RecruitNet: A global database of plant recruitment networks.

Plant recruitment interactions (i.e., what recruits under what) shape the composition, diversity, and structure of plant communities. Despite the huge body of knowledge on the mechanisms underlying recruitment interactions among species, we still know little about the structure of the recruitment networks emerging in ecological communities. Modeling and analyzing the community-level structure of plant recruitment interactions as a complex network can provide relevant information on ecological and evolutionary processes acting both at the species and ecosystem levels. We report a data set containing 143 plant recruitment networks in 23 countries across five continents, including temperate and tropical ecosystems. Each network identifies the species under which another species recruits. All networks report the number of recruits (i.e., individuals) per species. The data set includes >850,000 recruiting individuals involved in 118,411 paired interactions among 3318 vascular plant species across the globe. The cover of canopy species and open ground is also provided. Three sampling protocols were used: (1) The Recruitment Network (RN) protocol (106 networks) focuses on interactions among established plants ("canopy species") and plants in their early stages of recruitment ("recruit species"). A series of plots was delimited within a locality, and all the individuals recruiting and their canopy species were identified; (2) The paired Canopy-Open (pCO) protocol (26 networks) consists in locating a potential canopy plant and identifying recruiting individuals under the canopy and in a nearby open space of the same area; (3) The Georeferenced plot (GP) protocol (11 networks) consists in using information from georeferenced individual plants in large plots to infer canopy-recruit interactions. Some networks incorporate data for both herbs and woody species, whereas others focus exclusively on woody species. The location of each study site, geographical coordinates, country, locality, responsible author, sampling dates, sampling method, and life habits of both canopy and recruit species are provided. This database will allow researchers to test ecological, biogeographical, and evolutionary hypotheses related to plant recruitment interactions. There are no copyright restrictions on the data set; please cite this data paper when using these data in publications.

Tocopherol contents and antioxidant activity in grape pomace after fermentation and alcohol distillation.

The wine industry in Georgia produces vast amounts of grape pomace that is currently mostly wasted, while only a minor amount is used for distilling alcohol. The study was carried out on the grape pomace from the three most widely used grapevine sorts (Vitis vinifera var. Rkatsiteli, V. vinifera var. Saperavi, V. labrusca var. Isabella)  in Georgia, and quantities of tocopherols and antioxidants were evaluated. The antioxidant activity was assessed by diphenyl-picrylhydrazyl (DPPH) and measurement of visible light absorption at 515 nm, and tocopherol was measured by absorption at 470 nm via a spectrophotometer. The results indicated that the grape pomace contains considerable tocopherols and antioxidant activity. However, the antioxidant activity had slightly been decreased. These results suggest that grape pomace can be an economically attractive resource for the pharmaceutical and food industries. Utilization of grape pomace for producing pharmaceutical and cosmetic goods with tocopherol and antioxidants can solve two problems: it can recycle waste and develop new profitable businesses in biotechnology.

Network motifs involving both competition and facilitation predict biodiversity in alpine plant communities.

Biological diversity depends on multiple, cooccurring ecological interactions. However, most studies focus on one interaction type at a time, leaving community ecologists unsure of how positive and negative associations among species combine to influence biodiversity patterns. Using surveys of plant populations in alpine communities worldwide, we explore patterns of positive and negative associations among triads of species (modules) and their relationship to local biodiversity. Three modules, each incorporating both positive and negative associations, were overrepresented, thus acting as "network motifs." Furthermore, the overrepresentation of these network motifs is positively linked to species diversity globally. A theoretical model illustrates that these network motifs, based on competition between facilitated species or facilitation between inferior competitors, increase local persistence. Our findings suggest that the interplay of competition and facilitation is crucial for maintaining biodiversity.

Unity in diversity-food plants and fungi of Sakartvelo (Republic of Georgia), Caucasus.

