Eugenia dittocrepis O.Berg

https://thekeep.eiu.edu/herbarium_specimens_byname/14679/thumbnail.jp

Lianas Have A Seasonal Growth Advantage Over Co‐Occurring Trees

The seasonal growth advantage hypothesis posits that plant species that grow well during seasonal drought will increase in abundance in forests with increasing seasonality of rainfall both in absolute numbers and also relative to co‐occurring plant species that grow poorly during seasonal drought. That is, seasonal drought will give some plant species a growth advantage that they lack in aseasonal forests, thus allowing them attain higher abundance. For tropical forest plants, the seasonal growth advantage hypothesis may explain the distribution of drought‐adapted species across large‐scale gradients of rainfall and seasonality. We tested the seasonal growth advantage hypothesis with lianas and trees in a seasonal tropical forest in central Panama. We measured the dry‐season and wet‐season diameter growth of 1,117 canopy trees and 648 canopy lianas from 2011 to 2016. We also evaluated how lianas and trees responded to the 2015–2016 El Niño, which was the third strongest el Niño drought on record in Panama. We found that liana growth rate was considerably higher during the dry‐season months than the wet‐season months in each of the five years. Lianas achieved one‐half of their annual growth during the 4‐month dry season. By contrast, trees grew far more during the wet season; they realized only one‐quarter of their annual growth during the dry season. During the strong 2015–2016 El Niño dry season, trees essentially stopped growing, whereas lianas grew unimpeded and as well as during any of the previous four dry seasons. Our findings support the hypothesis that seasonal growth gives lianas a decided growth advantage over trees in seasonal forests compared to aseasonal forests, and may explain why lianas peak in both absolute and relative abundance in highly seasonal tropical forests. Furthermore, the ability of lianas to grow during a strong el Niño drought suggests that lianas will benefit from the predicted increasing drought severity, whereas trees will suffer, and thus lianas are predicted to increase in relative abundance in seasonal tropical forests

Lianas Reduce Community-level Canopy Tree Reproduction in a Panamanian Forest

Lianas are a key component of tropical forests, where they compete intensely with trees, reducing tree recruitment, growth and survival. One of the most important potential outcomes of liana competition is the reduction of tree reproduction; however, no previous study has experimentally determined the effects of lianas on tree reproduction beyond a single tree species. We used a large‐scale liana removal experiment to quantify the effect of lianas on community‐level canopy and understorey tree and palm reproduction. In 2011, we removed lianas from eight 6,400‐m2 plots (eight plots served as controls) and surveyed understorey tree reproduction in 2012, canopy tree and palm reproduction in 2013, and a second census of all plants in 2016. We found that lianas significantly reduced canopy tree community flowering and fruiting after liana removal. Two years after liana removal, the number of canopy trees with fruits was 173% higher, fruiting individuals had 50% more of their canopy covered by fruits and the number of tree species with fruits was 169% higher than in control plots where lianas were present. Five years after liana removal, the number of canopy trees with fruits was 150% higher, fruiting individuals had 31% more of their canopy covered by fruits and the number of tree species with fruits was 109% higher than in unmanipulated control plots. Liana removal had only a slight positive effect on palms and on understorey tree flower and fruit production, even though understorey light levels had increased 20% following liana cutting. Synthesis. Our findings provide the first experimental demonstration that competition from lianas significantly reduces community‐level canopy tree reproduction. Reduced reproduction increases canopy tree seed and dispersal limitations, and may interfere with deterministic mechanisms thought to maintain tropical canopy tree species diversity, as well as reduce food availability to many animal species. Because lianas are increasing in abundance in many neotropical forests, the effects of lianas on tree reproduction will likely increase, and if the effects of lianas on tree reproduction vary with tree species identity, lianas ultimately could have a destabilizing effect on both tree and animal population dynamics

Tree Species Vary Widely in Their Tolerance for Liana Infestation: A Case Study of Differential Host Response to Generalist Parasites

