RESUMO
The Bailongjiang watershed of Gansu is an important water conservation and ecological barrier area in the upper reaches of Yangtze River. It is necessary to reveal the tradeoffs and synergies of ecosystem services (ESs) for the "win-win" of watershed ecological system and social eco-nomy development. Based on the InVEST model, four typical ESs including soil conservation (SC), water conservation (WC), food supply (FS), and habitat quality (HQ) were assessed, and the multi-scale tradeoffs and synergies of ESs and its drivers were analyzed by correlation and root mean square deviation (RMSD). The results showed that there were significant synergies among SC, WC, and HQ, and a significant tradeoff between FS and HQ, SC, WC, respectively. The areas with high tradeoff intensity between the three pairs of synergistic services (SC-WC, SC-HQ, WC-HQ), and between FS and HQ were mainly concentrated in the steep forest area of middle-high mountain in Wenxian, Diebu and Zhouqu. The high intensity of tradeoffs between FS-SC, FS-WC were mainly concentrated in the gentle apricus farming and pastoral areas of middle-low mountain in Tanchang and Wudu. The spatial variation of land use/cover caused by human activities was an important factor affecting the degree of ES tradeoffs and its scale effect.
Assuntos
Conservação dos Recursos Naturais , Ecossistema , China , Florestas , Humanos , SoloRESUMO
The external pollution of Dianchi Lake has been effectively controlled with the implementation of the integrated water environment control project. However, further attention should be paid to endogenous pollutants, such as surface sediments. To investigate the distribution of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments of Dianchi Lake, PAH concentrations in 19 surface sediment samples (collected in December 2016) were quantitatively measured by gas chromatography-mass spectrometry (GC-MS). The spatial and temporal distribution, sources, and ecological risks were also analyzed. The concentration of total PAHs (TPAHs) in the Dianchi Lake surface sediments varied in the range of 92.31-1546.78 ng·g-1 with an average of 496.30 ng·g-1. The average concentration of TPAHs in the surface sediments from Caohai (932.37 ng·g-1) was much greater than that from Waihai (380.02 ng·g-1). With the implement of the integrated water environment control project, the concentration of TPAHs in the surface sediments from Dianchi Lake was significantly lower than those detected in 2012, and was already relatively low level among other key waterbodies in China. The PAH with the highest concentration was fluoranthene (80.65 ng·g-1) and the substance with the highest toxic equivalent quantity (TEQ) was dibenz[a, h] anthracene (42.97 ng·g-1). The PAHs were mainly composed of 4 ring and 5-6 ring compounds (with the concentration ratio of 40.38% and 40.22%, respectively), which indicated that the proportions of middle-ring and high-ring compounds were generally consistent. The results of the molecular diagnostic ratio analysis showed that the primary source of PAHs in Dianchi Lake surface sediments are biomass and coal combustion. Based on the potential ecological risk marker comparison method, the entire lake was classified as having a low ecological risk, while the ecological risk of Caohai was relatively higher, which should be concerned further. The results provide initial data and act as an important reference for the conservation and improvement of water quality in Dianchi Lake.
RESUMO
The potato rot nematode, Ditylenchus destructor, is a very destructive nematode pest on many agriculturally important crops worldwide, but the molecular characterization of its parasitism of plant has been limited. The effectors involved in nematode parasitism of plant for several sedentary endo-parasitic nematodes such as Heterodera glycines, Globodera rostochiensis and Meloidogyne incognita have been identified and extensively studied over the past two decades. Ditylenchus destructor, as a migratory plant parasitic nematode, has different feeding behavior, life cycle and host response. Comparing the transcriptome and parasitome among different types of plant-parasitic nematodes is the way to understand more fully the parasitic mechanism of plant nematodes. We undertook the approach of sequencing expressed sequence tags (ESTs) derived from a mixed stage cDNA library of D. destructor. This is the first study of D. destructor ESTs. A total of 9800 ESTs were grouped into 5008 clusters including 3606 singletons and 1402 multi-member contigs, representing a catalog of D. destructor genes. Implementing a bioinformatics' workflow, we found 1391 clusters have no match in the available gene database; 31 clusters only have similarities to genes identified from D. africanus, the most closely related species to D. destructor; 1991 clusters were annotated using Gene Ontology (GO); 1550 clusters were assigned enzyme commission (EC) numbers; and 1211 clusters were mapped to 181 KEGG biochemical pathways. 22 ESTs had similarities to reported nematode effectors. Interestedly, most of the effectors identified in this study are involved in host cell wall degradation or modification, such as 1,4-beta-glucanse, 1,3-beta-glucanse, pectate lyase, chitinases and expansin, or host defense suppression such as calreticulin, annexin and venom allergen-like protein. This result implies that the migratory plant-parasitic nematode D. destructor secrets similar effectors to those of sedentary plant nematodes. Finally we further characterized the two D. destructor expansin proteins.