BACKGROUND: The Republic of Georgia is part of the Caucasus biodiversity hotspot, and human agricultural plant use dates back at least 6000 years. Over the last years, lots of ethnobotanical research on the area has been published. In this paper, we analyze the use of food plants in the 80% of Georgia not occupied by Russian forces. We hypothesized that (1) given the long tradition of plant use, and the isolation under Soviet rule, plant use both based on home gardens and wild harvesting would be more pronounced in Georgia than in the wider region, (2) food plant use knowledge would be widely and equally spread in most of Georgia, (3) there would still be incidence of knowledge loss despite wide plant use, especially in climatically favored agricultural regions in Western and Eastern Georgia. METHODS: From 2013 to 2019, we interviewed over 380 participants in all regions of Georgia not occupied by Russian forces and recorded over 19,800 mentions of food plants. All interviews were carried out in the participants' homes and gardens by native speakers of Georgian and its dialects (Imeretian, Rachian, Lechkhumian, Tush, Khevsurian, Psavian, Kakhetian), other Kartvelian languages (Megrelian, Svan) and minority languages (Ossetian, Ude, Azeri, Armenian, Greek). RESULTS: The regional division was based primarily on historic provinces of Georgia, which often coincides with the current administrative borders. The total number of taxa, mostly identified to species, including their varieties, was 527. Taxonomically, the difference between two food plant groups-garden versus wild-was strongly pronounced even at family level. The richness of plant families was 65 versus 97 families in garden versus wild plants, respectively, and the difference was highly significant. Other diversity indices also unequivocally pointed to considerably more diverse family composition of wild collected versus garden plants as the differences between all the tested diversity indices appeared to be highly significant. The wide use of leaves for herb pies and lactofermented is of particular interest. Some of the ingredients are toxic in larger quantities, and the participants pointed out that careful preparation was needed. The authors explicitly decided to not give any recipes, given that many of the species are widespread, and compound composition-and with it possible toxic effects-might vary across the distribution range, so that a preparation method that sufficiently reduces toxicity in the Caucasus might not necessary be applicable in other areas. CONCLUSIONS: Relationships among the regions in the case of wild food plants show a different and clearer pattern. Adjacent regions cluster together (Kvemo Zemo Racha, and Zemo Imereti; Samegrelo, Guria, Adjara, Lechkhumi and Kvemo and Zemo Svaneti; Meskheti, Javakheti, Kvemo Kartli; Mtianeti, Kakheti, Khevsureti, Tusheti. Like in the case of the garden food plants, species diversity of wild food plants mentioned varied strongly. Climate severity and traditions of the use of wild food plants might play role in this variation. Overall food plant knowledge is widely spread all-across Georgia, and broadly maintained.

A comparative ethnobotany of Khevsureti, Samtskhe-Javakheti, Tusheti, Svaneti, and Racha-Lechkhumi, Republic of Georgia (Sakartvelo), Caucasus.

BACKGROUND: The Republic of Georgia (Sakartvelo in Georgian language) is part of the Caucasus biodiversity hotspot, and human agricultural plant use dates bat at least 6000 years. However, little ethnobiological research has been published from the region since the 1940s. Given the lack of recent research in the region, the present study we report on plant uses in Skartvelo (Republic of Georgia), Caucasus. We hypothesized that, (1) given the long tradition of plant use, and the isolation under Soviet rule, plant use both based on homegardens and wild harvesting would be more pronounced in Georgia than in the wiser region, (2) the Soviet occupation would have had broad influence on plant use, and (3) there would still be incidence of knowledge loss despite wide plant use. METHODS: Fieldwork was conducted in Khevsureti, Samtskhe-Javakheti, Tusheti, Svaneti, and Racha in July-August 2013, July-August 2014, and September-October 2015. Interviews using semi-structured questionnaires were conducted with 170 participants (80 women and 90 men) after obtaining their oral prior informed consent. All interviews were carried out in the participants' homes and gardens by native speakers of Georgian and its local dialects (Svan, Tush, Khevsur, Psav), or, where participants spoke these as their native language, Armenian, Russian, or Greek. RESULTS: In the present study we encountered 480 plant species belonging to 249 genera of 95 families being used in the research region. The highest number of species and of unique species were reported from the remote Tusheti-Khevsureti region. Informant consensus and number of use reports were highest for each region in the food and medicinal use categories. Of the 480 plants being used in the research region 282 species were exclusively wild-harvested, 103 were grown in homegardens, and 84 were both grown in gardens and sourced in the wild. CONCLUSIONS: Plant species, and uses, found in our study, both for Georgia in general, as well as for its regions, showed clear relations to the wider Caucasus - Asia Minor - Balkans cultural complex. However, plant use in Georgia was much more diverse than reported in other studies from Eurasia.

The effects of foundation species on community assembly: a global study on alpine cushion plant communities.