Lianas are structural parasites of trees and reduce individual host tree growth, survival and fecundity. Thus, liana infestation is expected to affect tree population growth rates, with potentially different effects in different species depending on the frequency of liana infestation and the impact of liana infestation on population growth rates. Previous studies have documented the myriad negative effects of lianas on trees and variation in liana infestation among tree species; however, no study has quantified the impact of liana infestation on individual tree species population growth rates. Lianas are increasing in abundance in multiple Neotropical sites, which may have profound consequences for tree species composition if lianas differentially affect host tree species population growth. Here, we use long‐term data to evaluate the effects of liana infestation on the reproduction, growth, survival and ultimately population growth rates of dozens of tree species from Barro Colorado Island, Panama. We then test whether liana infestation affects tree species differentially with respect to two axes of life‐history variation: adult stature and position along the fast–slow axis, a measure of shade tolerance. Liana infestation decreased tree growth, survival and reproduction, with the strongest effects on survival in fast‐growing, light‐demanding species and on reproduction in large‐statured species. In combination, these effects reduced tree population growth rates such that liana‐infested populations declined by an average of 1.4% annually relative to conspecific liana‐free populations. The reduction in population growth rates was greatest among fast‐growing species and smaller in slow‐growing species. Synthesis. Our results demonstrate that liana infestation has strong negative effects on tree population growth rates, which vary systematically among tree species with tree life history. The finding that liana infestation is more harmful to fast‐growing tree species appears to be at odds with the general expectations in the literature. We propose that this is likely due to survivorship bias, as infestation greatly decreases survival in fast‐growing species such that the observable sample is biased towards those that survived and liana‐free. In combination with data on how tree species vary in liana infestation rates, these results provide a basis for predicting the impacts of changes in liana abundance on tree species composition

Interactive web-taxonomy for the Araceae: www.cate-araceae.org

CATE (Creating a Taxonomic E-science) is a pilot project funded by the UK Natural Environment Research Council (NERC) to test a model of internet taxonomy which aims to construct and maintain online a full descriptive taxonomic revision as a collective enterprise carried out by the specialist taxonomic community. The software application includes the functionality to allow taxonomists to make contributions and proposals for change that are passed for peer review to an editorial and moderating body drawn from the taxonomic community. The model is being tested on the Hawkmoths (Sphingidae) and Aroid (Araceae) families. The paper describes the aims of the project and current progress on the Araceae e-revision

Phylogenetic and ecological correlates of pollen morphological diversity in a Neotropical rainforest

Morphology varies enormously across clades, and the morphology of a trait may reflect ecological function or the retention of ancestral features. We examine the tension between ecological and phylogenetic correlates of morphological diversity through a case study of pollen grains produced by angiosperms in Barro Colorado Island, Panama (BCI). Using a molecular phylogeny of 730 taxa, we demonstrate a statistically significant association between morphological and genetic distance for these plants. However, the relationship is non‐linear, and while close relatives share more morphological features than distant relatives, above a genetic distance of ~ 0.7 increasingly distant relatives are not more divergent in phenotype. The pollen grains of biotically pollinated and abiotically pollinated plants overlap in morphological space, but certain pollen morphotypes and individual morphological traits are unique to these pollination ecologies. Our data show that the pollen grains of biotically pollinated plants are significantly more morphologically diverse than those of abiotically pollinated plants

Growth Strategies of Tropical Tree Species: Disentangling Light and Size Effects

An understanding of the drivers of tree growth at the species level is required to predict likely changes of carbon stocks and biodiversity when environmental conditions change. Especially in species-rich tropical forests, it is largely unknown how species differ in their response of growth to resource availability and individual size. We use a hierarchical Bayesian approach to quantify the impact of light availability and tree diameter on growth of 274 woody species in a 50-ha long-term forest census plot in Barro Colorado Island, Panama. Light reaching each individual tree was estimated from yearly vertical censuses of canopy density. The hierarchical Bayesian approach allowed accounting for different sources of error, such as negative growth observations, and including rare species correctly weighted by their abundance. All species grew faster at higher light. Exponents of a power function relating growth to light were mostly between 0 and 1. This indicates that nearly all species exhibit a decelerating increase of growth with light. In contrast, estimated growth rates at standardized conditions (5 cm dbh, 5% light) varied over a 9-fold range and reflect strong growth-strategy differentiation between the species. As a consequence, growth rankings of the species at low (2%) and high light (20%) were highly correlated. Rare species tended to grow faster and showed a greater sensitivity to light than abundant species. Overall, tree size was less important for growth than light and about half the species were predicted to grow faster in diameter when bigger or smaller, respectively. Together light availability and tree diameter only explained on average 12% of the variation in growth rates. Thus, other factors such as soil characteristics, herbivory, or pathogens may contribute considerably to shaping tree growth in the tropics

Syngonium steyermarkii Croat

Guatemala, San Marcos, San Rafael Pie de la Cuesta La Trinidad ca. 2 kmk from Finca Armenia above San Rafael. LAT (0) N; LONG (0) W. ALT (1100)