种子特征和结实量对啮齿动物取食和扩散种子行为的影响

为了深入了解啮齿动物在不同种子丰富度条件下对不同大小和单宁含量种子的觅食行为策略及其与植物种群更新的关系,在宁夏六盘山区的华北落叶松人工林,研究了不同大小和单宁含量0%Tannin(T)、2%T、8%T和15%T]的人工种子在模拟结实小年和结实大年对啮齿动物取食和扩散行为的影响.结果表明: 啮齿动物消耗种子速度在结实小年更快,结实大年的种子消耗速度相对缓慢. 种子就地取食率(ISPR)在不同结实年份间无显著差异,扩散后取食率(PRAD)在结实小年显著高于结实大年,但前者的扩散后贮藏率(HRAD)显著低于后者;种子扩散后的取食距离(PDAD)和贮藏距离(HDAD)在结实小年均显著大于结实大年.在结实小年,大种子的PDAD和HDAD均大于小种子,前者在不同大小种子间均差异显著,而后者仅在2%T和15%T的不同大小种子间差异显著;在结实大年,除0%T外的其他单宁含量种子的PDAD和HDAD在不同大小种子间均差异显著.ISPR在中等单宁含量种子最大,高单宁含量种子最小;PRAD分别在结实小年的高单宁含量种子和结实大年的无单宁种子最大;不论在结实大年还是结实小年,HRAD均在高单宁含量种子最大,中等单宁含量种子最小.这说明结实大年可延缓啮齿动物对种子的消耗速率,提高种子的HRAD,但种子扩散距离减小;啮齿动物在结实大年和小年均表现出对大种子的扩散偏好,且大种子被扩散的距离更远;啮齿动物在不同结实年份均偏好于就地取食中等单宁含量种子,而扩散高单宁含量种子.

Effects of seed traits and seed production on the seed predation and dispersal behavior of rodents

To deeply understand the foraging behavioral strategies of the rodents in response to seeds of different sizes and tannin contents under different seed densities and its relationship with plant regeneration, field experiments were conducted to explore the effects of artificial seeds of different sizes (large and small) and tannin (T) contents (0%T, 2%T, 8%T, and 15%T) on seed predation and dispersal behavior of rodents during simulated non-mast and mast seeding year in Larix principis-rupprechtii plantation of Liupan Mountains in Ningxia. The results showed that seeds were consumed rapidly by rodents in non-mast seeding year but relatively slow in mast seeding year. No significant difference of in situ predation rate (ISPR) was observed between non-mast and mast seeding year. The predation rates of seeds after dispersal (PRAD) by rodents in non-mast year were significantly higher than those in mast year, while the hoarding rate of seed after dispersal (HRAD) of the former was significantly lower than the latter. Both seed predation distance after dispersal (PDAD) and hoarding distance after dispersal (HDAD) by rodents in non-mast year were substantially higher than those in mast year. In non-mast year, both PDAD and HDAD of large seeds were longer than those of small seeds. Significant difference of the former was observed between large and small seeds for all tannin content seeds, but significant difference of the latter between large and small seeds was detected only for seeds of 2% and 15% tannin. In mast year, significant difference of PDADs and HDADs between large and small seeds was found in all other seeds of tannin contents except for 0% Tannin seeds. The ISPR maximized in medium tannin seeds and minimized in high tannin seeds. Maximums of PRAD were observed in high tannin seeds in non-mast year and 0% tannin seeds in mast year respectively. High tannin seeds had the highest HRAD while medium tannin seeds had the lowest HRAD in both mast and non-mast year. Our results suggested that mast seeding year could delay the seed consumption rate of rodents and increase the HRAD, but reduce the dispersal distance. Hoarding preference of the rodents on large seeds was demonstrated in both mast and non-mast years and the dispersal distance of large seeds was longer than those of small ones. It is probably that rodents prefer to predate in situ seeds of medium tannin and disperse high tannin seeds during both mast and non-mast years.