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1. Biomass accumulation in trees and downed wood in northern hardwood forests: Repeated measures of a successional chronosequence in New Hampshire, USA

   https://doi.org/10.1139/cjfr-2023-0060  

   Nash, Joseph M.; Vadeboncoeur, Matthew A.; McGee, Gregory G.; Woodall, Christopher W.; Yanai, Ruth D. (October 2023, Canadian Journal of Forest Research)

   Successional, second-growth forests dominate much of eastern North America; thus, patterns of biomass accumulation in standing trees and downed wood are of great interest for forest management and carbon accounting. The timing and magnitude of biomass accumulation in later stages of forest development are not fully understood. We applied a “chronosequence with resampling” approach to characterize live and dead biomass accumulation in 16 northern hardwood stands in the White Mountains of New Hampshire. Live aboveground biomass increased rapidly and leveled off at about 350 Mg/ha by 145 years. Downed wood biomass fluctuated between 10 and 35 Mg/ha depending on disturbances. The species composition of downed wood varied predictably with overstory succession, and total mass of downed wood increased with stand age and the concomitant production of larger material. Fine woody debris peaked at 30–50 years during the self-thinning of early successional species, notably pin cherry. Our data support a model of northern hardwood forest development wherein live tree biomass accumulates asymptotically and begins to level off at ∼140–150 years. Still, 145-year-old second-growth stands differed from old-growth forests in their live ( p = 0.09) and downed tree diameter distributions ( p = 0.06). These patterns of forest biomass accumulation would be difficult to detect without a time series of repeated measurements of stands of different ages. 

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2. Assessing the Old-Growth Dependency of Two Saproxylic Beetle Species in the Southern Appalachian Mountains

   https://doi.org/10.1093/isd/ixac012  

   Traylor, Clayton R; Caterino, Michael S; Ulyshen, Michael D; Ferro, Michael L; McHugh, Joseph V (May 2022, Insect Systematics and Diversity)

   Lozier, Jeffrey (Ed.)

   Abstract The southern Appalachian Mountains were intensively logged during the early 1900s, leaving little remaining old-growth forest. Much of the region is now second-growth forest, which may not be suitable to specialist saproxylic species. Moreover, if suitable habitat exists, poorly dispersing species may not be able to colonize it. To investigate this, we assessed the distribution and old-growth dependency of two low-mobility saproxylic beetles in Great Smoky Mountains National Park. Using both field surveys and community science data, we found Megalodacne heros (Say 1823) (Coleoptera: Erotylidae) to be limited to lower elevations regardless of disturbance history, while Phellopsis obcordata (Kirby 1837) (Coleoptera: Zopheridae) was restricted to inside or near old-growth forests. Although trees were generally smaller in second-growth, we detected no habitat limitation for P. obcordata: fungal hosts were present in second-growth areas and the beetle was present on trees as small as 11 cm in diameter. This suggests its distribution is shaped by its low dispersal capability and need for temporal continuity of deadwood habitat, therefore qualifying it as an indicator species. For P. obcordata, old-growth acted as refugia during landscape-wide, anthropogenic disturbances in the early 1900s, though we can draw no conclusions about M. heros from our dataset. The difference in sensitivity to human disturbance displayed between species may be linked to their relative dispersal abilities: P. obcordata is entirely flightless while M. heros is capable of some flight. This study highlights the value of using saproxylic invertebrates with limited dispersal ability for assessing impacts from anthropogenic forest disturbances. 

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3. Low Abundance of Three Tick Species in the Piedmont of North Carolina

   https://doi.org/10.1093/jme/tjaa171  

   Seagle, MP; Vierling, MR; Almeida, RJ; Clary, DJ; Hidell, W; Scott, EV; Vargas, C; Smith, KG (August 2020, Journal of medical entomology)

