Partitioning the biodiversity effects on productivity into density and size components

Plant density and size — two factors that represent plant survival and growth — are key determinants of yield but have rarely been analysed explicitly in the context of biodiversity–productivity relationships. Here, we derive equations to partition the net, complementarity and selection effects of biodiversity into additive components that reflect diversity-induced changes in plant density and size. Applications of the new method to empirical datasets reveal contrasting ways in which plant density and size regulate yield in species mixtures. In an annual plant diversity experiment, overyielding is largely explained by selection effects associated with increased size of highly productive plant species. In a tree diversity experiment, the cause of overyielding shifts from enhanced growth in tree size to reduced mortality by complementary use of canopy space during stand development. These results highlight the capability of the new method to resolve crucial, yet understudied, demographic links between biodiversity and productivity.     

Plant density affects measures of biodiversity effects

Aim s: We tested for the effect of final sowing plant density (i.e. density of established seedlings) on the values of biodiversity effects [transgressive overyielding, net effect, complementarity effect (CE) and selection effect (SE), trait-dependent complementarity and dominance effect] in a glasshouse pot experiment.Methods: We conducted a single-season (4 months) glasshouse experiment. Species monocultures and mixtures containing up to four common meadow species from different functional groups were sown and subsequently thinned to five density levels (8–128 individuals per pot, i.e. 200–3200 individuals m ?2). Community functioning was characterized by yield (both living and dead biomass) of all constituent species.Important Findings: Our results show that plant density (final sowing density in our case, but this finding can be generalized) affects the yields of both monocultures and mixtures. As these and their relationships are the basis for calculation of biodiversity effects, these effects also varied along the density gradient. Net biodiversity effect, CE and SE all increased with density. The net biodiversity effect and the CE switched from negative to quite positive in the four-species mixture. Using Fox's tripartite partitioning, trait-dependent complementarity was minor in comparison to the dominance effect. One of our experimental species did not follow the density-productivity relationship, called constant final yield (CFY), which was reflected in the biodiversity measures. The shape of the density-productivity relationship for experimental species affects also the values of biodiversity indices, particularly when species do not follow the CFY relationship. According to our data and recent simulation experiments, the values of commonly used biodiversity effects can be rather misleading if a species has, e.g. a unimodal dependence of yield for the density gradient and the density level used in the experiment is higher than the peak density.     

The impact of agricultural intensification and land-use change on the European arable flora

The impact of crop management and agricultural land use on the threat status of plants adapted to arable habitats was analysed using data from Red Lists of vascular plants assessed by national experts from 29 European countries. There was a positive relationship between national wheat yields and the numbers of rare, threatened or recently extinct arable plant species in each country. Variance in the relative proportions of species in different threat categories was significantly explained using a combination of fertilizer and herbicide use, with a greater percentage of the variance partitioned to fertilizers. Specialist species adapted to individual crops, such as flax, are among the most threatened. These species have declined across Europe in response to a reduction in the area grown for the crops on which they rely. The increased use of agro-chemicals, especially in central and northwestern Europe, has selected against a larger group of species adapted to habitats with intermediate fertility. There is an urgent need to implement successful conservation strategies to arrest the decline of this functionally distinct and increasingly threatened component of the European flora.     

Impact of arable farming management on the biodiversity of Carabidae (Coleoptera)

