Boreal and hemiboreal forests are biomes where regular severe disturbance has been an important evolutionary process affecting many species Among these are certain herbaceous plants that are believed to rely on periodic forest wildfire for seed germination and seedling establishment occurred with an average interval of 50e150 years, depending on soil properties, topography, forest age, and human impact Nowadays, human intervention has significantly reduced the area of forest that is burned annually and lengthened the fire interval throughout the boreal zone In boreal forests dominant ericaceous vegetation and mosses can negatively influence the establishment of certain vascular plants, with stagnant growth of seedlings often observed in the presence of ericaceous undergrowth Various mechanisms including allelopathic interference reduced soil N mineralisation soil enzyme inhibition and direct resource competition have been put forward to explain this phenomenon. Moreover, several studies have highlighted the importance of polyphenol-rich ericoid humus. Polyphenols form stable complexes with protein, thereby reducing soil N mineralisation and retarding nutrient cycling and the growth of tree seedlings In addition, feathermosses (such as Hylocomium splendens and Pleurozium schreberi) which are able to efficiently uptake nutrients from precipitation, throughfall and litter decomposing on the surface of mosses , can prevent the leaching of nutrients to lower soil horizons and can form a barrier between seedlings and the mineral soil Hence, one of the most pronounced effect of forest wildfire on field-layer vegetation is through the destruction of the moss and litter layer, which can considerably enhance the recruitment of forest herbs as a result Nonetheless, forest fire has several other consequences that might also enhance the recruitment of fire-adapted boreal forest herbs The detoxifying and rejuvenating effect of fire may be due in part to the effect of charcoal, which is capable of absorbing secondary metabolites such as the humus polyphenols produced by ericaceous vegetation . Light conditions for herbaceous plants improve considerably after fire and various soil properties are also affected, including increased decomposition of plant litter and humus, cation availability, pH and soil microbial activity, and enhanced cycling of nitrogen
Pulsatilla patens (L.) Mill. (Eastern Pasque Flower, synonym Anemone patens L., Ranunculaceae) is a boreal herbaceous plant species that may be dependent on a periodic fire regime While there is no firm evidence that P. patens is strictly fire-dependent, the species can survive extensive forest fires (Uotila, 1996), and prescribed burning has been shown to enhance its germination and establishment Among the multitude of ecological factors connected with forest fire, it is unclear which play a key role in the recruitment of boreal herbs in general and, more specifically, of P. patens. It is also unclear whether plants require specific adaptations in order to benefit from aspects of wildfire. An alternative scenario is that any herbaceous perennial plant that is suppressed by ericoid litter and moss might benefit from the effect of fire. To answer these questions, we designed an experiment including P. patens and two other herbaceous species: Pulsatilla pratensis and Ranunculus polyanthemos. P. pratensis is taxonomically and ecologically close to P. patens but is known to prefer grasslands and is rarely found growing in wooded habitats. Thus, it is reasonable to expect that this species should not demonstrate specific adaptations to post-fire conditions. R. polyanthemos belongs to the same family as the Pulsatilla species and is morpologically similar to them, but it grows in moist grasslands where specific adaptations to wildfire should not enhance fitness in any way. In this study, we focussed on possible adaptations of herbaceous plants to three aspects of the environment that are influenced by recent forest wildfire: the amount of ericoid litter on the forest floor, the presence of charcoal and the light climate. We did not address fire survival strategies in our experiment since adaptations for surviving high temperatures and other direct physical impacts of wildfire are highly specific and would have demanded an entirely different experimental design. We used a factorial design to determine (i) whether the presence of ericoid litter in boreal forest soil has a direct negative impact on the germination and growth of P. patens (and the two other species included for comparison); and (ii) whether post-fire accumulation of charcoal mitigates the effect of ericoid litter. Since improvement of light conditions may also play an important role in the complex effect of forest fire on herbs, we included lighting treatments as an additional factor in the experiment.
Specifically, we tested the following working hypotheses: 1) If P. patens, a species inhabiting boreal forests, is fire-adapted and able to respond to environmental cues in a post-fire situation, it will exhibit responses to the presence of both ericoid litter and charcoal in the soil; responses will be less pronounced in the more grassland-bound congener, P. pratensis, and absent in the purely grassland species, R. polyanthemos. 2) Since acquisition of photosynthetically active radiation (PAR) is more closely related to herbaceous neighbours in P. pratensis and R. polyanthemos than in P. patens, the former species will show greater plasticity in rooteshoot allocation and elongation in their response to shading.
