Growth and nutrient content of perennial grasslands following burning in semi-arid, sub-tropical Australia
Growth and nutrient content of perennial grasslands following burning in semi-arid, sub-tropical Australia
复制标题
DOI：
10.1023/a:1021253600712
复制
发表时间：
2003-02-01
期刊：
影响因子：
1.7
通讯作者：
Adams, MA
中科院分区：
文献类型：
--
作者：
Bennett, LT;Judd, TS;Adams, MA
火通常会增加生产力的多年生草丛草地在中温带环境，但可以减少生长一个或多个生长季节在干旱和半干旱环境。我们研究的影响，单烧伤的生长和养分含量的草地在亚热带，澳大利亚西北部。这些草原以Themeda triandra为主，这是一种在潮湿的温带和热带地区经常通过定期燃烧来管理的物种。烧伤是在旱季后期，并复制使用小块（5 × 5米）在两个网站的围栏区域内。总投影覆盖和地上生物量显着减少燃烧后，尽管四个生长季节，包括第一个夏天，高于平均降雨量的2.5年，相对于控制燃烧地块。在第二年，延长干燥期阻碍了烧毁地块的恢复，表明在随后的季节降雨量在确定半干旱环境中的草原烧后生产力的第一个季节降雨量一样重要。更大的减少草覆盖在燃烧的地块在延长干燥期可能是由于站立死亡和凋落物比对照组少，因此，从极端的夏季温度绝缘，虽然覆盖变化和覆盖之间的关系在此期间的开始是弱的。除了附近的草丛pH值增加，燃烧的影响不大，在第一周的表层土壤的化学特性。N，特别是P，在地上植物材料的浓度更大的燃烧后4个月，夏季降雨后，燃烧的地块，但无论是小于或类似于那些在控制日益干燥的条件。显着较低的浓度的P在绿色叶子燃烧地块在旱季，从土壤池中的吸收将是最小的，表明燃烧减少P从植物商店的再转运。然而，我们没有发现任何证据表明，单烧增加营养限制生长，因为植物的N和P含量是可比的燃烧和控制地块在充足的供水期间。我们的数据支持以前的概括，规定燃烧的多年生草丛草地在半干旱环境中，大多是不必要的，因为假定的好处，提高生产力和饲料质量，更mesic环境的特点，没有实现。
Fire often increases the productivity of perennial tussock grasslands in mesic environments but can reduce growth for one or more growing seasons in arid and semi-arid environments. We examined effects of single-burns on growth and nutrient content of grasslands in sub-tropical, northwestern Australia. These grasslands were dominated by Themeda triandra, a species often managed by regular burning in wetter temperate and tropical zones. Burns were in the late dry season and were replicated using small plots (5 x 5-m) within fenced areas at two sites. Total projective cover and aboveground biomass were significantly less in burnt plots relative to controls for 2.5 years after burning despite four growing seasons, including the first summer, of above-average rainfall. Recovery of burnt plots was hindered by an extended dry period in the second year, demonstrating that rainfall in subsequent seasons can be as important as rainfall in the first season in determining post-burn productivity of grasslands in semi-arid environments. Greater decreases in grass cover in burnt plots during the extended dry period may have been due to less standing dead and litter than controls, and therefore less insulation from extreme summer temperatures, although relationships between cover changes and cover at the start of the period were weak. With the exception of increased pH near grass tussocks, burning had little effect on chemical characteristics of surface soils in the first week. Concentrations of N, and particularly P, in aboveground plant material were greater in burnt plots four months after burning, following summer rains, but were either less than or similar to those in controls with increasingly dry conditions. Significantly lower concentrations of P in green foliage from burnt plots during dry seasons, when uptake from soil pools would be minimal, indicated that burning decreased P retranslocation from plant stores. However, we found no evidence that single-burns increased nutrient limitations to growth because plant contents of N and P were comparable in burnt and control plots during periods of adequate water supply. Our data support previous generalizations that prescribed burning of perennial tussock grasslands in semi-arid environments is mostly unnecessary because putative benefits of increased productivity and forage quality, characteristic of more mesic environments, were not realized.