This study examined the temporal variation of the Normalized Difference Vegetation Index （NDVI） and its relationship with climatic factors in the Changbai Mountain Natural Reserve （CMNR） during 2000 - 2009. The re...This study examined the temporal variation of the Normalized Difference Vegetation Index （NDVI） and its relationship with climatic factors in the Changbai Mountain Natural Reserve （CMNR） during 2000 - 2009. The results showed as follows. The average NDVI values increased at a rate of 0.0024 year-1. The increase rate differed with vegetation types, such as 0.0034 year-1 for forest and 0.0017 year-1 for tundra. Trend analyses revealed a consistent NDVI increase at the start and end of the growing season but little variation or decrease observed in July during the study period. The NDVI in CMNR showed a stronger correlation with temperature than with precipitation, especially in spring and autumn. A stronger correlation was observed between NDVI and temperature in the tundra zone （2,000-2,600m） than in the coniferous forest （1,100-1,700m） and Korean pine-broadleaved mixed forest （7oo-1,1oom） zones. The results indicate that vegetation at higher elevations is more sensitive to temperature change. NDVI variation had a strong correlation with temperature change （r=0.7311, p〈0.01） but less significant correlation with precipitation change. The result indicates that temperature can serve as a main indicator of vegetation sensitivity in the CMNR.展开更多
Hybrid speciation is increasingly recognized as a mechanism for novel evolutionary trajectories. However, we know very little about the ecology of a contact zone that has arisen in sympatry. This study examines the fo...Hybrid speciation is increasingly recognized as a mechanism for novel evolutionary trajectories. However, we know very little about the ecology of a contact zone that has arisen in sympatry. This study examines the foraging behavior and fitness of two species of Darwin＇s tree finches （Camarhynchus parvulus, C pauper） and hybrid offspring on Floreana Island. Previous study showed that the percentage of hybrids in the tree finch population increased from 19% in 2005 to 41% in 2010, and their body and beak size increased by -5% （parental phenotype did not change）. In 2005-2006, all three tree finch groups （two paren- tal species and hybrid birds） used the same foraging substrate, technique, and height. By 2010-2013, the small tree finch C. par- vulus had changed its foraging technique and the medium tree finch C. pauper had changed its foraging height. Both parental species had higher body condition when foraging at （divergent） mean foraging heights per species but hybrid birds did not. We discuss the implications of conserving forest to facilitate vertical niche expansion and the role of hybridization for genetic persis- tence [Current Zoology 61 （1）： 181-190, 2015].展开更多
基金supported by the Science and Technology Innovation Platforms Initiative of Northeast Normal University under the project "Ecological Security and Data Assemblage of the Changbai Mountains International Georegion(Project No.106111065202)"the National Grand Fundamental Research 973 Program of China (Project No.2009CB426305)
文摘This study examined the temporal variation of the Normalized Difference Vegetation Index （NDVI） and its relationship with climatic factors in the Changbai Mountain Natural Reserve （CMNR） during 2000 - 2009. The results showed as follows. The average NDVI values increased at a rate of 0.0024 year-1. The increase rate differed with vegetation types, such as 0.0034 year-1 for forest and 0.0017 year-1 for tundra. Trend analyses revealed a consistent NDVI increase at the start and end of the growing season but little variation or decrease observed in July during the study period. The NDVI in CMNR showed a stronger correlation with temperature than with precipitation, especially in spring and autumn. A stronger correlation was observed between NDVI and temperature in the tundra zone （2,000-2,600m） than in the coniferous forest （1,100-1,700m） and Korean pine-broadleaved mixed forest （7oo-1,1oom） zones. The results indicate that vegetation at higher elevations is more sensitive to temperature change. NDVI variation had a strong correlation with temperature change （r=0.7311, p〈0.01） but less significant correlation with precipitation change. The result indicates that temperature can serve as a main indicator of vegetation sensitivity in the CMNR.
文摘Hybrid speciation is increasingly recognized as a mechanism for novel evolutionary trajectories. However, we know very little about the ecology of a contact zone that has arisen in sympatry. This study examines the foraging behavior and fitness of two species of Darwin＇s tree finches （Camarhynchus parvulus, C pauper） and hybrid offspring on Floreana Island. Previous study showed that the percentage of hybrids in the tree finch population increased from 19% in 2005 to 41% in 2010, and their body and beak size increased by -5% （parental phenotype did not change）. In 2005-2006, all three tree finch groups （two paren- tal species and hybrid birds） used the same foraging substrate, technique, and height. By 2010-2013, the small tree finch C. par- vulus had changed its foraging technique and the medium tree finch C. pauper had changed its foraging height. Both parental species had higher body condition when foraging at （divergent） mean foraging heights per species but hybrid birds did not. We discuss the implications of conserving forest to facilitate vertical niche expansion and the role of hybridization for genetic persis- tence [Current Zoology 61 （1）： 181-190, 2015].
