Assessing the Significance of Microgram (mcg) Balance Accuracy for Leaf Functional Trait Measurements

Functional leaf traits and leaf economics in the Paleogene — A case study for Central Europe

自2007年三峡大坝试运行以来,其独特的人工水位调度节律给当地的水库消落带生态系统带来了巨大的负面影响。植物功能性状可以反映某一特殊生境植物的生理生态过程特殊性,是指示生态系统结构与功能的有效指标。因此,在三峡水库消落带形成2a后,于2009年调查了消落带的42种适生植物以及对照带33种植物的6个叶片功能性状:最大净光合速率(<em>A</em>_max)、叶片气孔导度(<em>Gs</em>)、比叶重(LMA)、叶片全氮含量(N_mass)、全磷含量(P_mass)和全钾含量(K_mass)。运用标准化主轴回归分析对消落带植物叶片各功能性状之间关系进行分析,并对照全球尺度叶片功能性状数据库,旨在说明反季节淹水对消落带植物叶片功能性状之间关系与全球尺度对比发生了哪些变化。同时,运用成对方差<em>t</em>检验的分析方法,对比了在消落带和对照带都存在的33个种的叶片光合与营养性状之间的差异,以阐明消落带植物对消落带特殊生境的生理响应。结果表明:(1)消落带植物叶片各性状关系呈现出与全球尺度基本一致的格局,表现出植物叶性状之间关系的趋同性;(2)消落带植物<em>A</em>_mass、N_mass、P_mass和K_mass显著高于全球尺度,而LMA则显著低于全球尺度。处于驯化阶段的消落带植物各叶片性状处在全球叶片经济型谱"低投入-快速回收"的一端。(3)消落带植物叶片<em>A</em>_mass与对照带相比,有显著提高。表明三峡水库消落带植物叶片光合能力得到显著提高,这可能是其适应消落带特殊生境的关键生理生态对策之一。;Since 2007, the unique anthropogenic hydrological regime of the Three Gorges Dam has had significant negative impacts on the reservoir riparian ecosystem. These include changes in the local climate pattern, habitat fragmentation, generation of methane gas, loss of biodiversity, and inundation of cities and highly productive agricultural land. The functional traits of plants in a particular area can reflect the eco-physiological processes that are specific to that environment, and can serve as crucial indicators of the structure and function of the local ecosystem. These functional traits play a key role in adaptation to anti-seasonal flooding, and might reveal clues about the adaptation mechanisms of plants in this area. Therefore, two years after the formation of the reservoir riparian region in the Three Gorges Area, we investigated six leaf functional traits of 42 species growing in the the reservoir riparian region in 2009. As a reference, we also investigated these functional traits in 33 species in an upland non-flooding belt, to determine variations in physiological processes associated with anti-seasonal flooding. The six leaf functional traits were leaf mass per area (LMA), maximum net photosynthesis rate (<em>A</em>_max), leaf stomata conductance (<em>Gs</em>), leaf nitrogen content per mass (N_mass), leaf phosphorus content per mass (P_mass) and leaf potassium content per mass (K_mass). A standardized major axis analysis method was used to determine the relationships among these traits. We compared these results with data in the global plant trait network to determine how the leaf traits relationships for plants in the the reservoir riparian region compare with those in the worldwide leaf spectrum. For species that coexist in the reservoir riparian region and non-flooding belt, we used paired-sample T-tests to compare differences in leaf functional traits between the two areas, to determine which physiological processes are important for growth in the the reservoir riparian region environment. The results showed that: 1) although there were slight differences in the standardized major axis slopes/elevation of some paired traits, there were similar patterns of leaf functional trait relationships between the reservoir riparian region and the global plant trait network, indicating convergence of leaf traits in the the reservoir riparian region ecosystem. 2) <em>A</em>_mass, N_mass, P_mass, and K_mass of the reservoir riparian region species were significantly higher than their corresponding values in the global plant trait network, but the LMAs of the reservoir riparian region species were statistically lower than LMA values in the global plant trait network. The traits of the reservoir riparian region species were constrained to the lower-investment and faster-return end of the global leaf spectrum, and were consistent with typical fast-growing species. 3) When the 33 species common to both the reservoir riparian region and non-flooding belt were compared, we found that those in the the reservoir riparian region showed significantly higher <em>A</em>_max. The results of the present study suggest that enhanced photosynthetic capacity is one of the key physiological strategies for growth in the the reservoir riparian region environment. However, there are many uncertainties that remain after this study, because the the reservoir riparian region area is only two years old and plants are likely to be in the response or acclimation stages rather than the adaptation stage. Therefore, long-term investigations and observations should be continued in this area to identify and monitor adaptive changes in plant species.

