Leaf functional traits differentiation in relation to covering materials of urban tree pits

Role of soil nutrient elements transport on Camellia oleifera yield under different soil types

BACKGROUND

Most of Camellia oleifera forests have low fruit yield and poor oil quality that are largely associated with soil fertility. Soil physical and chemical properties interact with each other affecting soil fertility and C. oleifera growing under different soil conditions produced different yield and oil composition. Three main soil types were studied, and redundancy, correlation, and double-screening stepwise regression analysis were used for exploring the relationships between C. oleifera nutrients uptake and soil physical and chemical properties, shedding light on the transport law of nutrient elements from root, leaves, and kernel, and affecting the regulation of fruit yield and oil composition.

RESULTS

In the present study, available soil elements content of C. oleifera forest were mainly regulated by water content, pH value, and total N, P and Fe contents. Seven elements (N, P, K, Mg, Cu, Mn and C) were key for kernel's growth and development, with N, P, K, Cu and Mn contents determining 74.0% the yield traits. The transport characteristics of these nutrients from root, leaves to the kernel had synergistic and antagonistic effects. Increasing oil production and unsaturated fatty acid content can be accomplished in two ways: one through increasing N, P, Mg, and Zn contents of leaves by applying corresponding N, P, Mg, Zn foliar fertilizers, while the other through maintaining proper soil moisture content by applying Zn fertilizer in the surface layer and Mg and Ca fertilizer in deep gully.

CONCLUSION

Soil type controlled nutrient absorption by soil pH, water content and total N, P and Fe content. There were synergistic and antagonistic effects on the inter-organ transport of nutrient elements, ultimately affecting N, P, K, Cu and Mn contents in kernel, which determined the yield and oil composition of C. oleifera.

Coordination of leaf hydraulic and economic traits in Cinnamomum camphora under impervious pavement

BACKGROUND

Paved urban environments can pose great threats to the physiological functioning and ecological services of street trees. In this context, assessment of leaf phenotypic plasticity is crucial for understanding the ecological strategy of tree species under impervious pavements.

RESULTS

In this study, we measured a set of leaf economic traits, hydraulic traits of Cinnamomum camphora, and surrounding environmental factors in a street site (the soil was covered by the impervious pavement) and a park site (the soil was covered by grass) in Hefei, eastern China. Compared with the park site, trees in the street site had higher stomatal length (SL), leaf thickness (LT), maximum photochemical quantum yield of photosystem II (Y(II)), and lower stomatal density (SD), specific leaf area (SLA), the leaf water potential at 50% loss of hydraulic conductance (P₅₀), and leaf turgor loss point (TLP). Redundancy analysis showed that air relative humidity and volumetric soil water content caused these traits to be altered.

CONCLUSIONS

Our results showed that C. camphora adapted to the street pavement environment through the coordination of leaf economic and leaf hydraulic traits, and adopted the slow investment return type in the leaf economic spectrum and high drought resistance to meet its actual physiological needs. This finding provides a new perspective for understanding the physiological strategies of street trees to adapt to urban pavement environments.

Response of Leaf Functional Traits of Landscape Plants to Urban Green Space Environment in Lanzhou, China

Leaf functional traits are the essential components of adaption plant strategies and have different responses to various environments, but our knowledge of how plants adapt to highly complex urban environments through coordinated changes in leaf functional traits is limited. In this study, we studied the response of landscape plants to the environments of sports field (SF), park (PAR), residential green space (RES), and greenway (GW), and analyzed the effects of the different green space environments on trade-off strategies of plants based on leaf functional traits. The results showed that leaf functional traits of plants and adaptation strategies varied among different urban environments in Lanzhou, China. Leaf length (LL), width (LW), area (LA), and special leaf area (SLA) were PAR > SF > RES > GW. Leaf nitrogen (LNC) and phosphorus content (LPC) were SF > PAR > RES > GW. Leaf carbon content (LCC), leaf dry matter content (LDMC), the ratio of leaf carbon and nitrogen (C/N), and the ratio of leaf carbon and phosphorus (C/P) was GW > RES > PAR > SF. The landscape plants in SF and PAR were more adaptive to the urban environment than those in RES and GW. Among different green space environments, landscape plants in SF and PAR tended to have an acquisitive strategy with high LL, LW, LA, SLA, LNC, and LPC. In contrast, plants in RES and GW tended to have a conservative strategy with a high level of concentration of LCC, LDMC, C/N, and C/P.