Use of seasonal freshwater wetlands by fishes in a temperate river floodplain

This study examined the use of freshwater wetland restoration and enhancement projects ( i.e . non-estuarine wetlands subject to seasonal drying) by fish populations. To quantify fish use of freshwater emergent wetlands and assess the effect of wetland enhancement ( i.e . addition of water control structures), two enhanced and two unenhanced emergent wetlands were compared, as well as two oxbow habitats within the Chehalis River floodplain. Eighteen fish species were captured using fyke nets and emigrant traps from January to the beginning of June, with the most abundant being three-spined stickleback Gasterosteus aculeatus and Olympic mudminnow Novumbra hubbsi . Coho salmon Oncorhynchus kisutch was the dominant salmonid at all sites. Enhanced wetlands, with their extended hydroperiods, had significantly higher abundances of yearling coho salmon than unenhanced wetlands. Both enhanced and unenhanced emergent wetlands yielded higher abundances of non-game native fishes than oxbow habitats. Oxbow habitats, however, were dominated by coho salmon. Fish survival in the wetland habitats was dependent on emigration to the river before dissolved oxygen concentrations decreased and wetlands became isolated and stranding occurred. This study suggests that wetland enhancement projects with an outlet to the river channel appear to provide fishes with important temporary habitats if they have the opportunity to leave the wetland as dissolved oxygen levels deteriorate.     

Carbon sequestration in freshwater wetlands in Costa Rica and Botswana

Tropical wetlands are typically productive ecosystems that can introduce large amounts of carbon into the soil. However, high temperatures and seasonal water availability can hinder the ability of wetland soils to sequester carbon efficiently. We determined the carbon sequestration rate of 12 wetland communities in four different tropical wetlands—an isolated depressional wetland in a rainforest, and a slow flowing rainforest swamp, a riverine flow-through wetland with a marked wet and dry season, a seasonal floodplain of an inland delta—with the intention of finding conditions that favor soil carbon accumulation in tropical wetlands. Triplicate soil cores were extracted in these communities and analyzed for total carbon content to determine the wetland soil carbon pool. We found that the humid tropic wetlands had greater carbon content (P ≤ 0.05) than the tropical dry ones (96.5 and 34.8 g C kg^?1, respectively). While the dry tropic wetlands had similar sequestration rates (63 ± 10 g Cm^?2 y^?1 on average), the humid tropic ones differed significantly (P < 0.001), with high rates in a slow-flowing slough (306 ± 77 g Cm^?2 y^?1) and low rates in a tropical rain forest depressional wetland (84 ± 23 g Cm^?2 y^?1). The carbon accumulating in all of these wetlands was mostly organic (92–100%). These results suggest the importance of differentiating between types of wetland communities and their hydrology when estimating overall rates at which tropical wetlands sequester carbon, and the need to include tropical wetland carbon sequestration in global carbon budgets.     

Aboveground decomposition dynamics in riparian depression and slope wetlands of central Pennsylvania

We examined two types of groundwater-fed wetlands (riparian depressions and slopes) classified using the hydrogeomorphic (HGM) system. These wetland types had previously been shown to differ hydrologically. Our first objective was to determine if HGM was a useful structuring variable when examining aboveground decomposition dynamics (rate of mass loss and rate of nitrogen loss). Our second objective was to determine what soil variables were related to any differences in aboveground decomposition dynamics we might find regardless of HGM subclass. We used the litterbag field bioassay technique, and employed a standard litter type (Phalaris arundinacea) across all wetlands. Our results indicated that HGM would not readily serve as an adequate structuring variable for aboveground decomposition in riparian depressions and slope wetlands of central Pennsylvania. Discriminant analysis and classification and regression tree (CART) modeling found soil cation exchange capacity, soil pH, soil organic matter, and soil % nitrogen to be potentially important soil variables related to mass loss, and soil % nitrogen and soil pH to be potentially important variables related to nitrogen loss rate.     

