Spatial variations in non-structural carbohydrates in stems of twelve temperate tree species

The radial, axial and inter-specific variations in concentrations and contents of non-structural carbohydrates (NSC) in stems were investigated for 12 Chinese temperate tree species. These species had contrasting leaf phenology (evergreen and deciduous) and wood types (non-, ring- and diffuse-porous wood). For each species, we sampled bark (periderm and phloem), outer wood (light-colored) and inner wood (dark-colored) at four heights along the stem (stump, breast height, crown base and mid-crown). Concentrations of total NSC (TNC, sum of sugars and starch), sugars and starch were much higher in bark than those in wood. On average, contents of sugars and starch accounted for 48 and 52 % of the TNC, respectively, and contents of TNC in bark, outer wood, and inner wood accounted for 34, 38, and 28 % of the stem total, respectively. Bark was the major pool of sugars in the stem (accounting for 50 % of the stem total on average), while outer wood was the major pool of starch (41 %). The concentration of sugars varied axially for all the conifers but did not for the broadleaved species. Mean concentrations of TNC, sugars and starch in stem varied by more than twofold among the species. However, there were no significant differences in these values for the species groups with different leaf phenology or wood types. Ignoring the radial, axial and inter-specific variations in NSC in stem would introduce large bias in estimating NSC storage at tree or ecosystem levels.     

Non-structural carbon compounds in temperate forest trees

The current carbon supply status of temperate forest trees was assessed by analysing the seasonal variation of non‐structural carbohydrate (NSC) concentrations in leaves, branch wood and stem sapwood of 10 tree species (six deciduous broad‐leafed, one deciduous conifer and three evergreen conifer trees) in a temperate forest that is approximately 100 years old. In addition, all woody tissue was analysed for lipids (acylglycerols). The major NSC fractions were starch, sucrose, glucose and fructose, with other carbohydrates (e.g. raffinose and stachyose) and sugar alcohols (cyclitols and sorbitol) playing only a minor quantitative role. The radial distribution of NSC within entire stem cores, assessed here for the first time in a direct interspecific comparison, revealed large differences in the size of the active sapwood fraction among the species, reflecting the specific wood anatomy (ring‐porous versus diffuse‐porous xylem). The mean minimum NSC concentrations in branch wood during the growing season was 55% of maximum, and even high NSC concentrations were maintained during times of extensive fruit production in masting Fagus sylvestris. The NSC in stem sapwood varied very little throughout the season (cross species mean never below 67% of maximum), and the small reductions observed were not significant for any of the investigated species. Although some species contained substantial quantities of lipids in woody tissues (‘fat trees’; Tilia, Pinus, Picea, Larix), the lipid pools did not vary significantly across the growing season in any species. On average, the carbon stores of deciduous trees would permit to replace the whole leave canopy four times. These data imply that there is not a lot of leeway for a further stimulation of growth by ongoing atmospheric CO₂ enrichment. The classical view that deciduous trees rely more on C‐reserves than evergreen trees, seems unwarranted or has lost its justification due to the greater than 30% increase in atmospheric CO₂ concentrations over the last 150 years.     

Radial and vertical variation of wood nutrients in Bornean tropical forest trees

Nitrogen, phosphorus, potassium, calcium, and magnesium concentrations in woody tissue are poorly documented, but are necessary for understanding whole-tree nutrient use and storage. Here, we report how wood macronutrient concentrations vary radially and along the length of a tree for 10 tropical tree species in Sabah, Malaysia. Bark nutrient concentrations were consistently high: 2.9–13.7 times greater than heartwood depending on the nutrient. In contrast, within the wood both the radial (sapwood vs. heartwood) and vertical (trunk bottom vs. trunk middle) variation was modest. Higher concentrations in sapwood relative to heartwood provide empirical support for wood nutrient resorption during sapwood senescence. Dipterocarp species showed resorption rates of 25.3 ± 7.1% (nitrogen), 62.7 ± 11.9% (phosphorus), and 56.2 ± 12.5% (potassium), respectively, while non-dipterocarp species showed no evidence of nutrient resorption in wood. This suggests that while dipterocarps have lower wood nutrient concentrations, this family is able to compensate for this by using wood nutrient resorption as an efficient nutrient conservation mechanism. In contrast to other nutrients, calcium and magnesium tended to accumulate in heartwood. Wood density (WD) showed little vertical variation along the trunk. Across the species (WD range of 0.33 to 0.94 mg/cm³), WD was negatively correlated with wood P and K concentration and positively correlated with wood Ca concentration. As our study showed exceptionally high nutrient concentrations in the bark, debarking and leaving the bark of the harvested trees on site during logging operations could substantially contribute to maintaining nutrients within forest ecosystems.     

