Effects of a spring prescribed burn on the soil seed bank in sagebrush steppe exhibiting pinyon-juniper expansion
Effects of a spring prescribed burn on the soil seed bank in sagebrush steppe exhibiting pinyon-juniper expansion
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春季规定烧伤对松树-杜松扩张的艾蒿草原土壤种子库的影响
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发表时间：
2008
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影响因子：
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通讯作者：
R. Nowak
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作者：
E. A. Allen;J. Chambers;R. Nowak
摘要松柏(Pinus monophylla-Juniperus steosperma)林地正在向盆地西部的灌丛生态系统扩展。通常，竞争激烈的树木取代了林下植被，规定的火越来越多地被用作修复工具。为了向管理层提供有关火灾后恢复的决策，我们研究了可萌发种子库对春季规定的火灾的即时和长期(即两个生长季)反应。在2002年5月规定的焚烧前一周和之后一周，在单叶青杨树下和三齿艾树下采集土壤样本。Vaseyana灌木，以及来自空间间微站点。在规定的焚烧后的两个生长季节，从相同的微型场地和相邻的未焚烧区域的相似微型场地采集土壤样本。火烧前，灌木下可萌发种子库的种子密度和物种丰富度最高，其次是空间和乔木微网点。灌木凋落物被烧毁，导致该微小场所的种子库完全丧失，并耗尽了三齿沙打旺种子库。有趣的是，单叶松树下土壤中可萌发种子的密度在烧伤后立即增加；其中70%的增加来自一年一度的斑点锦鸡儿。在规定火烧后的两个生长季节，可萌发种子密度在火烧和未火烧地之间没有观察到总体差异，但种子库物种组成不同，与未火烧地相比，规定火烧地的种子库中有更多的Eriogonum elatum、E.microthecum和Gayophytom Diusum，而未火烧的地块则有更多的三齿草、西方龙须草和斑茅。我们的结果表明，火前植被的快速恢复不能依靠土壤种子库。为了确保快速恢复，土地管理者应该选择具有耐火的多年生植被的规定烧伤地点。命名：美国农业部，NRCS。2006年。植物数据库[引用2006年11月13日]。国家工厂数据中心，巴吞鲁日，洛杉矶70874-4490.可从以下网址获得：http://plants.usda.gov
Abstract Pinyon-juniper (Pinus monophylla–Juniperus osteosperma) woodlands are expanding into shrubsteppe ecosystems in western portions of the Great Basin. Often, highly competitive trees displace the understory, and prescribed fire is increasingly used as a restoration tool. To inform management decisions about post-fire recovery, we examined immediate and long-term (i.e., 2 growing seasons) responses of the germinable seed bank to a spring prescribed fire. One week before and 1 week after a May 2002 prescribed burn, soil samples were taken under P. monophylla trees, under Artemisia tridentata ssp. vaseyana shrubs, and from interspace microsites. Two growing seasons after the prescribed burn, soil samples were taken from the same microsites and from similar microsites in an adjacent unburned area. Prior to the burn, the germinable seed bank under shrubs contained the highest seed density and the highest species richness followed by interspace and tree microsites. Shrub litter was consumed by the burn, causing complete loss of the seed bank from that microsite and depleting the A. tridentata seed bank. Interestingly, the density of germinable seeds in soil under P. monophylla trees increased immediately following the burn; 70% of that increase originated from the annual forb Descurainia pinnata. Two growing seasons following the prescribed burn, no overall differences in germinable seed density between burned and unburned plots were observed, but seed bank species composition differed, with seed banks in the prescribed burn having a greater abundance of Eriogonum elatum, E. microthecum, and Gayophytum diffusum compared to unburned plots, which had a greater abundance of A. tridentata, Lappula occidentalis, and Descurainia pinnata. Our results indicate that rapid restoration to prefire vegetation cannot rely upon the soil seed bank. To ensure rapid recovery, land managers should select sites for prescribed burns that have fire-tolerant perennial vegetation. Nomenclature: USDA, NRCS. 2006. The PLANTS Database [cited 13 November 2006]. National Plant Data Center, Baton Rouge, LA 70874–4490. Available from: http://plants.usda.gov