Foliar nutrient dynamics in tidal and non-tidal freshwater forested wetlands

Foliar nutrient dynamics were studied at 8 forest stands (three non-tidal and five tidal) along the lower 30 km of the Apalachicola River system in Florida, USA, during 2008. At each site, we sampled canopy foliage and litterfall from three to four trees representative of the dominant overstory species. Foliage and litterfall were analyzed for a variety of elements including N and P and these data were used to examine differences in element concentrations, nutrient ratios (C:P, C:N, and N:P), nutrient use efficiency, and nutrient proficiency. Measurements of tree diameter at basal height (DBH) at each plot were used with species allometric equations to estimate forest litterfall dry weight and N and P flux in non-tidal and tidal wetlands. Both non-tidal and tidal wetlands showed evidence of P limitation based on N:P ratios, but absolute levels of P were determined to be extremely low in tidal wetlands based on higher nutrient use efficiencies (measures of both P resorption efficiency and proficiency). Differences in P concentrations and fluxes between tidal and non-tidal wetlands are probably related to longer inundation and hydrologic export observed in tidal wetlands. Using estimations of annual litterfall dry weight and nutrient concentrations, N and P flux in non-tidal swamps were 2-4 times greater than in tidal wetlands. This study demonstrates the change in nutrient dynamics as wetlands shift from tidal to non-tidal conditions.     

Nutrient-poor freshwater wetlands

Until the introduction of fertilizers in the 19th century nutrient-poor conditions prevailed in the larger part of The Netherlands. Freshwater wetlands consequently were of nutrient-poor nature. During the first half of the 20th century many surface waters gradually eutrophied, but most waters in the Pleistocene area and even some polders in the Holocene area kept their nutrient-poor conditions. Only during the last decades virtually all waters became eutrophied or polluted. The main sources of nutrients are agriculture, precipitation and water from the large rivers.     

中国湿地碳储量分布特征及其影响因素

湿地巨大的碳储存能力使其在稳定全球气候变化中占有重要地位,并对全球土壤碳储量做出重要贡献.本文在阐明湿地碳储量估算方法的基础上,分析我国主要湿地区碳储量并讨论气候、植被、土壤性质、土地利用等因素对湿地碳储量的影响.结果表明:东北湿地区和青藏高原湿地区是八大湿地区中碳储量最高的两大区域;泥炭湿地的高稳定性、低分解率及酚氧化酶的作用使其成为内陆地区碳储量最高的湿地类型;单一因素的双向干扰及多重因素的交互作用使得湿地碳储量的影响因素和作用机理更加复杂.注重多重因素的交互作用,并结合数据同化技术,有利于湿地碳储量及湿地生态系统价值预测与评估.     

Nitrate uptake dynamics of surface transient storage in stream channels and fluvial wetlands

River systems are important regulators of anthropogenic nitrogen flux between land and ocean. Nitrogen dynamics in small headwater streams have been extensively measured, whereas less is known about contributions of other components of stream networks to nitrogen removal, including larger streams or fluvial wetlands. Here, we quantified nitrate reaction rates in higher-order stream channels and in surface transient storage (STS) zones (sub-systems with greater water residence time than the main channel) of the Ipswich River watershed, a temperate basin characterized by suburban development. We characterized uptake in STS both within higher-order stream channels and in fluvial wetlands that remain connected to advective fluxes but not constrained within channels. We compare reaction rates in these systems to those previously measured in headwater streams in the same basin. We found that (1) nitrate reaction rates (as uptake velocity, υ_f) in higher-order streams (n = 2) differed from each other but were consistent with previous estimates from headwater streams, (2) nitrate reaction rates in STS zones within higher-order stream channels (n = 2) were higher than rates estimated at the whole-stream scale, (3) ambient nitrate reaction rates in fluvial wetland STS (n = 7) were high but comparable to headwater streams with low nitrate concentration, (4) nitrate reaction rates were higher in fluvial wetland STS compared to headwater stream channels at elevated nitrate concentration, and (5) efficiency loss (EL) similar to that found in headwater streams was also apparent in fluvial wetlands. These results indicate that STS are potential hotspots of biogeochemical activity and should be explicitly integrated into network scale biogeochemical models. Further, experimental evidence of EL in fluvial wetlands suggests that the effectiveness of STS to retain N may decline if N loading increases.     

