The Waite Research Institute and the School of Agriculture, Food and Wine, The University of Adelaide, PMB 1, Glen Osmond, South Australia 5064, Australia; CSIRO Agriculture & Food, Waite Campus, Glen Osmond, South Australia 5064, Australia.
The Waite Research Institute and the School of Agriculture, Food and Wine, The University of Adelaide, PMB 1, Glen Osmond, South Australia 5064, Australia.
Sci Total Environ. 2019 May 10;664:276-282. doi: 10.1016/j.scitotenv.2019.01.316. Epub 2019 Feb 4.
In pine forest litters, decomposition rate is directly affected by the pathway the needle followed to the ground, whether that was via programmed apoptosis and abscission or via stress induced loss through branch damage or tree death. Stress induced losses may occur due to fire damage, which leads to a post-fire litter layer composed of non-senescent debris that fell during or after the event. This study investigates decomposition and nitrogen cycling in soils amended with two litters from Pinus radiata plantations that had different recent fire histories. Litters were incubated in the presence or absence of field collected char for up to 94 days. These soil treatments were analysed for microbial activity (soil respiration) and N pools (microbial, mineral, and potentially mineralisable). Soil and litter treatments were additionally incubated in the presence of ammonium nitrate solution to determine N absorption potential of the litters. Respiration was greatest in soils that received fire affected (FA) litter regardless of the presence or absence of char. Nitrogen pools were largely similar between the control (no litter) treatment and not fire affected (NFA) litter treatments. Measured N pools were exceedingly low (92% of samples <2 μg-N g soil where detected) or not detectable (37% of samples below detection limits) in all FA litter treatments at most times. Char appeared inert throughout and had no effects on microbial activity or nitrogen cycling. This study indicates that fire affected pine litter collected four months post fire has strong N absorption properties with or without the presence of char. The presence of fire affected litter is likely to affect N availability for regeneration of forest growth.
在松林凋落物中，分解速率直接受到针叶落地途径的影响，无论是通过程序性细胞凋亡和脱落，还是通过树枝损伤或树木死亡导致的胁迫诱导损失。胁迫诱导的损失可能是由于火灾造成的，这导致火灾后凋落物层由非衰老的碎屑组成，这些碎屑是在火灾期间或之后掉落的。本研究调查了两种来自辐射松人工林凋落物在添加土壤后的分解和氮循环情况，这两种凋落物具有不同的近期火灾历史。凋落物在存在或不存在野外收集的炭的情况下进行了长达 94 天的培养。这些土壤处理方法用于分析微生物活性（土壤呼吸）和氮库（微生物、矿物和潜在可矿化氮）。土壤和凋落物处理方法还在添加硝酸铵溶液的情况下进行了培养，以确定凋落物的氮吸收潜力。在有或没有炭的情况下，接收受火灾影响（FA）凋落物的土壤中呼吸作用最大。氮库在对照（无凋落物）处理和不受火灾影响（NFA）凋落物处理之间基本相似。在大多数情况下，所有 FA 凋落物处理中的测量氮库都极低（92%的样本中氮含量<2μg-N-g 土壤，其中有检测到的）或无法检测到（37%的样本低于检测限）。炭在整个过程中似乎没有活性，对微生物活性或氮循环没有影响。本研究表明，火灾发生四个月后收集的受火灾影响的松针凋落物具有很强的氮吸收特性，无论是否存在炭。受火灾影响的凋落物的存在很可能影响森林生长再生的氮素供应。