Boreal และป่า hemiboreal ที่รบกวนรุนแรงปกติแล้วกระบวนการวิวัฒนาการสำคัญที่ส่งผลกระทบต่อหลายชนิดในหมู่เหล่านี้เป็นพืชเฉพาะ herbaceous ที่เชื่อว่าอาศัยไฟป่าป่าเป็นครั้งคราวสำหรับการงอกของเมล็ดพืช และแหล่งก่อเกิดขึ้นกับช่วงเวลาเฉลี่ยของปี 50e150 คุณสมบัติของดิน ภูมิประเทศ ป่าอายุ และผลกระทบต่อมนุษย์ในปัจจุบัน บุคคลได้ลดพื้นที่ของป่าที่เขียนเป็นประจำทุกปี และ lengthened ช่วงไฟตลอดการ boreal biomes โซนป่า boreal ericaceous หลักพืชและ mosses สามารถส่งอิทธิพลก่อตั้งบางพืชสคิว ศิลปินเจริญเติบโตของกล้าไม้ที่มักพบในต่อหน้าของ ericaceous undergrowth กลไกต่าง ๆ รวมทั้งสัญญาณรบกวน allelopathic ลดยับยั้งเอนไซม์การดิน mineralisation ดิน N และได้ย้ายการแข่งขันทรัพยากรตรงไปข้างหน้าเพื่ออธิบายปรากฏการณ์นี้ นอกจากนี้ ศึกษาหลายได้เน้นความสำคัญของการเกิดการเปลี่ยนแปลงกลาย polyphenol ริช ericoid คอมเพล็กซ์มีเสถียรภาพแบบฟอร์มโพลีฟีนกับโปรตีน ลดดิน N mineralisation retarding จักรยานธาตุอาหารและเจริญเติบโตของต้นกล้าไม้แห่ง และ feathermosses (เช่น Hylocomium เกลือและ Pleurozium schreberi) ซึ่งจะสามารถดูดซับสารอาหารได้อย่างมีประสิทธิภาพจากฝน throughfall และแคร่พืชพันธุ์บนพื้นผิวของ mosses สามารถป้องกันการละลายของสารต่ำกว่าฮอลิซันส์ดิน และสามารถเป็นกำแพงกั้นระหว่างกล้าไม้และแร่ดินดังนั้น ป่าไฟป่าบนฟิลด์ชั้นพืชผลออกเสียงมากที่สุดคือผ่านทำลายของมอสและแคร่ชั้น ซึ่งสามารถมากสรรหาป่าสมุนไพรดัง Nonetheless ไฟป่ามีผลกระทบอื่น ๆ หลายที่ยังอาจเพิ่มสรรหาบุคลากรปรับไฟป่า boreal สมุนไพร ที่ล้างพิษ และฟื้นฟูผลกระทบของไฟอาจผลถ่านครบในส่วน ซึ่งมีความสามารถในการดูดซับแรงกระแทก metabolites รองเช่นโพลีฟีนเกิดการเปลี่ยนแปลงกลายที่ผลิต โดยพืชพรรณ ericaceous สภาพแสงในพืช herbaceous ปรับปรุงอย่างมากหลังจากไฟ และคุณสมบัติต่าง ๆ ของดินจะยังได้รับผล กระทบ แยกส่วนประกอบเพิ่มขึ้นแคร่พืช และเกิดการเปลี่ยนแปลงกลาย พร้อม cation ค่า pH และกิจกรรมจุลินทรีย์ดิน และจักรยานของไนโตรเจนเพิ่มขึ้น Pulsatilla patens (L.) Mill. (Eastern Pasque Flower, synonym Anemone patens L., Ranunculaceae) is a boreal herbaceous plant species that may be dependent on a periodic fire regime While there is no firm evidence that P. patens is strictly fire-dependent, the species can survive extensive forest fires (Uotila, 1996), and prescribed burning has been shown to enhance its germination and establishment Among the multitude of ecological factors connected with forest fire, it is unclear which play a key role in the recruitment of boreal herbs in general and, more specifically, of P. patens. It is also unclear whether plants require specific adaptations in order to benefit from aspects of wildfire. An alternative scenario is that any herbaceous perennial plant that is suppressed by ericoid litter and moss might benefit from the effect of fire. To answer these questions, we designed an experiment including P. patens and two other herbaceous species: Pulsatilla pratensis and Ranunculus polyanthemos. P. pratensis is taxonomically and ecologically close to P. patens but is known to prefer grasslands and is rarely found growing in wooded habitats. Thus, it is reasonable to expect that this species should not demonstrate specific adaptations to post-fire conditions. R. polyanthemos belongs to the same family as the Pulsatilla species and is morpologically similar to them, but it grows in moist grasslands where specific adaptations to wildfire should not enhance fitness in any way. In this study, we focussed on possible adaptations of herbaceous plants to three aspects of the environment that are influenced by recent forest wildfire: the amount of ericoid litter on the forest floor, the presence of charcoal and the light climate. We did not address fire survival strategies in our experiment since adaptations for surviving high temperatures and other direct physical impacts of wildfire are highly specific and would have demanded an entirely different experimental design. We used a factorial design to determine (i) whether the presence of ericoid litter in boreal forest soil has a direct negative impact on the germination and growth of P. patens (and the two other species included for comparison); and (ii) whether post-fire accumulation of charcoal mitigates the effect of ericoid litter. Since improvement of light conditions may also play an important role in the complex effect of forest fire on herbs, we included lighting treatments as an additional factor in the experiment.Specifically, we tested the following working hypotheses: 1) If P. patens, a species inhabiting boreal forests, is fire-adapted and able to respond to environmental cues in a post-fire situation, it will exhibit responses to the presence of both ericoid litter and charcoal in the soil; responses will be less pronounced in the more grassland-bound congener, P. pratensis, and absent in the purely grassland species, R. polyanthemos. 2) Since acquisition of photosynthetically active radiation (PAR) is more closely related to herbaceous neighbours in P. pratensis and R. polyanthemos than in P. patens, the former species will show greater plasticity in rooteshoot allocation and elongation in their response to shading.
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