The biogeochemistry of nitrogen in freshwater wetlands

The biogeochemistry of N in freshwater wetlands is complicated by vegetation characteristics that range from annual herbs to perennial woodlands; by hydrologic characteristics that range from closed, precipitation-driven to tidal, riverine wetlands; and by the diversity of the nitrogen cycle itself. It is clear that sediments are the single largest pool of nitrogen in wetland ecosystems (100's to 1000's g N m^-2) followed in rough order-of-magnitude decreases by plants and available inorganic nitrogen. Precipitation inputs (< 1–2 g N m^-2 yr^-1) are well known but other atmospheric inputs, e.g. dry deposition, are essentially unknown and could be as large or larger than wet deposition. Nitrogen fixation (acetylene reduction) is an important supplementary input in some wetlands (< < 1–3 g N m^-2 yr^-1) but is probably limited by the excess of fixed nitrogen usually present in wetland sediments.Plant uptake normally ranges from a few g N m^-2 yr^-1 to 35 g N m^-2 yr^-1 with extreme values of up to 100g N m^-2 yr^-1 Results of translocation experiments done to date may be misleading and may call for a reassessment of the magnitude of both plant uptake and leaching rates. Interactions between plant litter and decomposer microorganisms tend, over the short-term, to conserve nitrogen within the system in immobile forms. Later, decomposers release this nitrogen in forms and at rates that plants can efficiently reassimilate.The NO₃ formed by nitrification (< 0.1 to 10 g N m^-2 yr^-1 has several fates which may tend to either conserve nitrogen (uptake and dissimilatory reduction to ammonium) or lead to its loss (denitrification). Both nitrification and denitrification operate at rates far below their potential and under proper conditions (e.g. draining or fluctuating water levels) may accelerate. However, virtually all estimates of denitrification rates in freshwater wetlands are based on measurements of potential denitrification, not actual denitrification and, as a consequence, the importance of denitrification in these ecosystems may have been greatly over estimated.In general, larger amounts of nitrogen cycle within freshwater wetlands than flow in or out. Except for closed, ombrotrophic systems this might seem an unusual characteristic for ecosystems that are dominated by the flux of water, however, two factors limit the opportunity for N loss. At any given time the fraction of nitrogen in wetlands that could be lost by hydrologic export is probably a small fraction of the potentially mineralizable nitrogen and is certainly a negligible fraction of the total nitrogen in the system. Second, in some cases freshwater wetlands may be hydrologically isolated so that the bulk of upland water flow may pass under (in the case of floating mats) or by (in the case of riparian systems) the biotically active components of the wetland. This may explain the rather limited range of N loading rates real wetlands can accept in comparison to, for example, percolation columns or engineered marshes.     

Typha productivity in a Texas pond: Implications for energy and nutrient dynamics in freshwater wetlands

Above-and below-ground biomass of Typha angustifolia L. was sampled monthly for 18 months from a small Texas pond. Maximum above-ground biomass was 2559±284 g AFDW (ash-free dry weight) m⁻² in 1983 and 2895±217 g AFDW m⁻² in 1984. Peak below-ground biomass for these 2 years was 2506±278 g AFDW m⁻² and 2314±226 g AFDW m^t-2, respectively. Stepwise multiple linear regression analyses revealed that mean above-ground biomass accrual was related to duration of growing season, cumulative precipitation, cumulative degree days and/or cumulative pan evaporation. The same was not true for below-ground biomass increases. Analysis of covariance revealed that the rates of above-ground biomass production were not significantly different (F test, p < 0.05) between the 1983 and 1984 growing seasons. Below-ground biomass turnover times for 1983 and 1984 were 2.47 and 1.21 years, respectively.     

Methane emissions from freshwater riverine wetlands

To better understand methane emissions from freshwater riverine wetlands, seasonal and spatial patterns of methane emissions were measured over a 1-year period from created freshwater marshes and a river division oxbow, and at a river-floodplain edge (riverside) in central Ohio, USA. Plots were distributed from inflow to outflow and from shallow transition edges to deep water zones in the marshes and oxbow. Median values of CH₄ emissions ranged from 0.33 to 85.7 mg-CH₄-C m⁻² h⁻¹, at the riverside sites and 0.02-20.5 mg CH₄-C m⁻² h⁻¹ in the created marshes. The naturally colonizing marsh had more methane emissions (p = 0.047) than did the planted marsh, probably due to a history of higher net primary productivity in the former. A significant dry period and lower productivity in the oxbow may explain its low range of methane emissions of −0.04 to 0.09 mg CH₄-C m⁻² h⁻¹. There were significantly higher rates of methane emissions in deep water zones compared to transition zones in the created marshes. Overall CH₄ emissions had significant relationships with organic carbon and soil temperature and appear to depend on the hydroperiod and vegetation development. Riparian wetlands can be designed to minimize greenhouse gas emissions while providing other ecosystem services.     

