Fortier Julien, Truax Benoit, Gagnon Daniel, Lambert France
Fiducie de recherche sur la forêt des Cantons-de-l'Est/Eastern Townships Forest Research Trust, 1 Rue Principale, Saint-Benoît-du-Lac, QC J0B 2M0, Canada; Département des sciences biologiques, Université du Québec à Montréal, C.P. 8888 succ. Centre-ville, Montréal, QC H3C 3P8, Canada.
Fiducie de recherche sur la forêt des Cantons-de-l'Est/Eastern Townships Forest Research Trust, 1 Rue Principale, Saint-Benoît-du-Lac, QC J0B 2M0, Canada.
J Environ Manage. 2015 May 1;154:333-45. doi: 10.1016/j.jenvman.2015.02.039. Epub 2015 Mar 6.
In many temperate agricultural areas, riparian forests have been converted to cultivated land, and only narrow strips of herbaceous vegetation now buffer many farm streams. The afforestation of these riparian zones has the potential to increase carbon (C) storage in agricultural landscapes by creating a new biomass sink for atmospheric CO2. Occurring at the same time, the storage of nitrogen (N) and phosphorus (P) in plant biomass, is an important water quality function that may greatly vary with types of riparian vegetation. The objectives of this study were (1) to compare C, N and P storage in aboveground, belowground and detrital biomass for three types of riparian vegetation cover (9-year-old hybrid poplar buffers, herbaceous buffers and natural woodlots) across four agricultural sites and (2) to determine potential vegetation cover effects on soil nutrient supply rate in the riparian zone. Site level comparisons suggest that 9-year-old poplar buffers have stored 9-31 times more biomass C, 4-10 times more biomass N, and 3-7 times more biomass P than adjacent non managed herbaceous buffers, with the largest differences observed on the more fertile sites. The conversion of these herbaceous buffers to poplar buffers could respectively increase C, N and P storage in biomass by 3.2-11.9 t/ha/yr, 32-124 kg/ha/yr and 3.2-15.6 kg/ha/yr, over 9 years. Soil NO3 and P supply rates during the summer were respectively 57% and 66% lower in poplar buffers than in adjacent herbaceous buffers, potentially reflecting differences in nutrient storage and cycling between the two buffer types. Biomass C ranged 49-160 t/ha in woodlots, 33-110 t/ha in poplar buffers and 3-4 t/ha in herbaceous buffers. Similar biomass C stocks were found in the most productive poplar buffer and three of the four woodlots studied. Given their large and varied biomass C stocks, conservation of older riparian woodlots is equally important for C balance management in farmland. In addition, the establishment of poplar buffers, in replacement of non managed herbaceous buffers, could rapidly increase biomass C, N and P storage along farm streams, which would be beneficial for water quality protection and global change mitigation.
在许多温带农业地区，河岸森林已被开垦为耕地，如今许多农田溪流仅靠狭窄的草本植被带作为缓冲。这些河岸带的造林有可能通过为大气中的二氧化碳创造一个新的生物量汇，来增加农业景观中的碳（C）储量。与此同时，植物生物量中氮（N）和磷（P）的储存是一项重要的水质功能，可能会因河岸植被类型的不同而有很大差异。本研究的目的是：（1）比较四个农业地点三种河岸植被覆盖类型（9年生杂交杨树缓冲带、草本缓冲带和天然林地）地上、地下和碎屑生物量中的碳、氮和磷储量；（2）确定潜在的植被覆盖对河岸带土壤养分供应率的影响。地点层面的比较表明，9年生杨树缓冲带储存的生物量碳比相邻的未管理草本缓冲带多9至31倍，生物量氮多4至10倍，生物量磷多3至7倍，在肥力较高的地点差异最为明显。将这些草本缓冲带转变为杨树缓冲带，在9年时间里，生物量中的碳、氮和磷储量可分别增加3.2至11.9吨/公顷/年、32至124千克/公顷/年和3.2至15.6千克/公顷/年。夏季杨树缓冲带的土壤硝态氮和磷供应率分别比相邻草本缓冲带低57%和66%，这可能反映了两种缓冲带类型在养分储存和循环方面的差异。林地的生物量碳范围为49至160吨/公顷，杨树缓冲带为33至110吨/公顷，草本缓冲带为3至4吨/公顷。在所研究的四个林地中的三个以及生产力最高的杨树缓冲带中发现了相似的生物量碳储量。鉴于其大量且多样的生物量碳储量，保护较老的河岸林地对于农田碳平衡管理同样重要。此外，建立杨树缓冲带以取代未管理的草本缓冲带，可以迅速增加农田溪流沿线生物量中的碳、氮和磷储量，这将有利于水质保护和缓解全球变化。
