Trees use more non-structural carbohydrate reserves during epicormic than basal resprouting

Dual impacts of long-term vegetation management practices on plant-soil ecological multifunctionality: Call for sustainable management in desert ecosystems

Human-driven vegetation management practices (VMPs) employed in agricultural activities and livelihoods pose potential threats to native plant communities. However, there remains a significant gap in comprehensive understanding regarding the long-term effects of VMPs on the ecological multifunctionality of plant-soil systems within desert ecosystems. Therefore, it is essential to conduct thorough studies and analyses examining the implications of these practices on plant-soil interactions to enable informed decision-making regarding the effective management of desert ecosystems. The Taklamakan Desert in China, which is recognized as one of the largest and driest deserts globally, serves as a valuable model for investigating the impact of human activities on desert environments. This study assessed the long-term (16 years) effects of four distinct VMPs-control (no disturbance), burning, spring cutting, and autumn cutting, as well as irrigation-on Alhagi sparsifolia and its associated soil layers (0-50 cm and 50-100 cm) under realistic field conditions. The irrigation treatment increased aboveground biomass, reduced electrical conductivity and sodium concentration, and decreased soil organic carbon pools across both soil layers. Conversely, spring and autumn cutting led to diminished plant biomass and nutritional value. While autumn cutting increased soil cation levels and effectively lowered salinity compared to control plots, spring cutting did not yield significant effects on these functions. Burning, on the other hand, significantly reduced plant biomass and increased soil salinity but unexpectedly enhanced certain soil functions, likely attributable to the low intensity of the fire and the sparse plant coverage typical of desert ecosystems. All VMPs exhibited dual effects, promoting specific ecological functions while compromising others. The harvesting of vegetation, particularly during the spring, along with burning practices, may considerably disrupt the fragile equilibrium of the plant-soil system and associated ecosystem services. However, a comprehensive assessment to evaluate the overall balance of benefits and drawbacks of VMPs is crucial. To foster the sustainable management and utilization of desert plant communities to combat desertification, it is imperative to implement key actions, including providing alternative fuel sources, assessment of annual biomass consumption, and capacity-building initiatives for farmers.

Populus euphratica has stronger regrowth ability than Populus pruinosa under salinity stress

Pest infestation and soil salinization levels are increasing due to climate change. Comprehending plant regrowth after insect damage and salinity stress is crucial to understanding climate change's multifactorial impacts on forest ecosystems. This study examined Populus euphratica and P. pruinosa regrowth after different defoliation levels combined with salinity stress. Specifically, the biomass and regrowth ability, non-structural carbohydrate (NSC) and nitrogen (N) pools in different organs and the whole plant, and the leaf Cl- concentration of both poplars were analyzed. Our results showed that after 50% defoliation and no salt addition, the regrowth of both species recovered similarly to the control level, while their regrowth was about 70% after 90% defoliation. However, under salinity stress, the regrowth (% leaf biomass) of P. euphratica was significantly higher than P. pruinose at either the 50% or 90% defoliation levels. Additionally, P. euphratica had more soluble sugar, starch, NSC and N pools in leaf, stem, root and whole plant than P. pruinose under salinity stress. The regrowth based on leaf biomass increased linearly with soluble sugar, starch, NSC and N pools, and decreased linearly with leaf Cl- concentration across different salinity and defoliation levels. These results indicated that defoliation significantly decreased NSC and N pools, limiting the growth of both poplars, and salinity stress exacerbated the negative effect. Furthermore, when suffering from salinity stress, P. euphratica with higher NSC and N pools exhibited stronger regrowth ability than P. pruinose.

Effects of Clipping an Invasive Plant Species on the Growth of Planted Plants of Two Co-Occurring Species in a Greenhouse Study

The restoration of native plants in invaded habitats is constrained with the presence of highly competitive exotic species. Aboveground removal, such as clipping or mowing, of invasive plants is required for successful restoration. The effects of clipping an invasive plant species, Solidago canadensis, grown at five densities (1-5 plants per pot), and planting two co-occurring and competitive species, Sesbania cannabina and Imperata cylindrica, on the growth of both the invasive species and the co-occurring species were investigated in a greenhouse experiment. The established S. canadensis suppressed the growth of planted seedlings with 47.8-94.4% reduction in biomass, with stronger effects at higher densities; clipping significantly reduced 97.5-97.4% of biomass of S. canadensis and ameliorated the suppression effects (with only 8.7-52.7% reduction in biomass of the co-occurring plants), irrespective of density. Both the aboveground and belowground part of S. canadensis contributed to its suppression effects on planted co-occurring species. Seed sowing of co-occurring species reduced the belowground growth, but not the underground growth of S. canadensis. S. cannabina appeared to be more effective at reducing the growth of S. canadensis than I. cylindrica. Therefore, clipping together with planting competitive species that can overcome the belowground priority effects of S. canadensis could be a promising strategy for controlling S. canadensis invasion and restoring native plant communities.

