Plant functional traits play the second fiddle to plant functional types in explaining peatland CO2 and CH4 gas exchange

Characteristics of plant trait network and its influencing factors in impounded lakes and channel rivers of South-to-North Water Transfer Project, China

Trait-based approaches have been widely used to evaluate the effects of variable environments on submerged macrophytes communities. However, little research focused on the response of submerged macrophytes to variable environmental factors in impounded lakes and channel rivers of water transfer project, especially from a whole plant trait network (PTN) perspective. Here, we conducted a field survey designed to clarify the characteristic of PTN topology among impounded lakes and channel rivers of the East Route of South-to-North Water Transfer Project (ERSNWTP) and to unravel the effects of determining factors on the PTN topology structure. Overall, our results showed that leaf-related traits and organ mass allocation traits were the hub traits of PTNs in impounded lakes and channel rivers of the ERSNWTP, which traits with high variability were more likely to be the hub traits. Moreover, PTNs showed different structures among impounded lakes and channel rivers, and PTNs topologies were related to the mean functional variation coefficients of lakes and channel rivers. Specially, higher mean functional variation coefficients represented tight PTN, and lower mean functional variation coefficients indicated loose PTN. The PTN structure was significantly affected by water total phosphorus and dissolved oxygen. Edge density increased, while average path length decreased with increasing total phosphorus. Edge density and average clustering coefficient showed significant decreases with increasing dissolved oxygen, while average path length and modularity exhibited significant increases with increasing dissolved oxygen. This study explores the changing patterns and determinants of trait networks along environmental gradients to improve our understanding of ecological rules regulating trait correlations.

Effects of different soil types on gas exhange parameters and fruits of Hippophae rhamnoides ssp. mongolica "Ulanshalin" plants

Background

This study aims to explore the growth and production potential of Hippophae rhamnoides ssp. mongolica "Ulanshalin," a pioneer species of soil and water conservation, after being planted in the Yellow River Basin area with serious soil erosion. An analysis of the differences in photosynthesis and fruit yield of H. rhamnoides plants grown in two typical soils in the watershed is key to understanding whether local conditions are suitable for the growth and yield of H. rhamnoides, as well as the impact of the plants on soil and water conservation.

Methods

During the growing season, diurnal changes in the gas exchange parameters of Hippophae rhamnoides-like plants growing in Loess soil and Aeolian soil were continuously monitored, and the effects of total nitrogen (TN) and other elements on the net photosynthetic rate (P _N) of the plants were analyzed and compared in the two different soil types. The morphological and quality differences of Hippophae rhamnoides fruits were also compared after reaching the ripening stage.

Results

(1) There was a significant difference in the composition of Loess soil and of Aeolian soil. The organic matter content and AK content of the Loess soil was significantly higher than in the Aeolian soil, and the pH was closer to neutral. However, the TK content, TP content, and AP content of the Aeolian soil were slightly higher than in the Loess soil, the pH was higher, and it was alkaline. (2) After controlling the light and temperature, with all other external factors consistent, the daily variation trend of P _N, T _r, and G _s in the leaves of H. rhamnoides plants growing in the two different soils were basically the same. There were differences, however, in when these factors reached their peaks. Soil composition had an impact on the photosynthetic characteristics of H. rhamnoides, with TN, TP, AP, and SOM being the main factors promoting the photosynthetic rate of H. rhamnoides P _N. The peaks of P _N, T _r, and G _s of H. rhamnoides plants growing in Aeolian soil were higher than those growing in Loess soil. (3) The average stem length of H. rhamnoides plants growing in Aeolian soil was higher than the plants growing in Loess soil. The number of thorns in the branches of plants in the Aeolian soil was relatively low, and the weight of 100 fruits (28.28 g) was significantly higher than the weight of 100 fruits of the H. rhamnoides plants grown in Loess soil (11.14 g).

Conclusions

The results of this study show that in the Yellow River Basin area, Aeolian soil is more conducive to the growth of H. rhamnoides plants than Loess soil. H. rhamnoides plants growing in Aeolian soil had good adaptability and stress resistance, and a larger potential for fruit production. These findings provide insights for ecological restoration and the creation of economic value in the Yellow River Basin area.