發(fā)布時(shí)間：2018-06-21 00:19

  本文選題：擴(kuò)散限制假說(shuō) + Janzen-Connell假說(shuō)�。� 參考：《華東師范大學(xué)》2016年博士論文

【摘要】：探究群落物種共存機(jī)制是現(xiàn)今最重要的生態(tài)學(xué)問(wèn)題之一,其中群落幼苗更新過(guò)程作為影響群落物種共存的關(guān)鍵過(guò)程,更是生態(tài)學(xué)家研究的重點(diǎn)。因此許多假說(shuō)都試圖去解釋群落幼苗的更新過(guò)程,其中擴(kuò)散限制假說(shuō)、Janzen-Connell效應(yīng)(以下簡(jiǎn)稱J-C效應(yīng))假說(shuō)以及生境偏好假說(shuō)作為近年來(lái)預(yù)測(cè)水平較高的三個(gè)假說(shuō),被認(rèn)為是影響群落幼苗更新最重要的機(jī)制。然而,三種假說(shuō)獨(dú)立解釋群落幼苗整個(gè)更新過(guò)程的能力都相對(duì)較弱,如何將三者整合起來(lái),最大程度上發(fā)揮各個(gè)機(jī)制對(duì)群落幼苗更新過(guò)程的解釋能力,仍是困擾許多生態(tài)學(xué)家的問(wèn)題。為此,本研究以物種組成豐富的浙江天童20 ha常綠闊葉林群落動(dòng)態(tài)監(jiān)測(cè)樣地為平臺(tái),對(duì)樣地內(nèi)561個(gè)幼苗樣方(1m2)中的木本幼苗進(jìn)行了為期3年(7次)的動(dòng)態(tài)監(jiān)測(cè)。根據(jù)Kitajima 和 Fenner(2000)對(duì)群落幼苗更新的定義,將該群落內(nèi)的幼苗更新過(guò)程分為三個(gè)階段-新生幼苗出現(xiàn)階段、幼苗建立階段以及幼苗生長(zhǎng)階段。并利用能夠綜合群落內(nèi)不同物種、調(diào)查時(shí)間和空間位置等分類因素的混合效應(yīng)模型,分析在群落尺度上,不同更新機(jī)制對(duì)群落幼苗更新不同階段的影響,從而了解不同更新機(jī)制的時(shí)間分化特征。希望依據(jù)該時(shí)間分化特征能夠?qū)⑷N更新機(jī)制進(jìn)行有機(jī)的整合,使其能夠更準(zhǔn)確更全面地解釋群落幼苗的更新過(guò)程。本研究的主要研究結(jié)果如下：1.群落內(nèi)的新生幼苗(Newly germinated seedlings)是由種子子葉剛剛展開所形成的,其空間分布格局主要受同種可繁殖個(gè)體空間分布格局的限制,說(shuō)明擴(kuò)散限制過(guò)程是群落新生幼苗空間分布格局的主要形成機(jī)制。相比于代表擴(kuò)散限制的因子,代表生境偏好的微生境因子其影響程度相對(duì)較低,但仍有部分微生境因子對(duì)新生幼苗的空間分布范圍有顯著影響。比如,冠層開度因子對(duì)群落新生幼苗的個(gè)體分布產(chǎn)生了顯著負(fù)影響,說(shuō)明在林下光環(huán)境較好的生境中,群落新生幼苗的個(gè)體數(shù)反而相對(duì)較少。另外,代表J-C效應(yīng)的因子并未對(duì)群落新生幼苗的空間分布格局產(chǎn)生顯著性的影響。2.從群落新生幼苗出現(xiàn)到其建植的建立階段(Seedling establishment),其存活主要受代表J-C效應(yīng)的因子影響,使得幼苗在遠(yuǎn)離母株,靠近其它成樹的低密度區(qū)域建立。與此同時(shí),代表生境偏好的部分微生境因子也對(duì)其存活產(chǎn)生了顯著影響。然而,隨著群落幼苗苗齡的增加,J-C效應(yīng)和生境偏好對(duì)幼苗短期存活的影響都在減弱。3.建立后的群落幼苗會(huì)經(jīng)歷較長(zhǎng)時(shí)間的生長(zhǎng)階段(Seedling development)才能成為新的可繁殖個(gè)體,完成整個(gè)更新過(guò)程。由于群落幼苗生長(zhǎng)階段的年死亡率低,難以通過(guò)3年的短期監(jiān)測(cè)完整地了解影響其存活的大部分因子。為此,我們僅分析了各因子對(duì)其短期存活率的影響。結(jié)果顯示,幼苗的相對(duì)生長(zhǎng)速率是影響生長(zhǎng)期幼苗短期存活最重要的因子。因此,我們可以利用生長(zhǎng)期幼苗的生長(zhǎng)狀況預(yù)測(cè)其未來(lái)存活的可能性,并且通過(guò)分析外在因子對(duì)幼苗生長(zhǎng)的影響,間接地了解生長(zhǎng)期幼苗未來(lái)可能的存活格局。通過(guò)分析我們發(fā)現(xiàn)冠層開度是唯一顯著影響其相對(duì)生長(zhǎng)速率的因子。在林下冠層開度較大,光環(huán)境較好的生境中,群落幼苗的相對(duì)生長(zhǎng)速率會(huì)顯著提升,從而可能間接地提高了其未來(lái)存活的可能性。因此生境偏好過(guò)程是影響幼苗生長(zhǎng)階段更新的關(guān)鍵機(jī)制。綜上所述,我們發(fā)現(xiàn)在群落新生幼苗的出現(xiàn)階段,其空間分布格局主要受擴(kuò)散限制過(guò)程的影響,導(dǎo)致群落新生幼苗與母株間形成了明顯的聚集格局。在群落幼苗建立階段,J-C效應(yīng)主導(dǎo)了群落幼苗的建立格局,使得新生幼苗偏向遠(yuǎn)離母株的低密度區(qū)域建立,分散了原本不利于物種共存的母株與新生幼苗間的聚集格局,為群落中異種幼苗的更新提供空間。另外,在群落幼苗生長(zhǎng)階段,幼苗主要偏好在林下光環(huán)境較好的生境中生長(zhǎng)和存活,緩解了該生境條件下新生幼苗較少,更新不利的現(xiàn)象。因此依據(jù)群落幼苗更新機(jī)制的時(shí)間分化特征,能夠較好地整合三種群落幼苗更新機(jī)制,使其能夠更準(zhǔn)確更全面地解釋群落幼苗的更新過(guò)程。
[Abstract]:The mechanism of community species coexistence is one of the most important ecological problems. The regeneration process of community seedlings is the key process affecting the coexistence of community species, and it is also the focus of ecologists. Therefore, many hypotheses try to explain the process of regeneration of the community seedlings, including the diffusion restriction hypothesis, the Janzen-Connell effect (below) The J-C effect hypothesis and the habitat preference hypothesis, which are three hypotheses which have higher prediction level in recent years, are considered to be the most important mechanism to influence the regeneration of the community seedlings. However, the three hypotheses independently explain the ability of the whole regeneration process of the community to be relatively weak. How to integrate the three, to the greatest extent, to play various mechanisms The interpretation ability of community seedling regeneration is still a problem that puzzles many ecologists. In this study, the dynamic monitoring site of the 20 ha evergreen broad-leaved forest community in Zhejiang Tiantong, which is rich in species composition, was used to monitor the dynamic monitoring of the 3 year (7 times) of the wood seedlings of the 561 sample plots (1m2) in the sample plots. According to Kitajima And Fenner (2000) for the definition of community seedling renewal, the process of seedling regeneration in this community is divided into three stages, the emergence stage of new young seedlings, the stage of seedling establishment and the stage of seedling growth, and the mixed effect model which can be used to investigate the time and the spatial location of the different species in the community is used to analyze the community scale. In order to understand the