Abstract: Abstract Invasion by Acacia longifolia alters soil characteristics and processes. The present study was conducted to determine if the changes in soil C and N pools and processes induced by A. longifolia persist after its removal, at the São Jacinto Dunes Nature Reserve (Portugal). Some areas had been invaded for a long time (>20 years) and others more recently (<10 years). For each type of invasion, (i.e., long-invaded and recently invaded), three treatments were used: (1) A. longifolia left intact; (2) A. longifolia was removed; and (3) both A. longifolia and litter layer were removed. Soil samples were collected once a year for four and half years and analysed for chemical and microbial properties. In general, microbial parameters responded faster than C and N pools. In long-invaded areas, two and half years after removal of plants and litter, basal respiration and microbial biomass had already decreased >30%, β-glucosaminidase activity (N mineralization index) >60% and potential nitrification >95%. Removal of plants and litter resulted in a >35% decrease in C and N content after four and half years. In recently invaded areas, β-glucosaminidase activity and potential nitrification showed a marked decrease (>54% and >95%, respectively) after removal of both A. longifolia and litter. Our results suggest that after removal of an N2-fixing invasive tree that changes ecosystem-level processes, it takes several years before soil nutrients and processes return to pre-invasion levels, but this legacy slowly diminish, suggesting that the susceptibility of native areas to (re)invasion is a function of the time elapsed since removal. Removal of the N-rich litter layer facilitates ecosystem recovery.
Abstract: The effect of mechanical clearing and litter removal on control of Sydney golden wattle was studied in areas of Portugal that had been invaded for either long or short periods. The plant species that emerged and soil parameters were monitored to assess the recovery potential and the soil status of these areas after Sydney golden wattle control. More plant species emerged in the plots where mechanical control in combination with litter removal was applied than in nontreated plots or in plots where mechanical control alone was used. More plant species emerged in the recently invaded areas than in those that had been invaded for a long time. More Sydney golden wattle seedlings were found in the long-invaded area than in the recently invaded one. Total litter, nitrogen and carbon content, and beta-glucosaminidase activity were higher in the soil of the long-invaded compared with the recently invaded areas. Regarding the efficacy of the methods used to remove Sydney golden wattle, sprouting was not observed 10 mo after cutting the trees in both areas, although this was not the case in other parallel studies.
Notes: Suppl. S xD;890RI xD;Times Cited:0 xD;Cited References Count:29
