Effects of herbivory on the growth and reproduction of Picris hieracioides in the Mediterranean region
Effects of herbivory on the growth and reproduction of Picris hieracioides in the Mediterranean region
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DOI：
10.2307/3237165
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发表时间：
1999-02-01
影响因子：
2.8
通讯作者：
Gorse, V
中科院分区：
文献类型：
--
作者：
Escarré, J;Lepart, J;Gorse, V
在一个废弃15年的老农田种群中，通过连续3年比较杀虫剂处理和未处理的植物，研究了植食性昆虫对苦味酸苦味酸（Picris hieracioides）生长和繁殖的影响。在第三年，草食动物和竞争之间的相互作用进行了分析。在法国蒙彼利埃地区，在三个相邻的老领域放弃了一个（P1），15（P15）和40年（P40）的种子头前扩散种子捕食进行了调查。不同领域的植被覆盖和植物区系组成，也在密度酸地上生物量的苦味酸植物（从246克每株植物在P1，13.3克在P15，下降到3.3克在P40，为第一年的研究）。1992年至1994年，苦菜生长期1月至7月的累积降雨量减少，而且，1992年，5月和6月的降雨量是1993年和1994年的三倍。结果表明，在研究期间，环境胁迫加剧，在P15时，无脊椎动物对毛苦菜单株的生长和繁殖产生了负面影响。这种影响并不随时间而持续，三年中只有两年明显。这两年（1992年和1994年）的气候特征截然不同，而没有明显影响的一年（1993年）是气候中间。当草食动物对生长有影响时，经除草剂处理的植物具有显著更高的地上生物量，并产生两倍于对照植物的种子头。取食与竞争不存在交互作用，Pi-田的受害种穗率显著低于P40-田。P15-字段有中等水平的捕食。在1992年和1994年之间，三个老领域的种子头的捕食增加，而生物量和生殖输出下降。因此，种子捕食的结果（但不是地上生物量和繁殖）倾向于证实Mattson & Haack（1987）的“环境胁迫假说”，即植物在胁迫下更容易受到食草动物的攻击。
The impact of herbivorous insects on the growth and reproduction of Picris hieracioides (Compositae) was followed in three consecutive years by comparing plants treated with an insecticide and untreated plants in an old-field population abandoned for 15 yr (P15). In the third year the interactions between herbivory and competition were analysed as well. Pre-dispersal seed predation of seed heads was investigated in three adjacent old-fields abandoned for one (P1), 15 (P15) and 40 yr (P40) in the region of Montpellier, France. Fields differed in vegetation cover and floristic composition and also in density acid above-ground biomass of Picris hieracioides plants (from 246 g per plant in P1, 13.3 g in P15, down to 3.3 g in P40, for the first year of study). The cumulative rainfall between January and July, the period of Picris growth, decreased from 1992 to 1994, Moreover, in 1992, three times as much rainfall occurred in May and June - the period of stem elongation - as in 1993 and 1994. As a consequence, environmental stress increased during the study period.Herbivorous invertebrates had a negative effect on the growth and reproduction of individual plants of Picris hieracioides in P15. The effect was not constant with time, being apparent in only two years out of three. These two years (1992 and 1994) had contrasting climatic characteristics, whereas the year with no apparent effect (1993) was climatically intermediate. When herbivory had effects on growth, the insecticide-treated plants had a significantly higher aboveground biomass and produced twice as many seed heads as the control plants. There was no interaction between herbivory and competition.The percentage of damaged seed heads was significantly lower in the Pi-field than in the P40-field. The P15-field had intermediate levels of predation. Predation on seed heads increased whereas biomass and reproductive output decreased between 1992 and 1994 in the three old-fields. Therefore, the results on seed predation (but not for above-ground biomass and reproduction) tend to confirm 'the environmental stress hypothesis' of Mattson & Haack (1987) that states that plants under stress are more liable to be attacked by grazers.