[A new assessment method for the quality of ecological monitoring data: taking CERN's tree growth dataset as a case].

This paper presented a new and simple assessment method for the quality of ecological monitoring data. This method theorized the associations between the data reliability as an ordinal variable with different number of classes and the data sources such as natural main ecological processes, secondary ecological processes, and extraneous and exotic processes, and offered a new data quality index to estimate the quality of the whole dataset by using the reasonableness ratio of observations. The assessment results provided the reliability class of each dataset, good explanations for outlier (or error data) flagging decisions, and quality value of the whole dataset. The method was applied to assess two tree growth datasets from Chinese Ecosystem Research Network (CERN), and the results demonstrated that the new data quality index could quantitatively evaluate the quality of the tree growth datasets. The new method would facilitate the development of corresponding software.

[Application of indicator species in predicting forest management effect on forest species diversity and community composition].

By using indicator species analysis (ISA) method, this paper studied the feasibility of using indicator species to reflect the responses of species diversity and community composition of subtropical forests in Huitong of China to forest management. Ninety-four significant indicator species from 357 understory species were identified, and a new indicator species dataset (community level) was constructed to examine the association between indicator species dataset and original community dataset, and to evaluate the predictive potential of indicator species in reflecting forest management effect. There existed a strong association between the two datasets (Mantel r = 0.898). The indicator species dataset could well predict the management effect on species diversity (regression analysis, R2 > 0.74) and community composition (ANOVA, F >16.79). When the two datasets were applied to Nonmetric Multi-Dimensional Scaling (NMDS) ordination and K-mean cluster analysis, the indicator species dataset could well identify the forest types with different management treatments, as the original community dataset did. Also, the indicator species dataset nearly played the same role as the original community dataset in identifying the species diversity, community composition, and forest type. It was suggested that for saving costs in overall investigation of forest ecosystem, indicator species could be used as a surrogate of full community to predict forest management effect.

[Short-term effects of understory vegetation removal on nutrient cycling in litter layer of Chinese fir plantation].

A short-term understory vegetation removal experiment was conducted at three experimental sites of Chinese fir (Cunninghamia lanceolata) plantation in Huitong of Hunan Province, South-central China to examine the short-term effects of the absence of understory vegetation on litter decomposition. In the plantation, the standing stock of the litter in L layer (un-decomposed litter), F layer (semi-decomposed litter), and H layer (decomposed litter) under understory intact condition was (123.7 +/- 46.3) g m(-2), (204.2 +/- 79.1) g m(-2), and (187.1 +/- 94.8) g m(-2), and the corresponding nutrient storage was (447.51 +/- 16.75) g kg(-1), (418.89 +/- 35.75) g kg(-1), and (376.11 +/- 47.33) g kg(-1) for carbon, (4.87 +/- 1.24) g kg(-1), (6.4 +/- 2.38) g kg(-1), and (4.66 +/- 2.64) g kg(-1) for nitrogen, and (0.14 +/- 0.01) g kg(-1), (0.16 +/- 0.03) g kg(-1), and (0.16 +/- 0.02) g kg(-1) for phosphorus, respectively. At sites DL87 and MS90, understory vegetation removal had significant effects on the standing stock of litter and the corresponding storage of carbon, nitrogen, and phosphorus in F layer, though the effects varied with sites (e. g., the storage of litter carbon, nitrogen, and phosphorus decreased by more than 55% at DL87 while increased by about 1 time at MS90). Across the three sites, understory vegetation removal had little effects on the standing stock and nutrient storage of the litter in L layer and H layer. In addition, the removal had little effects on the litter decomposition at its early stage, but showed significant inhibitory effects after 150 days elapsed, with the decomposition rate decreased by 20.8%. These results suggested that the short-term effects of understory vegetation removal on the litter nutrient cycling could be depended on the forest site condition and the duration after the understory vegetation removal.

[Impact of heavy snow storm and freezing rain disasters on soil fauna in Chinese fir plantation in southern China].

In January 2008, southern China suffered an unusual heavy snowstorm and freezing rain over a large area for almost a month long. This catastrophic event was the worst one in past 50 years, which brought the area a serious impact on the infrastructure, ecology, and environment. To understand the long-term impact of this catastrophic event on the forest ecosystems in this area, a field investigation was conducted on the soil fauna in a pure Chinese fir plantation and a mixed Chinese fir plantation-alder plantation in Huitong County of Hunan Province on March 23, 2008, the date 40 days after the heavy snowstorm and freezing rain. With the abundance and community composition as the main parameters and the monitoring data from the two plantations on March 23, 2007 as the reference, the flexibility and resistance of soil fauna to the disturbances of the catastrophic event was preliminarily evaluated. The results showed that there was a significant deviation of soil fauna communities in the two plantations from the reference. An outbreak increase in microfauna nematode abundance was found from 12216.9 ind x m(-2) to 118343.9 ind x m(-2) in pure Chinese fir plantation and from 25435.9 ind x m(-2) to 84573.0 ind x m(-2) in mixed Chinese fir plantation-alder plantation, while a 27.0% and 85.6% decrease of macrofauna abundance was found in the two plantations, respectively, compared with the reference. Mesofauna abundance also had a significant decrease in litter layer but not in soil. The abundance recovery displayed a trend from quick rate for microfauna to slow rate for macrofauna, which indicated that the soil fauna functional groups, in terms of body size, could be used as a vulnerable indicator in evaluating disturbance event and post-disturbance recovery. By using community ordinations, no shift in soil fauna community composition was detected 40 days after the catastrophic event, suggesting that the community composition of soil invertebrate had a high resistance to catastrophic snowstorm and freezing rain disturbances.

[Effects of root system and litter of Chinese fir on soil microbial properties].

A simulation test was conducted to study the effects of the root system and litter of Chinese fir (Cunninghamia lancceolata) on soil microbial properties. After the amendment with C. lancceolata root system, the soil microbial biomass C, basal respiration, total organic C, and microbial quotient increased significantly (P < 0.05), while soil metabolic quotient (qCO2) presented an opposite trend. In the treatment amended with C. lancceolata litter, the soil basal respiration and qCO2 decreased significantly (P < 0.05), whereas soil microbial biomass C, total organic C, and microbial quotient had less change. A significant interaction between C. lancceolata root system and litter was observed on soil basal respiration and qCO2. The qCO2 had significant positive correlations with soil total organic C (R2 = 0.209) and dissolved organic C (R2 = 0.325), suggesting that the C use efficiency of soil microbes decreased with increasing soil organic C content. Comparing with litter, the root system of C. lancceolata played more important roles in soil ecological processes.