Spatial Variation of Leaf Chlorophyll in Northern Hemisphere Grasslands

Abstract

Chlorophyll is the molecular basis for the function of photosystems and is also a promising tool for ecological prediction. However, the large-scale patterns of chlorophyll variation in grasslands remain poorly understood. We performed consistent measurements of chlorophyll a , b , a + b , and the a : b ratio (chlorophyll a/b ) for 421 species across northern hemisphere grassland transects, recorded their distributions, variations, and influencing factors, and examined their relationships with leaf nitrogen. The results showed that the distributional ranges were 0.52–28.33 (mean 5.49) mg·g −1 dry weight, 0.15–12.11 (mean 1.83) mg·g −1 dry weight, 0.67–39.29 (mean 7.32) mg·g −1 dry weight, and 1.28–7.84 (mean 3.02) for chlorophyll a , b , a + b , and a / b , respectively. The chlorophyll averages differed among regions (higher in the Loess Plateau and the Mongolian Plateau than in the Tibetan Plateau), grassland types (desert grasslands > meadow > typical grasslands), life forms, life spans, and taxonomies. In the entire northern hemisphere grassland, chlorophyll concentrations and chlorophyll a / b were negatively correlated to photosynthetically active radiation and the soil N:P ratio, and positively correlated to the mean annual temperatures. These results implied that chlorophyll in grasslands was shaped by the layered structure of grasses, distinct plateau environments, and phylogeny. The allocation patterns of leaf nitrogen to chlorophyll differed among regions and grassland types, showing that caution is required if simply relating single leaf N or chlorophyll to productivity separately. These findings enhance our understanding of chlorophyll in natural grasslands on a large scale, as well as providing information for ecological predictive models.

Divergent Abiotic Stressors Drive Grassland Community Assembly of Tibet and Mongolia Plateau

“…In contrast, plant height increased at the two extremes of the temperature gradient across the MP because of the U-shaped relationship of summer precipitation with temperature, which resulted in lighter drought stress at the two extremes of the temperature gradient. Given that the temperature on the TP was lower than that on the MP ( Zhang et al, 2020 ), these results suggest that species strategy responses to different stressors depend on the environmental regime ( Muscarella et al, 2016 ; Crous et al, 2018 ). The variance of height and SLA were more strongly related to temperature-related factors on the TP but to water availability on the MP.…”

“…Habitat conditions may directly influence the trait distribution of plant communities ( Schöb et al, 2013 ). Temperature and drought stresses are likely the most important macrofilters for grassland community assembly on the TP and MP, respectively ( Zhang et al, 2020 ). Therefore, the observed shifts in different key features of trait distribution along these abiotic stress gradients can be linked to community assembly processes and how communities respond to climate change ( Enquist et al, 2015 ).…”

“…S pH was determined using a 1:2.5 (v/v) soil water aqueous extract. The S TN and S TP contents have been calculated in a previous study ( Zhang et al, 2020 ).…”

The adjustment of life history strategies drives the ecological adaptations of soil microbiota to aridity

“…A transect from the IMS (112.149°-120.332°E, 43.548°-45.108° N) and one from the QTP (80. 145°-95.455°E, 31.385°-32.484° N) along precipitation and temperature gradients were selected as proxies of aridity gradients with temperate and alpine climates, respectively (Figure S1 in App S1) (Zhang et al, 2020). The altitudes of our sampling sites in the IMS ranged from 660 to 1272 m above sea level and from 4104 to 4938 m in the QTP.…”

Justification and selection of vegetation indices to determine the early soybeans readiness for harvesting

“…One of the main pigments, chlorophyll, absorbs solar radiation to the greatest extent in the spectral ranges of the red and blue channels. While carotenoids, including xanthophylls, absorb small amounts of solar radiation in the blue and green bands and transmit it to the reaction center of photosynthesis [1]. Green vegetation is characterized by high reflection values in the green channel, giving the leaves their characteristic color [2].…”