Wood anatomy and dendrochronological potentiality of some woody shrubs from the southern Mediterranean coast in Egypt

In tropical and subtropical regions, much research is still required to explore the dendrochronological potential of their trees. This study aims to evaluate the anatomical structure and dendrochronological potential of three Mediterranean desert shrubs in Egypt (Lycium schweinfurthii var. schweinfurthii, L. europaeum, and Calligonum polygonoides subsp. comosum) supported by X-ray density. The results showed that the target species had distinct growth rings at macroscopic and microscopic levels. The vessel traits reflected the adaptability of each species with the prevailing arid climate conditions. After the exclusion of the non-correlated series, we obtained three site chronologies that cover the years 2013-2022 for L. schweinfurthii, 2012-2022 for L. europaeum, and 2011-2022 for C. comosum. The mean series intercorrelation was 0.746, 0.564, and 0.683 for L. schweinfurthii, L. europaeum, and C. comosum, respectively. The EPS (expressed population signal) values ranged from 0.72 to 0.80, while the SNR (species-to-noise ratio) ranged from 9.1 to 21.5. Compiling all series of L. schweinfurthii raised the EPS value to 0.86. The chronologies developed for the studied species were relatively short since we dealt with multi-stemmed shrubs. The average percentage difference between latewood density (LWD) and earlywood density (EWD) in C. comosum, L. europaeum, and L. schweinfurthii were 11.8% ± 5.5, 5.2%± 1.87, and 3.6% ± 1.86, respectively. X-ray densitometry helped in the precise determination of the ring borders of the studied species. The relationships between the radial growth of the studied species and the climate variables were weak to moderate but mostly not significant (i.e., r < 0.7). Generally, the radial growth of the target species had a weak to moderate positive correlation with temperature and precipitation during the wet season (winter), while negatively correlated with temperature for the rest of the year, particularly in summer. Our data agrees with earlier findings that ring formation starts at the beginning of the long vegetative stage, then the rest of the assimilated carbohydrates are directed to the flowering and fruiting at the end of the vegetative stages. For more efficient dendrochronological studies on subtropical and Mediterranean trees, we recommend carrying out xylogenesis studies, collection of phenological data, sampling 45-80 trees per species, using new techniques, and choosing homogeneous and close sites for wood sampling.

Symbiotic ant traits produce differential host-plant carbon and water dynamics in a multi-species mutualism

Cooperative interactions may frequently be reinforced by "partner fidelity feedback," in which high- or low-quality partners drive positive feedbacks with high or low benefits for the host, respectively. Benefits of plant-animal mutualisms for plants have been quantified almost universally in terms of growth or reproduction, but these are only two of many sinks to which a host-plant allocates its resources. By investigating how partners to host-plants impact two fundamental plant resources, carbon and water, we can better characterize plant-partner fidelity and understand how plant-partner mutualisms may be modulated by resource dynamics. In Laikipia, Kenya, four ant species compete for Acacia drepanolobium host-plants. These ants differ in multiple traits, from nectar consumption to host-plant protection. Using a 5-year ant removal experiment, we compared carbon fixation, leaf water status, and stem non-structural carbohydrate concentrations for adult ant-plants with and without ant partners. Removal treatments showed that the ants differentially mediate tree carbon and/or water resources. All three ant species known to be aggressive against herbivores were linked to benefits for host-plant resources, but only the two species that defend but do not prune the host, Crematogaster mimosae and Tetraponera penzigi, increased tree carbon fixation. Of these two species, only the nectivore C. mimosae increased tree simple sugars. Crematogaster nigriceps, which defends the tree but also castrates flowers and prunes meristems, was linked only to lower tree water stress approximated by pre-dawn leaf water potential. In contrast to those defensive ants, Crematogaster sjostedti, a poor defender that displaces other ants, was linked to lower tree carbon fixation. Comparing the effects of the four ant species across control trees suggests that differential ant occupancy drives substantial differences in carbon and water supply among host trees. Our results highlight that ant partners can positively or negatively impact carbon and/or water relations for their host-plant, and we discuss the likelihood that carbon- and water-related partner fidelity feedback loops occur across ant-plant mutualisms.

