EFFECTS OF THE TIMING OF MULTIPLE GRAZINGS BY GEESE ON NET ABOVE-GROUND PRIMARY PRODUCTION OF SWARDS OF PUCCINELLIA PHRYGANODES
EFFECTS OF THE TIMING OF MULTIPLE GRAZINGS BY GEESE ON NET ABOVE-GROUND PRIMARY PRODUCTION OF SWARDS OF PUCCINELLIA PHRYGANODES
复制标题
鹅多次放牧时间对柄茅草地上净初级生产力的影响
DOI：
10.2307/2260663
复制
发表时间：
1991
影响因子：
5.5
通讯作者：
R. Jefferies
中科院分区：
文献类型：
--
作者：
D. Hik;H. A. Sadul;R. Jefferies
（1）研究了圈养小雪雁雏鹅多次放牧（包括投喂粪便）的频率和时间对草地净初级生产力（NAPP）和草地上部氮含量的影响。修剪和氮的影响，在盆中的个别分蘖的这种草的生长也进行了研究，在析因实验设计，以分离每个处理的效果。这两项调查的实验设计是密切的基础上，对碱茅草地上的大雁觅食行为。(2)剪叶本身模仿了野生鸟类吃草的枝条的叶人口统计学，对枝条生长和NAPP产生了不利影响。营养物质的添加改善了修剪对新梢生长的不利影响。植物收到的营养，但其叶子没有修剪，产生地上生物量最高。(3)1987年夏天，在大雁离开沼泽地后，每12天（1 ~ 6次）或每24天（2 ~ 3次）或每隔12天（3次）放牧一次碱茅。地块放牧3次，间隔12天，从6月下旬到8月上旬期间的地上生物量的快速增长最密切地模仿觅食行为的大雁。(4)1987年的季节性累积NAPP显着较高的地块放牧三次比未放牧的地块，地块放牧一次，或地块放牧反复整个赛季。在1988年的地块没有放牧和类似的趋势，在NAPP得到的，除了在1987年的季节晚些时候放牧的地块的NAPP是低的。如果草地要从落叶的影响中恢复过来，野鹅在8月初离开可能是必要的。(5)在1987年的夏天，牧草质量（N含量）和NAPP一起最高的地块放牧三次，间隔12天-最接近的野生鸟类的觅食模式的治疗。在7月的第二个夏天拍摄氮含量没有不同的封闭的地块，无论在1987年的治疗，所有的值都低于从相邻的草地放牧和野鹅施肥的拍摄。(6)结果表明，NAPP对牧草的营养品质有明显的影响，
SUMMARY (1) The effects of the frequency and timing of multiple grazings (including faecal input) by captive goslings of the lesser snow goose on net above-ground primary production (NAPP) and shoot nitrogen content of swards of the forage grass, Puccinellia phryganodes were examined. The effects of clipping and addition of nitrogen on the growth in pots of individual tillers of this grass were also investigated in a factorial experiment designed to separate the effects of each treatment. The experimental design of both investigations was closely based on the foraging behaviour of wild geese on Puccinellia swards. (2) The clipping of leaves per se which mimicked the leaf demography of shoots grazed by wild birds had a detrimental effect on shoot growth and NAPP. Addition of nutrients ameliorated the adverse effects of clipping on shoot growth. Plants which received nutrients, but whose leaves were not clipped, produced the highest amount of above-ground biomass. (3) During the summer of 1987 plots of Puccinellia were either grazed once every 12 days (one to six occasions), or once every 24 days (two or three occasions), or on three occasions at intervals of 12 days late in the season after the wild geese had left the marsh. Plots grazed on three occasions at intervals of 12 days from late June to early August during the period of rapid growth of above-ground biomass most closely mimicked the foraging behaviour of the wild geese. (4) Seasonal cumulative NAPP in 1987 was significantly higher in plots grazed on three occasions than in ungrazed plots, plots grazed once, or plots grazed repeatedly throughout the season. In 1988 plots were not grazed and a similar trend in NAPP was obtained, except that the NAPP of plots grazed late in the season in 1987 was low. The departure of wild geese in early August may be necessary if swards are to recover from the effects of defoliation. (5) During the summer of 1987, forage quality (N content) and NAPP together were highest in plots grazed on three occasions at intervals of 12 days - the treatment closest to the foraging pattern of wild birds. In July of the following summer shoot nitrogen content did not differ among the exclosed plots, irrespective of the treatment in 1987, and all values were lower than that for shoots from adjacent swards which were grazed and fertilized by wild geese. (6) The results show that NAPP and the nutritional quality of forage are de