Nitrate dynamics in event-driven wetlands

The dynamics nitrate retention and export were studied at the Des Plaines River wetland demonstration site. Seven wetlands received pulses of river water in discrete pumping events. Twenty-eight wetland events were monitored over 4 years for all hydrologic variables, pumping, rain, storage change, and outflow. Nitrate was measured at high frequency for the ouflows, and at lower frequency for inflows and interior stations. Most events were isolated in time, with sufficient inter-event spacing to allow complete equilibration before the subsequent event. Pumping was selected to provide up to 45 displacements of the wetland water volume. River water averaged 2.3 mg/L of nitrate nitrogen, and wetland effluent averaged 0.9 mg/L. The average mass removal of nitrate was 67% over all events, with a range from 17% to 100%. A calibrated dynamic water mass balance was developed as the framework for interpreting results. Internal hydraulics were characterized by tanks-in-series (TIS) models calibrated to tracer studies. Residence time distributions were describable by three TIS (three wetlands) and five TIS (four wetlands). Dynamic nitrate mass balances were used, in conjunction with a first order areal uptake model, to model the time sequence of NO₃N concentrations and flows. Parameter estimation, based on NO₃N mass flow fitting, produced rate constants that best described the series of events the wetlands. Rate constants were much higher for the events than for previous steady state performance for the wetlands (k₂₀ = 107 vs. 37 m/yr). Rate coefficients increased at higher water temperatures, with a modified Arrhenius temperature factor of 1.090. Performance for N removal was found to be partially due to displacement of antecedent treated water, and partially due to treatment occurring during the event, and partially due to treatment after the event. Carbon availability was estimated not to limit denitrification, except possibly at the highest nitrate loadings.     

A comparison of created and natural wetlands in Pennsylvania,USA

Recent research suggests that created wetlands do not look, or function, like the natural systems they are intended to replace. Proper planning, construction, and the introduction of appropriate biotic material should initiate natural processes which continue indefinitely in a successful wetland creation project, with minimal human input. To determine if differences existed between created and natural wetlands, we compared soil matrix chroma, organic matter content, rock fragment content, bulk density, particle size distribution, vegetation species richness, total plant cover, and average wetland indicator status in created (n = 12) and natural (n = 14)wetlands in Pennsylvania (USA). Created wetlands ranged in age from two to 18 years. Soils in created wetlands had less organic matter content, greater bulk densities, higher matrix chroma, and more rock fragments than reference wetlands. Soils in reference wetlands had clay loam textures with high silt content, while sandy clay loam textures predominated in the created sites. Vegetation species richness and total cover were both greater in natural reference wetlands. Vegetation in created wetlands included a greater proportion of upland species than found in the reference wetlands. There were significant differences in soils and vegetation characteristics between younger and older created wetlands, though we could not say older created sites were trending towards the reference wetland condition. Updated site selection practices, more careful consideration of monitoring period lengths, and, especially, a stronger effort to recreate wetland types native to the region should result in increased similarity between created and natural wetlands.     

黑龙江省森林植被碳储量及其动态变化

黑龙江省的森林资源在全国森林资源中占有较为重要的位置.利用我国第一次(1973～1976年)至第六次(1999～2003年)森林资源清查资料,以及不同树种生物量和蓄积量之间的线性关系,对黑龙江省近30年来森林碳储量进行了求和推算.结果表明,黑龙江省6次森林资源清查中森林的总碳储量分别是7.916×10⁸ t、.413×10⁸ t、.661×10⁸ t、.880×10⁸ t、6.216×10⁸ t和6.011×10⁸ t,总体呈先下降后上升的趋势,说明30年间黑龙江省的森林是CO₂的"汇";特别是1977～1981年后,黑龙江省森林碳储量呈逐渐上升趋势,说明近20年来黑龙江省森林CO₂"汇"的作用在增强.如果对现有森林进行更好地抚育和管理,黑龙江省森林作为CO₂"汇"的潜力很大.     