Understanding variation in key functional traits across gradients in high diversity systems and the ecology of community changes along gradients in these systems is crucial in light of conservation and climate change. We examined inter‐ and intraspecific variation in leaf mass per area (LMA) of sun and shade leaves along a 3330‐m elevation gradient in Peru, and in sun leaves across a forest–savanna vegetation gradient in Brazil. We also compared LMA variance ratios (T‐statistics metrics) to null models to explore internal (i.e., abiotic) and environmental filtering on community structure along the gradients. Community‐weighted LMA increased with decreasing forest cover in Brazil, likely due to increased light availability and water stress, and increased with elevation in Peru, consistent with the leaf economic spectrum strategy expected in colder, less productive environments. A very high species turnover was observed along both environmental gradients, and consequently, the first source of variation in LMA was species turnover. Variation in LMA at the genus or family levels was greater in Peru than in Brazil. Using dominant trees to examine possible filters on community assembly, we found that in Brazil, internal filtering was strongest in the forest, while environmental filtering was observed in the dry savanna. In Peru, internal filtering was observed along 80% of the gradient, perhaps due to variation in taxa or interspecific competition. Environmental filtering was observed at cloud zone edges and in lowlands, possibly due to water and nutrient availability, respectively. These results related to variation in LMA indicate that biodiversity in species rich tropical assemblages may be structured by differential niche‐based processes. In the future, specific mechanisms generating these patterns of variation in leaf functional traits across tropical environmental gradients should be explored.

