Demographic and functional determinants of large-scale population dynamics and ecological niches of 26 serotinous Proteaceae

Thesis (PhDAgric)--Stellenbosch University, 2018.ENGLISH ABSTRACT: Understanding how organisms respond to the environment at large spatial scales is central to ecology, biodiversity research and conservation. Environmental variation affects the fitness (or performance), population dynamics and geographical distributions of species via morphological traits. Quantifying how demographic rates and functional traits vary across environmental gradients may thus yield insights into the underlying determinants of ecological performance and geographical distribution. However, studies of demographic and trait variation widely rely on observations from a few species, at small spatial scales and seldom include multiple abiotic and biotic drivers. A basic understanding of the drivers of large-scale demographic variation and how functional traits relate to population dynamics and species’ niches remains limited. Using the Hutchinsonian niche concept (i.e. the set of environmental conditions in which populations can grow), I investigated how environmental conditions and functional traits affect the demography, population dynamics and ecological niches of 26 serotinous Proteaceae species with fire-dependent life cycles from the Cape Floristic Region (South Africa). My objectives were to: (i) identify the environmental drivers of large-scale demographic variation, (ii) investigate whether plant functional traits explain demographic performance and Hutchinsonian niches, and (iii) study geographical variation in population sensitivity to wildflower harvesting. I addressed these objectives using data on key demographic rates and plant functional traits sampled across species’ entire geographical ranges. Environmental drivers (climate, fire disturbance, soil nutrient status and population density) explained variation in key demographic rates of reproduction and survival across species’ geographical distributions. The relative importance of these drivers varied throughout the life cycle of the study species: fecundity was mostly driven by fire interval whereas recruitment depended more on climate. A trade-off between survival and reproduction was also found where species with fire-protected buds (resprouters) had substantially higher fire survival compared to species without fire-protected buds (nonsprouters). Overall, intraspecific variation in fecundity and recruitment was greater than that of fire survival. I also investigated whether variation in functional traits (leaf, plant-architectural and seed traits) explains the Hutchinsonian niches of species. Results showed that interspecific trait variation explained considerable variation in global maximum population growth rates (rmax), as well as niche optima and widths along different environmental gradients. Intraspecific trait variation had positive effects on niche widths. Overall, relatively few individual traits stood out as predictors of species’ demographic niches. Finally, I integrated range-wide demographic data and dynamic population models to assess spatial variation in sensitivity to harvesting across species’ geographical distributions. I detected considerable variation in sensitivity to harvesting across species and populations. Range-wide intraspecific variation in sensitivity to harvesting showed distinct geographical and environmental relationships. Notably, sensitivity to harvesting was highest at the environmental limits of species’ ranges. Combined, these range-wide demographic and functional approaches on species niches provide fundamental and applied perspectives in ecology and conservation biogeography. These are necessary steps to understand how range dynamics emerge from variation in demography and functional traits, and how species may be affected by ongoing global change.AFRIKAANSE OPSOMMING: ’n Begrip van hoe organismes op ’n groot ruimtelike skaal op die omgewing reageer, is van belang vir ekologie, biodiversiteitsnavorsing en bewaring. Omgewingsvariasie beïnvloed die geskiktheid (of prestasie), populasiedinamiek en geografiese verspreiding van spesies deur middel van morfologiese kenmerke. ’n Kwantifisering van hoe demografiese koerse en funksionele kenmerke oor omgewingsgradiënte wissel, kan dus waardevolle insig bied in die onderliggende bepalers van ekologiese prestasie en geografiese verspreiding. Bestaande studies van demografiese en kenmerkvariasie maak egter meestal staat op waarnemings van slegs ’n paar spesies op ’n klein ruimtelike skaal, en neem selde ’n verskeidenheid abiotiese en biotiese dryfvere in ag. ’n Basiese begrip van die dryfvere van grootskaalse demografiese variasie, en die verband tussen funksionele kenmerke, populasiedinamiek en spesie-nisse, is nog beperk. Met behulp van Hutchinson se niskonsep (d.w.s. die stel omgewingsfaktore waarin populasies kan groei) het ek ondersoek watter invloed omgewingsomstandighede en funksionele kenmerke het op die demografie, populasiedinamiek en ekologiese nisse van 26 laatbloeiende Proteaceaespesies met brandafhanklike lewensiklusse in die Kaapse planteryk (Suid-Afrika). My oogmerke was (i) om te bepaal watter omgewingsdryfvere grootskaalse demografiese variasie veroorsaak, (ii) om te ondersoek watter funksionele plantkenmerke demografiese prestasie en Hutchinson se nisse verklaar, en (iii) om geografiese variasie in populasiesensitiwiteit vir veldblomoesting te bestudeer. Om hierdie oogmerke te verwesenlik, het ek gebruik gemaak van data oor die vernaamste demografiese koerse en funksionele plantkenmerke wat ingesamel is oor geografiese verspreidingsgebiede van spesies. Omgewingsdryfvere (klimaat, brandontwrigting, grondvoedingstatus en populasiedigtheid) het ’n verklaring gebied vir variasie in die vernaamste demografiese voortplantings- en oorlewingskoerse oor geografiese spesieverspreidings heen. Die relatiewe belang van hierdie dryfvere wissel deur die lewensiklus van die studiespesies: Vrugbaarheid word meestal deur brandgereeldheid bepaal, terwyl aanwas meer op klimaat berus. ’n Kompromis tussen oorlewing en voortplanting blyk ook uit die beduidend hoër brandoorlewingskoerse onder spesies met brandbeskermde knoppe (heruitlopers) vergeleke met spesies daarsónder (nieuitlopers). Intraspesifieke variasie in vrugbaarheid en aanwas was oor die algemeen hoër as variasie in brandoorlewing. Daarbenewens het ek ondersoek of variasie in funksionele kenmerke (blaar-, plantargitektuuren saadkenmerke) Hutchinson se spesie-nisse verklaar. Resultate toon dat interspesifieke kenmerkvariasie beduidende variasie in globale maksimum populasiegroeitempo’s (rmaks) sowel as nis-optima en -breedtes oor verskillende omgewingsgradiënte verklaar. Intraspesifieke kenmerkvariasie het’n positiewe uitwerking op nisbreedtes. Oor die algemeen staan betreklik min individuele kenmerke uit as voorspellers van demografiese spesie-nisse. Laastens het ek grootskaalse demografiese data en dinamiese populasiemodelle geïntegreer om ruimtelike variasie in oestingsensitiwiteit oor die geografiese verspreidings van spesies heen te beoordeel. Ek het bevind dat daar beduidende variasie in oestingsensitiwiteit is tussen spesies en populasies. Intraspesifieke variasie in oestingsensitiwiteit oor spesies se verspreidingsgebiede heen bring duidelike geografiese en omgewingsverwantskappe aan die lig. Oestingsensitiwiteit is veral die hoogste op die omgewingsperke van spesies se verspreidingsgebiede. Tesame bied hierdie grootskaalse demografiese en funksionele benaderings tot spesie-nisse fundamentele en toegepaste perspektiewe vir ekologie en bewaringsbiogeografie. Dit voorsien nodige inligting om te verstaan hoe verspreidingsgebieddinamiek uit variasie in demografie en funksionele kenmerke ontstaan, en hoe voortdurende globale verandering spesies kan raak

