Variety Of Growth Forms Research Articles

Diversity and Distribution of Monocot Understory Herbs during Tropical Forest Succession in Northeastern Costa Rica

Broad-leaved monocot herbs form one of the most common and diverse growth forms of Neotropical plants. Their significance and frequency of occurrence is particularly notable in the understories of tropical rainforests, where they form a dominant element. We assessed and quantified changes in the cover and diversity of understory herb communities in a chronosequence of 1 ha permanent plots established as part of a multidisciplinary study on tropical forest regeneration in the Atlantic lowlands of northeastern Costa Rica. Sampled were two young stands cleared 12 years ago, two secondary forests with 21 and 39 of years of recovery since clearance, and two stands in old-growth primary forest. Changes in species composition during succession were assessed using Chao’s Jaccard similarity index. Observed species richness ranged from 15 to 26 species in individual plots, with the greatest number of species in the 21-year intermediate-age and fewest in the young 12-year plots. Herb species sampled represented 6 families, 15 genera, and 39 species, with the Araceae contributing the largest number of species. Ten species were sampled in all six stands, while fourteen species were found exclusively in one plot. Herb density (ramets m−2) showed a hump-shade trend, with peak density in the intermediate stands and a lower level in mature and young secondary forests. Mean herb cover in 25 m2 quadrats ranged from 2.0% (young stand) to 22.7% (intermediate-age stand) and differed significantly both among stand types and among sites. Both observed and estimated species richness increased along the chronosequence as a whole, with the highest number of species in primary forest, although only slightly higher than in intermediate-age stands. Over half of the species exhibited some degree of clonal growth, with the extent of clonal spread varying among species and forest stands. Although we did not find a clear pattern between clonality and forest age, we observed a greater number of clonal patches in secondary over primary forest stands.

Leaf nutrient-based processes of conservatism and convergence regulate the vertical stratification of plant growth forms during subtropical forest degradation

Unveiling the ecological and evolutionary mechanisms that guide the differentiation of various plant growth forms into vertical forest strata during forest degradation continues to pose a challenge. We utilized the biogeochemical niche theory to decipher these mechanisms. We measured leaf concentrations of basal elements (C, N, P, K, Ca, and Mg) and used them to generate the biogeochemical niches in herbs, shrubs, trees, and climbers from different vertical strata within a degraded forest and its neighboring mature forest in subtropical montane zones. Our results showed that biogeochemical niches varied significantly among growth forms. Biogeochemical niches also differed significantly between species in the degraded and mature forests, as evidenced by the significantly lower leaf C concentration relative to other nutrients in degraded forest species. This could be attributable mainly to the expansive canopy openness in the degraded forest, facilitating the colonization of light-demanding self-supporters and climbers. The phylogenetic signals in leaf nutrient concentrations were significantly present across all species, suggesting the general similarities in biogeochemical niches among closely related species. Following evolutionary model comparisons, stabilizing selection towards varying optimal leaf nutrient concentrations for distinct growth forms in the degraded or mature forest emerged as the most suitable model. Our study thus highlights the important role of phylogenetic biogeochemical niche conservatism and stabilizing selection towards various optimal leaf nutrient compositions for diverse growth forms in both degraded and mature forests in the formation of vertical plant communities during subtropical forest degradation.

Diversity, productivity and biomass patters of epiphytes along successional gradient in the Andean Colombian

Our objective was to determine the relationship of different successional stages with the diversity, assimilation rates and net productivity of different growth forms of vascular epiphytes in a humid montane forest in Andean Colombian. Three successional stages were selected according to the site conditions. The 30 trees sampled in the three successional stages 4,610 epiphytic individuals to 54 species. A main finding was that species richness, abundance and biomass increased with stage age. Additionally true epiphytes were the growth form with the greatest richness, abundance and biomass. Regarding photosynthesis rates decreased with stage age and were higher for treelets, shrubs and lower for true epiphytes. According the analysis of the ordering of the epiphytes found by stages shows the existence of a successional trajectory with the presence of representative species of each stage. This research can contribute as a basis to the knowledge of epiphytes, with the purpose of enriching and supporting management measures for these species.

Advancing the science and practice of rare plant conservation with the Center for Plant Conservation Reintroduction Database.