PDF HTML阅读 XML下载 导出引用 引用提醒 柯-青冈常绿阔叶林优势树种叶片性状变异及适应策略 DOI: 10.5846/stxb202103100659 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 湖南省教育厅重点项目（17A227）；国家自然科学基金青年科学基金项目（31901136） Variation in leaf functional traits and adaptation strategies of dominant tree species in a Lithocarpus glaber-Cyclobalanopsis glauca evergreen broad-leaved forest Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:厘清叶片功能性状的变异及性状间的权衡关系，对揭示植物对环境变化的响应及适应策略具有重要意义。以中亚热带柯(Lithocarpus glaber)-青冈(Cyclobalanopsis glauca)常绿阔叶林为对象，测量了1 hm2固定监测样地内6个优势树种的叶面积(LA)、比叶面积(SLA)、干物质含量(LDMC)、叶片厚度(LT)、叶片碳(LC)、叶片氮(LN)、叶片磷(LP)含量和叶片碳氮比(LC ∶ LN)8个功能性状，采用多重比较、主成分分析(PCA)法分析了群落叶片功能性状的生活型、种内和种间变异及性状间关系。结果表明：(1)群落内叶片功能性状种内、种间差异显著，变异中等(CV： 0.02-0.59)，其结构性状的可塑性较化学性状保守，变异格局符合"性状空间变异分割假说"；针叶树种的LA、SLA显著低于阔叶树种，常绿树种的LC和LDMC最小，而落叶树种的SLA、LN和LP最大以及LT和LC ∶ LN最小。(2)群落叶片功能性状变异主要来源于生活型和种间变异，种内变异亦有显著贡献；生活型对多数性状的贡献率较大，其对LDMC、LC ∶ LN的贡献分别高达93.11%和91.76%；种间变异(LDMC除外)对结构性状的贡献率均高于化学性状；种内变异对LP的贡献率(23.66%)较种间变异高。(3)叶片性状之间多表现出显著相关关系，针叶树和阔叶树在PCA排序图中聚集于不同区域，叶经济型谱在柯-青冈群落中具有适用性。不同树种通过叶片结构、化学性状之间的权衡策略来适应环境变化，从而实现群落物种共存。结果可为理解森林群落物种的环境适应策略、预测群落动态变化和制定植被恢复措施提供科学依据。 Abstract:Elucidating the variation in leaf functional traits and the trade-off relationships among those traits are of great significances to reveal the response mechanism's and adaptation strategies of plants towards changing environment. The variation of plant functional traits organically links the species adaptation strategy with the ecosystem functions and processes, and the ranges including interspecific and intraspecific variations vary with species and are closely related to environmental gradients. Meanwhile, the leaf economics spectrum (LES) at the global scale can reflects the trade-off relationships between the main structural, chemical and physiological traits. However, local community puts environmental factors and functional traits in the same system, and the main reasons responsible for the variation in functional traits and the applicability of LES still need to be deeply investigated. In this study, we collected 8 leaf functional traits of 6 dominant tree species in a 1 ha permanent monitoring plot of a Lithocarpus glaber-Cyclobalanopsis glauca subtropical evergreen broad-leaved forest, and the studied traits included leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (LT), leaf carbon (LC), leaf nitrogen (LN), leaf phosphorus (LP) content and carbon-nitrogen ratio (LC :LN). We used multiple comparison and principal component analysis (PCA) to explore the variation in leaf functional traits at the interspecific, intraspecific and life form levels, and to analyze the relationship among those functional traits. The results showed that:(1) Leaf functional traits were significantly different at the intraspecific and interspecific levels in this community. There was a moderate variation with a coefficient variation (CV) ranging from 0.02 to 0.59, and the structural traits were more conservative than chemical traits. The variation pattern of leaf functional traits conformed to "a spatial trait variance partitioning hypothesis". Leaf functional traits significantly differed among life forms, with lower SLA and LA for coniferous tree species compared to those for broad-leaved tree species, lowest LC and LDMC for evergreen trees, yet the deciduous tree species exhibited the highest SLA, LN and LP along with the lowest LT and LC :LN. (2) Life form and interspecific differences contributed the most to the variation in leaf functional traits, and intraspecific differences also contribute significantly to those variations with lower contribution rate. Life forms had relative higher contribution to the variation in most functional traits with the contribution rate reaching 93.11% and 91.76% for LDMC and LC:LN, respectively. The contribution rate of interspecific variation (except LDMC) to structural traits was higher than that to chemical traits. Intraspecific variation had a higher contribution rate to LP (23.66%) than interspecific variation. (3) There was a significant correlation between leaf functional traits. Conifers and broad-leaved trees clustered in different areas of PCA ordination chart. The leaf economics spectrum was applicable in the subtropical evergreen broad-leaved forest, and diverse tree species could coexist in this community by the trade-off strategies among leaf structural and chemical traits. The results could provide a scientific basis for understanding the adaptation strategies of diverse tree species to environment, predicting the dynamic changes of community and formulating vegetation restoration strategy. 参考文献 相似文献 引证文献

Variations and driving factors of leaf functional traits in the dominant desert plant species along an environmental gradient in the drylands of China

