Irrigated urban trees exhibit greater functional trait plasticity compared to natural stands

Urbanization creates novel ecosystems comprised of species assemblages and environments with no natural analogue. Moreover, irrigation can alter plant function compared to non-irrigated systems. However, the capacity of irrigation to alter functional trait patterns across multiple species is unknown but may be important for the dynamics of urban ecosystems. We evaluated the hypothesis that urban irrigation influences plasticity in functional traits by measuring carbon-gain and water-use traits of 30 tree species planted in Southern California, USA spanning a coastal-to-desert gradient. Tree species respond to irrigation through increasing the carbon-gain trait relationship of leaf nitrogen per specific leaf area compared to their native habitat. Moreover, most species shift to a water-use strategy of greater water loss through stomata when planted in irrigated desert-like environments compared to coastal environments, implying that irrigated species capitalize on increased water availability to cool their leaves in extreme heat and high evaporative demand conditions. Therefore, irrigated urban environments increase the plasticity of trait responses compared to native ecosystems, allowing for novel response to climatic variation. Our results indicate that trees grown in water-resource-rich urban ecosystems can alter their functional traits plasticity beyond those measured in native ecosystems, which can lead to plant trait dynamics with no natural analogue.

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.

Forest ecosystem service functions and their associations with landscape patterns in Renqiu City

Forest ecosystems are crucial to the survival and development of human societies. Urbanization is expected to impact forest landscape patterns and consequently the supply of forest ecosystem services. However, the specific ways by which such impacts manifest are unclear. Therefore, to discuss the relationship between them is of great significance for realizing regional sustainable development. Here, we quantitatively assess the intensity of forest ecosystem service functions and forest landscape patterns in Renqiu City of China's Hebei Province in 2019 using ArcGIS and FRAGSTATS. We characterize the relationships between forest ecosystem service capacity and landscape patterns, and identify strategies for the spatial optimization of forests. We find that the ecosystem service intensity of forests are significantly correlated with their spatial distribution, forest area ratio, and landscape patterns. Specifically, the percentage of landscape (PLAND) index, landscape shape index (LSI), and contagion (CONTAG) index indices display second-order polynomial relationships with various forest ecosystem service functions, with critical values of 80, 5, and 70, respectively. We propose that forest ecosystem functions can be optimized by optimizing forest landscape patterns. Specifically, to maximize the function of forest ecosystem services, managers should consider the integrity of forest ecosystems, optimize their ability to self-succession, repair service functions of key nodes within forests, enhance forests' structural stability, optimize forest quality and community structure, and strengthen the efficiency of functional transformation per unit area. Finally, we propose a strategy for the spatial optimization of forests in Renqiu to optimize their associated ecosystem services. This involves protecting important areas for forest ecosystems, rationally organizing different ecological patches such as forests and water bodies to maximize their functions, strengthening the connectivity of scattered forests, and supplementing woodland areas.