   Multiple species of ticks, including Ixodes scapularis (Say, Ixodida:Ixodidae), Amblyomma americanum (L., Ixodida:Ixodidae), and Dermacentor variabilis (Say, Ixodida:Ixodidae), occur in high and increasing abundance in both the northeast and southeast United States. North Carolina is at the nexus of spread of these species, with high occurrence and abundance of I. scapularis to the north and A. americanum to the south. Despite this, there are few records of these species in the Piedmont of North Carolina, including the greater Charlotte metropolitan area. Here, we update the known occurrence and abundance of these species in the North Carolina Piedmont. We surveyed for ticks using cloth drags, CO2 traps, and leaf litter samples at a total of 79 sites within five locations: Mecklenburg County, South Mountains State Park, Stone Mountain State Park, Duke Forest, and Morrow Mountain State Park, all in North Carolina, during the late spring, summer, and fall seasons of 2019. From these surveys, we had only 20 tick captures, illuminating the surprisingly low abundance of ticks in this region of North Carolina. Our results indicate the possibility of underlying habitat and host factors limiting tick distribution and abundance in the North Carolina Piedmont. 

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4. Active restoration increases tree species richness and recruitment of large‐seeded taxa after 16–18 years

   https://doi.org/10.1002/eap.3053  

   Schubert, Spencer C; Zahawi, Rakan A; Oviedo‐Brenes, Federico; Rosales, Juan Abel; Holl, Karen D (November 2024, Ecological Applications)

   Tropical forest restoration presents a potential lifeline to mitigate climate change and biodiversity crises in the Anthropocene. Yet, the extent to which human interventions, such as tree planting, accelerate the recovery of mature functioning ecosystems or redirect successional trajectories toward novel states remains uncertain due to a lack of long‐term experiments. In 2004–2006, we established three 0.25‐ha plots at 10 sites in southern Costa Rica to test three forest restoration approaches: natural regeneration (no planting), applied nucleation (planting in patches), and plantation (full planting). In a comprehensive survey after 16–18 years of recovery, we censused >80,000 seedlings, saplings, and trees from at least 255 species across 26 restoration plots (nine natural regeneration, nine applied nucleation, eight plantation) and six adjacent reference forests to evaluate treatment effects on recruitment patterns and community composition. Both applied nucleation and plantation treatments resulted in significantly elevated seedling and sapling establishment and more predictable community composition compared with natural regeneration. Similarity of vegetation composition to reference forest tended to scale positively with treatment planting intensity. Later‐successional species with seeds ≥5 mm had significantly greater seedling and sapling abundance in the two planted treatments, and plantation showed similar recruitment densities of large‐seeded (≥10 mm) species to reference forest. Plantation tended toward a lower abundance of early‐successional recruits than applied nucleation. Trees (≥5 cm dbh) in all restoration treatments continued to be dominated by a few early‐successional species and originally transplanted individuals. Seedling recruits of planted taxa were more abundant in applied nucleation than the other treatments though few transitioned into the sapling layer. Overall, our findings show that active tree planting accelerates the establishment of later‐successional trees compared with natural regeneration after nearly two decades. While the apparent advantages of higher density tree planting on dispersal and understory establishment of larger seeded, later‐successional species recruitment is notable, more time is needed to assess whether these differences will persist and transition to the more rapid development of a mature later‐successional canopy. Our results underscore the need for ecological restoration planning and monitoring that targets biodiversity recovery over multiple decades. 

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5. Biodiversity recovery of Neotropical secondary forests

   https://doi.org/10.1126/sciadv.aau3114  

   Rozendaal, Danaë M.; Bongers, Frans; Aide, T. Mitchell; Alvarez-Dávila, Esteban; Ascarrunz, Nataly; Balvanera, Patricia; Becknell, Justin M.; Bentos, Tony V.; Brancalion, Pedro H.; Cabral, George A.; et al (March 2019, Science Advances)

   null (Ed.)

   Old-growth tropical forests harbor an immense diversity of tree species but are rapidly being cleared, while secondary forests that regrow on abandoned agricultural lands increase in extent. We assess how tree species richness and composition recover during secondary succession across gradients in environmental conditions and anthropogenic disturbance in an unprecedented multisite analysis for the Neotropics. Secondary forests recover remarkably fast in species richness but slowly in species composition. Secondary forests take a median time of five decades to recover the species richness of old-growth forest (80% recovery after 20 years) based on rarefaction analysis. Full recovery of species composition takes centuries (only 34% recovery after 20 years). A dual strategy that maintains both old-growth forests and species-rich secondary forests is therefore crucial for biodiversity conservation in human-modified tropical landscapes. 

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