Reintroductions or translocations are an increasingly important activity to recover and conserve at-risk plant species. Yet because many are not published in the scientific literature, learning from previous attempts may often require considerable time and effort. The Center for Plant Conservation Reintroduction Database (CPCRD; https://saveplants.org/reintroduction-database/), a new centralized and standardized repository of U.S.-based plant reintroductions, aims to improve the efficiency and effectiveness of accessing data on rare plant reintroductions. The CPCRD is the product of multiple efforts to assemble information on rare plant reintroductions in the United States. The database comprises a wealth of standardized data on the key stages of a reintroduction, from the planning and implementation phases, to monitoring and management techniques. The CPCRD is a dynamic resource, allowing data contributors to continually update their entries as projects progress. While contributions are ongoing, the CPCRD currently includes 460 projects involving 201 plant taxa, spanning diverse growth forms, ecosystems, and regions. The CPCRD and its well-documented and monitored projects provide a valuable practical resource for conservation practitioners, and have supported multiple scientific studies and contributed to the internationally recognized Center for Plant Conservation Best Practices Guidelines.

MelastomaTRAITs 1.0: A database of functional traits in Melastomataceae, a large pantropical angiosperm family.

The recent availability of open-access repositories of functional traits has revolutionized trait-based approaches in ecology and evolution. Nevertheless, the underrepresentation of tropical regions and lineages remains a pervasive bias in plant functional trait databases, which constrains large-scale assessments of plant ecology, evolution, and biogeography. Here, we present MelastomaTRAITs 1.0, a comprehensive and updatable database of functional traits for the pantropical Melastomataceae, the ninth-largest angiosperm family with 177 genera and more than 5800 species. Melastomataceae encompass species with a wide diversity of growth forms (herbs, shrubs, trees, epiphytes, and woody climbers), habitats (including tropical forests, savannas, grasslands, and wetlands from sea level to montane areas above the treeline), ecological strategies (from pioneer, edge-adapted and invasive species to shade-tolerant understory species), geographic distribution (from microendemic to continental-wide distribution), reproductive, pollination, and seed dispersal systems. MelastomaTRAITs builds on 581 references, such as taxonomic monographs, ecological research, and unpublished data, and includes four whole-plant traits, six leaf traits, 11 flower traits, 18 fruit traits, and 27 seed traits for 2520 species distributed in 144 genera across all 21 tribes. Most data come from the Neotropics where the family is most species-rich. Miconieae (the largest tribe) contains the highest number of trait records (49.6%) and species (41.1%) records. The trait types with the most information in the database were whole-plant traits, flowers, and leaf traits. With the breadth of functional traits recorded, our database helps to fill a gap in information for tropical plants and will significantly improve our capacity for large-scale trait-based syntheses across levels of organization, plant-animal interactions, regeneration ecology, and thereby support conservation and restoration programs. There are no copyright restrictions on the dataset; please cite this data paper when reusing the data.

Advances in Legume Systematics 14. Classification of Caesalpinioideae. Part 2: Higher-level classification.