Large seasonal fluctuations in whole-tree carbohydrate reserves: is storage more dynamic in boreal ecosystems?

Background and AimsCarbon reserves are a critical source of energy and substrates that allow trees to cope with periods of minimal carbon gain and/or high carbon demands, conditions which are prevalent in high-latitude forests. However, we have a poor understanding of carbon reserve dynamics at the whole-tree level in mature boreal trees. We therefore sought to quantify the seasonal changes in whole-tree and organ-level carbon reserve pools in mature boreal Betula papyrifera.MethodsNon-structural carbohydrate (NSC; soluble sugars and starch) tissue concentrations were measured at key phenological stages throughout a calendar year in the roots, stem (inner bark and xylem), branches and leaves, and scaled up to estimate changes in organ and whole-tree NSC pool sizes. Fine root and stem growth were also measured to compare the timing of growth processes with changes in NSC pools.Key ResultsThe whole-tree NSC pool increased from its spring minimum to its maximum at bud set, producing an average seasonal fluctuation of 0.96 kg per tree. This fluctuation represents a 72 % change in the whole-tree NSC pool, which greatly exceeds the relative change reported for more temperate conspecifics. At the organ level, branches accounted for roughly 48–60 % of the whole-tree NSC pool throughout the year, and their seasonal fluctuation was four to eight times greater than that observed in the stemwood, coarse roots and inner bark.ConclusionsBranches in boreal B. papyrifera were the largest and most dynamic storage pool, suggesting that storage changes at the branch level largely drive whole-tree storage dynamics in these trees. The greater whole-tree seasonal NSC fluctuation in boreal vs. temperate B. papyrifera may result from (1) higher soluble sugar concentration requirements in branches for frost protection, and/or (2) a larger reliance on reserves to fuel new leaf and shoot growth in the spring.     

Seasonal dynamics of non-structural carbohydrates in two species of mediterranean sub-shrubs with different leaf phenology

The seasonal dynamics of non-structural carbohydrates in the woody organs of two co-existing mediterranean sub-shrubs were analyzed. The two species show different leaf phenology during summer: Linum suffruticosum, maintains many of its green leaves, while Lepidium subulatum sheds most of its leaves. These different leaf phenologies are related to different strategies with regard to summer stress. The maintenance of leaves in Linum is related to its stress tolerance while Lepidium avoids stress by shedding its leaves. The main objectives were to: (1) determine the differences in the seasonal dynamics of non-structural carbohydrates among the main woody organs of both species; (2) verify if differences in the leaf phenology, and hence in the strategy with regard to summer drought, lead to different seasonal patterns of carbohydrate storage and use between the two species; (3) compare the seasonal dynamics of carbohydrates of the two studied sub-shrubs with those of mediterranean trees and shrubs previously reported in the literature. The concentration of soluble sugars (SS), starch and total non-structural carbohydrates (TNC) were assessed monthly, over 17 months, in the main roots, stems and the transition zone between root and shoot systems of both species. Starch storage capacity and SS, starch and TNC pools were calculated. The seasonal pattern of carbohydrate accumulation was similar among the woody organs analyzed, but it differed with those reported for mediterranean trees and shrubs. The two species showed different pools and seasonal patterns of non-structural carbohydrate concentrations in its woody organ, which corresponded to their different extent of leaf shedding. The stress-avoider Lepidium accumulated starch during spring shoot growth as a carbon store for summer respiration and had low pools of SS, whereas the stress-tolerant Linum increased SS during summer drought to maintain photosynthetic activity during summer and had low starch pools and storage capacity. However, irrespective of their different leaf shedding patterns, both species had a similar relative variation of their TNC concentration, which contrasts with previous results on deciduous and evergreen woody species.     

去叶对青杨雌雄植株生长和非结构性碳水化合物的影响

近年来,森林食叶害虫在全世界呈爆发趋势.树木的非结构性碳水化合物(NSC)如何响应叶片损失对其生长和生存至关重要.雌雄异株植物在维持森林生态系统稳定性方面扮演着重要角色.然而,目前对该类植物性别之间如何响应去叶的研究还比较少.本文以我国重要的经济和生态恢复树种青杨(Populus cathayana)为研究材料,比较了...     