Monitoring is essential to restoration, but the standard metrics used to monitor wetland restoration do not explicitly account for function in plant communities. Functional traits may be a useful addition to the wetland monitoring toolkit, because they can represent aspects of ecosystem functioning that standard metrics may not. Our objective was to determine how abiotic factors that influence wetland community composition and structure relate to both functional leaf traits and standard vegetation monitoring metrics to determine if functional leaf traits could add a functional component to wetland monitoring. We surveyed 66 100-m2 plots in 22 floodplain wetlands in Illinois that were restored between 1997 and 2010. We used plant species data to calculate the mean coefficient of conservatism (mean C) and richness, and collected leaves to determine community weighted means of specific leaf area (SLA) and leaf dry matter content (LDMC) at each plot. Hydrologic data were used to calculate variables related to frequency, depth, and duration of inundation, and soil samples were collected to determine soil pH, organic matter content, and nitrogen and phosphorous content at each plot. We used structural equation models to understand how predictor variables (hydrological variables, soil variables, canopy cover, time since restoration, and latitude) influenced each other, and ultimately how they influenced response variables (mean C, richness, percent non-native species cover, SLA, and LDMC). LDMC and SLA were poorly explained by predictor variables and had relatively few significant relationships within models. Predictor variables best explained variance in mean C, followed by percent non-native cover, richness, then LDMC and SLA. Mean C was positively influenced by canopy cover and negatively influenced by soil fertility, whereas richness was negatively influenced by latitude. There was a strong latitudinal gradient of species richness from north to south, such that southern plots were significantly more diverse and had less cover by non-native species than northern plots. Our research suggests that SLA and LDMC may not be well suited for use as wetland restoration monitoring tools in Midwestern floodplain wetlands, and that monitoring tools already in place may sufficiently reflect abiotic conditions.

Plants use physical barriers and chemical compounds to defend themselves against natural enemies. For instance, tough leaves are considered to be better defended than soft leaves, part of a spectrum of defences defined by functional traits such as leaf chemistry, lifespan, toughness and leaf mass per area (LMA). Plants with longer lifespans, which invest more in leaf tissue and higher LMA, typically feature robust constitutive defences (e.g. toughness, thickness and dense cell walls). In contrast, plants with lower LMA and more leaf nutrients often invest more in induced defences. Leaf traits represent an environmental filter for foliar endophytic fungi (FEF), which may play an additional role in plant defence. Our overarching assumption is that FEF alter leaf fate by interacting directly or indirectly with leaf traits, thus shaping successive FEF colonization, development of leaf traits and response to plant enemies. To evaluate this hypothesis, we inoculated seedlings of seven tropical tree species, which varied in leaf traits, with natural and diverse endophyte communities. We characterized leaves by low FEF load (E‐low) and high FEF load (E‐high) based on culturing and culture‐free amplicon sequencing. We measured leaf removal by leaf‐cutter ants and leaf necrosis due to a generalist fungal pathogen. Across the experiment, we observed greater leaf removal from the E‐low treatment compared to the E‐high treatment, but no difference in pathogen damage. Dimensionality reduction of leaf functional traits (i.e. LMA, toughness, thickness and anthocyanin levels) revealed relationships among traits and distinct host species characteristics. All leaf functional traits had significant correlations with FEF community composition. In turn, indicator species analyses revealed functional traits and taxonomic identities of FEF associated with high and low leaf damage by natural enemies. Our findings highlight the complex dynamics of plant‐herbivore‐pathogen relationships and underscore the importance of endophytes as a potentially low‐cost, preemptive defence strategy for plants, especially during early growth stages. These insights shed light on the nuanced role of endophytes in plant ecology. Further, they open avenues for future research, particularly in exploring strategic resource allocation in plants and the specific contributions of endophytes to plant resilience. Read the free Plain Language Summary for this article on the Journal blog.