Caesalpinioideae is the second largest subfamily of legumes (Leguminosae) with ca. 4680 species and 163 genera. It is an ecologically and economically important group formed of mostly woody perennials that range from large canopy emergent trees to functionally herbaceous geoxyles, lianas and shrubs, and which has a global distribution, occurring on every continent except Antarctica. Following the recent re-circumscription of 15 Caesalpinioideae genera as presented in Advances in Legume Systematics 14, Part 1, and using as a basis a phylogenomic analysis of 997 nuclear gene sequences for 420 species and all but five of the genera currently recognised in the subfamily, we present a new higher-level classification for the subfamily. The new classification of Caesalpinioideae comprises eleven tribes, all of which are either new, reinstated or re-circumscribed at this rank: Caesalpinieae Rchb. (27 genera / ca. 223 species), Campsiandreae LPWG (2 / 5-22), Cassieae Bronn (7 / 695), Ceratonieae Rchb. (4 / 6), Dimorphandreae Benth. (4 / 35), Erythrophleeae LPWG (2 /13), Gleditsieae Nakai (3 / 20), Mimoseae Bronn (100 / ca. 3510), Pterogyneae LPWG (1 / 1), Schizolobieae Nakai (8 / 42-43), Sclerolobieae Benth. & Hook. f. (5 / ca. 113). Although many of these lineages have been recognised and named in the past, either as tribes or informal generic groups, their circumscriptions have varied widely and changed over the past decades, such that all the tribes described here differ in generic membership from those previously recognised. Importantly, the approximately 3500 species and 100 genera of the former subfamily Mimosoideae are now placed in the reinstated, but newly circumscribed, tribe Mimoseae. Because of the large size and ecological importance of the tribe, we also provide a clade-based classification system for Mimoseae that includes 17 named lower-level clades. Fourteen of the 100 Mimoseae genera remain unplaced in these lower-level clades: eight are resolved in two grades and six are phylogenetically isolated monogeneric lineages. In addition to the new classification, we provide a key to genera, morphological descriptions and notes for all 163 genera, all tribes, and all named clades. The diversity of growth forms, foliage, flowers and fruits are illustrated for all genera, and for each genus we also provide a distribution map, based on quality-controlled herbarium specimen localities. A glossary for specialised terms used in legume morphology is provided. This new phylogenetically based classification of Caesalpinioideae provides a solid system for communication and a framework for downstream analyses of biogeography, trait evolution and diversification, as well as for taxonomic revision of still understudied genera.

Contrasting biomass allocations explain adaptations to cold and drought in the world's highest-growing angiosperms.

Understanding biomass allocation among plant organs is crucial for comprehending plant growth optimization, survival and responses to the drivers of global change. Yet, the mechanisms governing mass allocation in vascular plants from extreme elevations exposed to cold and drought stresses remain poorly understood. We analysed organ mass weights and fractions in 258 Himalayan herbaceous species across diverse habitats (wetland, steppe, alpine), growth forms (annual, perennial taprooted, rhizomatous and cushiony) and climatic gradients (3500-6150 m elevation) to explore whether biomass distribution adhered to fixed allometric or optimal partitioning rules, and how variations in size, phylogeny and ecological preferences influence their strategies for resource allocation. Following optimal partitioning theory, Himalayan plants distribute more biomass to key organs vital for acquiring and preserving limited resources necessary for their growth and survival. Allocation strategies are mainly influenced by plant growth forms and habitat conditions, notably temperature, water availability and evaporative demands. Alpine plants invest primarily in below-ground stem bases for storage and regeneration, reducing above-ground stems while increasing leaf mass fraction to maximize carbon assimilation in their short growing season. Conversely, arid steppe plants prioritize deep roots over leaves to secure water and minimize transpiration. Wetland plants allocate resources to above-ground stems and below-ground rhizomes, enabling them to resist competition and grazing in fertile environments. Himalayan plants from extreme elevations optimize their allocation strategies to acquire scarce resources under specific conditions, efficiently investing carbon from supportive to acquisitive and protective functions with increasing cold and drought. Intraspecific variation and shared ancestry have not significantly altered biomass allocation strategies of Himalayan plants. Despite diverse evolutionary histories, plants from similar habitats have developed comparable phenotypic structures to adapt to their specific environments. This study offers new insights into plant adaptations in diverse Himalayan environments and underscores the importance of efficient resource allocation for survival and growth in challenging conditions.

Assessment of Edible Woody Plants’ Diversity, Their Threats, and Local People’s Perception in Borecha Woreda of Buno Bedele Zone, Southwestern Ethiopia

Edible woody plants play an essential role in ensuring the food and livelihood security of communities. However, the management practice and diversity of those plants are declined, particularly in an urbanizing world, due to a lack of traditional awareness among the people. This research identified edible woody plants’ diversity, their threats, and local people’s perception in Borecha woreda of Buno Bedele Zone, southwestern Ethiopia. Data on edible woody plants were gathered through interviews with 105 households (67 men and 38 women) between the ages of 21 and 90. Structured and semistructured questionnaires were used to obtain the data from informants. The collected data were analyzed using descriptive statistics in Statistical Package for the Social Sciences (SPSS) software. Results showed significant differences (P<0.05) between the number of edible woody plants reported by age and literacy level of respondents. Forty-three species of edible woody plants, belonging to 34 genera and 24 families, were identified. Fruits (79.1%), roots (14%), leaves (2.3%), stems (2.3%), and seeds (2.3%) were identified as the edible parts of these plants. Fruits are the most edible plant part usually consumed fresh without cooking in the study area. The identified plants have a variety of growth forms: shrubs (49%), trees (37%), and lianas (14%) respectively. The most common plant growth forms in the study site were shrubs. In the study area, agricultural expansion, overharvesting, and lack of natural regeneration were the major threats to edible woody plants. In the study area, cutting for constructions was the primary hazard to edible woody plants. In situ and ex situ conservation strategies and efforts of plantation practices in the agricultural landscape are needed for sustaining the edible woody plants in the study area.

