ABSTRACT Ceanothus verrucosus (CEVE) is a globally rare, long-lived, chaparral shrub endemic to coastal southern California (CA) and northern Mexico. There is concern for CEVE persistence because of habitat loss, fire, and climate change, yet little is known about basic features of the plant, including whether it contains annual rings, plant age, and climate–growth response. Growth-ring analysis was challenging because of semi-ring-porous structure, false, and missing rings. We successfully crossdated CEVE annual rings, primarily from Cabrillo National Monument, CA, using a nearby Pinus torreyana chronology. The oldest living individual had 116 rings; the oldest inner-ring date was 1873; and most of the plants established between 1894 and 1905, all older than previous estimates. CEVE mortality occurred during a dry period from the late 1940s through the early 1960s. Correlations between age and stem measurements were weak to moderate (r = 0.10 to 0.56) posing challenges for field-based estimates of plant ages, which are important for population modeling. Variability in CEVE ring width had a strong positive correlation with prior cool-season (October–April) precipitation, yet 2- to 7-day warm-season precipitation events were recorded as rare false rings in multiple years, indicating extreme plasticity in cambial phenology and growth response to moisture.

中文翻译：

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一种稀有、长寿的地中海灌木的树木年代学

摘要 Ceanothus verrucosus (CEVE) 是一种全球罕见的、长寿的、丛林灌木，原产于加利福尼亚州南部 (CA) 和墨西哥北部沿海地区。由于栖息地丧失、火灾和气候变化，人们担心 CEVE 的持久性，但对该植物的基本特征知之甚少，包括它是否包含年轮、植物年龄和气候-生长反应。由于半环孔结构、假环和缺失环，年轮分析具有挑战性。我们使用附近的芫荽年轮成功地交叉了 CEVE 年轮，主要来自加利福尼亚州卡布里洛国家纪念碑。最长寿的个体有 116 个环；最古老的内环日期是 1873 年；大多数工厂建于 1894 年至 1905 年之间，都比之前估计的要古老。CEVE 死亡发生在 1940 年代末到 1960 年代初的干旱时期。年龄和茎测量之间的相关性弱到中等（r = 0.10 到 0.56），这对基于田间的植物年龄估计提出了挑战，这对种群建模很重要。CEVE 环宽的变异性与之前的冷季（10 月至 4 月）降水呈强正相关，但 2 至 7 天的暖季降水事件在多年中被记录为罕见的假环，表明形成层物候具有极端的可塑性和生长对水分的反应。