The Carabidae (Coleoptera) are a useful tool for monitoring the effects of different types of control and theretofore it is important to highlight about their role as possible ecological indicators. We studied the composition of carabids in ecological and integrated farming, in three different crops in southern Slovakia. The ground beetles were caught using pitfall traps during a period of three years, from 2018 to 2020. 7 801 adult carabids belonging to 26 species were collected and recorded altogether. The number of species varied from 11 to 15 between traps. The distribution and number of individuals were positively influenced by ecological management with the amount of 4784 individuals, compared to integrated management, where 3017 individuals were obtained. The influence of the crops was in the following order: Triticum aestivum, Pisum sativum and Medicago sativa. In both farming systems, representatives of the Carabidae family were almost the same species. The most abundant species of the pooled number was Harpalus rufipes (from 61.16 to 88.08%). Brachinus crepitans also dominated (from 5.98 to 16.47%). Other species were Poecilus cupreus, Anchomenus dorsalis, Brachinus explodens. The species identity index according to Jaccard when comparing both farming types for the observed period reached 60.00%. The average comparison of the identity of dominance for the observed period of ecological vs integrated management represents 90.39%. The Shannon-Weaver diversity index for ecological farming was 0.9957 and 1.0184 for integrated farming.     

Dedicated biomass crops can enhance biodiversity in the arable landscape

Suggestions that novel, non‐food, dedicated biomass crops used to produce bioenergy may provide opportunities to diversify and reinstate biodiversity in intensively managed farmland have not yet been fully tested at the landscape scale. Using two of the largest, currently available landscape‐scale biodiversity data sets from arable and biomass bioenergy crops, we take a taxonomic and functional trait approach to quantify and contrast the consequences for biodiversity indicators of adopting dedicated biomass crops on land previously cultivated under annual, rotational arable cropping. The abundance and community compositions of biodiversity indicators in fields of break and cereal crops changed when planted with the dedicated biomass crops, miscanthus and short rotation coppiced (SRC) willow. Weed biomass was consistently greater in the two dedicated biomass crops than in cereals, and invertebrate abundance was similarly consistently higher than in break crops. Using canonical variates analysis, we identified distinct plant and invertebrate taxa and trait‐based communities in miscanthus and SRC willows, whereas break and cereal crops tended to form a single, composite community. Seedbanks were shown to reflect the longer term effects of crop management. Our study suggests that miscanthus and SRC willows, and the management associated with perennial cropping, would support significant amounts of biodiversity when compared with annual arable crops. We recommend the strategic planting of these perennial, dedicated biomass crops in arable farmland to increase landscape heterogeneity and enhance ecosystem function, and simultaneously work towards striking a balance between energy and food security.     

浅述生物多样性的价值及其保护

阐明了生物多样性的概念与含义,以及生物多样性3个层次之间的相互关系。探讨了生物多样性的价值及保护问题。针对中国（或）世界生物多样性目前现状及存在的问题提出合理建议,为生物多样性的可持续利用与发展提供理论依据。     

Exploring the pteridophyte flora of the Eastern Afromontane biodiversity hotspot

In this review, we explore our current understanding of the fern and lycophyte diversity occurring in the Eastern Afromontane Biodiversity Hotspot (EABH). The review explores the species diversity of this region in the context of the Afromadagascan pteridophyte diversity based on an exhaustive species list assembled in the synopsis of Afromadagascan pteridophytes published by Roux in 2009. The list was updated by incorporating recent progress in our understanding of the taxonomy and phylogeny of these plants. Evidence for a distinct pteridophyte flora occurring in the East African mountain region was discovered using ordination and clustering analyses. This EABH floras shares links to other Afromadagascan pteridophyte floras such as the one in the tropical lowland forests of central and western Africa. These floras share the dominance of species that preferably occur in humid climates whereas other African pteridophyte floras tend to contain a higher proportion of xeric adapted ferns. The phylogenetic composition of the EABH pteridophyte flora was assessed by comparing global versus local proportion of orders, families, and genera. This analysis revealed distinct patterns that are partly caused by the radiation of Blotiella and Triplophyllum besides selective colonization of species pre-adapted to Afromadagascan climates. In situ speciation in the East African tropical mountains may have contributed to the global diversity of widespread genera such as Asplenium and Pteris. In summary, this is the first comprehensive attempt to assess the pteridophyte diversity of the East African mountains providing the framework for future studies on their conservation, ecology, and evolution.     

