Foliar C/N stoichiometry in urban forest trees on a global scale

Wei, Hongxu; He, Xingyuan

doi:10.1007/s11676-020-01188-6

Cited by 8 publications

(6 citation statements)

References 58 publications

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“…However, the relationship between foliar N concentrations and distance to an urban core is not well known, because while foliar N concentrations are positively correlated with rates of atmospheric N deposition (McNeil et al, 2007; Roth, 2021), they are negatively correlated with urbanization metrics such as percent impervious surface area (% ISA; Rao et al, 2013). Foliar N concentration and N resorption proficiency (i.e., the extent to which trees retain N following leaf senescence and abscission) are higher and foliar carbon to N ratios (C:N) are lower in urban compared to rural temperate forests when urbanization is defined by distance to a city center (Chen et al, 2010; Wei & He, 2020). Results from fragmented tropical forests in both South Africa (Mutanga et al, 2019) and Madagascar (Crowley et al, 2012) show decreasing foliar N with increasing distance from forest edges, possibly due to reduced soil N availability in the forest interior compared to edge.…”

Section: Introductionmentioning

confidence: 99%

Urbanization and fragmentation have opposing effects on soil nitrogen availability in temperate forest ecosystems

Caron

Garvey

Gewirtzman

et al. 2023

Global Change Biology

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Nitrogen (N) availability relative to plant demand has been declining in recent years in terrestrial ecosystems throughout the world, a phenomenon known as N oligotrophication. The temperate forests of the northeastern U.S. have experienced a particularly steep decline in bioavailable N, which is expected to be exacerbated by climate change. This region has also experienced rapid urban expansion in recent decades that leads to forest fragmentation, and it is unknown whether and how these changes affect N availability and uptake by forest trees. Many studies have examined the impact of either urbanization or forest fragmentation on nitrogen (N) cycling, but none to our knowledge have focused on the combined effects of these co‐occurring environmental changes. We examined the effects of urbanization and fragmentation on oak‐dominated (Quercus spp.) forests along an urban to rural gradient from Boston to central Massachusetts (MA). At eight study sites along the urbanization gradient, plant and soil measurements were made along a 90 m transect from a developed edge to an intact forest interior. Rates of net ammonification, net mineralization, and foliar N concentrations were significantly higher in urban than rural sites, while net nitrification and foliar C:N were not different between urban and rural forests. At urban sites, foliar N and net ammonification and mineralization were higher at forest interiors compared to edges, while net nitrification and foliar C:N were higher at rural forest edges than interiors. These results indicate that urban forests in the northeastern U.S. have greater soil N availability and N uptake by trees compared to rural forests, counteracting the trend for widespread N oligotrophication in temperate forests around the globe. Such increases in available N are diminished at forest edges, however, demonstrating that forest fragmentation has the opposite effect of urbanization on coupled N availability and demand by trees.

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Section: Introductionmentioning

confidence: 99%

Urbanization and fragmentation have opposing effects on soil nitrogen availability in temperate forest ecosystems

Caron

Garvey

Gewirtzman

et al. 2023

Global Change Biology

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“…Anthropogenic activities have caused an increase in atmospheric nitrogen (N) deposition to forest ecosystems under climate change [1][2][3]. Intensive N input has altered the pattern of N cycling in tree populations [4], where sunlight spectra generated a combined influence with N deposition on understory regeneration. Empirical practices suggest a frequent photosynthetic photon flux density (PPFD) that was perceived by tree plants ranging within 60-80 μmol m -2 s -1 [5,6].…”

Section: Introductionmentioning

confidence: 99%

Effects of light spectra and 15N pulses on growth, leaf morphology, physiology, and internal nitrogen cycling in Quercus variabilis Blume seedlings

