Williams Claire G, LaDeau Shannon L, Oren Ram, Katul Gabriel G
Duke University, Department of Biology, Durham, North Carolina 27708, USA.
Ecol Appl. 2006 Feb;16(1):117-24. doi: 10.1890/04-1901.
Predicting forest-tree seed dispersal across a landscape is useful for estimating gene flow from genetically engineered (GE) or transgenic trees. The question of biocontainment has yet to be resolved, although field-trial permits for transgenic forest trees are on the rise. Most current field trials in the United States occur in the Southeast where Pinus taeda L., an indigenous species, is the major timber commodity. Seed dispersal distances were simulated using a model where the major determinants were: (1) forest canopy height at seed release, (2) terminal velocity of the seeds, (3) absolute seed release, and (4) turbulent-flow statistics, all of which were measured or determined within a P. taeda plantation established from seeds collected from wild forest-tree stands at the Duke Forest near Durham, North Carolina, USA. In plantations aged 16 and 25 years our model results showed that most of the seeds fell within local-neighborhood dispersal distances, with estimates ranging from 0.05 to 0.14 km from the source. A fraction of seeds was uplifted above the forest canopy and moved via the long-distance dispersal (LDD) process as far as 11.9-33.7 km. Out of 10(5) seeds produced per hectare per year, roughly 440 seeds were predicted to be uplifted by vertical eddies above the forest canopy and transported via LDD. Of these, 70 seeds/ha traveled distances in excess of 1 km from the source, a distance too great to serve as a biocontainment zone. The probability of LDD occurrence of transgenic conifer seeds at distances exceeding 1 km approached 100%.
预测森林树木种子在景观中的传播，对于估算基因工程（GE）树或转基因树的基因流动很有用。尽管转基因森林树木的田间试验许可数量在增加，但生物遏制问题仍未得到解决。美国目前的大多数田间试验都在东南部进行，当地的主要木材商品是本土物种火炬松（Pinus taeda L.）。使用一个模型模拟种子传播距离，该模型的主要决定因素包括：（1）种子释放时的森林冠层高度，（2）种子的终端速度，（3）绝对种子释放量，以及（4）湍流统计数据，所有这些都是在美国北卡罗来纳州达勒姆附近的杜克森林从野生森林树木林分收集的种子建立的火炬松种植园中测量或确定的。在树龄为16年和25年的种植园中，我们的模型结果表明，大多数种子落在局部邻域传播距离内，估计距离源地0.05至0.14公里。一小部分种子被提升到森林冠层上方，并通过长距离传播（LDD）过程移动到11.9 - 33.7公里远的地方。每公顷每年产生的10⁵颗种子中，大约有440颗种子预计会被垂直涡流提升到森林冠层上方，并通过LDD进行运输。其中，每公顷有70颗种子传播的距离超过源地1公里，这个距离太大，无法作为生物遏制区。转基因针叶树种子在超过1公里的距离发生LDD的概率接近100%。