Regulating carbon and water balance as a strategy to cope with warming and drought climate in Cunninghamia lanceolata in southern China

Human activities have increased the possibility of simultaneous warming and drought, which will lead to different carbon (C) allocation and water use strategies in plants. However, there is no conclusive information from previous studies. To explore C and water balance strategies of plants in response to warming and drought, we designed a 4-year experiment that included control (CT), warming (W, with a 5°C increase in temperature), drought (D, with a 50% decrease in precipitation), and warming and drought conditions (WD) to investigate the non-structural carbohydrate (NSC), C and nitrogen (N) stoichiometry, and intrinsic water use efficiency (iWUE) of leaves, roots, and litter of Cunninghamia lanceolata, a major tree species in southern China. We found that W significantly increased NSC and starch in the leaves, and increased NSC and soluble sugar is one of the components of NSC in the roots. D significantly increased leaves' NSC and starch, and increased litter soluble sugar. The NSC of the WD did not change significantly, but the soluble sugar was significantly reduced. The iWUE of leaves increased under D, and surprisingly, W and D significantly increased the iWUE of litter. The iWUE was positively correlated with NSC and soluble sugar. In addition, D significantly increased N at the roots and litter, resulting in a significant decrease in the C/N ratio. The principal component analysis showed that NSC, iWUE, N, and C/N ratio can be used as identifying indicators for C. lanceolata in both warming and drought periods. This study stated that under warming or drought, C. lanceolata would decline in growth to maintain high NSC levels and reduce water loss. Leaves would store starch to improve the resiliency of the aboveground parts, and the roots would increase soluble sugar and N accumulation to conserve water and to help C sequestration in the underground part. At the same time, defoliation was potentially beneficial for maintaining C and water balance. However, when combined with warming and drought, C. lanceolata growth will be limited by C, resulting in decreased NSC. This study provides a new insight into the coping strategies of plants in adapting to warming and drought environments.

Pathogen-induced hydraulic decline limits photosynthesis and starch storage in grapevines (Vitis sp.)

Xylella fastidiosa (Xf) is the bacterial pathogen responsible for Pierce's Disease (PD) in grapevine (Vitis vinifera L.) and numerous diseases in agriculturally and ecologically important species. Current theory suggests that localized inoculations via insect feeding lead to bacterial spread through the xylem, reducing water transport capacity, leading to declines in productivity, and ultimately death. Yet, the underlying mechanisms of Xf-induced mortality are not fully understood. In this study, we documented the development of PD symptoms over 12-13 weeks postinoculation. Subsequently assessed photosynthetic capacity, starch storage, and stem hydraulics in four grapevine genotypes (two PD-resistant and two PD-susceptible), comparing those physiological changes to control plants. PD-susceptible genotypes showed a coordinated decline in photosynthesis, starch storage, and stem hydraulics, whereas Xf-inoculation led to no change in starch and stem hydraulics in the PD-resistant genotypes. Together these data support the idea of a link between loss of hydraulic conductivity due to tylosis production with a downstream photosynthetic decline and starch depletion in the PD-susceptible genotypes. Our data support the theory that hydraulic failure and carbon starvation underlie plant mortality resulting from PD.

Shifting season of fire and its interaction with fire severity: Impacts on reproductive effort in resprouting plants

Fire regimes shape plant communities but are shifting with changing climate. More frequent fires of increasing intensity are burning across a broader range of seasons. Despite this, impacts that changes in fire season have on plant populations, or how they interact with other fire regime elements, are still relatively understudied. We asked (a) how does the season of fire affect plant vigor, including vegetative growth and flowering after a fire event, and (b) do different functional resprouting groups respond differently to the effects of season of fire? We sampled a total of 887 plants across 36 sites using a space-for-time design to assess resprouting vigor and reproductive output for five plant species. Sites represented either a spring or autumn burn, aged one to three years old. Season of fire had the clearest impacts on flowering in Lambertia formosa with a 152% increase in the number of plants flowering and a 45% increase in number of flowers per plant after autumn compared with spring fires. There were also season × severity interactions for total flowers produced for Leptospermum polygalifolium and L. trinervium with both species producing greater flowering in autumn, but only after lower severity fires. Severity of fire was a more important driver in vegetative growth than fire season. Season of fire impacts have previously been seen as synonymous with the effects of fire severity; however, we found that fire season and severity can have clear and independent, as well as interacting, impacts on post-fire vegetative growth and reproductive response of resprouting species. Overall, we observed that there were positive effects of autumn fires on reproductive traits, while vegetative growth was positively related to fire severity and pre-fire plant size.