Functional traits explain the Hutchinsonian niches of plant species

CITATION: Martina, T. et al. 2019. Functional traits explain the Hutchinsonian niches of plant species. Global Ecology and Biogeography, 29(3):534–54. doi:10.1111/geb.13048The original publication is available at https://onlinelibrary.wiley.com/journal/14668238Aim: The Hutchinsonian niche is a foundational concept in ecology and evolutionary biology that describes fundamental characteristics of any species: the global maximum population growth rate (rmax); the niche optimum (the environment for which rmax is reached); and the niche width (the environmental range for which intrinsic population growth rates are positive). We examine whether these characteristics are related to inter- and intraspecific variation in functional traits. Location: Cape Floristic Region, South Africa. Time period: Present day. Major taxa studied: Twenty-six plant species (Proteaceae). Methods: We measured leaf, plant-architectural and seed traits across species geographical ranges. We then examined how species-mean traits are related to demographically derived niche characteristics of rmax, in addition to niche optima and widths in five environmental dimensions, and how intraspecific trait variation is related to niche widths. Results: Interspecific trait variation generally exceeded range-wide intraspecific trait variation. Species-mean trait values were associated with variation in rmax (R2 = 0.27) but were more strongly related to niche optima (mean R2 = 0.56). These relationships generally matched trait–environment associations described in the literature. Both species-mean traits and intraspecific trait variability were strongly related to niche widths (R2 = 0.66 and 0.59, respectively). Moreover, niche widths increased with intraspecific trait variability. Overall, the different niche characteristics were associated with few, largely non-overlapping sets of traits. Main conclusions: Our study relating functional traits to Hutchinsonian niches demonstrates that key demographic properties of species relate to few traits with relatively strong effects. Our results further support the hypothesis that intraspecific trait variation increases species niche widths. Given that niche characteristics were related to distinct sets of traits, different aspects of environmental change might affect axes of trait variation independently. Trait-based studies of Hutchinsonian niches thus yield important insights into the mechanisms shaping functional biodiversity, which should reinforce the role of traits in functional biogeography.https://onlinelibrary.wiley.com/doi/10.1111/geb.13048Publishers versio

