CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan 666303, China; Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Yunnan 666303, China.
CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan 666303, China; Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Yunnan 666303, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2021 Mar 1;758:143619. doi: 10.1016/j.scitotenv.2020.143619. Epub 2020 Nov 12.
Litterfall helps maintaining primary production and nutrient cycling in forest ecosystems. However, few studies have investigated long-term characteristics of litterfall in tropical karst and non-karst forests co-occurring in the same region. A 10-year comparative study was conducted to estimate the biomass, litter accumulation, turnover rate, nutrient return and nutrient use efficiency associated with litterfall in a karst forest (KF) and a nearby non-karst forest (NKF) in northern tropical China. Significant spatial-temporal variation was observed in monthly and annual litterfall biomass in the two forests. Annual mean litterfall biomass in KF (9.75 Mg ha year) was obviously lower than that in NKF (10.49 Mg ha year). The litterfall biomass in NKF was significantly correlated with maximum air temperature, wind speed and total solar radiation, whereas that in KF was significantly correlated with relative humidity, wind speed and low temperature. Average stand litter in KF (2.92 Mg ha year) was significantly higher than that in NKF (2.38 Mg ha year). Stand litter mostly occurred during the cool and dry season, which coincided with litterfall input and exhibited bimodal pattern. Turnover rate was 1.3 time higher in NKF than in KF, suggesting that litter decomposed slowly in karst habitats. Distinct temporal dynamic and significant differences were observed in chemical composition of litterfall between KF and NKF. Total amounts of C, P, K and total nutrients returned to the topsoil in KF were significantly lower than those in NKF. The KF exhibited relatively high P and K use efficiency because of their low availability in karst soils. Compared with the non-karst habitat, the tropical karst habitats are more likely to develop a plant community with certain nutrient concentrations of litterfall and with a nutrient cycling mechanism that is well-adapted to harsh and heterogeneous condition.
凋落物有助于维持森林生态系统的初级生产力和养分循环。然而，很少有研究调查在同一地区共存的热带喀斯特和非喀斯特森林中长期凋落物的特征。在中国北方热带地区，进行了一项为期 10 年的对比研究，以估计喀斯特森林（KF）和附近非喀斯特森林（NKF）中与凋落物相关的生物量、凋落物积累、周转率、养分归还和养分利用效率。在这两个森林中，每月和每年的凋落物生物量都存在明显的时空变化。KF 的年平均凋落物生物量（9.75 Mg ha year）明显低于 NKF（10.49 Mg ha year）。NKF 的凋落物生物量与最高空气温度、风速和总太阳辐射显著相关，而 KF 的凋落物生物量与相对湿度、风速和低温显著相关。KF 的平均林分凋落物（2.92 Mg ha year）明显高于 NKF（2.38 Mg ha year）。林分凋落物主要发生在凉爽和干燥的季节，与凋落物的输入相吻合，并呈双峰模式。NKF 的周转率比 KF 高 1.3 倍，表明在喀斯特生境中凋落物分解缓慢。KF 和 NKF 的凋落物化学组成表现出明显的时间动态和显著差异。KF 归还到表土的 C、P、K 和总养分总量明显低于 NKF。由于喀斯特土壤中 P 和 K 的可用性较低，KF 表现出相对较高的 P 和 K 利用效率。与非喀斯特生境相比，热带喀斯特生境更有可能形成具有一定凋落物养分浓度和适应恶劣、非均一条件的养分循环机制的植物群落。