PDF HTML阅读 XML下载 导出引用 引用提醒 杉木叶片、细根功能性状对毛竹扩张及伐除的响应 DOI: 10.5846/stxb202108262394 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31770680,32171786);浙江省自然科学基金项目(LY14C160010);暨阳"533英才计划"项目 Responses of leaf and fine root functional traits of Cunninghamia lanceolata to Phyllostachys edulis expansion and removal Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:功能性状能够反映植物对不同环境的适应策略。毛竹扩张与外来植物入侵相似,常引起原有植物生存环境的改变,而原有植物功能性状对毛竹扩张及伐除的响应机制尚不清楚。选取毛竹-杉木混交林和去竹杉木林为研究对象,以杉木纯林为对照,比较分析杉木比叶面积、叶干物质含量、叶组织密度等叶功能性状以及比根长、细根生物量、细根根长密度等细根功能性状的变化以及其间的相关关系。结果表明:(1)与杉木纯林相比,混交林中杉木的叶相对含水量以及叶干物质含量分别减少了5.07%、0.032 g/g,叶组织密度以及比叶面积分别增加了0.005 g/cm3、10.33 cm2/g;而去竹杉木林中,杉木比叶面积、叶相对含水量减少,叶干物质含量和叶组织密度则呈上升趋势。(2)与杉木纯林相比,混交林中杉木细根生物量、细根体积密度以及细根根长密度都不断下降,而杉木细根比根长在0-20 cm土深处显著增加(P<0.05);而去竹杉木林中杉木细根比根长、细根根长密度和细根生物量则显著降低(P<0.05),细根体积密度在20-30 cm土深处有所增加。(3)杉木纯林中杉木细根功能性状间相关性较为紧密,混交林及去竹杉木林中杉木叶片功能性状间相关性较高。研究表明,杉木可通过比叶面积、叶组织密度以及细根比根长等功能性状的调整及性状关联,以适应毛竹扩张或去除毛竹后引起的空间、资源竞争的变化。研究结果有利于更好地理解杉木叶片、细根对不同生境的响应特征及生态适应策略,可为毛竹林合理经营与扩张调控提供科学依据。 Abstract:Functional traits can reflect the adaptation strategies of plants to different environments. The expansion of Phyllostachys edulis is similar to the invasion of alien plants, which often causes changes in the living environment of native plants. However, the response mechanism of the functional traits of native plant functional traits to the expansion and removal of Phyllostachys edulis is still unclear. The mixed forest of moso bamboo and Chinese fir and Chinese fir forest after bamboo removal were selected as the research objects, and the pure Chinese fir forest was used as the control. The changes of leaf functional traits, such as specific leaf area, dry matter content and tissue density, as well as fine root functional traits, like specific root length, fine root biomass and fine root length density, and their correlation were measured and analyzed. The results show that: (1) Compared with the pure Chinese fir forest, the leaf relative water content and leaf dry matter content of Chinese fir in mixed forest decreased by 5.07% and 0.032 g/g respectively. However, the leaf tissue density and specific leaf area in mixed forest increased by 0.005 g/cm3 and 10.33 cm2/g respectively. Compared with the pure Chinese fir forest, the specific leaf area and leaf relative water content of Chinese fir forest after bamboo removal decreased, while the leaf dry matter content and leaf tissue density increased. (2) Compared with the pure Chinese fir forest, the fine root biomass, fine root volume density and fine root length density of Cunninghamia lanceolata decreased continuously in mixed forest, but the ratio of fine root to root length increased significantly in 0-20 cm soil depth (P<0.05). Compared with the pure Chinese fir forest, fine root length, fine root length density and fine root biomass decreased significantly in Chinese fir forest after bamboo removal (P<0.05), while fine root volume density increased in soil depth of 20-30 cm. (3) The correlation between fine root functional traits of Cunninghamia lanceolata in pure forest was close, and the correlation between leaf functional traits in Chinese fir forest after bamboo removal and mixed forest was high. These results suggest that Cunninghamia lanceolata can adapt to the changes of space and resource competition caused by bamboo expansion or removal by adjusting and correlating the functional traits such as specific leaf area, leaf tissue density and fine root to root length. The results will help to better understand the response characteristics of leaves and fine roots of Cunninghamia lanceolata to different habitats and ecological adaptation strategies, and provide scientific basis for rational management and expansion regulation of bamboo forest. 参考文献 相似文献 引证文献

Dramatic altitudinal variations in leaf mass per area of two plant growth forms at extreme heights