Cell wall polysaccharide and glycoprotein content tracks growth-form diversity and an aridity gradient in the leaf-succulent genus Crassula.

Cell wall traits are believed to be a key component of the succulent syndrome, an adaptive syndrome to drought, yet the variability of such traits remains largely unknown. In this study, we surveyed the leaf polysaccharide and glycoprotein composition in a wide sampling of Crassula species that occur naturally along an aridity gradient in southern Africa, and we interpreted its adaptive significance in relation to growth form and arid adaptation. To study the glycomic diversity, we sampled leaf material from 56 Crassula taxa and performed comprehensive microarray polymer profiling to obtain the relative content of cell wall polysaccharides and glycoproteins. This analysis was complemented by the determination of monosaccharide composition and immunolocalization in leaf sections using glycan-targeting antibodies. We found that compact and non-compact Crassula species occupy distinct phenotypic spaces in terms of leaf glycomics, particularly in regard to rhamnogalacturonan I, its arabinan side chains, and arabinogalactan proteins (AGPs). Moreover, these cell wall components also correlated positively with increasing aridity, which suggests that they are likely advantageous in terms of arid adaptation. These differences point to compact Crassula species having more elastic cell walls with plasticizing properties, which can be interpreted as an adaptation toward increased drought resistance. Furthermore, we report an intracellular pool of AGPs associated with oil bodies and calcium oxalate crystals, which could be a peculiarity of Crassula and could be linked to increased drought resistance. Our results indicate that glycomics may be underlying arid adaptation and drought resistance in succulent plants.

Novel species discrimination method elucidates colony growth form variation between the New Zealand soft corals Kotatea aurantiaca and Kotatea lobata

In New Zealand, Kotatea aurantiaca and Kotatea lobata are two common, endemic, co-occurring, and morphologically similar soft coral species that currently cannot be distinguished without microscopic examination of sclerites and of which little is known regarding any aspect of their ecology or biology. The aim of the present study is to ascertain if, and in what ways, their colony growth forms differ, and to test the taxonomic value of macroscopic morphological character measurements using statistical discrimination analyses. A binary logistic regression model is developed whereby macroscopic characters of colony morphology can be used to assign specimens to either species with ~ 90% accuracy. Species assignment accuracy is greatest when ratios formed from morphological measurements are used rather than direct measurements. Here, these ratios are used for the first time to account for the appearance-altering habit among soft corals of hydrostatically expanding and contracting their coelenteron with seawater. Relationships between colony morphology and depth are also examined, and it is suggested that phenotypic plasticity detected in K. lobata, causing it to resemble K. aurantiaca more closely at greater depths, may contribute to their morphological overlap. It is anticipated that this discrimination technique will facilitate future research on the ecology and biology of these species and will be replicated on other sets of morphologically similar soft corals for which species discrimination has been problematic.

Both species richness and growth forms affect nutrient removal in constructed wetlands: A mesocosm experiment

IntroductionPlant richness is thought to improve the function of constructed wetlands (CWs), but most CWs are planted with monocultures, with only a few employed polycultures, which have drawn contradictory conclusions. We suppose functional diversity is the key to better performance of plant communities and hypothesize that CWs planted with diverse growth forms are superior in plant growth and nutrient removal.MethodsIn this study, six emergent plant species categorized into slender type (Schoenoplectus tabernaemontani, Typha orientalis), fan type (Iris sibirica, Acorus calamus) and large type (Canna indica and Thalia dealbata) were planted in monocultures, combinations (two species of the same growth form) and mixed polycultures (six species of three growth forms). We then compared how plant growth and nutrient uptake differed among treatments.ResultsIt showed that the polyculture considerably increased the removal of total nitrogen (TN) and total phosphorus (TP), but the combination did not outperform monoculture. High consistency in the patterns between underground biomass and total biomass indicated that plant roots were essential for nutrient consumption. Compared with slender and fan plants, the large plants had a greater biomass increase in polycultures, which greatly accelerated the absorption and assimilation of TN and TP.ConclusionOur study indicated that plant community with various growth forms reduced the intensity of interspecific competition, increased the functional diversity, and greatly enhanced the ability of pollutant removal. Our results also provide some suggestions for plant selection and combination designs in CWs.

