Purposes

Prescribed burning is projected to be adopted more frequently with intensifying climate change; thus, a long-term study is necessary to understand the burning impacts on forest productivity and carbon (C) and nitrogen (N) cycling. Litter fall production rate can be used to indicate burning impacts on forest productivity, whereas N concentration, and C and N isotope composition (δ¹³C and δ¹⁵N) can be used to infer burning impacts on C and N cycling in plant-soil system.

Materials and methods

In this study, the impacts of low-intensity prescribed burning on litter production, N concentration, and C and N isotope compositions were continuously investigated for 6 years at five study sites in a natural eucalypt forest of subtropical Australia.

Results and discussion

Higher leaf litter production rate, N concentration and δ¹⁵N, and lower δ¹³C could be seen shortly after prescribed burning. The higher leaf litter N concentration and lower δ¹³C were likely due to the ease of competition for soil N and moisture from understory vegetation in the short term by prescribed burning. Leaf δ¹⁵N and N concentration were closely correlated, and seasonal changes in leaf litter production rate, δ¹³C and δ¹⁵N were observed. Burning season and related severity might determine the suppression degree of understory vegetation. Time since fire (TSF) was a significant impact factor influencing the litter fall production rate, N concentration, δ¹³C and δ¹⁵N of leaf litter fall for a decade following prescribed burning. However, monthly rainfall and temperature were less consistent in their impacts.

Conclusions

Nitrogen limitation was enhanced by prescribed burning through the removal of litter and understory vegetation in the N poor forest and might be responsible for the long-term burning impacts. Low-intensity prescribed burning might have a long-lasting impact on forest litter productivity in nutrient poor forests in subtropical Australia.

中文翻译：

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在澳大利亚亚热带郊区桉树天然林中，规定的燃烧对枯枝落叶产量，氮浓度，δ13 C和δ15 N的影响

目的

随着气候变化的加剧，预计将更频繁地采用规定的燃烧方法；因此，有必要进行长期研究以了解燃烧对森林生产力以及碳（C）和氮（N）循环的影响。凋落生产速率可以被用于指示对森林生产率燃烧的影响，而N浓度，并且C和N同位素组合物（δ ¹³ C和δ ¹⁵ N）可以被用来推断燃烧在植物的土壤上的C和N循环的影响系统。

材料和方法

在这项研究中，在亚热带澳大利亚天然桉树林中的五个研究地点，连续6年对低强度规定燃烧对凋落物产量，N浓度以及C和N同位素组成的影响进行了连续研究。

结果和讨论

较高的叶垫料的生产速率，N浓度和δ ¹⁵ N，并且降低δ ¹³ C可火烧后不久看到。较高的落叶层N浓度，降低δ ¹³ C水平可能是由于便于通过火烧短期内为土壤氮竞争和水分从下层的植被。叶δ ¹⁵ N和N浓度密切相关，并且在叶子废弃物生产速率季节变化，δ ¹³ C和δ ¹⁵观察ñ。燃烧季节和相关的严重程度可能决定地下植被的抑制程度。因为火（TSF）时间是影响凋落物的生产速度显著影响因子，N浓度，Δ ¹³C和δ ¹⁵叶枯落了十年的N按照规定的燃烧。但是，月降雨量和温度对其影响的一致性较差。

结论

通过去除贫瘠的氮林中的枯枝落叶和林下植被，通过规定的燃烧来增加氮的限制，这可能是造成长期燃烧影响的原因。在澳大利亚亚热带的营养不良森林中，低强度的规定燃烧可能会对森林凋落物生产力产生长期影响。