不同烈度林火干扰下呼中国家级自然保护区森林各碳库储量的动态变化

本研究通过FireBGCv2模型,模拟不同烈度林火干扰下未来100年呼中自然保护区森林各碳库的动态变化特征,以探究森林不同碳库对火干扰的响应规律,为保护区森林可燃物的管理提供科学依据。结果表明: 林火干扰显著降低了保护区森林碳储量,且林火烈度越大,碳储量降低越多。火干扰影响森林各碳库储量的变化,也改变了森林总碳库的分配特征。林火干扰对各碳库碳储量的影响表现为:林火干扰使活立木、半腐殖质层碳储量降低,使粗木质残体碳储量在模拟前、中期增加,在模拟后期降低,灌草碳库碳储量在模拟后期增加。林火烈度越大,活立木、灌草碳库碳储量越低,枯立木和粗木质残体碳库碳储量越高。林火干扰对总碳库分配的影响表现为:林火干扰后,灌草、枯立木、粗木质残体和土壤碳库占比增加,活立木、半腐殖层碳库在总碳库中的占比减小。林火烈度越大,灌草碳库占比越小,粗木质残体碳库占比越大,烈度对其他碳库占比影响较小。枯落物的周期性变化规律为: 20年达到高值,然后10年内降到低值,这一发现为确定森林可燃物处理的时间间隔提供了有力的依据,建议在大兴安岭地区每隔20年进行一次计划火烧,以合理保护该地区的森林资源。     

Water stress, shoot growth and storage of non-structural carbohydrates along a tree height gradient in a tall conifer

We analysed concentrations of starch, sucrose, glucose and fructose in upper branch wood, foliage and trunk sapwood of Douglas-fir trees in height classes ranging from ~2 to ~57 m. Mean concentrations of non-structural carbohydrates (NSC) for all tissues were highest in the tallest height class and lowest in the lowest height class, and height-related trends in NSC were most pronounced in branches. Throughout a 17-month sampling period, mean values of branch NSC from the 57 m trees ranged between 30 and 377% greater than the 2 m trees. Branch NSC was inversely correlated with midday shoot water potential (Ψ(l)), shoot osmotic potential at full turgor (Ψ) and shoot extension. Temporal fluctuation in branch NSC was inversely correlated with height, and positively correlated with midday Ψ(l) , Ψ and shoot extension. The positive correlation between height and storage of NSC, and the negative correlation between NSC storage and shoot extension provide evidence that size-related growth decline in trees is not strongly associated with constraints on photosynthesis. The negative correlation between height and fluctuation in NSC suggests that mobilization of photosynthate in taller trees is constrained by some factor such as reductions in turgor-driven cell expansion or constraints on phloem transport.     

End of season carbon supply status of woody species near the treeline in western China

As trees and shrubs approach the high elevation tree limit, it is often assumed that they fall short in photosynthate (source limitation). Alternatively, low temperature may restrict carbon investment (growth, sink limitation). The content of mobile non-structural carbohydrates (NSC) in tissues is considered a measure of the carbon source–sink balance. To test the source vs. sink limitation hypothesis, we compared late-season NSC concentrations of various woody taxa across altitudinal gradients from the subalpine forest to the treeline at the eastern edge of the Tibetan Plateau. Since we were interested in the generality of trends, we present “community” trends across four taxa, namely Quercus aquifolioides, Abies faxoniana, Rhododendron fabri subsp. prattii and Sorbus rufopilosa. NSC concentrations increased significantly with altitude in branch wood, current-year and last-year leaves, while there were no significant trends in stem sapwood and root xylem. The sugar to starch ratio was roughly 1:1 in branches and evergreen leaves, while stems and roots showed a higher starch fraction. Analyses of total nitrogen in leaves and wood tissues indicated no change in the trees’ nitrogen supply with elevation. The overall altitudinal trends of NSC in this group of woody plant species revealed no depletion of carbon reserves near the tree limit, suggesting that sink limitation predominates woody plant life across this treeline ecotone community.     

