The Effects Of Local Variation In Light Availability On Pollinator Visitation,Pollen And Resource Limitation Of Female Reproduction In Hosta Ventricosa

Light availability could have direct effects on reproduction through resource availability,and indirect effects on female reproduction by affecting plant-pollinator interactions.We investigated pollinator visitation and female reproduction success of Hosta ventricosa in Bifengxia in Ya'an,Sichuan and Shan Wang Ping forested farm in Nan chuan,Chongqing.We quantified floral display size,pollinator visitation per flower,resource and pollen limitation of fruit and seed production at adjacent forested patch and open patch of two populations of the perennial herb Hosta ventricosa.The main results were as follows:(1)In BFX population,number of racemes per plant was 2.9± 1.0(SD)and 3.3 ± 1.1(SD)at the forested patch and the open patch;in SNC population,number of racemes per plant was 2.24 ± 0.7(SD)and 2.8 ± 0.8(SD)at the forested patch and the open patch.Plant produced more racemes at the open patch than at the forested patch in both populations.(2)In BFX population,number of flowers per raceme was 22.4 ± 6.3(SD)and 23.9 ± 5.8(SD)at the forested patch and the open patch;in SNC population,number of flowers per raceme was 16.0 ±4.6(SD)and 18.9 ±4.7(SD)at the forested patch and the open patch.Single raceme produced more flowers at the open patch than at the forested patch in both populations.(3)In BFX population,floral display size was 2.3 ± 0.6(SD)and 2.6 ± 0.8(SD)at the forested patch and the open patch;in SNC population,floral display size was 1.9±0.6(SD)and 2.1 ± 0.6(SD)at the forested patch and the open patch.Floral display size was larger at the open patch than at the forested patch in both populations.(4)Display size had a positive effect on pollinator visits per flower in BFX population and no effect in SNC population.(5)Plants at the open patch received about 8 or 11 times more pollinator visits and produced more fruit and seeds per flower than those at the forested patch.(6)Supplemental pollination increased fruit and seed production per flower over natural pollination at the forested patch but not at the open patch in BFX population:fruit and seed per flower were 0.6±0.1(SD)and 10.7± 2.6(SD)under supplemental pollination and were 0.5 ±0.1(SD)and 8.5±2.2(SD)under natural pollination at the forested patch.In SNC population,supplemental pollination did not enhance fruit and seed production at either the forested patch or the open patch;fruit and seed per flower were 0.6±0.1(SD)and 10.3±2.1(SD)under supplemental pollination,and 0.6 0.1(SD)and 10.1±1.9(SD)under natural pollination at the open patch;and were 0.5 ±0.1(SD)and 7.5±1.9(SD)under supplemental pollination and 0.5 ±0.1(SD)and 7.4± 1.9(SD)under natural pollination at the forested patch.(7)Supplementally-pollinated plants at the open patch produced more fruit and seeds per flower than those at the forested patch in both populations.In conclusions,in H.ventricosa,local variation in light conditions could affect pollinator activity and influence female reproduction through resource availability,but differences in the degree of pollen limitation between local habitats were population-specific.