Non fire-adapted dry forest of Northwestern Madagascar: Escalating and devastating trends revealed by Landsat timeseries and GEDI lidar data.

Ankarafantsika National Park (ANP), the last significant remnant of Northwestern Madagascar's tropical dry forests, is facing rapid degradation due to increased incidences of fire. This poses severe threats to biodiversity, local livelihoods, and vital ecosystem services. Our study, conducted on 3,052-ha of ANP's pristine forests, employed advanced remote-sensing techniques to assess fire impacts during the past 37 years.

Leaf, root, and soil microbiomes of an invasive plant, , differ between its native and exotic ranges.

Introduction: Ecological underpinnings of the invasion success of exotic plants may be found in their interactions with microbes, either through the enemy release hypothesis and the enhanced mutualism hypothesis. Whereas recent high-throughput sequencing techniques have significantly expanded our understanding of plant-associated microbiomes and their functional guilds, few studies to date have used these techniques to compare the microbiome associated with invasive plants between their native and exotic ranges.

Methods: We extracted fungal and bacterial DNA within leaf endosphere, root endosphere and soil of an invasive plant, , sampled from their native range Japan and exotic range Florida, USA.

Lamina-specific localization of silicon accumulation in two broadleaf tree species.

Silicon (Si) accumulation differs greatly among plant species, as revealed by an increasing number of studies reporting whole-leaf Si concentration for a wide range of land plants. Yet, we have limited knowledge about Si distribution across leaf parts (e.g.

Perspective: sustainability challenges, opportunities and solutions for long-term ecosystem observations.

As interest in natural capital grows and society increasingly recognizes the value of biodiversity, we must discuss how ecosystem observations to detect changes in biodiversity can be sustained through collaboration across regions and sectors. However, there are many barriers to establishing and sustaining large-scale, fine-resolution ecosystem observations. First, comprehensive monitoring data on both biodiversity and possible anthropogenic factors are lacking.

Traits along the leaf economics spectrum are associated with communities of foliar endophytic symbionts.

Leaf traits of plants worldwide are classified according to the Leaf Economics Spectrum (LES), which links leaf functional traits to evolutionary life history strategies. As a continuum ranging from thicker, tough leaves that are low in nitrogen (N) to thinner, softer, leaves that are high in N, the LES brings together physical, chemical, and ecological traits. Fungal endophytes are common foliar symbionts that occur in healthy, living leaves, especially in tropical forests.

Leaf silicon accumulation rates in relation to light environment and shoot growth rates in paper mulberry (Broussonetia papyrifera, Moraceae).

While increasing numbers of studies report wide variations of leaf silicon (Si) accumulation among plant species, within-species variations of leaf Si accumulation have scarcely been examined for tree species. As in crop plants, environmental factors that affect transpiration rates may influence passive transpiration-dependent transport of Si uptake in trees. Here, we tested a hypothesis that leaf Si accumulation rate should be higher in shoots that receive more light and thus achieve faster growth, using Broussonetia papyrifera, a pioneer tree species with successive leaf production and Si accumulation with leaf age.

Comparative analysis of borate fusion versus sodium carbonate extraction for quantification of silicon contents in plants.

Studies of plant-silicon (Si) interaction benefit from safe, affordable and accurate methods to measure acid-insoluble silica (phytoliths) for a large number of plant samples. This study aimed to evaluate the comparability between two chemical methods to dissolve leaf silica, borate fusion and 1% sodium carbonate (NaCO) extraction, in combination of two detection methods (ICP, molybdenum-blue colorimetry).We compared the results obtained by these methods, using dried leaf samples of five tropical tree species that differ widely in Si concentrations (4 to 100 mg g DW).

Negative plant-soil feedbacks are stronger in agricultural habitats than in forest fragments in the tropical Andes.