PDF HTML阅读 XML下载 导出引用 引用提醒 气孔特征与叶片功能性状之间关联性沿海拔梯度的变化规律——以长白山为例 DOI: 10.5846/stxb201411042162 作者: 作者单位: 中国科学院地理科学与资源研究所,中国科学院地理科学与资源研究所,中国科学院地理科学与资源研究所,中国科学院地理科学与资源研究所,中国科学院地理科学与资源研究所,中国科学院地理科学与资源研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重大项目(31290221); 中国科学院地理科学与资源研究所可桢杰出青年学者计划(2013RC102) Altitudinal variation in the covariation of stomatal traits with leaf functional traits in Changbai Mountain Author: Affiliation: Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences,,Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:气孔是陆生植物与外界环境进行水分和气体交换的主要通道,控制着植物的光合作用和蒸腾过程。植物往往通过多种性状的组合来适应变化的环境,叶片功能性状之间的紧密关系已经在不同尺度得到证实。然而,植物气孔特征与叶片其它功能性状是否存在关联性以及这种关联性是否会受到环境变化梯度的影响仍鲜少报道。沿长白山北坡6个海拔梯度,测定了150种植物的气孔特征和叶片功能性状。结果发现,气孔密度(SD)与比叶面积(SLA)负相关,与单位面积的叶氮含量(Narea)正相关;除了SLA和Narea外,气孔长度(SL)与SLA、叶片厚度(LT)和单位质量的叶氮含量(Nmass)均存在显著的相关性(P < 0.05)。然而,气孔特征与叶片功能性状的相关性只在部分海拔梯度存在。此外,发现SD与SL之间存在稳定一致的负相关关系。这些结果表明,植物气孔特征与叶片形态和化学特征对环境变化的适应存在一定的协同变异性,但这种关系不具有普适性,主要与气孔特征和叶片功能性状的选择压力存在差异以及物种分布范围相关。未来仍需要在更多物种和不同区域内来验证气孔特征与植物功能性状之间的关联关系。 Abstract:Stomata, small pores on the surfaces of plant leaves and stalks, act as turgor-operated valves to control gas (e.g. water vapor and carbon dioxide) exchange between plant tissues and the atmosphere. Stomata therefore play a major role in the regulation of water and carbon cycling. Generally, plants adapt to changing environments through the combination of multiple traits. The strong relationships between leaf morphological, chemical, and physiological traits have been documented within and across plant species, biomes, and even globally. Despite the importance of leaf stomata, little is known about interspecific covariation in stomatal traits and their relations with other leaf functional traits on a large scale, partly due to a lack of data on leaf stomata in most studies. In the present study, we measured stomatal and leaf functional traits, including stomatal density (SD), stomatal length (SL), specific leaf area (SLA), leaf area (LA), leaf thickness (LT), and nitrogen content (mass- and area-based, Nmass and Narea) of 150 plant species along an altitudinal gradient (540-2357 m) in Changbai Mountain, China. Our results showed that, for all species, the average values of SD and SL were 155.91 stomata/mm2 and 34.51 μm, respectively; the average values of SLA, LA, and LT were 33.58 m2/kg, 3291.30 mm2, and 0.14 mm, respectively; the mean values of Nmass and Narea were 24.48 g/kg and 1.07 g/m2. There were significant relationships between stomatal traits and other leaf functional traits (P < 0.05). Specifically, SD was negatively correlated with SLA, and positively correlated with Narea (P < 0.05); SL was negatively correlated with LA and Nmass, and positively correlated with LT (all P < 0.05). Additionally, SL was negatively correlated with SD (P < 0.05). Standardized major axis (SMA) analysis showed that these significant relationships between stomatal traits and morphological and chemical traits of leaves differed among different altitudes. However, the strong relationship between SD and SL was observed at all altitudes. Furthermore, although no significant difference (P > 0.05) was found among these slopes of SD-SL relationships, the y-intercepts differed significantly (P < 0.05), in which the maximum occurred at 1286 m, and the minimum at 2357 m, indicating plants with larger stomata (higher SL) at any given SD occurred at 1286 m than those with smaller stomata (lower SL) at 2357 m. These findings suggest that there is a covariation between stomatal traits and leaf morphological and chemical traits. However, this may not be universal for all plants due to different stress responses between stomata and other leaf structures. Moreover, the narrow taxonomic range at each altitude may also restrict the expression of bivariate relationships. Future research needs to verify the relationships between stomatal traits and plant functional traits in more plant species from different areas. Finally, our findings highlight the trade-off between SD and SL, which regulates the short-term (plastic) and long-term (evolutionary) strategies in plant adaptation to the external environment. These data provide a basis for revealing adaptation strategies in plants, and help us predict their responses to future climate changes. 参考文献 相似文献 引证文献