Comparing carbon sequestration in temperate freshwater wetland communities

High productivity and waterlogged conditions make many freshwater wetlands significant carbon sinks. Most wetland carbon studies focus on boreal peatlands, however, with less attention paid to other climates and to the effects of hydrogeomorphic settings and the importance of wetland vegetation communities on carbon sequestration. This study compares six temperate wetland communities in Ohio that belong to two distinct hydrogeomorphic types: an isolated depressional wetland site connected to the groundwater table, and a riverine flow‐through wetland site that receives water from an agricultural watershed. Three cores were extracted in each community and analyzed for total carbon content to determine the soil carbon pool. Sequestration rates were determined by radiometric dating with ¹³⁷Cs and ²¹⁰Pb on a set of composite cores extracted in each of the six communities. Cores were also extracted in uplands adjacent to the wetlands at each site. Wetland communities had accretion rates ranging from 3.0 to 6.2 mm yr^?1. The depressional wetland sites had higher (P < 0.001) organic content (146 ± 4.2 gC kg^?1) and lower (P < 0.001) bulk density (0.55 ± 0.01 Mg m^?3) than the riverine ones (50.1 ± 6.9 gC kg^?1 and 0.74 ± 0.06 Mg m^?3). The soil carbon was 98–99% organic in the isolated depressional wetland communities and 85–98% organic in the riverine ones. The depressional wetland communities sequestered 317 ± 93 gC m^?2 yr^?1, more (P < 0.01) than the riverine communities that sequestered 140 ± 16 gC m^?2 yr^?1. The highest sequestration rate was found in the Quercus palustris forested wetland community (473 gC m^?2 yr^?1), while the wetland community dominated by water lotus (Nelumbo lutea) was the most efficient of the riverine communities, sequestering 160 gC m^?2 yr^?1. These differences in sequestration suggest the importance of addressing wetland types and communities in more detail when assessing the role of wetlands as carbon sequestering systems in global carbon budgets.     

Carbon emission along a eutrophication gradient in temperate riverine wetlands: effect of primary productivity and plant community composition

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长白山原始针叶林沼泽湿地生态系统碳储量

采用年轮分析及相对生长方程法与碳/氮分析仪测定法,测定温带长白山沿湿地过渡带环境梯度依次分布的5种典型原始沼泽类型(草丛沼泽-C、灌丛沼泽-G、落叶松泥炭藓沼泽-LN、落叶松藓类沼泽-LX和落叶松苔草沼泽-LT)生态系统碳储量(植被和土壤)、植被净初级生产力与年净固碳量,定量评价温带森林湿地固碳能力及其长期碳汇作用,并揭示其沿过渡带水分环境梯度的空间分异规律。结果表明:①5种天然沼泽类型的植被碳储量(3.18±1.70)—(112.2±18.3) tC/hm~2沿过渡带环境梯度总体上呈递增趋势,针叶林沼泽显著高于C和G 12.2—34.3倍,G高于C 0.6倍,且LX和LT显著高于LN 0.3—0.6倍;②土壤碳储量(296.3±42.2)—(824.50±50.79) tC/hm~2沿过渡带环境梯度总体上呈递减趋势,C显著高于G和针叶林沼泽30.8%—178.3%(P0.05),G显著高于针叶林沼泽38.7%—112.8%,且LN和LT显著高于LX 32.8%—53.4%;③生态系统碳储量(408.42±57.53)—(827.52±50.96) tC/hm~2沿过渡带环境梯度总体上也呈递减趋势,C显著高于G和针叶林沼泽30.2%—102.7%,G显著高于针叶林沼泽21.5%—55.6%,且LN和LT显著高于LX 18.8%—28.0%;④5种沼泽类型的植被净初级生产力与年净固碳量分布在(5.74±0.08)—(10.98±1.67) t hm~(-2) a~(-1)和(2.44±0.03)—(5.17±0.83)tC hm~(-2) a~(-1),其中,LX和LT的植被净初级生产力显著高于C、G和LN 61.2%—91.3%和34.5%—59.6%;而在植被年净固碳量方面,3种针叶林沼泽类型均显著高于C和G 28.7%—111.9%和19.4%—96.6%。故长白山5种天然沼泽类型的植被净初级生产力与年净固碳量沿湿地过渡带环境梯度总体上呈现出阶梯式递增趋势,且仅有LX和LT达到了中国陆地植被及全球陆地植被平均固碳水平。因此,温带长白山沼草丛沼泽和灌丛沼泽长期碳汇作用强于森林沼泽,湿地碳汇管理实践中应重视草丛沼泽和灌丛沼泽的保护与恢复。     

