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Changes in forage lichen biomass after insect outbreaks and fuel reduction treatments in the Blue Mountains, Oregon

机译:俄勒冈州蓝山山脉爆发昆虫和减少燃料后,饲用地衣生物量的变化

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Forage lichens are pendulous, hairlike species eaten by a wide range of mammals. Our overall goal was to estimate losses of? Bryoria , a genus of ecologically important forage species, in forests subjected to disease and fuel reduction treatments at Starkey Experimental Forest in the Blue Mountains of northeastern Oregon. Specific objectives were to (1) estimate? Bryoria? biomass in stands decimated by insects and disease, (2) compare? Bryoria? biomass in untreated stands with those treated by mechanical fuels reduction and prescribed fire, and (3) estimate the range of pre-insect outbreak? Bryoria? biomass using historical data. Our general approach was to estimate tree-level? Bryoria? biomass on a sample of trees, regress estimates against tree size and species using nonparametric multiplicative regression (NPMR), then predict stand-level biomass by applying NPMR to tree size and density data. For live trees, logarithm of dbh was a strong predictor of? Bryoria? biomass (cross validated? R? 2 = x? R? 2 = 0.83). Biomass on dead trees showed a similar but weaker pattern (x? R? 2 = 0.45); including? Abies grandis? as an indicator variable substantially improved the model (x? R? 2 = 0.52). Current? Bryoria? biomass is clearly much lower than the potential biomass for forests of this type. Based on our prediction of pre-outbreak? Bryoria? biomass and benchmarks from related studies, we conclude that the biomass in intact, mature forests should be about 0.5 – 2.0 T/ha. This means insects and disease caused a loss of about 50-80% of starting? Bryoria? biomass, and fuel reduction treatments removed roughly another 10%. How long it will take for the biomass to recover is unknown, but we assume that? Bryoria? recovery will keep pace with structural recovery of the canopy. Even though small, young trees individually supported very low? Bryoria? biomass, their combined contribution to standing biomass will soon be appreciable due to high regeneration density.
机译:牧草地衣是多种哺乳动物所食用的下摆,毛状物种。我们的总体目标是估计损失?苔藓菌属(Bryoria)是具有重要生态意义的牧草种类,在俄勒冈州东北部蓝山(Blue Mountains)的斯塔克斯实验森林(Starkey Experiment Forest)中经过疾病和减油处理的森林中。具体目标是(1)估算?苔藓虫?被昆虫和疾病破坏的林分中的生物量,(2)比较?苔藓虫?未经处理的林分中的生物量与经机械燃料减少和规定的火处理过的林分相比,(3)估计虫前爆发的范围?苔藓虫?使用历史数据的生物量。我们的一般方法是估计树级别?苔藓虫?树木样本上的生物量,使用非参数乘法回归(NPMR)对树木的大小和物种进行估计回归,然后通过将NPMR应用于树木的大小和密度数据来预测林分生物量。对于活树,dbh的对数可以强烈预测?苔藓虫?生物质(交叉验证的R 2 = x 2 R 2 = 0.83)。枯树上的生物量显示出相似但较弱的模式(x?R?2 = 0.45)。包含?冷杉吗?作为指标变量,可以大大改善模型(x?R?2 = 0.52)。当前?苔藓虫?生物量显然比这类森林的潜在生物量低得多。根据我们对爆发前的预测?苔藓虫?生物量和相关研究的基准,我们得出结论,完整,成熟的森林中的生物量应约为0.5 – 2.0 T / ha。这意味着昆虫和疾病造成的损失约为开始的50-80%?苔藓虫?生物量和减少燃料的处理大约又减少了10%。恢复生物质需要多长时间是未知的,但是我们认为是吗?苔藓虫?恢复将与冠层的结构恢复保持同步。即使幼小的树木单独支撑得很低?苔藓虫?由于高再生密度,它们对固定生物量的综合贡献很快将变得可观。

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