Non-structural carbohydrates and nitrogen dynamics in mediterranean sub-shrubs: an analysis of the functional role of overwintering leaves

Previous studies have led to contrasting results about the role of overwintering leaves as storage sites, which is related to leaf longevity and life-form. The aim of this study was to evaluate the functional role of the leaves of four species of Mediterranean sub-shrubs, with different leaf phenology, as sources of nitrogen (N) and non-structural carbohydrates (NSC) for shoot growth. The seasonal dynamics of the concentrations and pools of N and NSC were assessed monthly in the leaves and woody organs of each species. Overwintering and spring leaves served as N and NSC sources for shoot growth in the evergreen species analyzed, providing up to 73 % and 324 % of the N demand for spring and autumn growth, respectively. Excess autumn N was stored in woody structures which contributed to the N and NSC requirements of spring growth. In the winter deciduous species, woody organs were the main N source for spring growth, while current photosynthesis from immature brachyblasts seemed to be the main carbon (C) source. Due to their short lifespan, overwintering and spring leaves did not show several translocation processes throughout their life time, their contribution to new growth being made during senescence. The successive exchange of leaf cohorts displayed by Mediterranean sub-shrubs might serve as a mechanism to recycle N and C between consecutive cohorts as plants perform the pheno-morphological changes needed to adapt their morphology to the seasonality of their environment.     

白桦和紫椴树干非结构性碳水化合物的空间变异

以中国东北温带森林两个散孔材树种白桦和紫椴为对象,研究落叶后树干木质部中非结构性碳水化合物(NSC)浓度的空间变异.结果表明: 两种树种的可溶性糖与淀粉的总和(TNC)与可溶性糖浓度均随树干径向深度增加而缓慢下降,淀粉的径向变化不明显,即使在树干径向深处仍存有大量的NSC.两种树种树干的TNC、可溶性糖和淀粉浓度从根颈到胸高降低,之后逐渐升高,最大值出现的高度因树种和TNC组分而异.两种树种树干糖淀粉比值的纵向变化趋势为：白桦随树干升高而增大,紫椴则随之减小.树干NSC储量估算的误差主要来源于NSC浓度的纵向变化,其次是径向变化.喜光树种白桦的树干TNC浓度(1.0%干质量)显著低于耐阴树种紫椴(4.3%干质量),可能与其生活史对策差异有关.采用考虑了树干NSC纵向和径向变化的取样方法,可以有效地降低树木或林分水平上NSC储量估算的不确定性.
     

Contrasting seasonal overlaps between primary and secondary growth are linked to wood anatomy in Mediterranean sub‐shrubs

Whole‐plant approaches allow quantification of the temporal overlap between primary and secondary growth. If the amount of time available to grow is short, there may be a high temporal overlap between shoot growth and wood formation. We hypothesise that such overlap depends on the duration of the growing season and relates to wood anatomy. We evaluated wood anatomy, shoot longitudinal and radial growth rates, fine root production and the concentrations of non‐structural carbohydrates (NSC) in the wood of six sub‐shrub species growing in sites with contrasting climatic conditions (Lepidium subulatum, Linum suffruticosum, Salvia lavandulifolia, Satureja montana, Ononis fruticosa, Echinospartum horridum). Sub‐shrub species living in sites with a short growing season displayed a high overlap between aboveground primary and secondary growth and formed wide vessels, whereas species from the warmest and driest sites presented the reverse characteristics. The highest overlap was linked to a rapid shoot extension and thickening through the enhanced hydraulic conductivity provided by wide vessels. The reductions in NSC concentrations when growth peaked were low or moderate, indicating that sub‐shrubs accumulate NSC in excess, as do trees. The temporal overlap among primary and secondary growth in woody plants may be connected to the duration and rates of shoot and wood growth, which in turn depend on the vessel lumen area.     

Consequences of Sphaeropsis tip blight disease for the phytohormone profile and antioxidative metabolism of its pine host

Phytopathogenic fungi infections induce plant defence responses that mediate changes in metabolic and signalling processes with severe consequences for plant growth and development. Sphaeropsis tip blight, induced by the endophytic fungus Sphaeropsis sapinea that spreads from stem tissues to the needles, is the most widespread disease of conifer forests causing dramatic economic losses. However, metabolic consequences of this disease on bark and wood tissues of its host are largely unexplored. Here, we show that diseased host pines experience tissue dehydration in both bark and wood. Increased cytokinin and declined indole‐3‐acetic acid levels were observed in both tissues and increased jasmonic acid and abscisic acid levels exclusively in the wood. Increased lignin contents at the expense of holo‐cellulose with declined structural biomass of the wood reflect cell wall fortification by S. sapinea infection. These changes are consistent with H₂O₂ accumulation in the wood, required for lignin polymerization. Accumulation of H₂O₂ was associated with more oxidized redox states of glutathione and ascorbate pools. These findings indicate that S. sapinea affects both phytohormone signalling and the antioxidative defence system in stem tissues of its pine host during the infection process.     