The use of fuzzy plant species density to indicate the effects of land-cover changes on biodiversity

The assessment of the effects of land-cover changes on biodiversity requires expensive and time-consuming surveys. It is often the case that few data are readily available and time constraints and limited resources do not allow further data collection. In such cases, cost-effective assessment methods are needed. This study puts forward an assessment method which is based on approximate reasoning and is supported by Similarity theory. The suggested method uses Geographic Information Systems and free or low-cost floristic databases and time-series land-cover data. A main assumption is made, that species density, i.e. the number of plant species per unit area, could be used as a good indicator to estimate spatial biodiversity changes due to land-cover changes. The method produces, for a given area, “plausible maps of plant species density” considering land-cover maps. The method, based on approximate reasoning, overcomes the uncertainties inherent to floristic databases, allowing environmental conservation efforts to benefit from these information sources. An example application of the suggested assessment method is presented for the area of Butser Hill in the United Kingdom. The performance of the suggested approach and its limitations are then discussed.     

The value of biodiversity experiments

Recent biodiversity experiments have investigated the relationship between diversity and ecosystem functioning by synthesizing plant communities from pools of species that have been experimentally manipulated to vary numbers and types of species present while holding abiotic factors constant. Biodiversity experiments therefore focus on a previously under-explored aspect of global change: the feedback from diversity to environment. Consequences of random manipulation of species communities may not correspond well to those of specific extinction sequences observed in the past in response to extinction drivers that cause highly non-random loss. However, random manipulation provides a good starting point given that existing communities could undergo many alternative orders of species loss in the future in response to a variety of different potential extinction drivers. Further, the effects of some extinction drivers are currently poorly understood and therefore difficult to predict (e.g. climate change) and it may be premature to dismiss the predictions of random scenarios as irrelevant to all real examples of species loss. The first generations of biodiversity experiments have provided valuable, and sometimes unexpected, discoveries about the general nature of the relationship between diversity and ecosystem functioning. These discoveries could not have been made using observational studies. We propose that different examples of extinction loss in the real or a potential future world form a continuum from situations where the results of the first-generation biodiversity experiments will be highly relevant to less relevant. At the one extreme are examples where the effects of biodiversity on ecosystem functioning will be overwhelmed by direct effects of the extinction driver on processes (e.g. chronic eutrophication). At the other extreme are situations where ecosystem processes are not strongly affected by direct effects of the extinction driver and where the effects of species loss on functioning may be more important (e.g. habitat fragmentation). Given the unprecedented uncertainty about the future of biodiversity and the functioning of ecosystems, a general approach with randomly varying species pools was the right place to start in order to provide a general foundation. The new challenge is to test for effects of biodiversity on functioning in real-world examples of species loss.

Zusammenfassung

Biodiversitätsversuche zeichnen sich dadurch aus, dass natürliche Artenpools experimentell reduziert werden und anschließend der Zusammenhang zwischen der Artenzahl und Ökosystemfunktionen unter konstanten abiotischen Umweltbedingungen untersucht wird. Dadurch unterscheiden sich Biodiversitätsexperimente grundsätzlich von anderen Versuchen, die die Biodiversität als Zielvariable behandeln und stattdessen die abiotische Umwelt manipulieren. Die Auswahl der Arten für die reduzierten Artenpools in Biodiversitätsexperimenten erfolgte bisher meist zufällig, während natürliche Aussterbefaktoren wie Eutrophierung nicht alle Arten gleichermassen gefährden. Für verschiedene Aussterbefaktoren ist aber so wenig bekannt, dass ein zufälliges Aussterbeszenario die beste gegenwärtig verfügbare Option ist. Dies trifft insbesondere für mögliche zukünftige Aussterbeprozesse zu, die durch globale Umweltveränderungen (Klima, biologische Invasionen) oder Habitatsfragmentierung ausgelöst werden könnten. Die erste Generation von Biodiversitätsexperimenten mit zufälligen Aussterbeszenarien hat wertvolle, teilweise unerwartete, generelle Zusammenhänge zwischen Artenzahl und Ökosystemfunktionen aufgedeckt. Diese Zusammenhänge ließen sich durch vergleichende Studien nicht erkennen. In Zukunft sollten Biodiversitätsexperimente dennoch vermehrt Aussterbeszenarien simulieren, die in der realen Umwelt mit größter Wahrscheinlichkeit auftreten.     