Distribution of aerobic anoxygenic phototrophs in temperate freshwater systems

The presence of aerobic anoxygenic phototrophs (AAPs) was recently reported from various marine environments; however, there is little information regarding their distribution in fresh waters. We surveyed a number of freshwater systems in central Europe, by infra-red fluorometry, infra-red epifluorescence microscopy, fluorescence emission spectroscopy and pigment analyses. AAPs were found to be abundant in several oligotrophic and mesotrophic lakes (50–400 ng of bacteriochlorophyll a l⁻¹, 10–80% of bacterial biomass), while in more eutrophized water bodies they represented a negligible part of the total microbial community (< 1%). The observed freshwater AAPs were morphologically diverse and different from previously observed marine species. Under temperate European climatic conditions, AAP populations undergo strong seasonal changes in terms of both abundance and species composition, with the maximum biomass in summer and the minimum in winter. In the mountain lakes Čertovo and Plešné, AAPs contributed more than one half of total bacterial biomass during their summer maximum. These results show that photoheterotrophic bacteria represent an important part of the microbial community in many freshwater systems.     

中国寒温带不同林龄白桦林碳储量及分配特征

为了解中国寒温带地区不同林龄白桦林生态系统碳储量及固碳能力, 在样地调查基础上, 以大兴安岭地区25、40与61年白桦(Betula platyphylla)林生态系统为研究对象, 对其乔木层、林下地被物层(灌木层、草本层、凋落物层)、土壤层(0-100 cm)碳储量与分配特征进行调查研究。结果表明白桦林乔木层各器官碳含量在440.7-506.7 g·kg ^-1之间, 各器官碳含量随着林龄的增长而降低; 灌木层、草本层碳含量随林龄的增加呈先降后升的变化趋势; 凋落物层碳含量随林龄增加而降低; 土壤层(0-100 cm)碳含量随林龄增加而显著升高, 随着土层深度的增加而降低。白桦林生态系统各层次碳储量均随林龄的增加而明显升高。25、40与61年白桦林乔木层碳储量分别为11.9、19.1和34.2 t·hm ^-2, 各器官碳储量大小顺序表现为树干>树根>树枝>树叶, 树干碳储量分配比例随林龄增加而升高。25、40与61年白桦林生态系统碳储量分别为77.4、180.9和271.4 t·hm ^-2, 其中土壤层占生态系统总碳储量的81.6%、87.7%和85.9%, 是白桦林生态系统的主要碳库。随林龄增加, 白桦林年净生产力(2.0-4.4 t·hm ^-2·a ^-1)、年净固碳量(1.0-2.1 t·hm ^-2·a ^-1)均出现增长, 老龄白桦林仍具有较强的碳汇作用。     

Carbon allocation to defense, storage, and growth in seedlings of two temperate broad-leaved tree species

Optimal carbon allocation to growth, defense, or storage is a critical trait in determining the shade tolerance of tree species. Thus, examining interspecific differences in carbon allocation patterns is useful when evaluating niche partitioning in forest communities. We hypothesized that shade-tolerant species allocate more carbon to defense and storage and less to growth compared to shade-intolerant species. In gaps and forest understory, we measured relative growth rates (RGR), carbon-based defensive compounds (condensed tannin, total phenolics), and storage compounds (total non-structural carbohydrate; TNC) in seedlings of two tree species differing in shade tolerance. RGR was greater in the shade-intolerant species, Castanea crenata, than in the shade-tolerant species, Quercus mongolica var. grosseserrata, in gaps, but did not differ between the species in the forest understory. In contrast, concentrations of condensed tannin and total phenolics were greater in Quercus than in Castanea at both sites. TNC pool sizes did not differ between the species. Condensed tannin concentrations increased with increasing growth rate of structural biomass (GRstr) in Quercus but not in Castanea. TNC pool sizes increased with increasing GRstr in both species, but the rate of increase did not differ between the species. Accordingly, the amount of condensed tannin against TNC pool sizes was usually higher in Quercus than in Castanea. Hence, Quercus preferentially invested more carbon in defense than in storage. Such a large allocation of carbon to defense would be advantageous for a shade-tolerant species, allowing Quercus to persist in the forest understory where damage from herbivores and pathogens is costly. In contrast, the shade-intolerant Castanea preferentially invested more carbon in growth rather than defense (and similar amounts in storage as Quercus), ensuring establishment success in gaps, where severe competition occurs for light among neighboring plants. These contrasting carbon allocation patterns are closely associated with strategies for persistence in these species’ respective habitats.