Defoliation Significantly Suppressed Plant Growth Under Low Light Conditions in Two Leguminosae Species

Seedlings in regenerating layer are frequently attacked by herbivorous insects, while the combined effects of defoliation and shading are not fully understood. In the present study, two Leguminosae species (Robinia pseudoacacia and Amorpha fruticosa) were selected to study their responses to combined light and defoliation treatments. In a greenhouse experiment, light treatments (L+, 88% vs L-, 8% full sunlight) and defoliation treatments (CK, without defoliation vs DE, defoliation 50% of the upper crown) were applied at the same time. The seedlings' physiological and growth traits were determined at 1, 10, 30, and 70 days after the combined treatment. Our results showed that the effects of defoliation on growth and carbon allocation under high light treatments in both species were mainly concentrated in the early stage (days 1-10). R. pseudoacacia can achieve growth recovery within 10 days after defoliation, while A. fruticosa needs 30 days. Seedlings increased SLA and total chlorophyll concentration to improve light capture efficiency under low light treatments in both species, at the expense of reduced leaf thickness and leaf lignin concentration. The negative effects of defoliation treatment on plant growth and non-structural carbohydrates (NSCs) concentration in low light treatment were significantly higher than that in high light treatment after recovery for 70 days in R. pseudoacacia, suggesting sufficient production of carbohydrate would be crucial for seedling growth after defoliation. Plant growth was more sensitive to defoliation and low light stress than photosynthesis, resulting in NSCs accumulating during the early period of treatment. These results illustrated that although seedlings could adjust their resource allocation strategy and carbon dynamics in response to combined defoliation and light treatments, individuals grown in low light conditions will be more suppressed by defoliation. Our results indicate that we should pay more attention to understory seedlings' regeneration under the pressure of herbivorous insects.

Directional Selection on Tree Seedling Traits Driven by Experimental Drought Differs Between Mesic and Dry Populations

We evaluated population differences and drought-induced phenotypic selection on four seedling traits of the Australian forest tree Eucalyptus pauciflora using a glasshouse dry-down experiment. We compared dry and mesic populations and tested for directional selection on lamina length (reflecting leaf size), leaf shape, the node of ontogenetic transition to the petiolate leaf (reflecting the loss of vegetative juvenility), and lignotuber size (reflecting a recovery trait). On average, the dry population had smaller and broader leaves, greater retention of the juvenile leaf state and larger lignotubers than the mesic population, but the populations did not differ in seedling survival. While there was statistical support for directional selection acting on the focal traits in one or other population, and for differences between populations in selection gradient estimates for two traits, only one trait—lamina length—exhibited a pattern of directional selection consistent with the observed population differences being a result of past adaptation to reduce seedling susceptibility to acute drought. The observed directional selection for lamina length in the mesic population suggests that future increases in drought risk in the wild will shift the mean of the mesic population toward that of the dry population. Further, we provide evidence suggesting an early age trade-off between drought damage and recovery traits, with phenotypes which develop larger lignotubers early being more susceptible to drought death. Such trade-offs could have contributed to the absence of population mean differences in survival, despite marked differentiation in seedling traits.

Limits to post-fire vegetation recovery under climate change

Record-breaking fire seasons in many regions across the globe raise important questions about plant community responses to shifting fire regimes (i.e., changing fire frequency, severity and seasonality). Here, we examine the impacts of climate-driven shifts in fire regimes on vegetation communities, and likely responses to fire coinciding with severe drought, heatwaves and/or insect outbreaks. We present scenario-based conceptual models on how overlapping disturbance events and shifting fire regimes interact differently to limit post-fire resprouting and recruitment capacity. We demonstrate that, although many communities will remain resilient to changing fire regimes in the short-term, longer-term changes to vegetation structure, demography and species composition are likely, with a range of subsequent effects on ecosystem function. Resprouting species are likely to be most resilient to changing fire regimes. However, even these species are susceptible if exposed to repeated short-interval fire in combination with other stressors. Post-fire recruitment is highly vulnerable to increased fire frequency, particularly as climatic limitations on propagule availability intensify. Prediction of community responses to fire under climate change will be greatly improved by addressing knowledge gaps on how overlapping disturbances and climate change-induced shifts in fire regime affect post-fire resprouting, recruitment, growth rates, and species-level adaptation capacity.