Consistent responses to moisture stress despite diverse growth forms within mountain fynbos communities

Understanding climate change impacts on the Cape Floristic Region requires improved knowledge of plant physiological responses to the environment. Studies examining physiological responses of mountain fynbos have consisted of campaign-based measurements, capturing snapshots of plant water relations and photosynthesis. We examine conclusions drawn from prior studies by tracking in situ physiological responses of three species, representing dominant growth forms (proteoid, ericoid, restioid), over 2 years using miniature continuous sap flow technology, long-term observations of leaf/culm water potential and gas exchange, and xylem vulnerability to embolism. We observed considerable inter-specific variation in the timing and extent of seasonal declines in productivity. Shallow-rooted Erica monsoniana exhibited steep within-season declines in sap flow and water potentials, and pronounced inter-annual variability in total daily sap flux (Js). Protea repens showed steady reductions in Js across both years, despite deeper roots and less negative water potentials. Cannomois congesta—a shallow-rooted restioid—was least negatively impacted. Following rehydrating rain at the end of summer, gas exchange recovery was lower in the drier year compared with the normal year, but did not differ between species. Loss of function in the drier year was partially accounted for by loss of xylem transport capacity in Erica and Cannomois, but not Protea. Hitherto unseen water use patterns, including inter-annual variability of gas exchange associated with contrasting water uptake properties, reveal that species use different mechanisms to cope with summer dry periods. Revealing physiological responses of key growth forms enhances predictions of plant function within mountain fynbos under future conditions.

Physiological response and photosynthetic recovery to an extreme drought: Evidence from plants in a dry-hot valley savanna of Southwest China

The frequency of extreme drought events has been rising worldwide, but due to its unpredictability, how plants will respond remains poorly understood. Here, we aimed to characterize how the hydraulics and photosynthesis of savanna plants respond to extreme drought, and tested whether they can subsequently recover photosynthesis after drought. There was an extreme drought in 2019 in Southwest (SW) China. We investigated photosynthetic gas exchange, leaf-, stem-, and whole-shoot hydraulic conductance of 18 plant species with diverse leaf habits (deciduous, semi-deciduous and evergreen) and growth forms (tree and shrub) from a dry-hot valley savanna in SW China for three rainy seasons from 2019 to 2021. We also compared photosynthetic gas exchange to those of a regular year (2014). We found that leaf stomatal and hydraulic conductance and maximum photosynthetic rate were significantly lower during the drought in 2019 than in the wetter years. In 2019, all studied plants maintained stomatal conductance at their minimum level observed, which could be related to high vapor pressure deficits (VPD, >2 kPa). However, no significant difference in stem and shoot hydraulic conductance was detected across years. The reductions in leaf hydraulic conductance and stomatal regulation under extreme drought might help keep the stem hydraulic function. Stomatal conductance and photosynthesis after drought (2020 and 2021) showed comparable or even higher values compared to that of 2014, suggesting high recovery of photosynthetic gas exchange. In addition, the response of hydraulic and photosynthetic traits to extreme drought was convergent across leaf habits and growth forms. Our results will help better understand the physiological mechanism underlying the response of savanna ecosystems to climate change.

Carbon of Chaillu forests based on a phytosociological analysis in Republic of Congo, more than meets the eye?

