Summary The control of tree growth vs environment by carbon sources or sinks remains unresolved although it is widely studied. This study investigates components and sink–source dynamics at different temporal scales. We constructed a dynamic model ‘carbon allocation sink source interaction’ ( CASSIA ) that calculates tree‐level balance from photosynthesis, respiration, phenology temperature‐driven potential structural organs stored nonstructural NSC their modifying influence on growth. With...

Abstract. Estimates of volatile organic compound (VOC) emissions from forests are based on the assumption that foliage has a steady emission potential over its lifetime, and mainly modified by short-term variations in light temperature. However, many field studies this been challenged, high atmospheric concentrations have measured during periods low biological activity, such as springtime. We conducted measurements three years, using an online gas-exchange monitoring system to observe mature...

Photosynthesis is not entirely synchronized with carbon sinks, implying that trees are capable of storing non-structural carbohydrates (NSC) such as soluble sugars and starch. These storages provide a buffer between carbohydrate supply demand also allow to resist drought through osmoregulation. However, estimates the total pool size seasonal dynamics NSC storage mature still rare. Part allocated outside roots, mainly symbiotic, root-associated mycorrhizal fungi. The quantity this allocation...

Summary Reliable insights from key δ 2 H bioindicators, n ‐alkanes and carbohydrates, are hindered by our limited understanding of isotope fractionation processes related to leaf water primary assimilates. We addressed this with the first study investigate time‐integrated intra‐annual signals carbohydrates in a natural forest. sampled 1‐yr‐old needles (1N) current‐year (0N) five Scots Pine trees coniferous forest Hyytiälä, Finland, biweekly during 2019. The their (δ alkane ), water‐soluble...

Temporal variability of tree-ring cellulose δ2H (δ2Hring-cel) can be a unique tool for understanding tree physiology and climate. However, we do not fully understand the drivers temporal in δ2Hring-cel. Investigating seasonal δ2Hring-cel boreal forests is particularly challenging. Previous studies on intra-annual δ18Ohave shown that isotope result from combined but opposing effects source water leaf assimilates, dynamic likely relevant as well. To...

Intra-annual variations of oxygen isotope composition (δ18O) in tree rings offer insights into ecophysiology and how trees respond to climate. In this study, we focused on the interplay between δ¹⁸O from source-water, leaf-water photosynthates understand seasonal trends are integrated rings. We conducted a analysis Pinus sylvestris Finland. Our findings reveal significant reduction variability δ18O needle-water This dampening effect is due...

Nitrogen availability often limits photosynthesis and growth in boreal forests, where nitrogen is a key constraint for plant productivity. Trees other plants acquire through complex belowground interface comprising fine roots, symbiotic, non-symbiotic microorganisms. To sustain this interface, photosynthetically derived carbon allocated to root growth, mycorrhizal symbiosis, exudation—either into the surrounding soil or directly associated microbial communities. These exudates...

Scots pine (Pinus sylvestris L.) is one of the most important conifers in Northern Europe. In boreal forests, over one-third net primary production allocated to roots. Pioneer roots expand horizontal and vertical root systems transport nutrients water from belowground aboveground. Fibrous roots, often colonized by mycorrhiza, emerge pioneer absorb soil. this study, we installed three flatbed scanners detect daily growth both fibrous during growing season 2018, a year with an unexpected...

Continuous cover forestry (CCF) has been promoted as an environmentally sustainable option for drained peatlands. The CCF management challenged due to potentially lower tree growth compared traditional even-aged management, especially with suppressed trees that are released during a selection harvesting under management. Our objective was quantify the time lag of stem diameter response Norway spruce (Picea abies Karst.) after dominant trees. We also tested if carbon assimilation increased...

Forest ecosystem productivity is strongly linked to site nutrient availability, which influenced by litter inputs and their decomposition rates. Fine roots mycelia are key contributors in belowground soil carbon (C) accumulation, but studies have seldom reported how C input related types boreal forests. In this study, three mature one young Pinus sylvestris forests along a type gradient southern Finland were chosen for measurements of fine root biomass, longevity, below- aboveground growth...

Adding nitrogen to boreal forest ecosystems commonly increases gross primary production (GPP). The effect of addition on ecosystem GPP is convoluted due the impacts and interactions among leaf scale photosynthetic productivity, canopy structure, site fertility, environmental constraints. We used a unique controlled fertilisation experiment combined with eddy covariance measurements calibration LUE-based (light use efficiency) model in order reveal differences capacity addition.A...

Shoot elongation in boreal and temperate trees typically follows a sigmoid pattern where the onset cessation of growth are related to accumulated effective temperature (thermal time). Previous studies on leader shoots suggest that while maximum daily rate depends availability resources shoot, duration period may be an adaptation long-term conditions. However, other results indicate longer faster growing lateral with higher resources. This study investigates interactions between units thermal...