TRY plant trait database – enhanced coverage and open access

Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Wildflower farming on the Agulhas Plain : fynbos management and conservation

Thesis (MScConsEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2010.134, 43 p. : ill.ENGLISH ABSTRACT: The Agulhas Plain is a constituent of the Cape Floristic Region, internationally known as a global biodiversity hotspot. The species-rich Agulhas Plain consists mainly of fire-prone fynbos shrublands of which sandstone fynbos covers a significant surface area. This lowland region is characterised by mostly infertile soils yet has unique floristic complexity and contains a high amount of threatened lowland species. Natural vegetation on the Agulhas Plain has been prone to large scale land transformation activities, mainly attributed to the extent of alien plant invasions, urbanisation and agricultural expansion. Fynbos wildflower farming, specifically from natural vegetation, is an important economic activity and contributes to the region‟s agricultural sector. Farmers harvest large quantities of commercial fynbos species and supply these to the market in an attempt to sustain a livelihood. Certain wildflower farming practices (burning, ploughing and broadcast sowing) are applied to natural vegetation in an attempt to increase the abundance of commercial species (i.e. augmentation). Numerous farming practices are used in the industry and the application of these methods can be dynamic and divergent. Furthermore, the implementation of farming practices manifest as anthropogenically induced disturbance events and are a concern for conservation. Previous investigations suggest that farming practices could establish monocultures of commercial wildflower species by reducing species richness and plant diversity of wildflower vegetation. Although the impact of natural disturbance regimes (e.g. fire) and flower harvesting activities have been researched, the impact of farming practices on fynbos structure and composition remains largely unknown. This thesis reports on various aspects related to wildflower farming on the Agulhas Plain. Firstly, by administering a questionnaire, the extent and application of farming practices was investigated. Additionally, the opinion of wildflower farmers (referred to as landholders) about the impact of farming practices on wildflower populations was explored. Secondly, a vegetation survey aimed to assess the impact of farming practices on various structural (regeneration mode and growth form) and compositional attributes (plant family, dominant and rare species) of fynbos. Results from the questionnaire indicate that the application of farming methods are seasonally restricted, often used in varying combinations and relatively small in spatial extent. Furthermore, results show that wildflower farmers have an ecologically acceptable knowledge base and awareness of fynbos management and conservation. Secondly results, obtained from the vegetation survey, imply that natural vegetation subjected to particular farming practices differ from pristine fynbos vegetation by having both altered structural and compositional attributes. However, the impact of farming practices on rare species was less apparent. The conflict between commercial and conservation objectives are apparent from consultation with landholders. Nonetheless, landholders are optimistic about fynbos conservation and conservation can build upon these positive sentiments. Importantly, there is a need to communicate locally with landholders if a sustainable wildflower industry is a priority to stakeholders on the Agulhas Plain. Furthermore, fynbos ecosystems naturally entail complex ecological interactions. Wildflower farming practices reduce the ecological integrity (i.e. altered plant diversity, growth form and plant composition) of wildflower vegetation, at least at the local scale. These farming practices ultimately result both in distorted competitive interactions and disturbance regimes. Therefore, from a conservation perspective, the implementation of these farming practices (ploughing and broadcast sowing) should be cautioned