AbstractThe objectives were to quantify aboveground, belowground and dead wood carbon pools near Mayoko in the Chaillu massif of Republic of Congo and explore relationships between carbon storage and plant diversity of all growth forms. A total of 190 plots (25 m by 25 m) were sampled (5072 stems, 211 species) and data analysed using recommended central‐African forest allometric equations. Mean stem diameter at breast height was 33.6 cm, mean basal area 47.7 m2 ha−1 and mean density of individuals 407 ha−1. Mean aboveground carbon (AGC) ranged from 13.93–412.66 Mg C ha−1, belowground carbon from 2.86–96.97 Mg C ha−1 and dead wood from 0.00–7.59 Mg C ha−1. The maximum AGC value recorded in a plot was 916 Mg C ha−1. The analysis performed using phytosociological association as basis rather than broad vegetation type is unique. AGC values for undisturbed terra firme forest sites featured among the highest recorded for African tropical forests. Considering only tree diversity, a weak, yet significant, relationship existed between AGC and species richness, Shannon‐Wiener index of diversity and Fisher's alpha. However, if diversity of all plant growth forms is considered, no relationship between carbon and plant diversity existed.

Plant growth forms dictate adaptations to the local climate.

Adaptive radiation is a significant driver of biodiversity. Primarily studied in animal systems, mechanisms that trigger adaptive radiations remain poorly understood in plants. A frequently claimed indicator of adaptive radiation in plants is growth form diversity when tied to the occupation of different habitats. However, it remains obscure whether morphological adaptations manifest as growth form diversity per se or as its constituent traits. We use the classic Aeonium radiation from the Canary Islands to ask whether adaptation across climatic space is structured by growth form evolution. Using morphological sampling with site-associated climate in a phylogenetic context, we find that growth forms dictate adaptations to the local environment. Furthermore, we demonstrate that the response of specific traits to analogous environments is antagonistic when growth forms are different. This finding suggests for the first time that growth forms represent particular ecological functions, allowing the co-occurrence of closely related species, being a product of divergent selection during evolution in sympatry.

Allometric Models to Estimate Carbon Content in Arecaceae Based on Seven Species of Neotropical Palms

We present allometric models for estimating total carbon content and above ground carbon (AGC) for the Arecaceae family, and for seven abundant neotropical palm species: the canopy speciesSocratea exorrhiza(n= 10) andIriartea deltoidea(n= 10), the sub-canopy palmEuterpe precatoria(n= 10), and the understory speciesAsterogyne martiana(n= 15),Prestoea decurrens(n= 10),Geonoma interrupta(n= 10), andChamaedorea tepejilote(n= 22). Understanding the allometry of functional groups such as palms is critical for improving carbon stocks estimates in tropical forests and determining how allometric differences affect species functional diversity. The research was carried out in the tropical rainforests of the Caribbean slope of Costa Rica. We harvested 87 palms of a wide range of sizes, and separated them into roots, stems, and leaves, measured their fresh and dry biomass, and calculated their carbon content, tissue density, and dry mass fraction (dmf). Our general palm model estimating total carbon content based on these seven species and 87 samples accounted for 92% of the variation across species. We generated a similar model to estimate AGC and explained 91% of the variation. We compared our AGC model with two models used to estimate palm carbon content:Goodman et al. (2013)’s andChave et al. (2014)’s models and found that all three converged on the estimation of AGC although our model was the most parsimonious because it achieved the same efficiency with only two variables, stem diameter and stem height. To improve the accuracy of allometric models we need to incorporate more species, a greater diversity of growth forms, a wider range of sizes, a larger sample size, and more diversity of habitats dominated by palms. Estimating carbon content using allometric approaches could benefit from more consistency in data collection across plant groups.

Реинтродукция карельской березы

The paper offers a systematic overview of the results of research regarding reintroduction of curly (Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti published by Russian and foreign authors over the past few decades. We briefly outline the current situation with its resources and the key causes of their decline in the late 20th – early 21st centuries, such as mass-scope illegal logging, vanishing or substantial alteration of typical curly birch habitats, as well as some biological features (fragmented distribution, low competitive capacity, etc.). The main outcomes of the curly birch introduction activities in the areas lying far beyond its natural distribution (mainly to the south-east from it) are reported. It is shown that the experience of curly birch reintroduction in Russia is mostly based on planting of forests and establishment of specially protected areas. The results of curly birch reintroduction in Finland, Sweden, Norway, Germany, Belarus and other countries are observed. Although reintroduction is not equally effective in all countries (its success depends on many factors), it has made and is making a significant contribution to the preservation and augmentation of the resources of this unique member of the European forest tree flora. Importantly, the curly birch from the reintroductions performed in different years and different edaphic and climatic conditions steadily retains its key biological features, such as figured grain and diversity of growth forms and trunk surface characteristics, which once again confirms the authors’ previously expressed opinion that there are grounds for classifying the curly birch as a separate biological species. Proceeding from the analysis of the data amassed by now, it is suggested that that the efficiency of curly birch reintroduction to its natural habitats can be promoted by mainly using the stocking material of local provenance (when restoring populations) or by transferring it from other populations (for repatriation cases). An important role in the preservation and reproduction of curly birch belongs to the micropropagation technique.

