Woody biomass production can increase through establishment of non-native tree species exhibiting greater growth potential than traditional native species. Interest in growing Eucalyptus in the southeastern US has raised concern over its potential spread and invasion, which could impact ecosystem properties and functions. Within the matrix of land use where Eucalyptus establishment is being considered in the southeastern US, surrounding pine forests managed with fire represent a likely pathway for invasion. We used greenhouse and field experiments to evaluate the potential invasion risk of Eucalyptus benthamii. We were specifically interested in determining if seeds could successfully germinate in fire-maintained pine forests and if fire-return intervals influenced germination through impacts on litter accumulation and light availability. The greenhouse experiment investigated the influence of light availability on germination success, whereas the field study investigated the influence of time since fire, and thus litter accumulation and light availability, on germination success. Percent germination was similar under non-shaded controls and moderate shade, but complete shade resulted in low germination rates. Germination was lower in the field compared to the greenhouse and was influenced by litter and light availability, which varied according to fire-return intervals. Litter increased, and light availability decreased, with time since burn. Germination was negatively related to litter depth and positively related to light availability, thereby decreasing with time since fire. Germination increased with litter removal but remained positively related to light availability after litter removal. Higher germination with litter removal suggests germination is influenced by litter, but higher germination with increased light availability, regardless of raking, suggests germination is also influenced by light availability. Despite these relationships, no seedlings persisted through the growing season. The low germination rates under a variety of field conditions coupled with the lack of persistence suggests establishment may be unlikely, regardless of the surrounding land matrix.

中文翻译：

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在美国东南部，桉树不太可能逃离人工林并侵入以规定火种管理的周围森林

木质生物量的生产可以通过建立具有比传统本土物种更大的增长潜力的非本土树种来增加。对在美国东南部种植桉树的兴趣引起了人们对其潜在扩散和入侵的关注，这可能会影响生态系统的特性和功能。在美国东南部考虑建立桉树的土地利用矩阵中，周围有松火的松树林代表着可能的入侵途径。我们使用温室和田间实验来评估桉木的潜在入侵风险。我们特别感兴趣的是确定种子是否可以在火烧的松树林中成功发芽，并且回火间隔是否通过影响凋落物积累和光利用率来影响发芽。温室实验研究了光的可用性对发芽成功的影响，而野外研究则研究了自火灾以来的时间，以及垫料堆积和光的可用性对发芽成功的影响。在无阴影控制和中等阴影下，发芽百分比相似，但完全阴影导致发芽率低。与温室相比，田间发芽率较低，并且受凋落物和光的可用性影响，后者随回火间隔的不同而变化。自燃烧以来，随时间推移，垃圾增加，光利用率下降。发芽与凋落物深度成负相关，与光的利用率成正相关，因此自火灾以来随时间减少。清除垃圾后发芽量增加，但清除垃圾后与光的利用率仍呈正相关。除去凋落物的较高发芽率表明发芽受凋落物的影响，但是无论犁耙如何，发芽率较高且光利用率高的情况均表明发芽也受光照率的影响。尽管存在这些关系，但在整个生长季节中没有幼苗持续存在。在各种田间条件下较低的发芽率，再加上缺乏持久性，这表明不管周围的土地矩阵如何，建立的可能性都不大。自火灾以来随时间减少。清除垃圾后发芽量增加，但清除垃圾后与光的利用率仍呈正相关。除去凋落物的较高发芽表明发芽受凋落物的影响，但是无论耙草如何，较高的发芽率与可用光的增加都表明发芽也受光照的影响。尽管存在这些关系，但在整个生长季节中没有幼苗持续存在。在各种田间条件下较低的发芽率，再加上缺乏持久性，这表明不管周围的土地矩阵如何，建立的可能性都不大。自火灾以来随时间减少。清除垃圾后发芽量增加，但清除垃圾后与光的利用率仍呈正相关。除去凋落物的较高发芽率表明发芽受凋落物的影响，但是无论犁耙如何，发芽率较高且光利用率高的情况均表明发芽也受光照率的影响。尽管存在这些关系，但在整个生长季节中没有幼苗持续存在。在各种田间条件下较低的发芽率，再加上缺乏持久性，这表明不管周围的土地矩阵如何，建立的可能性都不大。除去凋落物的较高发芽率表明发芽受凋落物的影响，但是无论犁耙如何，发芽率较高且光利用率高的情况均表明发芽也受光照率的影响。尽管存在这些关系，但在整个生长季节中没有幼苗持续存在。在各种田间条件下较低的发芽率，再加上缺乏持久性，这表明不管周围的土地矩阵如何，建立的可能性都不大。除去凋落物的较高发芽率表明发芽受凋落物的影响，但是无论犁耙如何，发芽率较高且光利用率高的情况均表明发芽也受光照率的影响。尽管存在这些关系，但在整个生长季节中没有幼苗持续存在。在各种田间条件下较低的发芽率，再加上缺乏持久性，这表明不管周围的土地矩阵如何，建立的可能性都不大。