Ground‐dwelling arthropod responses to succession in a pinyon‐juniper woodland

Abstract

Abstract. Stand-replacing wildfire is an infrequent but important disturbance in southwestern pinyonjuniper woodlands. A typical successional cycle in these woodlands is approximately 300 years or more after a stand-replacing fire. Arthropods, especially ground-dwelling taxa, are one of the most abundant and diverse fauna in terrestrial ecosystems and are typically responsive to microhabitat change. Little is known regarding community responses of ground-dwelling arthropods to changes in woodland successional stages from early ecosystems dominated by grasses, herbaceous plants, and fire adapted shrubs to tree-dominated old-growth ecosystems. In 2007 and 2008, within Mesa Verde National Park, Colorado, we compared the community composition of ground-dwelling arthropods between old-growth pinyon-juniper stands that were 300-400 years old and early successional areas recovering from a standreplacing fire in 2002. The 2002 fire eliminated the dominant woody vegetation, which was replaced by increased herbaceous vegetation and bare ground. The early successional arthropod community showed a significantly higher abundance in major arthropod taxonomic groups, except spiders, compared to oldgrowth woodland. Old-growth species richness was greater in late August-September, 2007 and greater in early successional habitats during April-July, 2008. Spatial variability of the habitat was much greater in the recently burned early successional plots than the old-growth late successional plots. The differences in habitat were strongly correlated with arthropod community composition, suggesting that ground-dwelling arthropods are very sensitive to habitat changes. Habitat affiliation was strong, with 83% (early succession ruderal) and 91% (old-growth woodland) of the species found primarily or exclusively in one habitat. Many habitat indicator species (defined as species found in significantly greater abundance in one habitat) were found in both burned and old-growth habitats. Several species were found to be strict specialists exclusive to only one of these habitats. Collectively, the results suggest that heightened concern over loss of old-growth woodlands is warranted, given the distinct nature of the ground-dwelling arthropod community in old-growth habitats.

Ant communities in native sage scrub, non-native grassland, and suburban habitats in Los Angeles County, USA: conservation implications

“…Using the trap design employed by Higgins (2010), pitfall traps were constructed so they could remain in the field for 2 weeks between charging of a trap and collection of specimens. Each pitfall trap consisted of a heavy Pyrex glass ''test tube'' (3.2 cm diameter, 25 cm deep) inserted in a PVC sleeve (3.8 cm in diameter, 28 cm long) buried in the ground.…”

Ground-Dwelling Arthropod Community Responses to Recent and Repeated Wildfires in Conifer Forests of Northern New Mexico, USA

“…Finally, in the DM + LC fire group, Solenopsis ants were significantly related to the understory characteristics with an R 2 = 0.93. The relationship of Carabid beetles and two genera of Formicidae to the understory characteristics tested joins a number of reports of the post-fire environmental characteristics affecting these groups [28,56,[80][81][82][83].…”

“…Previous work in mixed-conifer forests subjected to prescribe fire [80] and piñon-juniper woodlands affected by wildfire [56] indicates that burning tends to increase the proportion of indicator arthropod taxa. We found similar overall ranges in indicator values as those in these studies, but found a smaller proportion of taxa to be significant indicators following wildfire compared to Higgins et al [56].…”

“…Previous work in mixed-conifer forests subjected to prescribe fire [80] and piñon-juniper woodlands affected by wildfire [56] indicates that burning tends to increase the proportion of indicator arthropod taxa. We found similar overall ranges in indicator values as those in these studies, but found a smaller proportion of taxa to be significant indicators following wildfire compared to Higgins et al [56]. Possible explanations for this difference are: (a) some of our sampling was completed in sites with more time to recover since fire; (b) we lumped our arthropods into higher taxonomic groupings than Higgins et al, thereby obscuring some species-level information regarding habitat preference; (c) our study covers gradients of fire severity and areas with high pre-fire environmental heterogeneity within each fire group that collectively introduced variation and led to a greater overlap in the post-fire environmental conditions among groups; and (d) stochastic community assembly processes are important drivers Forests 2019, 10, 667 9 of 15 across this landscape, leading to a reduced role of environmental filtering and niche-matching in determining the ground-dwelling arthropod community structure.…”

“…More recently, fire suppression has greatly lengthened fire return intervals with high-severity fires, especially repeated burns over relatively short periods, which have promoted shifts from pine-dominated and mixed-conifer forests toward communities of shrubs and grasses across the southwest [49][50][51][52]. Studies of wildfire effects on ground-dwelling arthropods in this region remain rare, but evidence indicates that changes in litter and fuel characteristics due to wildfires can impact ground-dwelling arthropod communities in pinyon-juniper woodlands [56]. Yet how wildfires affect arthropod communities in other southwest forest types remains unclear.…”