生物多样性的经济价值

生物多样性的总经济价值包含了它的可利用价值(use value, UV)和非利用价值(non-use values, NUV)。可利用价值可以被进一步分成直接利用价值(direct use values, DUV),间接利用价值(indirect use values, IUV)和可选择价值(option values, OV),即可能的利用价值。非利用价值主要是存在价值(existence values, EV)。生物多样性所提供的使用价值常常不能就地实现,而可能会通过某种通道,在空间上的流动,到达一个具备适当外部条件的地区,实现其使用价值。我们称这种现象为生物多样性价值在空间上的流动。     

Ecosystem functioning and intrinsic value of biodiversity

Trying to show the importance of biodiversity for ecosystem functioning, ecologists are repeatedly looking for a possible connection between species diversity and intensity of various ecosystem processes. However it appears that simple "proof" of such a connection cannot easily be demonstrated and involves a lot of contingencies. The different meanings of "ecosystem functioning" may be crucial for attempts to show the importance of biodiversity and to assess possible redundancy. If "ecosystem functioning" means only total production of organic matter or consumption of CO₂ then some degree of redundancy in species diversity of autotrophs will be obvious in most cases. However if "ecosystem functioning" includes the synthesis of all compounds that plants, animals and other organisms of a given community contain in their bodies or release in the environment, then any decrease in species diversity will be meaningful and any redundancy will be impossible by definition. In accordance with such a definition biodiversity obviously cannot be diminished without some loss of ecosystem functioning. I emphasize that attempts to conserve biodiversity do not need special justification in possible relationships between diversity and ecosystem services. If biodiversity has intrinsic value it means that it could in principle be "useless" for human needs or for "ecosystem functioning".     

Nuclear DNA C-values for biodiversity screening: Case of the Lebanese flora

The geographic position of Lebanon in the Mediterranean basin at the transition of two major landmasses, Eurasia and Africa, has contributed to its high plant diversity and makes its flora particularly interesting to study. This paper contributes to the plant DNA C-value database of native Lebanese taxa. These data should reinforce biodiversity evaluation, systematic and evolution studies involving processes of speciation such as polyploidisation. C-values have been estimated by flow cytometry using propidium iodide as intercalary fluorochrome stain. Each sample comprised at least five individuals. Where possible, several populations were measured for each species. This study presents C-values for 225 taxa belonging to 55 families and 141 genera. C-values are novel for 193 taxa including 126 plants endemic to the Eastern Mediterranean region. These are the first values for 50 genera. In this panel, genome size ranged from 1C = 0.28 pg in Hypericum thymifolium to 54.69 pg in Fritillaria alfredae. The life growth form and life cycle type are analysed according to the genome size class. Cases of polyploidy are reported for some species usually considered as only diploid. Examination of C-value variation through flow cytometry constitutes a powerful tool to screen taxonomic heterogeneity, opening further investigations.     

Pteridophytes as field indicators of natural biodiversity restoration in the Scottish flora

Summary

The pteridophyte flora of Scotland, as with that of the British Isles as a whole, is still recovering from the great reduction of its original diversity caused by the Pleistocene glaciations. However, the isolation of the British Isles, their range of suitable habitats and their climatic and edaphic opportunity has provided conditions in which processes of natural biodiversity restoration in pteridophytes can be demonstrated and monitored. The modern pteridophyte vegetation of Scotland is analyzed in this evolutionary perspective. Using the examples of both ferns and fern allies, it is suggested that it is at least as important to conserve suitable sites for the continued origin of novel taxa as it is to allow for the perpetuation of existing taxa and communities.     