Large mammalian herbivores modulate plant growth form diversity in a tropical rainforest

Abstract The world’s terrestrial biomes are broadly classified according to the dominant plant growth forms that define ecosystem structure and processes. Although the abundance and distribution of different plant growth forms can be strongly determined by factors such as climate and soil composition, large mammalian herbivores have a strong impact on plant communities, thus defaunation (the local or functional extinction of large animals) has the potential to alter the compositional structure of plant growth forms in natural ecosystems. Tropical rainforests sustain a high diversity of growth forms, including trees, palms, lianas, shrubs, herbs and bamboos, all of which play important ecosystem functions. Here, we experimentally evaluate how large mammalian herbivores affect the dominance, diversity and coexistence of these major tropical forest plant growth forms, by monitoring communities of saplings on the understorey in 43 paired exclusion plots in a long‐term replicated exclusion experiment in the understorey of the Atlantic forest of Brazil. Over the course of 10 years large herbivore exclusion decreased diversity among growth forms, increased the absolute abundance of palms and trees (22% and 38% respectively) and increased the diversity of species within these two groups, to the detriment of other growth forms. Furthermore, all pairwise relationships between growth forms were positive on plots where herbivores had access, whereas several strong negative relationships emerged in plots where herbivores were excluded. This occurred despite strong background directional temporal trends affecting plant communities in both experimental treatments across the region. Synthesis. Our work indicates that the defaunation alters growth form dominance by favouring palms and trees while eroding diversity among growth forms and coexistence on a temporal scale. Large herbivore mammals promote diversity among growth forms, preventing the hyper‐dominance of trees and palms, yet without supressing the diversity of species within growth forms. We argue that large herbivore mammals affect growth forms through several non‐mutually exclusive mechanisms, including herbivory, seed dispersal and physical disturbance, as well as differential effects linked to the morphological and physiological adaptations of growth forms. We conclude that defaunation might lead to profound impacts on important ecosystem functions underpinned by growth form diversity, and result in vertical and horizontal structural simplification of tropical rainforests.

Wood density relates negatively to maximum plant height across major angiosperm and gymnosperm orders.

Wood density is a crucial plant functional trait related to plant life history strategies. Its ecological importance in small-stature growth forms (e.g., shrubs) has not been extensively examined. Given that hydraulic conduit dimensions vary positively with plant height and that there is a negative relationship between conduits' diameter and wood density, I hypothesized an also negative relationship between wood density and plant height. Knowing that bark and pith proportions are significant in small-diameter stems, I additionally disentangled the contribution of wood, bark, and pith to stem density. I determined density in small-diameter stems across 153 species spanning all major angiosperm and gymnosperm orders by considering a diversity of growth forms (trees, treelets, shrubs, vines, and hemiparasites). Stem cross sections were dissected to consider the densities of wood with bark and pith; wood with pith and without bark; wood with bark and no pith; and wood without bark and pith. Secondary growth was also measured. Trees showed similar wood densities as non-self-supporting vines, and both showed significantly less dense wood than treelets, shrubs, and hemiparasites. General comparisons showed that wood was significantly denser than all other tissues, and these differences did not depend on growth form. Wood density was significantly and negatively related to growth rate and pith area proportions but not to bark thickness proportion. An implicit negative relationship between maximum plant height and stem density emerges as a property of plants likely linked to hydraulic conductive size.

Souzayuri/LMH_exclusion_experiment_plant_growth_forms: Large mammalian herbivores modulate plant growth form diversity in a tropical rainforest

souzayuri/LMH_exclusion_experiment_plant_growth_forms: Large mammalian herbivores modulate plant growth form diversity in a tropical rainforest