Shifts in wood anatomical traits after a major hurricane

•1. Trait variation across individuals and species influences the resistance and resilience of ecosystems to disturbance, and the ability of individuals to capitalize on postdisturbance conditions. In trees, the anatomical structure of xylem directly affects plant function and, consequently, it is a valuable lens through which to understand resistance and resilience to disturbance. •2. To determine how hurricanes affect wood anatomy of tropical trees, we characterized a set of anatomical traits in wood produced before and after a major hurricane for 65 individuals of 10 Puerto Rican tree species. We quantified variation at different scales (among and within species, and within individuals) and determined trait shifts between the pre- and posthurricane periods. We also assessed correlations between traits and growth rates. •3. While the majority of anatomical trait variation occurred among species, we also observed substantial variation within species and individuals. Within individuals, we found significant shifts for some traits that generally reflected increased hydraulic conductivity in the posthurricane period. We found weak evidence for an association between individual xylem anatomical traits and diameter growth rates. •4. Ultimately, within-individual variation of xylem anatomical traits observed in our study could be related to posthurricane recovery and overall growth (e.g. canopy filling). Other factors, however, likely decouple a relationship between xylem anatomy and diameter growth. While adjustments of wood anatomy may enable individual trees to capitalize on favourable postdisturbance conditions, these may also influence their future responses or vulnerability to subsequent disturbances

One Century of Forest Monitoring Data in Switzerland Reveals Species- and Site-Specific Trends of Climate-Induced Tree Mortality

Climate-induced tree mortality became a global phenomenon during the last century and it is expected to increase in many regions in the future along with a further increase in the frequency of drought and heat events. However, tree mortality at the ecosystem level remains challenging to quantify since long-term, tree-individual, reliable observations are scarce. Here, we present a unique data set of monitoring records from 276 permanent plots located in 95 forest stands across Switzerland, which include five major European tree species (Norway spruce, Scots pine, silver fir, European beech, and sessile and common oak) and cover a time span of over one century (1898–2013), with inventory periods of 5–10 years. The long-term average annual mortality rate of the investigated forest stands was 1.5%. In general, species-specific annual mortality rates did not consistently increase over the last decades, except for Scots pine forests at lower altitudes, which exhibited a clear increase of mortality since the 1960s. Temporal trends of tree mortality varied also depending on diameter at breast height (DBH), with large trees generally experiencing an increase in mortality, while mortality of small trees tended to decrease. Normalized mortality rates were remarkably similar between species and a modest, but a consistent and steady increasing trend was apparent throughout the study period. Mixed effects models revealed that gradually changing stand parameters (stand basal area and stand age) had the strongest impact on mortality rates, modulated by climate, which had increasing importance during the last decades. Hereby, recent climatic changes had highly variable effects on tree mortality rates, depending on the species in combination with abiotic and biotic stand and site conditions. This suggests that forest species composition and species ranges may change under future climate conditions. Our data set highlights the complexity of forest dynamical processes such as long-term, gradual changes of forest structure, demography and species composition, which together with climate determine mortality rates

One Century of Forest Monitoring Data in Switzerland Reveals Species- and Site-Specific Trends of Climate-Induced Tree Mortality

Climate-induced tree mortality became a global phenomenon during the last century and it is expected to increase in many regions in the future along with a further increase in the frequency of drought and heat events. However, tree mortality at the ecosystem level remains challenging to quantify since long-term, tree-individual, reliable observations are scarce. Here, we present a unique data set of monitoring records from 276 permanent plots located in 95 forest stands across Switzerland, which include five major European tree species (Norway spruce, Scots pine, silver fir, European beech, and sessile and common oak) and cover a time span of over one century (1898–2013), with inventory periods of 5–10 years. The long-term average annual mortality rate of the investigated forest stands was 1.5%. In general, species-specific annual mortality rates did not consistently increase over the last decades, except for Scots pine forests at lower altitudes, which exhibited a clear increase of mortality since the 1960s. Temporal trends of tree mortality varied also depending on diameter at breast height (DBH), with large trees generally experiencing an increase in mortality, while mortality of small trees tended to decrease. Normalized mortality rates were remarkably similar between species and a modest, but a consistent and steady increasing trend was apparent throughout the study period. Mixed effects models revealed that gradually changing stand parameters (stand basal area and stand age) had the strongest impact on mortality rates, modulated by climate, which had increasing importance during the last decades. Hereby, recent climatic changes had highly variable effects on tree mortality rates, depending on the species in combination with abiotic and biotic stand and site conditions. This suggests that forest species composition and species ranges may change under future climate conditions. Our data set highlights the complexity of forest dynamical processes such as long-term, gradual changes of forest structure, demography and species composition, which together with climate determine mortality rates

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

The role of imperforate tracheary elements and narrow vessels in wood capacitance of angiosperm trees

International audienceThere is a broad diversity of imperforate tracheary elements (ITEs) — libriform fibers, fiber-tracheids, true tracheids and vasicentric/vascular tracheids — described thoroughly by Sherwin Carlquist. However, in a quantitative sense, the functional meaning of different ITE types present in the wood of vessel-bearing angiosperms remains unclear because very few structure–function studies measure ITEs’ properties. ITEs with abundant pits and wide pit borders — vascular tracheids, vasicentric tracheids, and true tracheids sensu Carlquist — have been shown to conduct water and, thanks to this conductive ability and the multitude of pits, they could also contribute to wood capacitance. A dataset of 30 temperate angiosperm tree species was reanalysed to record the presence/absence of true, vasicentric, and vascular tracheids including data on conduits 15 fraction and vessel-conduit 15 contact fraction (conduits 15 were defined as cells resembling vessels and with a maximum lumen diameter of 15 μ m. They encompassed narrow vessels, vasicentric tracheids, and vessel tails). The presence of tracheids, conduits 15 fraction, and contact fraction had no effect on wood capacitance, except, per given wood volumetric lumen water content, species with true tracheids tended to have lower capacitance. These results suggest that the presence of tracheids or conduits 15 properties do not limit wood capacitance, but the results do not exclude the potential role these cells may play in internal water dynamics

Correction: Broad Anatomical Variation within a Narrow Wood Density Range—A Study of Twig Wood across 69 Australian Angiosperms

<p>Correction: Broad Anatomical Variation within a Narrow Wood Density Range—A Study of Twig Wood across 69 Australian Angiosperms</p

Relationship between total fibre fraction and total parenchyma fraction.

<p>Green circles—tropical rainforest (warm and wet site); red squares—tropical woodland (warm and dry site); blue triangles—temperate forest (cool and wet site). *** <i>P</i> < 0.001.</p

Site details.

<p>Notes: Temperature based on gridded 5km resolution data for 1961–2007. Precipitation data collected at the local weather stations (Cape Tribulation Store, Goshen and Thredbo Village stations) within 5 km from the sites for 1971–1990. All data obtained from Australian Bureau of Meteorology. NP—national park.</p><p>Site details.</p

Relationship between ray parenchyma fraction and pith area (log-transformed).

<p>Green circles—tropical rainforest (warm and wet site); red squares—tropical woodland (warm and dry site); blue triangles—temperate forest (cool and wet site). *** <i>P</i> < 0.001.</p