Nitrogen addition and experimental drought simplified arthropod network
in temperate grassland
Abstract
Changes in species interactions due to species loss are threatening
ecological networks. To explore the responses of arthropod networks to
global changes, we conducted a multifactorial field experiment in
temperate grassland, in which nitrogen (N) deposition, drought and
snowmelt timing were manipulated. We constructed modular networks for
arthropod functional groups and assessed their complexity by
connectance, interaction diversity and interaction strength.
Specifically, the pattern of reduction of network complexity was
different in N and drought conditions: (a) increased foliar N
strengthened single pathway and weakened the net effect of other
pathways in N treatment; (b) filtered plant species and changed
micro-habitats in drought conditions. Whereas delayed snowmelt increased
arthropod abundance only in early spring, but its interaction with N
treatment or drought showed various impacts on functional groups.
Therefore, it is suggested that the co-effect of multiple global change
factors, occurring in different seasons, should be considered as a
panorama.