Photodegradation of plant litter exposed to solar radiation appears to be important for carbon cycling in arid ecosystems. We measured how initial concentrations of ultraviolet (UV)-absorbing phenolics and epidermal UV-transmittance influenced abiotic photodecomposition of Artemisia tridentata ssp. Wyomingensis (Wyoming big sagebrush) leaves exposed to ultraviolet radiation in a laboratory setting. These leaves were collected from standing vegetation along a 1053-m elevation gradient in North-central Wyoming that represented a natural ecocline in UV-screening effectiveness in sagebrush. After 310 d, sagebrush litter lost 6.0–9.4% of its initial mass and abiotic decomposition rates were linear, rather than exponential. Initial concentrations of both UV-A and UV-B absorbing phenolics were strong predictors for litter mass remaining, with coefficients of determination (r²) values being −0.70 and −0.62, respectively. It appears that foliar biochemistry and epidermal UV-screening effectiveness may influence photodegradation by reducing UV flux into interior portions of plant litter.

暴露在太阳辐射下的植物凋落物的光降解似乎对于干旱生态系统的碳循环很重要。我们测量了吸收紫外线 (UV) 的酚类物质的初始浓度和表皮紫外线透射率如何影响三齿蒿的非生物光分解。怀俄明州（怀俄明州大山艾树）叶子在实验室环境中暴露在紫外线辐射下。这些叶子是从怀俄明州中北部 1053 米海拔梯度上的直立植被中采集的，代表了山艾树紫外线屏蔽效果的自然生态斜面。310 天后，山艾树凋落物损失了初始质量的 6.0-9.4%，非生物分解率呈线性而非指数。UV-A 和 UV-B 吸收酚类物质的初始浓度是剩余凋落物质量的有力预测因子，决定系数 (r ² ) 值分别为 -0.70 和 -0.62。叶面生物化学和表皮紫外线屏蔽效果似乎可能通过减少进入植物凋落物内部的紫外线通量来影响光降解。