Divergent growth-differentiation balance strategies and resource competition shape mortality patterns in ponderosa pine

Dynamic resource availability leads to trade-offs among functions in plants. The growth-differentiation balance hypothesis (GDBH) predicts greater allocation of carbon to defense than growth when resources are scarce; with optimum defense production occurring at a point between the minimum and maximum growth rates. While the GDBH has been widely tested, consideration of phenotypic variation in rates for which defense is traded for growth and what this variation means for plant resistance remains rare. For defense, pines produce and store oleoresin in “resin ducts.” Retrospective comparisons of resin ducts in pines have revealed that trees with greater numbers, sizes, or areas of xylem resin ducts are more likely to avoid or survive insect attacks. We used tree ring chronologies to quantify phenotypic variation in growth and resin duct defenses in pairs of living and bark beetle-killed Pinus ponderosa trees in southern New Mexico, USA, and to test the utility of the GDBH for explaining t...

资源的动态可获得性会导致植物各功能间产生权衡关系。生长-分化平衡假说（growth-differentiation balance hypothesis, GDBH）预测，当资源匮乏时，植物会将更多碳分配至防御过程而非生长过程；且最优防御产量会出现在最低与最高生长速率之间的某个节点。尽管GDBH已得到广泛验证，但针对"防御与生长之间的权衡速率所存在的表型变异"以及"该变异对植物抗虫性的意义"的相关研究仍较为罕见。在防御机制中，松树会在"树脂道"内合成并储存油树脂。针对松树树脂道的回顾性对比研究显示，木质部树脂道数量更多、尺寸更大或横截面积更广的树木，更有可能规避或存活于昆虫侵害。我们以美国新墨西哥州南部的活树与被树皮甲虫致死的黄松（Pinus ponderosa）成对样本为研究对象，利用树木年轮年表量化其生长与树脂道防御的表型变异，并验证GDBH在解释……方面的实用性。