Data from: Urbanisation and agricultural intensification modulate plant-pollinator network structure and robustness

Land use change is a major pressure on pollinator abundance, diversity,
and plant-pollinator interactions. Far less is known about how land use
alters the structure of plant-pollinator networks and their robustness to
plant-pollinator coextinctions. We analyzed the structure of
plant-pollinator networks sampled in 12 landscapes along an urbanisation
and agricultural intensity gradient, from early spring to late summer
2021, and used a stochastic coextinction model to correlate
plant-pollinator coextinction risk with network structure (species and
network-level metrics) and landscape context. Networks in intensively
managed (i.e. agricultural and urban) landscapes had a lower risk of
initiating a coextinction cascade, while networks in less-intensively
managed landscapes may be less robust. Network structure modulated the
frequency and severity of coextinctions and species loss, while the
strength of species interactions increased robustness. Urban networks were
more species-rich and symmetrical due to the high diversity of ornamental
plants, while intensively managed agricultural landscapes had smaller,
more tightly connected, and nested networks. Network structure modulated
the frequency of extinctions, which was decreased by greater linkage
density, interaction asymmetry, and interaction dependence in the
networks, while once an extinction occurred, nestedness and linkage
density propagated the degree of the coextinction cascade and species
loss. At the species level, species strength was inversely correlated with
extinction risk, implying that generalist species with a high number of
interactions with specialists had the lowest extinction risk.

土地利用变化是影响传粉者丰度、多样性及植物-传粉者互作的主要压力因素。然而，关于土地利用如何改变植物-传粉者网络（plant-pollinator networks）的结构及其对植物-传粉者共灭绝事件的稳健性，目前所知甚少。2021年春初至夏末期间，我们沿城市化与农业集约化梯度选取12个景观样区，分析了其中植物-传粉者网络的结构；并采用随机共灭绝模型（stochastic coextinction model），将植物-传粉者共灭绝风险与网络结构（物种及网络水平指标）及景观背景关联起来。集约化管理景观（即农业与城市景观）中的网络启动共灭绝级联的风险较低，而低集约化管理景观中的网络稳健性可能更弱。网络结构调控着共灭绝事件及物种丧失的频率与严重程度，而物种互作强度则提升了网络稳健性。城市网络因观赏植物多样性较高而具有更丰富的物种及对称性；而集约化管理农业景观中的网络规模更小、连接更紧密且呈嵌套结构。网络结构调控着灭绝事件的频率：网络中更高的连接密度、互作不对称性及互作依赖性可降低灭绝频率；而一旦发生灭绝，嵌套性与连接密度则会加剧共灭绝级联的程度及物种丧失。在物种水平上，物种强度与灭绝风险呈负相关，这意味着与专性物种存在大量互作的广性物种具有最低的灭绝风险。