Aiming to explore the species-specific responses of biomass allocation and whole-tree transpiration in urban trees to pavement and drought, a field manipulation experiment grew saplings of two common greening trees, ash (Fraxinus chinensis Roxb.) and ginkgo (Ginkgo biloba L.). Pavement slightly increased leaf area and leaf biomass in ginkgo under sufficient water supply. When water deficit occurs, the height, basal diameter, and biomass in ash reduced and more biomass was allocated to roots, pavement aggravated the reduction of stem biomass in ash. Pavement slightly increased soil evaporation and total evapotranspiration, irrespective of whether the water supply was sufficient or not. However, whole-tree transpiration and stem sap flow increased under pavement when the water supply was sufficient for ginkgo but not so for ash. The down-regulation of water use generated by an insufficient water supply was aggravated and retarded by pavement for ginkgo and ash, respectively. Ash grows faster and can maintain its transpiration better under pavement and drought stress, making it the preferred tree for planting on paved land in urban areas.

中文翻译：

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路面和水分亏缺对两种对比城市树木物种生物量分配和整棵树蒸腾作用的影响

为了探索城市树木的生物量分配和整棵树蒸腾对路面和干旱的物种特异性响应，田间操纵实验种植了两种常见的绿化树苗-水曲柳（Frazinus chinensis Roxb。）和银杏（Ginkgo biloba）的树苗。L.）。在充足的供水条件下，路面稍微增加了银杏的叶面积和叶片生物量。当发生水分亏缺时，灰分的高度，基径和生物量会减少，更多的生物量分配给根部，路面加剧了灰分中茎生物量的减少。不管供水是否充足，人行道都会略微增加土壤蒸发量和总蒸散量。然而，当水供应足够的银杏树而不是灰烬时，人行道上整棵树的蒸腾作用和茎液流增加。由于银杏和粉煤灰的路面，给水不足引起的用水量下调加剧和受阻。在路面和干旱胁迫下，灰烬生长更快，可以更好地保持蒸腾作用，