Interactions between calcium and copper or cadmium in Norway spruce

The accumulation of calcium (Ca), copper (Cu) and cadmium (Cd) in roots and stem of Norway spruce (Picea abies [L.] Karst) was examined. Two-year-old Norway spruce seedlings were treated with elevated concentrations of Ca, Cd or Cu, or as combinations of Ca with Cu or Cd in nutrient solutions for three months. The stem was divided into bark, wood formed during the treatment period (new wood), and wood formed before the treatment period (old wood). The accumulation of the metals in stem and roots increased with addition of the respective metal into nutrient solution. Addition of Cu decreased the accumulation of Ca in roots and wood, and Ca addition decreased the accumulation of Cu in the new wood. By adding Ca in combination with Cu the accumulation of Cu in the stem was decreased even more by Ca and the negative effect of Cu on the Ca content in the stem was diminished. Addition of Cd decreased the accumulation of Ca in wood, especially the old wood, and Ca addition decreased the accumulation of Cd in roots, bark and new wood. By adding Ca in combination with Cd the Ca content was reduced in the bark, instead of in the old wood.     

Leaf nonstructural carbohydrate concentrations of understory woody species regulated by soil phosphorus availability in a tropical forest

Leaf soluble sugars and starch are important components of nonstructural carbohydrates (NSCs), which are crucial for plant growth, development, and reproduction. Although there is a large body of research focusing on the regulation of plant NSC (soluble sugars and starch) concentrations, the response of foliar NSC concentrations to continuous nitrogen (N) and phosphorus (P) addition is still unclear, especially in tropical forests. Here, we used a long‐term manipulative field experiment to investigate the response of leaf NSC concentrations to continuous N and P addition (3‐, 5‐, and 8‐year fertilization) in a tropical forest in southern China. We found significant species‐specific variation in leaf NSC concentrations in this tropical forest. Phosphorus addition dramatically decreased both leaf soluble sugar and starch concentrations, while N addition had no significant effects on leaf soluble sugar and starch concentrations. These results suggest that, in plants growing in P‐limiting tropical soil, leaf NSC concentrations are regulated by soil P availability rather than N availability. Moreover, the negative relationships between NSC concentrations and leaf mass per area (LMA) revealed that NSCs could supply excess carbon (C) for leaf expansion under P addition. This was further supported by the increased structural P fraction after P fertilization in our previous study at the same site. We conclude that soil P availability strongly regulates leaf starch and soluble sugar concentrations in the tropical tree species included in this study. The response of leaf NSC concentrations to long‐term N and P addition can reflect the close relationships between plant C dynamics and soil nutrient availability in tropical forests. Maintaining relatively higher leaf NSC concentrations in tropical plants can be a potential mechanism for adapting to P‐deficient conditions.     

Homoeostatic maintenance of nonstructural carbohydrates during the 2015–2016 El Niño drought across a tropical forest precipitation gradient

Nonstructural carbohydrates (NSCs) are essential for maintenance of plant metabolism and may be sensitive to short‐ and long‐term climatic variation. NSC variation in moist tropical forests has rarely been studied, so regulation of NSCs in these systems is poorly understood. We measured foliar and branch NSC content in 23 tree species at three sites located across a large precipitation gradient in Panama during the 2015–2016 El Niño to examine how short‐ and long‐term climatic variation impact carbohydrate dynamics. There was no significant difference in total NSCs as the drought progressed (leaf P = 0.32, branch P = 0.30) nor across the rainfall gradient (leaf P = 0.91, branch P = 0.96). Foliar soluble sugars decreased while starch increased over the duration of the dry period, suggesting greater partitioning of NSCs to storage than metabolism or transport as drought progressed. There was a large variation across species at all sites, but total foliar NSCs were positively correlated with leaf mass per area, whereas branch sugars were positively related to leaf temperature and negatively correlated with daily photosynthesis and wood density. The NSC homoeostasis across a wide range of conditions suggests that NSCs are an allocation priority in moist tropical forests.     