Foundation species can change plant community structure by modulating important ecological processes such as community assembly, yet this topic is poorly understood. In alpine systems, cushion plants commonly act as foundation species by ameliorating local conditions. Here, we analyze diversity patterns of species' assembly within cushions and in adjacent surrounding open substrates (83 sites across five continents) calculating floristic dissimilarity between replicate plots, and using linear models to analyze relationships between microhabitats and species diversity. Floristic dissimilarity did not change across biogeographic regions, but was consistently lower in the cushions than in the open microhabitat. Cushion plants appear to enable recruitment of many relatively stress-intolerant species that otherwise would not establish in these communities, yet the niche space constructed by cushion plants supports a more homogeneous composition of species than the niche space beyond the cushion's influence. As a result, cushion plants support higher α-diversity and a larger species pool, but harbor assemblies with lower ß-diversity than open microhabitats. We conclude that habitats with and without dominant foundation species can strongly differ in the processes that drive species recruitment, and thus the relationship between local and regional species diversity.

Loss of traditional knowledge aggravates wolf-human conflict in Georgia (Caucasus) in the wake of socio-economic change.

Reports of the damage from wolf attacks have increased considerably over the last decade in Georgia (in the Caucasus). We interviewed locals about this problem in two focal regions: the Lanchkhuti area (in western Georgia) and Kazbegi District (in eastern Georgia) where livestock numbers had increased by an order of magnitude owing to dramatic shifts in the local economies over the last decade. This coincided with expanding habitats for wolves (abandoned plantations, for example). We found that the perceived damage from wolves was positively correlated with a poor knowledge of wolf habits and inappropriate livestock husbandry practices. Our results suggest a loss of traditional knowledge contributes strongly to the wolf-human conflicts in Georgia. Restoring traditional, simple but good practices--such as protecting herds using shepherd dogs and introducing bulls into the herds-can help one solve this problem.

The context dependence of beneficiary feedback effects on benefactors in plant facilitation.

Facilitative effects of some species on others are a major driver of biodiversity. These positive effects of a benefactor on its beneficiary can result in negative feedback effects of the beneficiary on the benefactor and reduced fitness of the benefactor. However, in contrast to the wealth of studies on facilitative effects in different environments, we know little about whether the feedback effects show predictable patterns of context dependence. We reanalyzed a global data set on alpine cushion plants, previously used to assess their positive effects on biodiversity and the nature of the beneficiary feedback effects, to specifically assess the context dependence of how small- and large-scale drivers alter the feedback effects of cushion-associated (beneficiary) species on their cushion benefactors using structural equation modelling. The effect of beneficiaries on cushions became negative when beneficiary diversity increased and facilitation was more intense. Local-scale biotic and climatic conditions mediated these community-scale processes, having indirect effects on the feedback effect. High-productivity sites demonstrated weaker negative feedback effects of beneficiaries on the benefactor. Our results indicate a limited impact of the beneficiary feedback effects on benefactor cushions, but strong context dependence. This context dependence may help to explain the ecological and evolutionary persistence of this widespread facilitative system.

A global analysis of bidirectional interactions in alpine plant communities shows facilitators experiencing strong reciprocal fitness costs.

Facilitative interactions are defined as positive effects of one species on another, but bidirectional feedbacks may be positive, neutral, or negative. Understanding the bidirectional nature of these interactions is a fundamental prerequisite for the assessment of the potential evolutionary consequences of facilitation. In a global study combining observational and experimental approaches, we quantified the impact of the cover and richness of species associated with alpine cushion plants on reproductive traits of the benefactor cushions. We found a decline in cushion seed production with increasing cover of cushion-associated species, indicating that being a benefactor came at an overall cost. The effect of cushion-associated species was negative for flower density and seed set of cushions, but not for fruit set and seed quality. Richness of cushion-associated species had positive effects on seed density and modulated the effects of their abundance on flower density and fruit set, indicating that the costs and benefits of harboring associated species depend on the composition of the plant assemblage. Our study demonstrates 'parasitic' interactions among plants over a wide range of species and environments in alpine systems, and we consider their implications for the possible selective effects of interactions between benefactor and beneficiary species.

Facilitative plant interactions and climate simultaneously drive alpine plant diversity.

Interactions among species determine local-scale diversity, but local interactions are thought to have minor effects at larger scales. However, quantitative comparisons of the importance of biotic interactions relative to other drivers are rarely made at larger scales. Using a data set spanning 78 sites and five continents, we assessed the relative importance of biotic interactions and climate in determining plant diversity in alpine ecosystems dominated by nurse-plant cushion species. Climate variables related with water balance showed the highest correlation with richness at the global scale. Strikingly, although the effect of cushion species on diversity was lower than that of climate, its contribution was still substantial. In particular, cushion species enhanced species richness more in systems with inherently impoverished local diversity. Nurse species appear to act as a 'safety net' sustaining diversity under harsh conditions, demonstrating that climate and species interactions should be integrated when predicting future biodiversity effects of climate change.

