Verma Pramit, Tiwari Priyanshi, Singh Rishikesh, Raghubanshi Akhilesh Singh
Integrative Ecology Laboratory (IEL), Institute of Environment and Sustainable Development (IESD), Banaras Hindu University (BHU), Varanasi, India.
Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, India.
Environ Monit Assess. 2022 Jun 29;194(8):537. doi: 10.1007/s10661-022-10220-7.
Plants in their life cycle go through a series of life processes. These phenological changes are influenced by different climatic conditions. Abiotic factors like temperature, precipitation, and photoperiodism affect the onset and offset of particular phenophase in the plant periodic cycle. In this study, we tested the influence of precipitation on the forest phenology at two sites of Dudhwa National Park (DNP), Uttar Pradesh and Simlipal National Park (SNP), Odisha, India. DNP and SNP receive an annual average rainfall of 1093.5 mm and 1500 mm, respectively, of which most rainfall (~ 90%) occurs during June-September. Normalized Difference Vegetation Index (NDVI) was measured for 2 years 2015 and 2018, with 2015 being a drought year and 2018 being a normal rainfall year. NDVI was analyzed at different temporal scales of months, season, and years using the t test (Welch's two-tailed) and General Linear Mixed Model (GLMM). Effect of drought (2015) and normal (2018) rainfall year was not significant at both the sites, whereas season, yearseason interaction, seasonrainfall interaction, and yearseasonrainfall interaction were found significant at DNP (P < 0.05, ICC = 0.68, marginal R = 0.81; conditional R = 0.94). At SNP, rainfall, year, season, and their interaction were non-significant, whereas several months showed a significant effect on the NDVI values for both sites. Winter and monsoon season in DNP, and post-monsoon season in SNP, showed a significant effect on the NDVI patterns. Thus, the effect of precipitation stress in the deciduous forests was evident at small intervals of observation. Tree phenology compensated for differences when observed from a higher temporal scale of a year. There existed a mechanism in trees to tide over adverse conditions and maintain the phenology over longer intervals of time. The resilience and vulnerability of such forest ecosystems against abiotic factors and extreme events would be instrumental in climate change adaptation strategies. Tree phenology can be used as an indicator of forest health and resilience.
植物在其生命周期中会经历一系列生命过程。这些物候变化受到不同气候条件的影响。诸如温度、降水和光周期等非生物因素会影响植物周期中特定物候阶段的开始和结束。在本研究中，我们在印度北方邦的杜德瓦国家公园（DNP）和奥里萨邦的西姆利帕尔国家公园（SNP）的两个地点测试了降水对森林物候的影响。DNP和SNP的年平均降雨量分别为1093.5毫米和1500毫米，其中大部分降雨（约90%）发生在6月至9月。在2015年和2018年这两年测量了归一化植被指数（NDVI），2015年是干旱年，2018年是正常降雨年。使用t检验（韦尔奇双尾检验）和广义线性混合模型（GLMM）在月、季节和年等不同时间尺度上分析NDVI。干旱（2015年）和正常（2018年）降雨年对两个地点的影响均不显著，而在DNP，季节、年季节交互作用、季节降雨交互作用和年季节降雨交互作用显著（P＜0.05，组内相关系数ICC = 0.68，边际R = 0.81；条件R = 0.94）。在SNP，降雨、年、季节及其交互作用不显著，而几个月对两个地点的NDVI值均有显著影响。DNP的冬季和季风季节以及SNP的季风后季节对NDVI模式有显著影响。因此，在落叶林中，降水胁迫的影响在小时间间隔观测时很明显。从一年的较高时间尺度观察时，树木物候弥补了差异。树木中存在一种机制来度过不利条件并在更长时间间隔内维持物候。这种森林生态系统对非生物因素和极端事件的恢复力和脆弱性将有助于制定气候变化适应策略。树木物候可作为森林健康和恢复力的指标。