against.AFRIKAANSE OPSOMMING: Die Agulhas-vlakte vorm deel van die Kaapse Blommeryk; „n gebied wat internasionale bekendheid verwerf het as „n biodiversiteits-brandpunt. Die spesieryke Agulhas-vlakte bestaan hoofsaaklik uit fynbosstruiklande wat geneig is tot veldbrande. Sandsteenfynbos beslaan „n beduidende oppervlak van die gebied (Agulhas-vlakte). Hierdie laagliggende area (Agulhas-vlakte) word meestal deur onvrugbare grondtipes gekenmerk maar beskik nogtans oor unieke fynbos kompleksiteit wat „n aantal bedreigde laagland spesies insluit. Natuurlike plantegroei op die Agulhas-vlakte is onderworpe aan grootskaalse grondgebruik transformasie; hoofsaaklik toe te skryf aan indringer plantegroei, verstedeliking en uitbreiding van landbou. Fynbos veldblomboerdery, spesifiek van natuurlike plantegroei, is „n belangrike ekonomiese aktiwiteit en lewer „n bydrae tot die Agulhas-vlakte se landbou sektor. Boere oes en lewer groot hoeveelhede kommersiële fynbos spesies aan die mark. Sekere veldblom-boerderypraktyke (brand, ploeg en saadstrooi) word ingespan op fynbosveld ten einde die opbrengs en afwisseling van kommersiële spesies te verhoog. „n Verskeidenheid boerderypraktyke word gevolg en die toepassing van hierdie boerderypraktyke is dinamies en uiteenlopend. Voorts manifesteer die implementering van hierdie boerderypraktyke as mensgemaakte versteurings wat kommerwekkend is vanuit „n bewaringsperspektief. Vorige ondersoeke dui moontlik daarop dat boerderypraktyke monokulture van kommersiële veldblomspesies kan vestig deur die veelheid van spesies en diversiteit van veldblomplantegroei te verminder. Ten spyte daarvan dat die impak van natuurlike versteuringsregimes (bv. vuur) en veldblompluk-aktiwiteite reeds nagevors is, bly die impak van veldblomboerderypraktyke op fynbosstruktuur en -samestelling grotendeels onbekend. Hierdie tesis doen verslag oor verskeie aspekte van veldblomboerdery op die Agulhas-vlakte. Eerstens, deur middel van „n vraelys, is die omvang en aanwending van verskillende boerderypraktyke nagevors. Verder is die menings van veldblomboere (na wie verwys word as grondeienaars) ondersoek met die klem op die impak van boerderypraktyke op veldblombevolkings. Tweedens, is „n plantegroei-opname met die doelwit om die impak van landboupraktyke op verskeie strukturele- (regenerasiemodus en groeivorm) en samestellende eienskappe (plantfamilie, dominante- en seldsame spesies) van fynbos vas te stel gedoen. Die resultate van die vraelys dui daarop dat die aanwending van boerderypraktyke seisoenaal beperk word, dikwels in wisselende kombinasies gebruik word en in ruimtelike omvang redelik klein is. Boonop toon die resultate dat veldblomboere oor „n ekologies-aanvaarbare kennisgrondslag en bewustheid van fynbosbestuur en –bewaring beskik. Tweedens, impliseer die resultate, vanuit die plantegroei-opname, dat fynbosveld wat onderwerp word aan sekere boerderypraktyke van natuurlike fynbosplantegroei verskil deurdat dit gewysigde strukturele- sowel as samestellende eienskappe toon. Die impak van die boerderypraktyke op seldsame spesies was egter minder waarneembaar. Die botsing tussen kommersiële- en bewaringsoogmerke blyk duidelik uit konsultasie met grondeienaars. Nietemin is die grondeienaars optimisties oor fynbosbewaring en bewaring kan op hierdie positiewe sentimente staatmaak en voortbou. Dit is belangrik om daarop te let dat dit noodsaaklik is om plaaslik met grondeienaars oorleg te pleeg indien „n volhoubare veldblomindustrie „n prioriteit vir belanghebbendes op die Agulhas-vlakte is. Verder, aangesien fynbos ekosisteme natuurlik komplekse ekologiese wisselwerkings behels, verminder veldblom-boerderypraktyke die ekologiese integriteit (m.a.w. gewysigde plantdiversiteit, groeivorm en plantsamestelling) van fynbosveld, ten minste op kleinskaal (plaaslik). Hierdie landboupraktyke het uiteindelik beide verwronge kompeterende wisselwerkinge asook versteuringsregimes tot gevolg. Vanuit „n bewaringsperspektief moet daar dus teen hierdie boerderypraktyke gewaarsku word

Conservation begins after breakfast: the relative importance of opportunity cost and identity in shaping private landholder participation in conservation