Ecologically driven selection of nonstructural carbohydrate storage in oak trees

Leaf habit is a major axis of plant diversity that has consequences for carbon balance since the leaf is the primary site of photosynthesis. Nonstructural carbohydrates (NSCs) produced by photosynthesis can be allocated to storage and serve as a resiliency mechanism to future abiotic and biotic stress. However, how leaf habit affects NSC storage in an evolutionary context has not been shown. Using a comparative physiological framework and an analysis of evolutionary model fitting, we examined if variation in NSC storage is explained by leaf habit. We measured sugar and starch concentrations in 51 oak species (Quercus spp.) growing in a common garden and representing multiple evolutions of three different leaf habits (deciduous, brevideciduous and evergreen). The best fitting evolutionary models indicated that deciduous oak species are evolving towards higher NSC concentrations than their brevideciduous and evergreen relatives. Notably, this was observed for starch (the primary storage molecule) in the stem (a long-term C storage organ). Overall, our work provides insight into the evolutionary drivers of NSC storage and suggests that a deciduous strategy may confer an advantage against stress associated with a changing world. Future work should examine additional clades to further corroborate this idea.

Tradeoff between storage capacity and embolism resistance in the xylem of temperate broadleaf tree species

Xylem traits are critical plant functional traits associated with water transport, mechanical support, and carbohydrate and water storage. Studies on the xylem hydraulic efficiency-safety tradeoff are numerous; however, the storage function of xylem parenchyma is rarely considered. The effects of a substantial number of xylem traits on water transport, embolism resistance, mechanical support, storage capacity and nonstructural carbohydrate (NSC) content were investigated in 19 temperate broadleaf species planted in an arid limestone habitat in northern China. There was no xylem hydraulic efficiency-safety tradeoff in the 19 broadleaf species. The total parenchyma fraction was negatively correlated with the fiber fraction. Embolism resistance was positively correlated with indicators of xylem mechanical strength such as vessel wall reinforcement, vessel wall thickness and fiber wall thickness, and was negatively related to the axial parenchyma fraction, especially the paratracheal parenchyma fraction. The paratracheal parenchyma fraction was positively correlated with the ratio of the paratracheal parenchyma fraction to the vessel fraction. In addition, the xylem NSC concentration was positively related to the total parenchyma fraction and axial parenchyma fraction. There was a storage capacity-embolism resistance tradeoff in the xylem of 19 broadleaf species in arid limestone habitats. We speculate that the temperate broadleaf species may show a spectrum of xylem hydraulic strategies, from the embolism resistance strategy related to a more negative P50 (the water potential corresponding to 50% loss of xylem conductivity) to the embolization repair strategy based on more paratracheal parenchyma.

Phenotypic plasticity and genetic adaptation of functional traits influences intra-specific variation in hydraulic efficiency and safety

Understanding which hydraulic traits are under genetic control and/or are phenotypically plastic is essential in understanding how tree species will respond to rapid shifts in climate. We quantified hydraulic traits in Eucalyptus obliqua L'Her. across a precipitation gradient in the field to describe (i) trait variation in relation to long-term climate and (ii) the short-term (seasonal) ability of traits to adjust (i.e., phenotypic plasticity). Seedlings from each field population were raised under controlled conditions to assess (iii) which traits are under strong genetic control. In the field, drier populations had smaller leaves with anatomically thicker xylem vessel walls, a lower leaf hydraulic vulnerability and a lower water potential at turgor loss point, which likely confers higher hydraulic safety. Traits such as the water potential at turgor loss point and ratio of sapwood to leaf area (Huber value) showed significant adjustment from wet to dry conditions in the field, indicating phenotypic plasticity and importantly, the ability to increase hydraulic safety in the short term. In the nursery, seedlings from drier populations had smaller leaves and a lower leaf hydraulic vulnerability, suggesting that key traits associated with hydraulic safety are under strong genetic control. Overall, our study suggests a strong genetic control over traits associated with hydraulic safety, which may compromise the survival of wet-origin populations in drier future climates. However, phenotypic plasticity in physiological and morphological traits may confer sufficient hydraulic safety to facilitate genetic adaptation.

