Prislan Peter, Gričar Jožica, de Luis Martin, Novak Klemen, Martinez Del Castillo Edurne, Schmitt Uwe, Koch Gerald, Štrus Jasna, Mrak Polona, Žnidarič Magda T, Čufar Katarina
Slovenian Forestry Institute, University of Ljubljana Ljubljana, Slovenia.
Department of Geography and Regional Planning, University of Zaragoza Zaragoza, Spain.
Front Plant Sci. 2016 Dec 26;7:1923. doi: 10.3389/fpls.2016.01923. eCollection 2016.
To understand better the adaptation strategies of intra-annual radial growth in and to local environmental conditions, we examined the seasonal rhythm of cambial activity and cell differentiation at tissue and cellular levels. Two contrasting sites differing in temperature and amount of precipitation were selected for each species, one typical for their growth and the other represented border climatic conditions, where the two species coexisted. Mature trees from Mediterranean (Spain) and sub-Mediterranean (Slovenia) sites, and from sub-Mediterranean (Slovenia) and temperate (Slovenia) sites were selected. Repeated sampling was performed throughout the year and samples were prepared for examination with light and transmission electron microscopes. We hypothesized that cambial rhythm in trees growing at the sub-Mediterranean site where the two species co-exist will be similar as at typical sites for their growth. Cambium in at the Mediterranean site was active throughout the year and was never truly dormant, whereas at the sub-Mediterranean site it appeared to be dormant during the winter months. In contrast, cambium in was clearly dormant at both sub-Mediterranean and temperate sites, although the dormant period seemed to be significantly longer at the temperate site. Thus, the hypothesis was only partly confirmed. Different cambial and cell differentiation rhythms of the two species at the site where both species co-exist and typical sites for their growth indicate their high but different adaptation strategies in terms of adjustment of radial growth to environmental heterogeneity, crucial for long-term tree performance and survival.
为了更好地理解[物种名称1]和[物种名称2]年内径向生长对当地环境条件的适应策略，我们在组织和细胞水平上研究了形成层活动和细胞分化的季节节律。为每个物种选择了两个温度和降水量不同的对比站点，一个是其典型生长站点，另一个代表边界气候条件，两个物种在该站点共存。从地中海（西班牙）和亚地中海（斯洛文尼亚）站点选取了成熟的[物种名称1]树，从亚地中海（斯洛文尼亚）和温带（斯洛文尼亚）站点选取了[物种名称2]树。全年进行重复采样，并制备样本用于光学显微镜和透射电子显微镜检查。我们假设，在两个物种共存的亚地中海站点生长的树木的形成层节律将与它们典型生长站点的节律相似。地中海站点的[物种名称1]形成层全年活跃，从未真正休眠，而在亚地中海站点，它在冬季似乎处于休眠状态。相比之下，[物种名称2]的形成层在亚地中海和温带站点都明显休眠，尽管温带站点的休眠期似乎明显更长。因此，该假设仅得到部分证实。两个物种在共存站点和典型生长站点的不同形成层和细胞分化节律表明，它们在将径向生长调整以适应环境异质性方面具有高度但不同的适应策略，这对树木的长期表现和生存至关重要。
