Higher latewood to earlywood ratio increases resistance of radial growth to severe droughts in larch.

As drought has caused great losses of tree growth across the world, the mechanism of how trees adapt to drought has been extensively investigated. However, how trees change their late- to earlywood ratio (LER) to adapt to severe drought events remains poorly understood. We used a network of Larix principis-rupprechtii earlywood and latewood width data from 1979 to 2018, covering most of the distribution of planted larch across North China, to investigate how latewood proportion affected trees' resistance to drought.

Fading regulation of diurnal temperature ranges on drought-induced growth loss for drought-tolerant tree species.

Warming-induced droughts caused tree growth loss across the globe, leading to substantial carbon loss to the atmosphere. Drought-induced growth loss, however, can be regulated by changes in diurnal temperature ranges. Here, we investigated long term radial growth responses of 23 widespread distributed tree species from 2327 sites over the world and found that species' drought tolerances were significantly and positively correlated with diurnal temperature range-growth loss relationships for the period 1901-1940.

Reassessment of growth-climate relations indicates the potential for decline across Eurasian boreal larch forests.

Larch, a widely distributed tree in boreal Eurasia, is experiencing rapid warming across much of its distribution. A comprehensive assessment of growth on warming is needed to comprehend the potential impact of climate change. Most studies, relying on rigid calendar-based temperature series, have detected monotonic responses at the margins of boreal Eurasia, but not across the region.

Reduced diurnal temperature range mitigates drought impacts on larch tree growth in North China.

Forests are facing climate changes such as warmer temperatures, accelerated snowmelt, increased drought, as well as changing diurnal temperature ranges (DTR) and cloud cover regimes. How tree growth is influenced by the changes in daily to monthly temperatures and its associations with droughts has been extensively investigated, however, few studies have focused on how changes in sub-daily temperatures i.e.

Insights into source/sink controls on wood formation and photosynthesis from a stem chilling experiment in mature red maple.

Whether sources or sinks control wood growth remains debated with a paucity of evidence from mature trees in natural settings. Here, we altered carbon supply rate in stems of mature red maples (Acer rubrum) within the growing season by restricting phloem transport using stem chilling; thereby increasing carbon supply above and decreasing carbon supply below the restrictions, respectively. Chilling successfully altered nonstructural carbon (NSC) concentrations in the phloem without detectable repercussions on bulk NSC in stems and roots.

Inter-annual and inter-species tree growth explained by phenology of xylogenesis.

Wood formation determines major long-term carbon (C) accumulation in trees and therefore provides a crucial ecosystem service in mitigating climate change. Nevertheless, we lack understanding of how species with contrasting wood anatomical types differ with respect to phenology and environmental controls on wood formation. In this study, we investigated the seasonality and rates of radial growth and their relationships with climatic factors, and the seasonal variations of stem nonstructural carbohydrates (NSC) in three species with contrasting wood anatomical types (red oak: ring-porous; red maple: diffuse-porous; white pine: coniferous) in a temperate mixed forest during 2017-2019.

Manipulating phloem transport affects wood formation but not local nonstructural carbon reserves in an evergreen conifer.

How variations in carbon supply affect wood formation remains poorly understood in particular in mature forest trees. To elucidate how carbon supply affects carbon allocation and wood formation, we attempted to manipulate carbon supply to the cambial region by phloem girdling and compression during the mid- and late-growing season and measured effects on structural development, CO efflux and nonstructural carbon reserves in stems of mature white pines. Wood formation and stem CO efflux varied with a location relative to treatment (i.

Evidence of unprecedented rise in growth synchrony from global tree ring records.

Changes in the temporal coherence between populations, which can influence their stability, resilience and persistence, remain a critical uncertainty of climate change. Recent studies have documented increasing spatial synchrony between populations at continental scales and linked it to anthropogenic climate change. However, the lack of long-term and global baseline perspectives on spatial synchrony presents a challenge to understanding the importance of these trends.

Snowmelt and early to mid-growing season water availability augment tree growth during rapid warming in southern Asian boreal forests.

Boreal forests are facing profound changes in their growth environment, including warming-induced water deficits, extended growing seasons, accelerated snowmelt, and permafrost thaw. The influence of warming on trees varies regionally, but in most boreal forests studied to date, tree growth has been found to be negatively affected by increasing temperatures. Here, we used a network of Pinus sylvestris tree-ring collections spanning a wide climate gradient the southern end of the boreal forest in Asia to assess their response to climate change for the period 1958-2014.

Stem Compression: A Means to Reversibly Reduce Phloem Transport in Tree Stems.

Stem compression reduces or terminates the phloem-mediated transport of carbohydrates and other solutes in tree stems, without causing permanent damage to phloem functioning (Henriksson et al. Tree Physiol. 35:1075-1085, 2015).

Ten-year assessment of the 100 priority questions for global biodiversity conservation.

In 2008, a group of conservation scientists compiled a list of 100 priority questions for the conservation of the world's biodiversity. However, now almost a decade later, no one has yet published a study gauging how much progress has been made in addressing these 100 high-priority questions in the peer-reviewed literature. We took a first step toward reexamining the 100 questions to identify key knowledge gaps that remain.

Modeling Tree Growth Taking into Account Carbon Source and Sink Limitations.

Increasing CO concentrations are strongly controlled by the behavior of established forests, which are believed to be a major current sink of atmospheric CO. There are many models which predict forest responses to environmental changes but they are almost exclusively carbon source (i.e.

Evaluation of climate-related carbon turnover processes in global vegetation models for boreal and temperate forests.

Turnover concepts in state-of-the-art global vegetation models (GVMs) account for various processes, but are often highly simplified and may not include an adequate representation of the dominant processes that shape vegetation carbon turnover rates in real forest ecosystems at a large spatial scale. Here, we evaluate vegetation carbon turnover processes in GVMs participating in the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP, including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT) using estimates of vegetation carbon turnover rate (k) derived from a combination of remote sensing based products of biomass and net primary production (NPP). We find that current model limitations lead to considerable biases in the simulated biomass and in k (severe underestimations by all models except JeDi and VISIT compared to observation-based average k), likely contributing to underestimation of positive feedbacks of the northern forest carbon balance to climate change caused by changes in forest mortality.

Carbon residence time dominates uncertainty in terrestrial vegetation responses to future climate and atmospheric CO2.

Future climate change and increasing atmospheric CO2 are expected to cause major changes in vegetation structure and function over large fractions of the global land surface. Seven global vegetation models are used to analyze possible responses to future climate simulated by a range of general circulation models run under all four representative concentration pathway scenarios of changing concentrations of greenhouse gases. All 110 simulations predict an increase in global vegetation carbon to 2100, but with substantial variation between vegetation models.