time differentiation characteristics of different regeneration mechanisms, we hope that the three regeneration mechanisms can be integrated organically to explain the regeneration process of young seedlings more accurately and more comprehensively. The main research results of this study are as follows: The new young seedlings (Newly germinated seedlings) in the community are formed by the just expansion of the seed cotyledon, and the spatial distribution pattern is mainly restricted by the spatial distribution pattern of the same species of reproducing individuals, indicating that the diffusion restriction process is the main mechanism of the spatial distribution pattern of the new young seedlings of the community. Factors, the microhabitat factors representing habitat preference are relatively low, but there are still some microhabitat factors that have a significant impact on the spatial distribution of the new young seedlings. For example, the canopy opening factor has a significant negative effect on the individual distribution of the new young seedlings. The number of individual seedlings was relatively small. In addition, the factors representing the J-C effect did not have a significant effect on the spatial distribution pattern of the new young seedlings of the community..2. from the emergence of the young seedlings to the establishment of the plant (Seedling establishment), the survival of the seedlings was mainly influenced by the factor of the J-C effect, so that the seedlings were far away from the mother plant. At the same time, some microhabitat factors that represent habitat preference also have a significant impact on survival. However, the effect of the J-C effect and habitat preference on the short-term survival of the seedlings will undergo a longer period of growth as the seedling age of the community increases. Seedling development can become a new reproducing individual and complete the whole process. Because of the low annual mortality rate at the growth stage of the community seedlings, it is difficult to understand most of the factors that affect its survival through 3 years' short-term monitoring. The relative growth rate is the most important factor affecting the short-term survival of the growth period seedlings. Therefore, we can predict the possibility of future survival by using the growth condition of the growth period seedlings, and indirectly understand the possible future survival pattern of the young seedlings by analyzing the effects of external factors on the growth of seedlings. The opening of the present canopy is the only factor that significantly affects its relative growth rate. The relative growth rate of the seedlings in the community is significantly elevated in a habitat with greater canopy opening and better light environment, which may indirectly increase the possibility of its future survival. Therefore, the habitat preference process is the key machine for the regeneration of the seedling growth stage. In summary, we found that the spatial distribution pattern was mainly influenced by the diffusion restriction process in the emergence stage of the new community young seedlings, which led to the formation of a distinct aggregation pattern between the new young seedlings and the mother plants. In the stage of the establishment of the community seedlings, the J-C effect dominated the establishment of the young seedlings, making the young seedlings far away from the mother. The establishment of low density region of the plant disperses the aggregation pattern between the mother plant and the new young seedlings which is not conducive to the coexistence of the species, and provides space for the regeneration of the young seedlings in the community. In addition, in the stage of the growth of the community seedlings, the seedlings mainly prefer to grow and survive in the habitats with better light environment, and alleviate the new young seedlings under this habitat. Less adverse phenomenon. Therefore, the update time updating mechanism based on community differentiation characteristics of seedlings, can better integrate the three kinds of seedling community update mechanism, which can explain the community seedling renewal process is more accurate and more comprehensive.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：S718.5

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本文編號(hào)：2046295