| Caragana microphylla Lam.is a wind and sand-fixing plant that is not only an important wind-fixing plant in the northwestern desert,but also an important forage economic plant.Kytorrhinus immixtus,Etiella zinckenella and Bruchophagus neocaraganae are the main pests of Caragana seeds.Patterns and processes are important paradigms of ecology,processes produce patterns,and patterns act on processes.To correctly understand the relationship between the pattern and the process,it must be recognized that it depends on the characteristics of the scale,namely the scale effect.Scale effect is one of the hotspots in landscape ecology.In this paper,the Caragana forest land planted under the desert landscape was selected in Gaoshawo,Yanchi,Ningxia.The plot area was 200×200m.According to the sample of 10m×10m,(30 Caragana pods were randomly picked in each sample.3 times).Conduct indoor stripping and artificial feeding experiments,and count the number of pests,carnivorous natural enemies,pods,and soybeans in the range of 20×20 m to 200x200 m,and study with sampling scales.Changes,the number of pests,the damage rate,and the diversity of parasitic natural enemies varied,and explored the spatial scale effect of Caragana species pests and parasitic natural enemies.The main results and conclusions are as follows:(1)The spatial variation of the number of pests and the damage rate of Caragana has significant scale effectBy establishing 19 area gradients,using traditional statistical methods to study the pests and damage rate of Caragana under this area gradient,and fitting the functional relationship between the number and damage rate of Caragana species and the sampling scale.The results showed that the number and damage rate of Kytorrhinus immixtus decreased gradually with the sampling scale,and then increased gradually.At 10000 m2.the number and the damage rate were the lowest.The number and damage rate of Etiella zinckenella were not obvious with the change of sampling scale,and the quantitative distribution was more concentrated.The number and damage rate of Bruchophagus neocaraganae first increased and then decreased with the increase of sampling scale,and it was the largest at 5000m2.(2)The diversity of natural enemies and the spatial variation of species number of Caragana seed pests have significant scale effects.For the 19 area gradients,the species-area relationship is fitted by the power function model,the logarithmic function model and the logistic model in the species-area relationship,and the best model is tested by the AIC value.The results show that the logistic model has the lowest AIC value,which is the optimal model.In the process of increasing area,the number of species and diversity index increase gradually,and the number of species is the largest at 5000m2,indicating that the caragana species are pests.Parasitic natural enemies are dependent on changes in scale.(3)The spatial distribution pattern of Caragana seed pests and natural enemies has significant scale effectBased on the geostatistics,the spatial variation and distribution pattern of the natural pests and natural enemies of Caragana were studied at different scales.It studied about different scales of nugget,range and sill.The number of Kytorrhinus immixtus,the number of Bruchophagus neocaraganae,the number of three species of Caragana seed pests and the number of parasitic natural enemies of the species of pests showed a significant scale effect,and the number of Etiella zinckenella was less dependent on the scale.Caragana seed pests-natural enemies have a certain scale effect and their space changes with the sampling scale,and parasitic natural enemies have a certain follow-up effect on the three seed of pests. |
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