Summary We explore needle sugar isotopic compositions (δ 18 O and δ 13 C) in boreal Scots pine ( Pinus sylvestris ) over two growing seasons. A leaf‐level dynamic model driven by environmental conditions based on current understanding of isotope fractionation processes was built to predict C hierarchical carbohydrate pools, accounting for the pool size presence an invariant pinitol pool. Model results agreed well with observed water O, water‐soluble carbohydrates (sugars + pinitol), R 2 =...

In warming climates, soil water content (SWC) may act as an important factor in determining belowground carbon dynamics boreal forests. Here, we estimated the respiration and nonstructural carbohydrate (NSC) concentrations of tree roots a mature Scots pine (Pinus sylvestris L.) stand southern Finland during two growing seasons with contrasting weather conditions. Root was four different methods: 1) incubating excised roots, 2) partitioning forest floor respirations root exclusion, or 3)...

Incomplete knowledge of carbon (C) allocation dynamics in trees hinders accurate modeling and future predictions tree growth. We studied C a mature Pinus sylvestris L. dominated forest with novel analytical approach, allowing the first comparison of: (i) magnitude δ13C shoot, stem soil CO2 fluxes (Ashoot, Rstem Rsoil), (ii) concentration compound-specific and/or bulk non-structural carbohydrates (NSCs) phloem roots (iii) growth fine roots. Results showed significant effect NSC concentrations...

Interpreting phloem carbohydrate or xylem tissue carbon isotopic composition as measures of water-use efficiency past tree productivity requires in-depth knowledge the factors altering within pathway from ambient air to contents and ring. One least understood these is mesophyll conductance (gm ). We formulated a dynamic model describing leaf photosynthetic including seven alternative gm descriptions simple transport sugars foliage down trunk. parameterised for boreal Scots pine stand...

There is evidence that carbon fluxes and stocks decrease with increasing latitude in boreal forests, suggesting a reduction use efficiency. While vegetation soil dynamics have been widely studied, the empirical finding ectomycorrhizal fungi (ECM) become more abundant towards north has not quantitatively linked to We formulated conceptual model of combined fine-root ECM efficiency (CUE) as NPP/GPP (net primary production/gross production). For this, we included mycorrhiza gains plant NPP but...

Summary Intrinsic water‐use efficiency (iWUE), a key index for carbon and water balance, has been widely estimated from tree‐ring δ 13 C at annual resolution, but rarely high‐resolution intraseasonal scale. We iWUE laser‐ablation analysis of tree‐rings (iWUE iso ) compared it with derived gas exchange eddy covariance EC data two Pinus sylvestris forests 2002 to 2019. By carefully timing via modeled growth, aligned well However, year‐to‐year patterns , were different, possibly due distinct...

Understanding the dynamics of δ

Continuous cover forestry (CCF) has gained interest as an alternative to even-aged management particularly on drained peatland forests. However, relatively little is known about the physiological response of suppressed trees when larger are removed a part CCF practices. Consequently, studies concentrating process-level modeling selection harvesting also rare. Here, we compared, modeled and measured harvest previously Norway spruce (Picea abies) harvest. We quantified by collecting tree-ring...

Knowledge about the early part of needle growth is deficient compared with what known shoot growth. It however important to understand different organs be able estimate changes in whole tree a changing environment. The onset spring has been observed occur over some certain threshold value momentary temperature or accumulation. We measured length Scots pine (Pinus sylvestris L.) needles and shoots from March until bud break 3 years. first concurrent Then, we quantified (i) logistic regression...

Models to predict the emissions of biogenic volatile organic compounds (BVOCs) from terrestrial vegetation largely use standardised emission potentials derived shoot enclosure measurements mature foliage. In these models, potential new foliage emit BVOCs is assumed be similar, or up twice as high, that foliage, and thus conifers predicted have a negligible minor contribution canopy BVOC during spring time due small mass emerging growing needles. Extensive observations have, however, recently...

Abstract. Estimates of volatile organic compound (VOC) emissions from forests are based on the assumption that foliage has a steady emission potential over its lifetime, and mainly modified by short term variations in light temperature. However, many field studies this been challenged, high atmospheric concentrations have measured during periods low biological activity such as springtime. We conducted measurements three years, using an online gas-exchange monitoring system to observe mature...

Isaac Newton's approach to developing theories in his book Principia Mathematica proceeds four steps. First, he defines various concepts, second, formulates axioms utilising the third, mathematically analyses behaviour of system defined by concepts and obtaining predictions fourth, tests with measurements. In this study, we formulated our theory boreal forest ecosystems, called NewtonForest, following steps introduced Newton. The ecosystem is a complicated entity hence needed altogether 27...