Aim Determining how differences in time of germination can affect plant establishment in plant communities that, after a disturbance, must reestablish from seeds under climatic conditions subject to extremes, such as the Mediterranean. Although early germination may be beneficial for survival in summer, when drought is severe, this may expose the seedlings to winter extremes, thus to higher mortality. Understanding how sensitive is the establishment of different species to temporal patterns of germination will help to understand the factors that control species distribution and community stability in disturbance-prone environments, as well as its sensitivity to changes in weather patterns as climate changes.Methods An experimental fire was made in early fall in an old Cistus-Erica shrubland in Toledo (central Spain). After fire, germination, survival and growth of the three dominant seeder species (Cistus ladanifer, Erica umbellata and Rosmarinus officinalis) were monitored during the first 3 years after fire. Seedlings were tagged to identify their time of emergence, and divided into cohorts according to their month of germination. Differences in survival of the various cohorts were evaluated by means of a Wilcoxon (Gehan) statistic. Height of surviving, tagged plants was compared among cohorts by means of a KolmogorovSmirnov test.Results The year following fire was one of the driest on record, while the next one was one of the wettest. Germination was more abundant during the first than during the second year. Establishment was mainly from first-year germination, as the majority of second-year germinated seedlings died. Temporal patterns of germination within a year and between years varied between species. Seedling mortality was highest immediately following germination, not in summer. Mortality was related to time of germination: during a given period of time, the mortality of younger seedlings was higher than that of older ones. However, survival was not highest for the first cohorts. In general, the earlier the seedlings germinated the more vigourous they became, more clearly so for Cistus than for Rosmarinus, but differences tended to disappear with time. Overall, time of germination varied between species and affected differently seedling survival and vigour of the various species. Rosmarinus and Cistus had sufficient survivors to reestablish the initial population. Erica, despite abundant germination, suffered a strong population reduction.Main conclusions Mediterranean shrub species differ in their temporal patterns of germination and survival after fire. The effect of time of germination is complex: germinating early is advantageous since old seedlings fared better than younger ones when confronted with the same rigours. However, germinating early might expose the seedlings to greater hazards and the first cohort might not survive best.

Summary• Lignotuberous plants store carbohydrates and mineral nutrients within the lignotuber. Resprouting vigour may depend on stored reserves, as well as on the availability of soil mineral nutrients and water.• Here the role played by plant reserves and soil resources on the resprouting response of Erica australis was analysed after clipping plants in 13 different stands, varying in soil resource availability and in plant reserves.• There were significant among-site differences for resprout biomass and maximum length, but not for resprout number, 1 yr after clipping. Plant reserves at the time of clipping were not significantly correlated with resprout number, length or biomass. However, resprouting variables were significantly correlated with soil nitrogen or extractable cations, or plant water potentials. Resprout biomass and maximum length were negatively correlated with lignotuber size.• These findings indicate that the assumption that resprouting vigor in lignotuberous plants is primarily dependent on the amount of reserves stored in the lignotuber must be revised, as well as the overall role of lignotubers in resprouting.

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Lignotuberous plants are frequently dominant in Mediterranean-type shrublands, and total non-structural carbohydrates (TNC) stored in the lignotuber are assumed to play an important role in resprouting after fire. However, seasonal variations in TNC in this organ and other plant parts have not been properly evaluated, particularly in relation to periods of fire risk, during which lignotuber TNC concentrations should be highest. We document the seasonal course of TNC concentrations in the stems, lignotubers and roots of 13 populations of the Mediterranean-type, lignotuberous, resprouter shrub Erica australis from central Spain. Plant water potentials were measured in parallel to correlate seasonal variations in water availability with fluctuations in TNC concentrations. Mean TNC concentrations in stems, lignotubers and roots throughout the year were 55, 73 and 120 mg g(-1) dry weight, respectively. Roots contained highest TNC concentrations, which were maximal in late spring. Starch concentrations decreased in all plant parts during spring, when plants were actively growing and reproducing. Lignotuber TNC concentrations were lowest in early summer, and remained relatively low during the period of maximum fire risk. Monosaccharide concentrations increased significantly in all plant parts during the summer, coinciding with a reduction in plant water potential. We conclude that seasonal fluctuations of TNC in E. australis are related to periods of plant growth and reproduction, and also occur in response to stressful conditions. No evidence was obtained supporting the idea that seasonal fluctuations of TNC may be a response to ensure highest TNC content in the lignotuber during periods with maximum fire risk.

Summary 1The vigour of plant resprouting after fire may be driven by the amount of stored non-structural carbohydrates (NC). However, the extent to which NC reserves limit this response in woody plants has not been established. 2 This study analyses the effects of modifying NC concentrations in the lignotuberous Mediterranean-type shrub Erica australis , on resprouting after experimental burning. A factorial experiment with two treatments (shade and burn) was carried out, with three levels per treatment. Plants were shaded (exposure to 100%, 50% or 20% of incident radiation for 1 year), following which they were clipped (control, no fire), or clipped and burned at one of two levels of severity. After this, they were allowed to resprout and grow for 2 years. 3 Shading modified NC concentrations in the lignotuber, but not in the roots. Two years after burning, plants subjected to the greatest shading, which reduced their NC concentrations to 44% (sum of NC) or 19% (starch) of that of control plants, had suffered higher mortality after resprouting, had a significantly lower number of resprouts, of shorter length, and had produced lower biomass per plant than less shaded or unshaded plants. However, plants subjected to intermediate shade, which suffered a reduction in NC concentrations to 70% of that of control plants, did not differ in resprouting response from control plants. 4 Burning caused more direct mortality, and a severe reduction in both number or biomass of resprouts, than just clipping. There were no significant shade × burning interaction effects. 5 While reductions in NC may limit resprouting, such limitation may only occur when NC is reduced to much lower concentrations than caused by commonly experienced conditions. The role of NC reserves in limiting resprouting of lignotuberous, woody plants such as E. australis might therefore not be as important as is commonly assumed.