Gao

Zhang

et al. 2021

PLoS ONE

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Light spectra of sunlight transmittance can generate an interactive effect with deposited nitrogen (N) on regenerated plants across varied shading conditions. Total N content in understory plants can be accounted for by both exogeneous and endogenous sources of derived N, but knowledge about the response of inner N cycling to interactive light and N input effects is unclear. We conducted a bioassay on Chinese cork oak (Quercus variabilis Blume) seedlings subjected to five-month N pulsing with 15NH4Cl (10.39 atom %) at 120 mg 15N plant-1 under the blue (48.5% blue, 33.7% green, and 17.8% red), red (14.6% blue, 71.7% red, 13.7% green), and green (17.4% blue, 26.2% red, 56.4% green) lighting-spectra. Half of the seedlings were fed twice a week using a 250 ppm N solution with micro-nutrients, while the other half just received distilled water. Two factors showed no interaction and neither affected growth and morphology. Compared to the red-light spectrum, that in blue light increased chlorophyll and soluble protein contents and glutamine synthetase (GS) activity, root N concentration, and N derived from the pulses. The green-light spectrum induced more biomass allocation to roots and a higher percentage of N derived from internal reserves compared to the red-light spectrum. The 15N pulses reduced the reliance on N remobilization from acorns but strengthened shoot biomass, chlorophyll content, GS activity, and N concentration. In conclusion, light spectrum imposed an independent force from external N pulse to modify the proportion of N derived from internal sources in total N content in juvenile Q. variabilis.

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“…Therefore, as aforementioned, remote sensing is a cheaper and more spatially oriented alternative in the mapping and monitoring of foliar C : N ratio in plants due to its repetitive acquisition of spectral information at both local and regional scales. A selected number of researchers have demonstrated the capability of optical remote sensing data with machine learning algorithms and the radiative transfer method to detect the C : N ratio in plants (Féret et al, 2021 ; Gao et al, 2020 ; Wei & He, 2020 ; Xu et al, 2018 ). However, remote sensing applications in C : N ratio estimation at a large scale and in heterogenous environments is limited (Gao et al, 2020 ).…”

Section: Remote Sensing Of Foliar Carbon To Nitrogen Ratiomentioning

confidence: 99%

“…For instance, Xiao et al ( 2019 ) reviewed the developments in remote sensing platforms and sensors of the carbon cycle over 50 years (1970 to 2019), while Naicker et al ( 2019 ) did a quantitative review of foliar nitrogen using remote sensing. In a related study, Wei and He ( 2020 ) conducted a global systematic review of the foliar C : N ratio in urban trees. Generally, there has been little research on the adoption of remote sensing techniques in quantifying the foliar C : N ratio, which is important in rangeland management.…”

Section: Introductionmentioning

confidence: 99%

The role of remote sensing in tropical grassland nutrient estimation: a review

Arogoundade

Mutanga

Odindi

et al. 2023

Environ Monit Assess

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The carbon (C) and nitrogen (N) ratio is a key indicator of nutrient utilization and limitations in rangelands. To understand the distribution of herbivores and grazing patterns, information on grass quality and quantity is important. In heterogeneous environments, remote sensing offers a timely, economical, and effective method for assessing foliar biochemical ratios at varying spatial and temporal scales. Hence, this study provides a synopsis of the advancement in remote sensing technology, limitations, and emerging opportunities in mapping the C:N ratio in rangelands. Specifically, the paper focuses on multispectral and hyperspectral sensors and investigates their properties, absorption features, empirical and physical methods, and algorithms in predicting the C:N ratio in grasslands. Literature shows that the determination of the C:N ratio in grasslands is not in line with developments in remote sensing technologies. Thus, the use of advanced and freely available sensors with improved spectral and spatial properties such as Sentinel 2 and Landsat 8/9 with sophisticated algorithms may provide new opportunities to estimate C:N ratio in grasslands at regional scales, especially in developing countries. Spectral bands in the near-infrared, shortwave infrared, red, and red edge were identified to predict the C:N ratio in plants. New indices developed from recent multispectral satellite imagery, for example, Sentinel 2 aided by cutting-edge algorithms, can improve the estimation of foliar biochemical ratios. Therefore, this study recommends that future research should adopt new satellite technologies with recent development in machine learning algorithms for improved mapping of the C:N ratio in grasslands.

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Foliar C/N stoichiometry in urban forest trees on a global scale

Cited by 8 publications

References 58 publications

Urbanization and fragmentation have opposing effects on soil nitrogen availability in temperate forest ecosystems

Urbanization and fragmentation have opposing effects on soil nitrogen availability in temperate forest ecosystems

Effects of light spectra and 15N pulses on growth, leaf morphology, physiology, and internal nitrogen cycling in Quercus variabilis Blume seedlings

The role of remote sensing in tropical grassland nutrient estimation: a review

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