Importance versus intensity of ecological effects: why context matters.

In any ecological study, target organisms are usually impacted by multiple environmental drivers. In plant interaction research, recent debate has focussed on the importance of competition; that is, its role in regulating plant success relative to other environmental drivers. Despite being clearly and specifically defined, the apparently simple concept of the importance of competition has been commonly overlooked, and its recognition has helped reconcile long-running debates about the dependence of competition on environmental severity. In this review, we argue that extending this formalised concept of importance to other aspects of ecology would be beneficial. We discuss approaches for measuring importance, and provide examples where explicit acknowledgement of this simple concept might promote understanding and resolve debate.

Don't diss integration: a comment on Ricklefs's disintegrating communities.

Ricklefs's recent call to investigate ecological processes at large scales helps focus ecologists' attention on an undoubtedly important topic. However, we believe that some of his accompanying arguments for the primacy of such work and, in particular, for the need to "disintegrate" the local community concept are flawed. We revisit Ricklefs's main tenets and demonstrate that research on local communities is a vital part of understanding processes and diversity across a range of spatial and temporal scales. The integration of research across spatial scales expands our horizons and understanding of ecology and evolution, and this should not be unnecessarily constrained to one extreme or the other.

Do biotic interactions shape both sides of the humped-back model of species richness in plant communities?

A humped-back relationship between species richness and community biomass has frequently been observed in plant communities, at both local and regional scales, although often improperly called a productivity-diversity relationship. Explanations for this relationship have emphasized the role of competitive exclusion, probably because at the time when the relationship was first examined, competition was considered to be the significant biotic filter structuring plant communities. However, over the last 15 years there has been a renewed interest in facilitation and this research has shown a clear link between the role of facilitation in structuring communities and both community biomass and the severity of the environment. Although facilitation may enlarge the realized niche of species and increase community richness in stressful environments, there has only been one previous attempt to revisit the humped-back model of species richness and to include facilitative processes. However, to date, no model has explored whether biotic interactions can potentially shape both sides of the humped-back model for species richness commonly detected in plant communities. Here, we propose a revision of Grime's original model that incorporates a new understanding of the role of facilitative interactions in plant communities. In this revised model, facilitation promotes diversity at medium to high environmental severity levels, by expanding the realized niche of stress-intolerant competitive species into harsh physical conditions. However, when environmental conditions become extremely severe the positive effects of the benefactors wane (as supported by recent research on facilitative interactions in extremely severe environments) and diversity is reduced. Conversely, with decreasing stress along the biomass gradient, facilitation decreases because stress-intolerant species become able to exist away from the canopy of the stress-tolerant species (as proposed by facilitation theory). At the same time competition increases for stress-tolerant species, reducing diversity in the most benign conditions (as proposed by models of competition theory). In this way our inclusion of facilitation into the classic model of plant species diversity and community biomass generates a more powerful and richer predictive framework for understanding the role of plant interactions in changing diversity. We then use our revised model to explain both the observed discrepancies between natural patterns of species richness and community biomass and the results of experimental studies of the impact of biodiversity on the productivity of herbaceous communities. It is clear that explicit consideration of concurrent changes in stress-tolerant and competitive species enhances our capacity to explain and interpret patterns in plant community diversity with respect to environmental severity.

Positive interactions among alpine plants increase with stress.

Plants can have positive effects on each other. For example, the accumulation of nutrients, provision of shade, amelioration of disturbance, or protection from herbivores by some species can enhance the performance of neighbouring species. Thus the notion that the distributions and abundances of plant species are independent of other species may be inadequate as a theoretical underpinning for understanding species coexistence and diversity. But there have been no large-scale experiments designed to examine the generality of positive interactions in plant communities and their importance relative to competition. Here we show that the biomass, growth and reproduction of alpine plant species are higher when other plants are nearby. In an experiment conducted in subalpine and alpine plant communities with 115 species in 11 different mountain ranges, we find that competition generally, but not exclusively, dominates interactions at lower elevations where conditions are less physically stressful. In contrast, at high elevations where abiotic stress is high the interactions among plants are predominantly positive. Furthermore, across all high and low sites positive interactions are more important at sites with low temperatures in the early summer, but competition prevails at warmer sites.