Lee E Henry, Beedlow Peter A, Waschmann Ronald S, Cline Steve, Bollman Michael, Wickham Charlotte, Testa Nicholas
US Environmental Protection Agency, 200 SW 35 Street, Corvallis, OR 97333, USA.
Department of Statistics, Oregon State University, Corvallis, OR 97331, USA.
J Plant Sci Phytopathol. 2021 Nov 25;5(3):76-87. doi: 10.29328/journal.jpsp.1001065.
The fungal pathogen, , occurs wherever Douglas-fir is found but disease damage is believed to be limited to the Coast Range and is of no concern outside the coastal fog zone (Shaw, et al., 2011). However, knowledge remains limited on the history and spatial distribution of Swiss Needle Cast (SNC) impacts in the Pacific Northwest (PNW). We reconstructed the history of SNC impacts on mature Douglas-fir trees based on tree ringwidth chronologies from the west slope of the Coast Range to the high Cascades of Oregon. Our findings show that SNC impacts on growth occur wherever Douglas-fir is found in western Oregon and is not limited to the coastal fog zone. The spatiotemporal patterns of growth impact from SNC disease were synchronous across the region, displayed periodicities of 25-30 years, strongly correlated with winter and summer temperatures and summer precipitation, and matched the patterns of enriched cellulosic stable carbon isotope indicative of physiological stress. While winter and summer temperature and summer precipitation influenced pathogen dynamics at all sites, the primary climatic factor of these three limiting factors varied spatially by location, topography, and elevation. In the 20 century, SNC impacts at low- to mid-elevations were least severe during the warm phase of the Pacific Decadal Oscillation (PDO, 1924-1945) and most severe in 1984-1986, following the cool phase of the PDO (1945-1977). At high elevations on the west slope of the Cascade Mountains, SNC impacts were the greatest in the 1990s and 2000s, a period of warmer winter temperatures associated with climate change. Warmer winters will likely continue to increase SNC severity at higher elevations, north along the coast from northern Oregon to British Columbia, and inland where low winter temperatures currently limit growth of the pathogen. Surprisingly, tree-ring records of ancient Douglas-fir logs dated ~53K radioactive years B.P. from Eddyville, OR displayed 7.5- and 20-year periodicities of low growth, similar to those found in modern day coastal Douglas-fir tree-ring records which we interpret as being due to cyclic fluctuations in SNC severity. Our findings indicate that SNC has persisted for as long as its host, and as a result of changing climate, may become a significant forest health problem in areas of the PNW beyond the coastal fog zone.
这种真菌病原体，无论在何处发现花旗松，它都存在，但据信病害损害仅限于海岸山脉，在沿海雾区以外无需担忧（Shaw等人，2011年）。然而，对于瑞士针叶枯病（SNC）在太平洋西北地区（PNW）的影响历史和空间分布，我们的了解仍然有限。我们根据从海岸山脉西坡到俄勒冈州高喀斯喀特山脉的树木年轮宽度年表，重建了SNC对成熟花旗松树木的影响历史。我们的研究结果表明，在俄勒冈州西部，无论何处发现花旗松，SNC都会对其生长产生影响，且不仅限于沿海雾区。SNC病害对生长的时空影响模式在整个地区是同步的，呈现出25 - 30年的周期，与冬季和夏季温度以及夏季降水量密切相关，并且与指示生理胁迫的纤维素稳定碳同位素富集模式相匹配。虽然冬季和夏季温度以及夏季降水量影响了所有地点的病原体动态，但这三个限制因素中的主要气候因素会因地点、地形和海拔的不同而在空间上有所变化。在20世纪，太平洋年代际振荡（PDO，1924 - 1945年）暖期，低至中海拔地区的SNC影响最不严重，而在PDO冷期（1945 - 1977年）之后的1984 - 1986年最为严重。在喀斯喀特山脉西坡的高海拔地区，SNC影响在20世纪90年代和21世纪最为显著，这一时期冬季温度较高，与气候变化有关。冬季变暖可能会继续加剧高海拔地区、从俄勒冈州北部沿海向北到不列颠哥伦比亚省以及目前冬季低温限制病原体生长内陆地区的SNC严重程度。令人惊讶的是，来自俄勒冈州埃迪维尔的约5.3万放射性年前的古代花旗松原木的树木年轮记录显示出7.5年和20年的低生长周期，类似于现代沿海花旗松树木年轮记录中发现的周期，我们将其解释为SNC严重程度的周期性波动所致。我们的研究结果表明，SNC与其寄主共存的时间一样长，并且由于气候变化，可能会成为PNW沿海雾区以外地区的一个重大森林健康问题。