The concept of functional diversity is critical in the field of forest ecology as it helps determine trends in community structure and worldwide change by examining variations in functional traits among plants. Functional traits like leaf traits, stem traits, root traits etc., are characteristics of a species that incorporate its ecological and evolutionary history and can be used to predict both its response and impact on ecosystem function. During the present study, six functional leaf traits viz., leaf size (LS), specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC), leaf phosphorus content (LPC), and leaf nitrogen to phosphorus ratio (N:P) were evaluated for a variety of trees and shrubs in the forests of semi-arid regions of Haryana, India i.e., Site I-Dulana (Mahendergarh), Site II-Kheri Batter (Charkhi Dadri) and Site III-Asalwas Dubia (Bhiwani). Functional leaf trait values showed a significant variation. LS was reported to be positively correlated with SLA(0.39) and N:P(0.11) while negatively correlated with LDMC(-0.26) LNC(-0.29) and LPC(-0.16). The selected plant species displayed a negative but weak correlation between SLA and LNC(-0.05) whilst a strong positive correlation between Nitrogen (N) and Phosphorus (P)(0.36). All three Sites had the value of N:P ranging from 12.58 to 65.69, thus exhibiting P limitation. The present study advances the field of functional ecology in Haryana's tropical dry forests significantly. This is also crucial to forecast community formation trends and characterize the contributions of different species to ecological processes.

Rapid nondestructive measurements at leaf level of nitrogen concentration (%N) and leaf mass per area (LMA) are needed to improve crop simulation model development and calibration, and better understanding of in‐season N management. Many contact reflectance‐based techniques for %N and LMA estimations require calibration across species, cultivars, growing stages, and cultural practices. Narrowband (hyperspectral) reflectance spectroscopy, in combination with partial least square regression (PLSR) models, offers improved performance over vegetation indices derived from standard linear regression analysis with simple ratios or combined formulas. Little research on the application of contact spectroscopy data and PLSR techniques has been conducted for sweet corn (Zea mays L.) and snap bean (Phaseolus vulgaris L.). In this study, we sought to determine the optimum wavelength ranges for %N and LMA estimations and to develop and evaluate spectroscopic models in estimating %N and LMA in the two species. Best PLSR predictions utilized 1500 to 2400 nm for %N estimations and 450 to 2400 nm for LMA estimations in both species, with high averaged coefficient of determination (R2) values (0.90–0.95 for cross‐validation, 0.52–0.71 for external validation) and low root mean square error (RMSE, reported as percentage of sample data range) (4.59–5.67% for cross‐validation, 9.50–18.46% for external validation). The results indicate that narrowband reflectance spectroscopy (450–2500 nm) combined with PLSR analysis is a promising method for rapid and nondestructive estimates of %N and LMA at leaf level in sweet corn and snap bean across growth stages, N management, and years.Core Ideas Spectroscopy combined with partial least square regression models is useful for estimates of leaf nitrogen concentration and leaf mass per area. The optimum spectra for nitrogen concentration and leaf mass per area estimations were 1500 to 2400 and 450 to 2400 nm. Spectroscopy appears appropriate for routine agronomic research field experiments.