There is now strong evidence suggesting that interactions between plants and their species-specific antagonistic microbes can maintain native plant community diversity. In contrast, the decay in diversity in plant communities invaded by nonnative plant species might be caused by weakening negative feedback strengths, perhaps because of the increased relative importance of plant mutualists such as arbuscular mycorrhizal fungi (AMF). Although the vast majority of studies examining plant-soil feedbacks have been conducted in a single habitat type, there are fewer studies that have tested how the strength and direction of these feedbacks change across habitats with differing dominating plants.

Divergent drivers of leaf trait variation within species, among species, and among functional groups.

Understanding variation in leaf functional traits-including rates of photosynthesis and respiration and concentrations of nitrogen and phosphorus-is a fundamental challenge in plant ecophysiology. When expressed per unit leaf area, these traits typically increase with leaf mass per area () within species but are roughly independent of across the global flora. is determined by mass components with different biological functions, including photosynthetic mass that largely determines metabolic rates and contains most nitrogen and phosphorus, and structural mass that affects toughness and leaf lifespan ().

Leaf trait variations associated with habitat affinity of tropical karst tree species.

Karst hills, that is, jagged topography created by dissolution of limestone and other soluble rocks, are distributed extensively in tropical forest regions, including southern parts of China. They are characterized by a sharp mosaic of water and nutrient availability, from exposed hilltops with poor soil development to valleys with occasional flooding, to which trees show species-specific distributions. Here we report the relationship of leaf functional traits to habitat preference of tropical karst trees.

Variations of leaf longevity in tropical moist forests predicted by a trait-driven carbon optimality model.

Leaf longevity (LL) varies more than 20-fold in tropical evergreen forests, but it remains unclear how to capture these variations using predictive models. Current theories of LL that are based on carbon optimisation principles are challenging to quantitatively assess because of uncertainty across species in the 'ageing rate:' the rate at which leaf photosynthetic capacity declines with age. Here, we present a meta-analysis of 49 species across temperate and tropical biomes, demonstrating that the ageing rate of photosynthetic capacity is positively correlated with the mass-based carboxylation rate of mature leaves.

Host-specific effects of soil microbial filtrates prevail over those of arbuscular mycorrhizae in a fragmented landscape.

Plant-soil interactions have been shown to determine plant community composition in a wide range of environments. However, how plants distinctly interact with beneficial and detrimental organisms across mosaic landscapes containing fragmented habitats is still poorly understood. We experimentally tested feedback responses between plants and soil microbial communities from adjacent habitats across a disturbance gradient within a human-modified tropical montane landscape.

Physiological and structural tradeoffs underlying the leaf economics spectrum.

The leaf economics spectrum (LES) represents a suite of intercorrelated leaf traits concerning construction costs per unit leaf area, nutrient concentrations, and rates of carbon fixation and tissue turnover. Although broad trade-offs among leaf structural and physiological traits have been demonstrated, we still do not have a comprehensive view of the fundamental constraints underlying the LES trade-offs. Here, we investigated physiological and structural mechanisms underpinning the LES by analysing a novel data compilation incorporating rarely considered traits such as the dry mass fraction in cell walls, nitrogen allocation, mesophyll CO diffusion and associated anatomical traits for hundreds of species covering major growth forms.

Leaf cellulose density as the key determinant of inter- and intra-specific variation in leaf fracture toughness in a species-rich tropical forest.

Leaves as the main photosynthetic organ of plants must be well protected against various hazards to achieve their optimal lifespans. Yet, within-species variation and the material basis of leaf strength have been explored for very few species. Here, we present a large dataset of leaf fracture toughness from a species-rich humid tropical forest on Barro Colorado Island, Panama, reporting both among- and within-species variation in relation to light environment (sun-lit canopy versus shaded understorey) and ontogeny (seedlings versus adults).

Influence of arbuscular mycorrhizal colonization on whole-plant respiration and thermal acclimation of tropical tree seedlings.

