植物種子生產(chǎn)的時空動態(tài)及潛在結實機制是決定種群動態(tài)及群落構建的重要生態(tài)過程(Norden et al.,2007;Canham et al.,2014)。種子生產(chǎn)大小年(Mast seeding)即多年生植物種群的種子生產(chǎn)在年內(nèi)同步且年際間高度變異的現(xiàn)象(Kelly,2008),這種生產(chǎn)格局在大量物種中都有出現(xiàn)(Janzen,1976;Kelly 1994,Kelly & Sork 2002)。傳粉效率增加和捕食者飽食(Janzen,1971)被認為是有利于mast seeding進化的兩個主要的選擇性壓力(Nilsson & W?stljung 1987),而氣候條件則是一個直接的作用因子(Schauber et al.,2002; Smaill et al.,2011)。
在溫帶森林,許多優(yōu)勢物種都出現(xiàn)mast seeding這一現(xiàn)象(Silvertown 1980; Kelly & Sork 2002)。群落水平的種子生產(chǎn)的時空同步性,可以使一些自身種子產(chǎn)量甚至都不足以滿足通食捕食者的物種受益(Cadotte et al 2006; Yi et al., 2011)。對森林群落水平上種子生產(chǎn)的長期監(jiān)測的缺乏,阻礙了我們了解和預測植物群落對物種特定生殖壓力和氣候變化的響應(Ostfeld& Keesing 2000)。因此,在全球變暖的大背景下,探究森林生態(tài)系統(tǒng)更新及動態(tài),特別是生殖動態(tài)及其導致的更新格局對森林具有廣泛而深遠的意義(Herrera et al., 1998; Kelly & Sork 2002)。
基于此,我組王蕓蕓博士等,以長白山闊葉紅松25-哈樣地內(nèi),連續(xù)8年的野外種子收集數(shù)據(jù)為研究對象,檢測了群落內(nèi)20個木本植物物種八年間的種子生產(chǎn)的變異性和同步性,并且驗證了傳粉效率假說以及氣象因子對種子生產(chǎn)的直接作用,即長白山溫帶闊葉紅松林群落水平的種子生產(chǎn)動態(tài)同時決定于進化中的選擇壓力(傳粉效率假說)和氣象因子的直接作用。而捕食者飽和假說在這八年的研究中僅僅表現(xiàn)出微弱的作用。
研究結果以Variation and synchrony of tree species mast seeding in an old-growth temperate forest(DOI: 10.1111/jvs.12494)發(fā)表于Journal of Vegetation Science (IF= 3.151)。該研究得到中國國家重點研究與發(fā)展計劃專項(2016YFC0500301),中國科學院國際合作項目(151221KYSB20130003, LFSE2014–03), 國家自然科學基金(413301057)資助。
Fig. 1Interannual seed production for 16 species (removing the four species presented in Fig. 4.2) in the order of descending seed abundance between the years 2006 and 2014. The full names of these species can be found in Table 4.1.
Fig. 2.Annual seed production for the four species that met the filtering criteria (synchrony) and with CVyear> 1 in the order of descending seed abundance from 2006 to 2014 in the Changbaishan, China (left panels). The dashed line represents the long-term mean seed production during the study. Filled squares represent mast seeding years for each species, and open dots are non–mast years. The full names of these species can be found in Table 1.
Fig. 3Mean (± SD) interannual variation of seed production (CVyear) weighted by seed abundance, for pollination vector (a) and dispersal mode (b) of 20 studied species. Significant differences of mean CVyear between vectors within each of these three reproductivetraits are indicated by different letters (ANOVA weighted by seed abundance of each species, P < 0.05).