The conservation opportunity literature increasingly emphasises opportunity cost as an important determinant of willingness to engage in conservation on private land. We investigated the explanatory power of a group of opportunity cost variables in the decision to participate in a landscape-level conservation initiative on the Agulhas Plain, Cape Floristic Region. Opportunity cost variables outperformed affiliation and demographic variables when used in one model and had almost as much explanatory power as the combined model when used on their own. In the opportunity cost model, conservation was positively related to farm size and education and negatively related to share of income from farming and size of the remnant of natural vegetation on the farm. Of these relationships, that between education and participation was the most elastic: a 1% increase in education led to an almost 2% increase in the likelihood of participating in conservation. A large group of identity variables jointly explained nothing, but a subset of age, gender and Afrikaans language status had some explanatory power when used separately. We suspected this subset of demographic variables to have done nothing but proxy patterns of opportunity cost in the farming community. When re-estimated with the untransformed remnant as a share of farm size rather than an area, similar results were obtained and the negative sign on the remnant was confirmed. We concluded that understanding what opportunity cost conservation imposes on private landholders is not only important, but critical, for predicting which private land will come into and stay in conservation

Range-wide population viability analyses reveal high sensitivity to wildflower harvesting in extreme environments

The ecological effects of harvesting from wild populations are often uncertain, especially since the sensitivity of populations to harvesting can vary across species' geographical ranges. In the Cape Floristic Region (CFR, South Africa) biodiversity hotspot, wildflower harvesting is widespread and economically important, providing an income to many rural communities. However, with very few species studied to date, and without considering range-wide sensitivity to harvesting, there is limited information available to ensure the sustainability of wildflower harvesting. We studied geographical variation in sensitivity to wildflower harvesting for 26 Proteaceae shrubs with fire-driven life cycles using population viability analyses. We developed stochastic, density-dependent population models that were parameterized from individual demographic rates (adult fecundity, seedling recruitment and adult fire survival) and local environmental conditions across the geographical ranges of the study species. We then simulated the effects of harvesting on populations in different environments across species ranges. Our model simulations predicted extinction risk per population, and we derived extinction probabilities over 100 years in response to different harvesting regimes. We used these population-level extinction probabilities to quantify inter- and intraspecific variation in sensitivity to wildflower harvesting, and to explore how geographical variation in sensitivity depends on environmental conditions (climate, soil fertility and fire disturbance). We detected considerable inter- and intraspecific variation in sensitivity to wildflower harvesting for the 26 study species. This held for both 'nonsprouters' and 'resprouters' (species with low and high fire persistence ability, respectively). Intraspecific variation in sensitivity to harvesting showed varying geographical patterns and associated with environmental variation. Notably, sensitivity was high towards range edges and at the climatic extremes of species ranges, respectively. Synthesis and applications: We show the importance of combining spatial demographic data, density-dependent population dynamics and environmental variation when assessing sensitivity to harvesting across species geographical ranges. Our findings caution against the application of general harvesting guidelines irrespective of species, geographical location or local environmental conditions. Our range-wide population viability analyses provide insights for developing species-specific, spatially nuanced guidelines for conservation management. Our approach also identifies species and areas to prioritise for monitoring to prevent the overexploitation of harvested species.23-Mar-2021This .zip directory contains R scripts, model code and data used to perform population viability analyses across the geographic ranges of 26 Proteaceae species in the South African Cape Floristic Region. *refer to ReadMe file for full descriptions of the data and usage. Usage Notes for the code and associated functions and parameters used in 'PVA.R': PVA.R R script to perform the described population viability analyses for populations in different environments across species' geographic ranges PVA_Fun.r R script defining auxiliary functions used in PVA.R ProteaModel.dll Compiled dynamic link library that implements the stochastic model of local population dynamics and is called from the R scripts ProteaModel.c C source code of ProteaModel.dll ModelParameters Folder containing the species-specific global and spatial parameters used in the population viability analyses Funding provided by: German Research Foundation (DFG) grants*Crossref Funder Registry ID: Award Number: SCHU 2259/5-1 and SCHU 2259/5-2Funding provided by: National Research Foundation of South Africa (NRF) through the South African Environmental Observation Network (SAEON)*Crossref Funder Registry ID: Award Number: Funding provided by: Claude Leon FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001337Award Number: Funding provided by: German Research Foundation (DFG) grantsCrossref Funder Registry ID: Award Number: SCHU 2259/5-1 and SCHU 2259/5-2Demographic data can be found in the cited literature of this article (notably Treurnicht et al. 2016; Pagel et al. 2020 and supporting information of these published articles). These demographic data were partly used under license agreements from provincial and national conservation organisations in South Africa (CapeNature and SANParks) and are available from the lead author ([email protected]) upon reasonable request and with the permission of these organisations. -Treurnicht, M., Pagel, J., Esler, K.J., Schutte‐Vlok, A., Nottebrock, H., Kraaij, T. et al. (2016) Environmental drivers of demographic variation across the global geographical range of 26 plant species. Journal of Ecology, 104, 331–342. -Pagel, J., Treurnicht, M., Bond, W.J., Kraaij, T., Nottebrock, H., Schutte-Vlok, A., Tonnabel, J., Esler, K.J. & Schurr, F.M. (2020) Mismatches between demographic niches and geographic distributions are strongest in poorly dispersed and highly persistent plant species. Proceedings of the National Academy of Sciences 117, 3663-3669. Environmental data are from various sources cited in the main text of this article (Treurnicht et al. 2021) and include: - Schulze, R.E. (2007) South African Atlas of Climatology and Agrohydrology, Technical Report 1489/1/06. Water Research Commission, Pretoria, South Africa. - Wilson, A.M., Latimer, A.M. & Silander, J.A. (2015) Climatic controls on ecosystem resilience: postfire regeneration in the Cape Floristic Region of South Africa. Proceedings of the National Academy of Sciences of the USA, 112, 9058–9063