The mechanical role of bark

The ability of stem bark to resist bending forces was examined by testing in bending segments of Acer saccharum, Fraxinus americana, and Quercus robur branches with and without their bark. For each species, the bark contributed significantly to the ability of stem segments differing in age to resist bending forces, but its contribution was age-dependent and differed among the three species. The importance of the mechanical role of the bark decreased basipetally with increasing age of F. americana and Q. robur stem segments and was superceded by that of the wood for segments ≥ 6 yr old. A. saccharum bark was as mechanically important as the wood for stem segments 7 yr old but was not a significant stiffening agent for younger or older portions of stems. On average, the stiffness of the bark from all three species was 50% that of the wood. However, the geometric contribution to the flexural rigidity of stems made by the bark (i.e., the bark's second moment of area) was sufficiently large to offset its lower stiffness (Young's modulus) relative to that of the wood. A simple model is presented that shows that the bark must be as mechanically important as the wood when its radial thickness equals 32% that of the wood and its stiffness is 50% that of the wood. Based on this model, which is shown to comply with the data from three species purported to have stiff woods, it is evident that the role of the bark cannot be neglected when considering the mechanical behavior of juvenile woody stems subjected to externally applied bending forces.     

Bicarbonate stimulates non‐structural carbohydrate pools of Camptotheca acuminata

The role of root‐derived dissolved inorganic carbon (DIC) has been emphasized lately, as it can provide an alternative source of carbon for photosynthesis. The fate of newly fixed DIC and its effect on non‐structural carbohydrate (NSC) pools has not been thoroughly elucidated to date. To this end, we used ¹³C (NaHCO₃) as a substrate tracer to investigate the incorporation of newly fixed bicarbonate into the plant organs and NSC compounds of Camptotheca acuminata seedlings for 24 and 72 h. NSC levels across the organs were all markedly increased within 24 h of labeling treatment and afterward only decreased in stems at 72 h. The variation range of NSC concentrations in roots was considerably smaller than in the stem and leaves. As time passed, the δ¹³C in NSC compounds was significantly affected by ¹³C labeling and was more positive in the roots than in the stem and leaves. Starch was more ¹³C‐enriched than was soluble carbohydrate, and the δ¹³C of root starch was as high as ?4.70‰. Bicarbonate incorporation into newly formed NSC compounds contributed up to 0.24% of the root starch within 72 h. These data provided strong evidence that bicarbonate not only acted as a C source that contributed slightly to the NSC pools but also stimulated the increase in NSC pools. The present study expands our understanding of the rapid change of NSC pools across the organs in response to bicarbonate.     

Growth and Wood/Bark Properties of Abies faxoniana Seedlings as Affected by Elevated CO2

Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient 350 (=1= 25) μmol/mol) under two planting densities (28 or 84 plants/mz) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same.     

Ants,fire, and bark traits affect how African savanna trees recover following damage

Bark damage resulting from elephant feeding is common in African savanna trees with subsequent interactions with fire, insects, and other pathogens often resulting in tree mortality. Yet, surprisingly little is known about how savanna trees respond to bark damage. We addressed this by investigating how the inner bark of marula (Sclerocarya birrea), a widespread tree species favoured by elephants, recovers after bark damage. We used a long‐term fire experiment in the Kruger National Park to measure bark recovery with and without fire. At 24 months post‐damage, mean wound closure was 98, 92, and 72%, respectively, in annual and biennial burns and fire‐exclusion treatments. Fire exclusion resulted in higher rates of ant colonization of bark wounds, and such ant colonization resulted in significantly lower bark recovery. We also investigated how ten common savanna tree species respond to bark damage and tested for relationships between bark damage, bark recovery, and bark traits while accounting for phylogeny. We found phylogenetic signal in bark dry matter content, bark N and bark P, but not in bark thickness. Bark recovery and damage was highest in species which had thick moist inner bark and low wood densities (Anacardiaceae), intermediate in species which had moderate inner bark thickness and wood densities (Fabaceae) and lowest in species which had thin inner bark and high wood densities (Combretaceae). Elephants prefer species with thick, moist inner bark, traits that also appear to result in faster recovery rates.