Continental-scale patterns in modern wood cellulose δ18O : Implications for interpreting paleo-wood cellulose δ18O
Continental-scale patterns in modern wood cellulose δ18O : Implications for interpreting paleo-wood cellulose δ18O
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现代木材纤维素 δ18O 的大陆尺度模式：对解释古木材纤维素 δ18O 的影响
DOI：
10.1016/j.gca.2008.01.030
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发表时间：
2008
影响因子：
5
通讯作者：
K. D. Taylor
中科院分区：
文献类型：
--
作者：
S. Richter;A. Johnson;M. Dranoff;K. D. Taylor
古木材的同位素组成可能是过去某些气候或地球化学条件的有用档案，但目前有许多不确定因素限制了这种解释。我们在北美和加勒比地区的林区采集了以本地树木为主的自然生长的树木样本，以评估纤维素δ18O(δ18Ocel)、相对湿度(RH)、降水量δ18O(δ18Oppt)和大陆尺度的平均年温度(MAT)之间的关系的强度，以及δ18O的一般变异性范围与立地水文条件和物种差异的关系。我们发现生长在同一地点的不同物种之间存在多达4个‰差异，同一地点的针叶树纤维素比被子植物纤维素丰富1.5‰(p<；0.001)，并且景观位置的差异反映了不同的地下水位获取途径，导致了‰18Ocel的<；1δ。在大陆尺度上，δ18OCEL受到模式δ18Oppt的强烈影响(R2=0.8，p<；0.001)。夏季平均最低相对湿度(RHmin)和δ18Oppt更好地解释了北美和加勒比海森林δ18Oppt的变化(R2=0.93p<；0.001)。MAT和δ18Ocel在整个北美也有很强的相关性(被子植物和针叶树的相关系数分别为0.91p<；0.001)。δ18Oppt与δ18Oppt的差值不是恒定的(35-44‰)，与δ18Oppt呈负相关。为北美和加勒比地区建立的δ18Oppt、RHmin、δ18Ocel和MAT之间的关系在用δ18Oppt估算亚洲、欧洲和南美洲的MAT和δ18Oppt时适用得相当好，但也有重要的例外。从δ18Ocel对MAT和δ18Oppt的最准确预测需要RHmin。对δ18Oppt和MAT的预测仅从δ18Ocelone就产生了高达8‰和16°C的误差。
The isotopic composition of ancient wood may be a useful archive of some climatic or geochemical conditions of the past, but presently there are many uncertainties that constrain such interpretations. We sampled naturally growing, predominantly native trees in forested regions of North America and the Caribbean to evaluate the strength of the relationships among cellulose δ18O (δ18Ocel), relative humidity (RH), precipitation δ18O (δ18Oppt), and mean annual temperature (MAT) at the continental scale, and the general range of variability in δ18Ocelassociated with site hydrologic conditions and species differences. We found up to 4‰ differences among different species growing at the same site, that conifer cellulose at a site is more enriched than angiosperm cellulose by 1.5‰ (p<0.001), and that differences in landscape position, reflecting differing access to the water table, produced differences of <1‰ in δ18Ocel. At the continental scale, δ18Ocelwas strongly influenced by modeled δ18Oppt(R2=0.80, p<0.001). Average summer minimum RH (RHmin) combined with δ18Opptexplained more of the variability (R2=0.93, p<0.001) in δ18Ocelacross North American and Caribbean forests. MAT and δ18Ocelwere also strongly correlated across North America (R=0.91 and 0.95, p<0.001, for angiosperms and conifers, respectively). The difference between δ18Opptand δ18Ocelis not constant (varying from 35–44‰) and is inversely correlated with δ18Oppt. The relationships among δ18Oppt, RHmin, δ18Ocel, and MAT established for North America and the Caribbean applied reasonably well when δ18Ocelwas used to estimate MAT and δ18Opptin Asia, Europe, and South America, but there were important exceptions. The most accurate predictions of MAT and δ18Opptfrom δ18Ocelrequire RHmin. Predictions of δ18Opptand MAT made from δ18Ocelalone produced errors of up to 8‰ and 16°C, respectively.