Beyond value: biodiversity and the freedom of the mind

Circumstances have conspired to render the conservation movement curiously diffident in the expression of the fundamental beliefs that underpin it. ‘Oppositional’ activists assume their case as proven, while ‘institutional’ tacticians tend to adopt the point of view of those they oppose, deploying utilitarian/economic arguments. The latter arguments represent an unstable long‐term option because they are an inadequate defence against compelling forces of corrosion and corruption. On present evidence, in a few hundred years the planet will be devoid of major natural areas, and the quality of human life will have been utterly compromised. A more honest admission that the natural world is an inalienable component of the human capacity to experience freedom (which is also a mental circumstance) would transform the way we treat the natural environment and hence the prospects for the long‐term survival of biological diversity.     

Using methods of plant biotechnology for conservation and study of the world flora biodiversity

Ex situ germplasm bank of plant species of world flora has been created at the Institute of Cell Biology and Genetic Engineering of the National Academy of Sciences of Ukraine as a result of investigations in the fields of botany and plant biotechnology. At present the bank contains more than 4000 samples in seed bank and more than 2000 cell lines in in vitro bank. The germplasm bank which has been put on the List of scientific objects of national property of Ukraine is the basis of elaboration ofbiotechnological methods of plant biodiversity preservation and of plant material screening for biologically active substances.     

Biotechnology for saving rare and threatened flora in a biodiversity hotspot

The Southwest Australian Floristic Region (SWAFR) is a plant biodiversity hotspot with a geographically isolated and predominantly endemic flora. Known threatening processes (i.e. excessive clearing of native vegetation, soil salinity, soil erosion and chronic weed infestation) combined with uncertain but potentially deleterious environmental (climate) changes pose great challenges for conservation and restoration efforts. With a paucity of nature reserves, in situ protection of species can be problematic. For many species, ex situ conservation becomes the only viable strategy for saving species from extinction via seed banking or living collections established through vegetative propagation, or tissue (in vitro) culture methods. Development of specific in vitro protocols is necessary to successfully initiate culture lines, with considerable development of nutrient media, plant growth regulator regimes and incubation conditions required to optimise shoot regeneration and multiplication, especially with woody species of the SWAFR. In addition, integration of root induction and acclimatization stages has allowed significant improvements in speed and success of plant production of both endangered and difficult-to-propagate woody species. We contend that there is also considerable potential for expansion of alternative in vitro technologies such as somatic embryogenesis for difficult taxa to complement existing ex situ conservation and restoration strategies in biodiversity hotspots such as SWAFR.     

On the use of parataxonomy in biodiversity monitoring: a case study on wild flora

Monitoring programs that assess species-richness and turnover are now regarded as essential to document biodiversity loss worldwide. Implementation of such programs is impeded by a general decrease in the number of skilled naturalists. Here we studied how morphotypes, instead of species, might be used by unskilled participants (referred to as “volunteers”) to survey common plant communities. Our main questions were: (1) Can morphotypes be used as a robust estimator of species-richness (α-diversity) and assemblage turnover (β-diversity)? and (2) What is the robustness (reproducibility and repeatability) of such methods? Double inventories were performed on 150 plots in arable field margins, one by a non-expert using morphotypes, the other by a taxonomist using species. To test the robustness of morphotype identification among participants, 20 additional plots were surveyed by eight volunteers using the same protocol. We showed that (1) the number of morphotypes identified by unskilled volunteers in a plot was always strongly correlated with species-richness. (2) Morphotypes were sensitive to differences among habitats but were less accurate than species to detect these differences. (3) Morphotype identification varied significantly within and between volunteers. Due to this lack of repeatability and reproducibility, parataxonomy cannot be considered a good surrogate for taxonomy. Nevertheless, assuming that morphotypes are identified with standardized methods, and that results are used only to evaluate gross species-richness but not species turnover, parataxonomy might be a valuable tool for rapid biodiversity assessment of common wild flora.