DOI: 10.5061/dryad.63xsj3v43
title: Effects of time since invasion and control actions on a coastal ecosystem invaded by non-native pine trees

description: Invasive non-native trees cause structural and functional changes in plant
 communities, which tend to increase over time since invasion. Native
 vegetation responses after control operations provide important
 information for restoration. We evaluated the effects of time since
 invasion and of pine control on plant community structure and on
 functional traits in a coastal open ecosystem in southern Brazil. We
 compared richness, diversity, abundance and cover of woody and non-woody
 native plant species, as well as species composition and
 community-weighted means (CWM) based on functional traits (dispersal
 syndrome, fruit type, maximum height, and shade tolerance) of plant
 communities, in four conditions: a non-invaded area, an area where pines
 were controlled (managed area), an area of recent invasion, and an area
 invaded longer ago. Woody species abundance, richness and diversity
 declined over time since invasion. However, while abundance recovered to
 the point of not differing from the non-invaded condition in areas where
 pines were controlled, species diversity and richness were lower in the
 managed area than in the area that was never invaded. The effects of pine
 invasion on richness and diversity of non-woody plants did not increase
 over time, but plant cover progressively diminished. Woody and non-woody
 species composition varied between the four conditions. Species
 composition similarity was lower between conditions for non-woody than for
 woody species. CWM differed between the older invasion and the other
 conditions, determined especially by native plant height and shade
 tolerance. Taller plants and more shade tolerant native species were
 exclusively sampled in the older invasion. Synthesis and application. Pine
 invasion reduced species abundance, plant cover, richness, and diversity,
 altering the composition of plant community. The escalation of negative
 temporal effects of pine invasion was observed on the composition of woody
 and non-woody species and on functional traits. Although pine control
 favored the natural regeneration of non-woody species, diversity of woody
 species in the area submitted to pine control was lower than in the
 non-invaded condition. Restoration activities are therefore required to
 increase woody species diversity. These results provide relevant guidance
 for the restoration of coastal ecosystems following invasive pine control.
description: Data collection was conducted
 between August and October, 2018, in four areas between sand dunes with
 similar environmental characteristics. Four conditions were
 evaluated:
 A) area not invaded by
 <em>P. eliottii</em>, defined as non-invaded (NI – 0.075 ha);
 B) area previously invaded, where pines were managed in 2013, defined as
 managed area (MA – 0.075 ha); C) area invaded more recently, defined as
 recent invasion (RI – 0.025 ha); and D) area invaded for a longer time,
 defined as older invasion (OI – 0.050 hectares) (Figure 1). The total area
 of plots was 0.225 hectares. All plots and subplots were set up in areas
 between sand dunes where the original vegetation was characterized by
 herbs and shrubs (Guimarães, 2006).
 The NI condition represents
 the control area – i.e., what the other areas would look like if pines had
 not invaded (Figure 1A).
 In the MA condition, seedlings were pulled out (&lt; 50 cm height) and
 juveniles (&gt; 50 cm height) and adults cut down in 2013 - in other
 words, every pine tree or seedling was removed (Dechoum et al., 2019). All
 residue of control was left in the area to degrade (Figure 1B). The
 estimated number of pines eliminated, including adults, juveniles, and
 seedlings in the area, was 16,000 (ca. 114 pines/ha) (Dechoum et al.,
 2019). In the RI
 condition, the herb-shrub physiognomy is still dominant, and the majority
 of pines consist of seedlings and small to medium size juveniles, as well
 as some scattered adults (Figure 1C). The forest physiognomy in the OI condition is dominated by adult pines, with
 scattered native shrubs and low herb cover (Figure 1D). There were no pine
 seedlings, only a few juvenile trees. None of the invaded areas (RI and
 OI) had been subjected to previous conversion and/or other management
 intervention. We postulate that the difference in time since invasion is a
 consequence of density and age of adult pines planted
 in private properties in
 the park surroundings (see subitem 2.1). In other words, there was a
 higher density of larger/older adult trees in private areas closer to the
 OI condition compared with the RI condition.
 Ninety 5 x 5 m plots were set
 up in the four conditions. Conditions NI and MA comprised 30 plots each,
 10 plots were set up in RI and 20 in OI. The minimum distance between plots was 20
 meters. The number of plots varied due to the size of the areas in each of
 the four conditions. All native woody plants above 1 meter in height
 were identified and had their height measured in each plot. Four subplots
 measuring 1 x 1 m were set up at the vertices of each plot, totaling 360
 subplots. All plants
 between 0.1 and 1 m in height were identified at the species level
 (whenever possible) and categorized as “woody” or “non-woody”. Plants not
 identified in the field were collected for later identification with
 identification keys and taxonomic references, or with support from
 experts. Among the specimens not identified at the genus or species level,
 most are in family Poaceae (grasses), which are very hard to distinguish
 if not fertile, or in families Myrtaceae and Lauraceae, which are two of
 the richest woody species families along the Brazilian coast, therefore
 often hard to identify from sterile material (see Appendix
 1). Percentage of plant cover by woody and non-woody
 species and class of soil exposure were also measured in the
 subplots. The proportion
 of soil without live plant cover in the subplots was classified as exposed
 soil. Percentage of cover
 was divided in the following classes: Class 1: 0 a 5% (2.5%); Class 2: 5
 to 15% (10%); Class 3: 15 to 25% (20%); Class 4: 25 to 50% (37.5%); Class
 5: 50 to 75% (62.5%) e
 Class 6: 75 to 100% (87.5%) (Assumpção & Nascimento, 2000).
 Median values were used in
 statistical analyses. All pines in the RI and OI plots were counted
 and the perimeter at ground level (PGL) of all trees with PGL ≥ 25 cm was
 measured. All the stumps
 remaining after pine control in MA were counted and classified in two size
 classes: trees with PGL ≥ 25 cm (adults) and trees with PGL &lt; 25 cm
 (juveniles). All woody species taller than 1 m in the plots
 were classified according to four functional traits: (1) dispersal
 syndrome: anemochory (wind), zoochory (animals) or autochory
 (self-dispersed); (2)
 fruit type: dry dehiscent or indehiscent, fleshy dehiscent or indehiscent;
 (3) maximum height of woody plants measured in the plots; and (4) shade
 tolerance: tolerant or intolerant. These four functional traits were
 selected from scientific literature (Reitz, 1965; van der Pijl, 1982;
 Carvalho, 2003, 2008, 2010; Lorenzi, 2009; Pires et al., 2009; Seubert et
 al., 2017; Flora do Brasil, 2020).