Counting complete? Finalising the plant inventory of a global biodiversity hotspot

The Cape Floristic Region—the world’s smallest and third richest botanical hotspot—has benefited from sustained levels of taxonomic effort and exploration for almost three centuries, but how close is this to resulting in a near-complete plant species inventory? We analyse a core component of this flora over a 250-year period for trends in taxonomic effort and species discovery linked to ecological and conservation attributes. We show that >40% of the current total of species was described within the first 100 years of exploration, followed by a continued steady rate of description. We propose that <1% of the flora is still to be described. We document a relatively constant cohort of taxonomists, working over 250 years at what we interpret to be their ‘taxonomic maximum.’ Rates of description of new species were independent of plant growth-form but narrow-range taxa have constituted a significantly greater proportion of species discoveries since 1950. This suggests that the fraction of undiscovered species predominantly comprises localised endemics that are thus of high conservation concern. Our analysis provides important real-world insights for other hotspots in the context of global strategic plans for biodiversity in informing considerations of the likely effort required in attaining set targets of comprehensive plant inventories. In a time of unprecedented biodiversity loss, we argue for a focused research agenda across disciplines to increase the rate of species descriptions in global biodiversity hotspots

Environmental drivers of demographic variation across the global geographical range of 26 plant species

International audience1 Understanding how rates of reproduction and survival respond to environmental variation across species’ geographical ranges is a key task for both basic and applied ecology. So far, however, environmental drivers of range‐wide demographic variation have only been studied in a few plant species without considering the potentially confounding effects of population density on demographic rates.2We present a large‐scale demographic study of 26 shrub species (Proteaceae) from the Cape Floristic Region. All study species have a fire‐dependent life cycle and are serotinous: they exclusively form a canopy seed bank which contains the seeds produced since the last fire. Fire triggers seed release from the canopy so that recruitment is largely limited to a short period after fire.3 Across the global geographical ranges of the study species, we collected 3454 population‐level records of total fecundity since the last fire (size of individual canopy seed banks), per‐capita recruitment (ratio between post‐fire recruits and pre‐fire adults) and adult fire survival. We used linear regressions to quantify how climate, population density, fire interval and soil nutrients affect demographic variation.4 A trade‐off between survival and reproduction is evident throughout the geographical ranges of our study species: resprouting species with fire‐protected buds had much higher fire survival than nonsprouters without fire‐protected buds (97% vs. 2%) but they also had substantially lower fecundity and recruitment rates. We found little intraspecific variation in fire survival rates but considerable intraspecific variation in fecundity and recruitment.5 Range‐wide variation in fecundity was dominated by fire interval whereas recruitment was mostly climate‐driven. Population density and soil nutrients generally had smaller effects but were important for the fecundity and recruitment of several species. Effects of fire interval on fecundity were consistent across species, but other demography–environment relationships showed substantial interspecific differentiation.6 Synthesis. This study extends demographic research beyond the population to cover the geographical ranges of multiple species. Such large‐scale studies are a necessary first step of a research agenda that aims to understand how range dynamics emerge from first principles of demography, how they are shaped by functional traits and macroevolution and how they will be impacted by global change

TRY plant trait database - enhanced coverage and open access

10.1111/gcb.14904GLOBAL CHANGE BIOLOGY261119-18