterise non-arable habitats. Here we test, for the first time, whether the potential arable weed taxa widely used to identify wild plant cultivation also occur in non-cultivated wild cereal populations. Based on modern survey data from the southern Levant we show that the proposed weed taxa characterise both grasslands and fields. Our findings, therefore, do not support the use of these taxa for reconstructing early cultivation. Instead, for future studies we suggest an approach based on the analysis of plant functional traits related to major agroecological variables such as fertility and disturbance, which has the potential to overcome some of the methodological problems.

Land-use history affects vascular plant composition of calcareous grasslands – Does it affect cryptogam composition, too?

Land-use history and habitat age are considered highly important regarding the species composition and conservation value of, e.g., grasslands and forests. Ancient sites, i.e., sites with a continuous habitat history, are thought to be richer in rare, threatened, and more specialised species than recent sites. However, species composition is also affected by abiotic and ecological factors such as soil and climate parameters, and further analyses are needed to determine whether history or other factors are more important. In previous studies carried out at two study areas in the German Jurassic mountains, land-use history was identified as the main factor shaping vascular plant composition of ancient vs. recent grassland sites. Ancient was defined that there was a continuous grazing history since at least 200 years, while recent grasslands have developed from arable fields considerably after this time. Many species such as arable weeds and crop species, being residuals of the former land-use type, were found in the recent grasslands. In the present study, we assessed the terricolous cryptogam vegetation (bryophytes, lichens, macromycetes) of the same ancient and recent sites regarding species composition, occurrence of endangered species, and the applicability of the indicator species concept and Ellenberg indicator values. Although land-use history was the strongest explaining factor regarding vascular plant vegetation in previous studies, cryptogam vegetation did not reflect this signal. Species numbers and Ellenberg indicator values were quite similar in ancient and recent grasslands but we could, nevertheless, identify indicator species for both grassland types, with Rhytidium rugosum, Cladonia furcata ssp. subrangiformis and Hygrocybe persistens as strongest indicators of ancient grasslands, and Rhytidiadelphus squarrosus as strongest indicator of recent grasslands. When we compared the results for vascular plant and cryptogam vegetation we found that land-use history seems to have much less influence on the composition of the cryptogam vegetation in grasslands, given a certain time of recreation and succession. This is very likely due to an enhanced dispersability of cryptogam propagules. We found rare and endangered cryptogam species in ancient and recent sites; therefore, species maintenance measures can be worthwile in both grassland types.