| 04 Mar 2026
Saturation effect of background temperature and aridity on vegetation phenology sensitivity to urban warming
Abstract. In this study, urban warming effects on vegetation phenology were assessed for 293 cities in China. The variations in urban warming effects were expected to be attributed to the baseline land surface temperature (LST) and the aridity index (AI) of each locale. LST and AI related phenology and their temperature sensitivity (Rt-SOS and Rt-EOS) was quantified. We observed an urban-rural phenological disparity of 12.06 days for Start of Season (ΔSOS) and 9.86 days for End of Season (ΔEOS) among the studied cities. Spatially, cities in high latitude regions and coastal areas exhibited pronounced negative ΔSOS shifts and positive ΔEOS shifts, positively correlating with Rt-SOS and Rt-EOS, respectively. Employing a continent-wide preseason temperature (T), we observed a logistic decrease for SOS and an increase for EOS, illustrating the "saturated effect" of warming on plant phenology-patterns echoed within urban settings. First-order derivatives of those logistic curves identified a highest phenological sensitivity at T = 4 °C and T = 6 °C, as well as the warming benefit range of −3.5 °C–10 °C and 2 °C–14 °C for SOS and EOS respectively. Substituting T with LST, weaker ΔSOS and ΔEOS would be presented in warmer regions only when LST exceeded 12.5 °C and 4 °C for spring and autumn, respectively. Except for LST, AI exhibited a positive correlation with ΔSOS and ΔRt-SOS, but a negative one with ΔEOS and ΔRt-EOS. Collectively, LST and AI explained 75.05 % and 76.21 % of the phenological variance across the continent for ΔSOS and ΔEOS, respectively. These findings lay the groundwork for predicting vegetation changes under global warming at large scales.
This paper investigates the saturation effect of background temperature and aridity on vegetation phenology sensitivity to urban warming across 293 Chinese cities, using multi-year MODIS and climate data. The topic is relevant to urban ecology and climate change adaptation, with clear scientific questions and reasonable methods. Below are constructive comments.
1 Abstract: The structure of the abstract needs strengthening. The beginning should clearly articulate the current gaps and limitations in quantifying vegetation phenology sensitivity to urban warming. This should be followed by a concise summary of the methodology, and finally, a systematic presentation of the results.
2 Line 61-63: The authors state that “While these studies offer empirical evidence, they do not sufficiently elucidate the underlying cause and its quantifiable relationship.”. However, based on the stated objectives, the study primarily aims to identify a so-called saturation inflection point rather than conducting an deep exploration of the underlying mechanisms. If this is the case, the Introduction needs to more clearly highlight the specific novelty and contribution of this work.
3 Line 126-128: The authors appear to define the urban center as Urban and a 20 km buffer zone as Rural. The reason for this specific delineation needs to be clearly explained in this section.
4 The figure legends require more precise descriptions. For instance, Figure 3, 9, and 10 contains panels (a) and (b), yet the current legend is imprecise and fails to clearly distinguish or explain them, and also in Figure 8, please avoid errors such as obscured numerical values in Figure 8. Therefore, the authors should be carefully verify that all other figure legends are expressed clearly and rigorously. Furthermore, given the large number of figures in the main text, please consider moving some of them to the Supplementary Materials.
5 Line 422-431: This section reads more like a summary of the Results. I recommend avoiding such redundancy. The section of Discussion should focus on analyzing and interpreting the findings rather than simply restating them.
6 Line 433-435: The study covers a large geographical area, so the word “same habitation” is confusing. Please clarify this point.
7 Line 455-457: There are instances of incorrect or non-idiomatic language. Please rephrase these sentences to ensure accuracy and readability. Given that similar issues appear throughout the manuscript, I strongly recommend a thorough proofreading and comprehensive language polishing of the entire text to eliminate errors and inappropriate expressions.
8 Line 469-470, Line 476: what’s the meaning of 50-51, and 46? Please carefully review the entire manuscript to avoid such mistakes.
9 The authors provide interpretations of the results in the Discussion section, such as the possible reasons for SOS, ECOS, and drought effect. However, these mechanistic explanations mainly rely on several literature citations without sufficient supporting data from the current study, making this part of the analysis appear weak. I recommend that the authors incorporate specific data to substantiate their inferences.
10 Line 484-488: This section also reads more like a description of the results and lacks substantive discussion. The authors should focus on interpreting the findings, exploring their implications, and comparing them with existing literature. Similarly, Line 496-500 merely repeat the presentation of results without offering in-depth analysis or discussion.
11 In Section 4.4, the authors aim to discuss the responses of phenology in different vegetation types to temperature changes and drought. While this is a valuable point, as a standalone discussion section, it appears abrupt given the study's objectives and the introduction. There is virtually no prior groundwork laid for this specific topic earlier in the manuscript. I recommend that the authors reconsider the coherence of this research point throughout the paper, ensuring better alignment between the introduction, objectives, and discussion, and provide a more in-depth exploration of these findings.