Temperature and Rainfall Are Separate Agents of Selection Shaping Population Differentiation in a Forest Tree

Research highlights: We present evidence indicating that covariation of functional traits among populations of a forest tree is not due to genetic constraints, but rather selective covariance arising from local adaptation to different facets of the climate, namely rainfall and temperature. Background and Aims: Traits frequently covary among natural populations. Such covariation can be caused by pleiotropy and/or linkage disequilibrium, but also may arise when the traits are genetically independent as a direct consequence of natural selection, drift, mutation and/or gene flow. Of particular interest are cases of selective covariance, where natural selection directly generates among-population covariance in a set of genetically independent traits. We here studied the causes of population-level covariation in two key traits in the Australian tree Eucalyptus pauciflora. Materials and Methods: We studied covariation in seedling lignotuber size and vegetative juvenility using 37 populations sampled from throughout the geographic and ecological ranges of E. pauciflora on the island of Tasmania. We integrated evidence from multiple sources: (i) comparison of patterns of trait covariation within and among populations; (ii) climate-trait modelling using machine-learning algorithms; and (iii) selection analysis linking trait variation to field growth in an arid environment. Results: We showed strong covariation among populations compared with the weak genetic correlation within populations for the focal traits. Population differentiation in these genetically independent traits was correlated with different home-site climate variables (lignotuber size with temperature; vegetative juvenility with rainfall), which spatially covaried. The role of selection in shaping the population differentiation in lignotuber size was supported by its relationship with fitness measured in the field. Conclusions: Our study highlights the multi-trait nature of adaptation likely to occur as tree species respond to spatial and temporal changes in climate.

Leaf Physiological Responses to Drought Stress and Community Assembly in an Asian Savanna

Deciduous dipterocarp forest (DDF) is the most extensive forest type in continental Southeast Asia, but across much of its range is functionally more similar to tropical savannas than tropical forests. We investigated water relations and drought responses of the four dominant tree species (two Shorea and two Dipterocarpus species) of the DDF in central Vietnam to determine how they responded to prolonged periods of drought stress. We quantified leaf water relations in nursery- and field-grown seedlings of the four species and conducted a dry-down experiment on 258 seedlings to study leaf water potential and morphological responses of the seedlings following the drought stress. The two Shorea and two Dipterocarpus species differed significantly in leaf water potential at turgor loss point and osmotic potential at full turgor, but they showed similar responses to drought stress. All species shed leaves and suffered from stem loss when exposed to water potentials lower than their turgor loss point (approximately −1.7 MPa for Dipterocarpus and −2.6 MPa for Shorea species). Upon rewatering, all species resprouted vigorously regardless of the degree of leaf or stem loss, resulting in only 2% whole-plant mortality rate. Our results suggest that none of the four deciduous dipterocarp species is drought tolerant in terms of their water relations; instead, they employ drought-adaptive strategies such as leaf shedding and vigorous resprouting. Given that all species showed similar drought avoidance and drought-adaptive strategies, it is unlikely that seasonal drought directly influences the patterns of species assembly in the DDF of Southeast Asia.

Identifying the relevant carbohydrate storage pools available for remobilization in aspen roots

Nonstructural carbohydrate (NSC) remobilization remains poorly understood in trees. In particular, it remains unclear (i) which tissues (e.g., living bark or xylem) and compounds (sugars or starch) in woody plants are the main sources of remobilized carbon, (ii) to what extent these NSC pools can be depleted and (iii) whether initial NSC mass or concentration is a better predictor of regrowth potential following disturbance. To address these questions, we collected root segments from a large mature trembling aspen stand; we then allowed them to resprout (sucker) in the dark and remobilize NSC until all sprouts had died. We found that initial starch mass, not concentration, was the best predictor of subsequent sprout mass. In total, more NSC mass (~4×) was remobilized from the living inner bark than the xylem of the roots. After resprouting, root starch was generally depleted to <0.6% w/w in both tissues. In contrast, a large portion of sugars appear unavailable for remobilization: sugar concentrations were only reduced to 12% w/w in the bark and 2% in the xylem. These findings suggest that in order to test whether plant processes like resprouting are limited by storage we need to (i) measure storage in the living bark, not just the xylem, (ii) consider storage pool size-not just concentration-and (iii) carefully determine which compounds are actually components of the storage pool.