Responses of Fine Root Functional Traits to Soil Nutrient Limitations in a Karst Ecosystem of Southwest China
Responses of Fine Root Functional Traits to Soil Nutrient Limitations in a Karst Ecosystem of Southwest China
复制标题
西南喀斯特生态系统细根功能性状对土壤养分限制的响应
DOI：
10.3390/f9120743
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发表时间：
2018-12-01
期刊：
影响因子：
2.9
通讯作者：
Zhang, Wei
中科院分区：
文献类型：
--
作者：
Pan, Fujing;Liang, Yueming;Zhang, Wei
喀斯特生态系统中，土壤氮、磷的缺乏限制了灌木的生长，而磷的缺乏又限制了树木的生长。根系功能性状的变化是植物应对养分短缺的重要策略。然而，在喀斯特生态系统的这种反应知之甚少。为明确细根功能性状对土壤氮、磷变化的响应，确定其在生态系统中的资源利用策略，测定了细根功能性状的比根长（SRL）、根尖/根生物量（RT/RB）、4种植物细根中N浓度（N-根）（两种灌木（Alchornea trewioides和Ligustrum sinense）和两种乔木（Celtis biondii和Pteroceltis tatarinowii））在旱季（1月）和雨季（7月）。结果表明，灌木细根的SRL、RT/RB和N-根均低于乔木，且湿季高于旱季。线性回归模型表明，总体物种的SRL、RT/RB和N根随着土壤N、P浓度和有效性的增加而增加，并与根际土壤草酸、微生物量碳（C）和水解酶活性的增加正相关。此外，植物个体在这三个细根性状上表现出独特的模式，这是受土壤养分和生物化学变化影响的结果。因此，比根长、根尖比根生物量和细根氮浓度具有种特异性，受季节变化的影响，并与土壤养分和生物化学相关。研究结果表明，优良的根系功能性状提高了喀斯特生态系统植物对养分短缺的耐受能力，并可能表明喀斯特生态系统中乔木植物表现出磷的利用策略，而灌木植物表现出氮的保守策略。
Soil nitrogen (N) and phosphorus (P) shortages limit the growth of shrubs, and P shortage limit the growth of trees in karst ecosystems. Changes in fine root functional traits are the important strategies for plants to respond to such nutrient shortages. However, such responses in karst ecosystems are poorly known. To determine the responses of fine root functional traits to soil N and P changes and define their resource-use strategies in the ecosystem, we tested the specific root length (SRL), root tips over the root biomass (RT/RB), and N concentration (N-root) in the fine roots of four plant species (two shrubs (Alchornea trewioides and Ligustrum sinense) and two trees (Celtis biondii and Pteroceltis tatarinowii)) during the dry (January) and the wet (July) season. The results showed that the SRL, RT/RB, and N-root in the fine roots of shrub species were lower than those of tree species, and the three parameters were higher in the wet season than in the dry season. Linear regression models revealed that the SRL, RT/RB, and N-root of overall species increased with increasing soil N and P concentrations and availabilities, and were positively correlated with increasing rhizosphere soil oxalic acid, microbial biomass carbon (C), and the activities of hydrolytic enzymes. In addition, the individual plant species had unique patterns of the three fine root traits that resulted affected by the change of soil nutrients and biochemistry. Thus, the specific root length, root tips over the root biomass, and N concentrations of fine roots were species-specific, affected by seasonal change, and correlated with soil nutrients and biochemistry. Our findings suggests that fine root functional traits increase the ability of plant species to tolerate nutrient shortage in karst ecosystems, and possibly indicated that a P-exploitative strategy in tree species and an N-conservative strategy in shrub species were exhibited.