当前位置: X-MOL 学术J. Ecol. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Higher sample sizes and observer inter-calibration are needed for reliable scoring of leaf phenology in trees
Journal of Ecology ( IF 5.5 ) Pub Date : 2021-03-23 , DOI: 10.1111/1365-2745.13656
Guohua Liu 1, 2 , Isabelle Chuine 3 , Rémy Denéchère 2, 4 , Frédéric Jean 5 , Eric Dufrêne 2 , Gaëlle Vincent 2 , Daniel Berveiller 2 , Nicolas Delpierre 2, 6
Affiliation  

  1. Reliable phenological observations are needed to quantify the impact of climate change on tree phenology. Ground observations remain a prime source of phenological data, but their accuracy and precision have not been systematically quantified. The high subjectivity of ground phenological observations affects their accuracy, and the high within-population variability of tree phenology affects their precision. The magnitude of those effects is unknown to date.
  2. We first explored the inter-observer variability in the timing of bud development and leaf senescence in trees using a unique dataset of seven observer inter-calibration sessions. Then, using tree phenological data collected in three European forests (n = 2,346 observations for budburst, n = 539 for leaf senescence), we quantified how the ‘observer uncertainty’ (accuracy of the observations) and the ‘population sampling uncertainty’ (precision of the observations) combine to affect the estimates of the budburst and the leaf senescence dates.
  3. The median observer uncertainty was 8 days for budburst (BBCH = 7) and 15 days for leaf senescence (BBCH = 95). As expected, the population sampling uncertainty decreased with increasing sample size, and was about 6 days for budburst and 10 days for leaf senescence for a sample of 10 individuals monitored per population (corresponding to the median sample size in the phenological literature). As a whole, the overall uncertainty of phenological observations could reach up to 2 weeks for budburst and 1 month for leaf senescence.
  4. Synthesis. This paper quantifies for the first time the accuracy and precision of ground phenological observations in forest trees and as such offers tables to estimate the uncertainty of phenological data. We show that reliable estimates of budburst and leaf senescence require three times (n = 30) to two times (n = 20) larger sample sizes as compared to sample sizes usually considered in phenological studies. We further call for an increased effort of observer inter-calibration, required to increase the accuracy of phenological observations. These recommendations reduce the uncertainty of phenological data, thereby improving the estimation of phenological trends over time, the response of phenology to temperature or the inference of phenological model parameters.


中文翻译:

需要更大的样本量和观察者的相互校准才能可靠地对树木的叶子物候进行评分

  1. 需要可靠的物候观测来量化气候变化对树木物候的影响。地面观测仍然是物候数据的主要来源,但其准确性和精确度尚未得到系统量化。地面物候观测的高度主观性会影响其准确性,而树木物候学的高种群内变异性会影响其准确性。迄今为止,这些影响的程度尚不清楚。
  2. 我们首先使用七个观察者相互校准会话的独特数据集探索了树木芽发育和叶子衰老时间的观察者间变异性。然后,使用在三个欧洲森林中收集的树木物候数据( 芽苗期n = 2,346 个观测值, 叶片衰老n = 539 个),我们量化了“观察者不确定性”(观测的准确性)和“种群抽样不确定性”(精度观察结果)结合起来影响萌芽和叶片衰老日期的估计。
  3. 观察者不确定性的中位数为 8 天(BBCH = 7)和 15 天的叶片衰老(BBCH = 95)。正如预期的那样,种群抽样的不确定性随着样本量的增加而降低,对于每个种群监测的 10 个个体的样本(对应于物候学文献中的中位数样本量),芽苗期约为 6 天,叶片衰老约为 10 天。总体而言,物候观察的总体不确定性可能达到 2 周的萌芽期和 1 个月的叶片衰老期。
  4. 合成。本文首次量化了林木地面物候观测的准确性和精度,并因此提供了估算物候数据不确定性的表格。我们表明, 与物候研究中通常考虑的样本量相比,对萌芽和叶片衰老的可靠估计需要三倍 ( n  = 30) 到两倍 ( n = 20) 的样本量。我们进一步呼吁加大观测者间校准的力度,以提高物候观测的准确性。这些建议降低了物候数据的不确定性,从而改进了物候趋势随时间推移的估计、物候对温度的响应或物候模型参数的推断。
更新日期:2021-03-23
down
wechat
bug