AimCharacterizing the variation of functional traits in nature is a first step towards linking environmental changes to changes in ecosystem function. Here we aim to characterize the spatial variability of major plant functional traits along wide environmental gradients in Mediterranean and temperate forests, and assess to what extent this variability differs between two dominant families in Northern Hemisphere forests: Fagaceae and Pinaceae.LocationCatalonia (north‐east Iberian Peninsula).MethodsFour functional traits were selected to incorporate information on both the leaf and the wood economic spectra: maximum tree height (Hmax), wood density (WD), leaf mass per area (LMA) and nitrogen content of leaves (Nmass). We quantified the variance distribution of each functional trait across three nested ecological scales: population, species and family. Through such scales, we explored the spatial variation of functional traits through climatic and biotic gradients, as well as the covariation among traits.ResultsFunctional trait variability was distributed across all the ecological scales considered, but mostly at the family level, with functional traits differing markedly between Fagaceae and Pinaceae. Within families, variation in functional traits was similar or higher within species than between species. The spatial variability in functional traits was related to biotic and abiotic gradients, although this effect was quantitatively small compared with differences between families. Covariation among functional traits was not necessarily conserved across ecological scales. Trait covariation across all species was structured along the Hmax−WD and LMA−Nmass axes, but this structure was partially lost within families, where variation was mostly structured along the Hmax−LMA and WD−Nmass axes.Main conclusionsIntraspecific variation emerges as a fundamental component of functional trait structure along wide environmental gradients. Understanding the sources of intraspecific variation, as well as how it contributes to community assembly and ecosystem functioning, thus becomes a primary research question.

Key leaf functional traits, such as chlorophyll and carotenoids content (Cab and Cxc), equivalent water thickness (EWT), and leaf mass per area (LMA), are essential to the characterization and monitoring of ecosystem function. Spectroscopy provides access to these four leaf traits by relying on their specific spectral absorptions over the 0.4–2.5 µm domain. In this study, we compare the performance of three categories of estimation methods to retrieve these four leaf traits from laboratory directional-hemispherical leaf reflectance and transmittance measurements: statistical, physical, and hybrid methods. To this aim, a dataset pooling samples from 114 deciduous and evergreen oak trees was collected on four sites in California (woodland savannas and mixed forests) over three seasons (spring, summer and fall) and was used to assess the performance of each method. Physical and hybrid methods were based on the PROSPECT leaf radiative transfer model. Physical methods included inversion of PROSPECT from iterative algorithms and look-up table (LUT)-based inversion. For LUT-based methods, two distance functions and two sampling schemes were tested. For statistical and hybrid methods, four distinct machine learning regression algorithms were compared: ridge, partial least squares regression (PLSR), Gaussian process regression (GPR), and random forest regression (RFR). In addition, we evaluated the transferability of statistical methods using an independent dataset (ANGERS Leaf optical properties database) to train the regression algorithms. Thus, a total of 17 estimations were compared. Firstly, we studied the PROSPECT leaf structural parameter N retrieved by iterative inversions and its distribution over our oak-specific dataset. N showed a more pronounced seasonal dependency for the deciduous species than for the evergreen species. For the four traits, the statistical methods trained on our dataset outperformed the PROSPECT-based methods. More particularly, statistical methods using GPR yielded the most accurate estimates (RMSE = 5.0 µg·cm−2; 1.3 µg·cm−2; 0.0009 cm; and 0.0009 g·cm−2 for Cab, Cxc, EWT, and LMA, respectively). Among the PROSPECT-based methods, the iterative inversion of this model led to the most accurate results for Cab, Cxc, and EWT (RMSE = 7.8 µg·cm−2; 2.0 µg·cm−2; and 0.0035 cm, respectively), while for LMA, a hybrid method with RFR (RMSE = 0.0030 g·cm−2) was the most accurate. These results showed that estimation accuracy is independent of the season. Considering the transferability of statistical methods, for the four leaf traits, estimation performance was inferior for estimators built on the ANGERS database compared to estimators built exclusively on our dataset. However, for EWT and LMA, we demonstrated that these types of statistical methods lead to better estimation accuracy than PROSPECT-based methods (RMSE = 0.0016 cm and 0.0013 g·cm−2 respectively). Finally, our results showed that more differences were observed between plant functional types than between species or seasons.

Diachronic adjustments of functional traits scaling relationships to track environmental changes: revisiting Cistus species leaf cohort classification