Symbiotic arbuscular mycorrhizal fungi (AMF) are ubiquitous in tropical forests. AMF play a role in the forest carbon cycle because they can increase nutrient acquisition and biomass of host plants, but also incur a carbon cost to the plant. Through their interactions with their host plants they have the potential to affect how plants respond to environmental perturbation such as global warming.

Whole-plant respiration and its temperature sensitivity during progressive carbon starvation.

Plant respiration plays a critical role in the C balance of plants. Respiration is highly temperature sensitive and small temperature-induced increases in whole-plant respiration could change the C balance of plants that operate close to their light-compensation points from positive to negative. Nonstructural carbohydrates are thought to play an important role in controlling respiration and its temperature sensitivity, but this role has not been studied at the whole-plant level.

Global convergence in leaf respiration from estimates of thermal acclimation across time and space.

Recent compilations of experimental and observational data have documented global temperature-dependent patterns of variation in leaf dark respiration (R), but it remains unclear whether local adjustments in respiration over time (through thermal acclimation) are consistent with the patterns in R found across geographical temperature gradients. We integrated results from two global empirical syntheses into a simple temperature-dependent respiration framework to compare the measured effects of respiration acclimation-over-time and variation-across-space to one another, and to a null model in which acclimation is ignored. Using these models, we projected the influence of thermal acclimation on: seasonal variation in R; spatial variation in mean annual R across a global temperature gradient; and future increases in R under climate change.

General patterns of acclimation of leaf respiration to elevated temperatures across biomes and plant types.

Respiration is instrumental for survival and growth of plants, but increasing costs of maintenance processes with warming have the potential to change the balance between photosynthetic carbon uptake and respiratory carbon release from leaves. Climate warming may cause substantial increases of leaf respiratory carbon fluxes, which would further impact the carbon balance of terrestrial vegetation. However, downregulation of respiratory physiology via thermal acclimation may mitigate this impact.

Thermal acclimation of leaf respiration of tropical trees and lianas: response to experimental canopy warming, and consequences for tropical forest carbon balance.

Climate warming is expected to increase respiration rates of tropical forest trees and lianas, which may negatively affect the carbon balance of tropical forests. Thermal acclimation could mitigate the expected respiration increase, but the thermal acclimation potential of tropical forests remains largely unknown. In a tropical forest in Panama, we experimentally increased nighttime temperatures of upper canopy leaves of three tree and two liana species by on average 3 °C for 1 week, and quantified temperature responses of leaf dark respiration.

Shifting baselines on a tropical forest frontier: extirpations drive declines in local ecological knowledge.

The value of local ecological knowledge (LEK) to conservation is increasingly recognised, but LEK is being rapidly lost as indigenous livelihoods change. Biodiversity loss is also a driver of the loss of LEK, but quantitative study is lacking. In our study landscape in SW China, a large proportion of species have been extirpated.

Foliar respiration and its temperature sensitivity in trees and lianas: in situ measurements in the upper canopy of a tropical forest.

Leaf dark respiration (R) and its temperature sensitivity are essential for efforts to model carbon fluxes in tropical forests under current and future temperature regimes, but insufficient data exist to generalize patterns of R in species-rich tropical forests. Here, we tested the hypothesis that R and its temperature sensitivity (expressed as Q10, the proportional increase in R with a 10 °C rise in temperature) vary in relation to leaf functional traits, and among plant functional types (PFTs). We conducted in situ measurements of R of 461 leaves of 26 species of tree and liana in the upper canopy of a tropical forest in Panama.

Seed reserve dependency of Leucaena leucocephala seedling growth for nitrogen and phosphorus.

Mineral elements stored in seed reserves meet the nutrient demands of seedlings during their initial development and growth. We experimentally examined when seed reserves become insufficient to meet demands for nitrogen (N) and phosphorus (P) of seedlings of Leucaena leucocephala (Lam.) de Wit, a tropical woody legume.