Impact of Harvest Intensity on Long-Term Base Cation Budgets in Swedish Forest Soils

The effects of harvesting on the long-term mass balances of calcium (Ca), magnesium (Mg) and potassium (K) were evaluated on a regional level in Sweden. A new high-resolution weathering database was used together with estimates of total deposition, losses through harvest and leaching. Estimates were made for pine and spruce separately and for two harvesting intensity scenarios: stem harvesting and whole-tree harvesting. The mass balance calculations showed net losses of Ca and Mg in almost the whole country for both scenarios. The losses were smaller for pine than for spruce. The K balances were mainly positive for pine but negative for spruce. Leaching was a main factor in the mass balances, especially for Ca and Mg. Whole-tree harvesting in spruce forests led to substantially higher net losses of K and Ca than stem harvesting, according to the calculations. In the whole-tree harvesting scenario in spruce forests the estimated yearly net losses of Ca, Mg and K corresponded to at least 5%, 8% and 3% of the pools of exchangeable base cations, respectively, at 25% of the analysed sites. If losses of this magnitude continue the depletion of the pools of Ca, Mg and K may lead to very low base saturation of the soils, possibly accompanied by negative effects on soil fertility, runoff water quality, tree vitality and tree growth within a forest rotation in parts of Sweden. Avoiding whole-tree harvesting can improve the situation substantially for K, but the losses of Ca and Mg will still be significant.     

不同植茶年龄茶园蒸散速率的日变化——以宜兴市为例

以宜兴市盛道茶场3、9和20 a 3个不同植茶年龄的茶园为研究对象,基于静态箱/红外气体分析仪法,辅以植被生态监测和土壤湿度监测,研究茶园清明采茶前蒸散速率日变化特征。结果发现：（1）3个不同植茶年龄的茶园日蒸散速率变化趋势一致,呈以12〖DK〗∶00~15〖DK〗∶00蒸散速率为峰值的单峰曲线;（2）虽然3 a茶园叶面积指数（LAI）最低,但最大平均日蒸散速率、一日内蒸散速率的极值、6〖DK〗∶00~18〖DK〗∶00最大总蒸散量、一日内不同时段的蒸散速率最大变化幅度均出现在3 a茶园;（3）茶园日蒸散速率与气温的日变化趋势相似,且两者存在极显著相关性（R2=081*〖KG-*2〗*）,在湿润条件下与土壤含水率日变化相关性不明显,但两者呈相反的变化趋势     

桤木混交对杉木人工林大型土壤动物群落的影响

调查了中亚热带会同地区13a生杉木纯林(纯林)和8杉木2桤木混交林(混交林)的大型土壤动物群落，并比较了两个林分在群落结构上的差别．结果表明：砹翅目是两个群落在数量上的优势类群，分别占全部大型土壤动物个体数的52．1％和82．4％．杉木跟桤木混交以后，保留了纯林的大部分属性，各类群在大型土壤动物群落中的地位基本保持不变，双翅目、蜘蛛目、膜翅目仍然是最主要的类群，但这种混交方式改变了一些土壤动物的群落结构参数，多度和丰富度出现上升的趋势，均匀度显著降低．在各类群中，主要以双翅目幼虫的多度和相对多度增加幅度较大，这种变化是降低整个群落均匀度的一个主要原因．图3表2参30     

亚热带红壤丘陵区湿地松人工林固碳释氧效益研究

用标准样方法对19年生湿地松（〖WTBX〗Pinus elliottii〖WTBZ〗）人工林碳素含量及碳贮量进行了测定。结果表明,湿地松各器官的碳素含量在5092±046%～5438±026%之间波动,按碳含量高低排列为树叶>树枝>树干>树根>树皮,且各器官的碳素含量随年龄的增长而提高。不同林冠层枝、叶碳素含量存在差异,上层叶与下层叶的碳素含量较低,下层枝条碳素含量明显比上、中层枝条高。灌木层、草本层、凋落物层的碳素含量依次为4516±04%、4228±041%、4088±031%,土壤层碳素含量平均为043±004%,且随土壤深度的增加而明显递减。湿地松林生态系统碳贮量为12194 t〖DK〗·hm-2,其中乔木层碳贮量为8618 t〖DK〗·hm-2,占总量的7067%,下木层和凋落物层碳贮量分别为06 t〖DK〗·hm-2(049%) 和886 t〖DK〗·hm-2（727%）。林地土壤（0～60 cm）为263 t〖DK〗·hm-2,占总碳贮量的2157%。乔木层年净固碳量为454 t〖DK〗·hm-2,年净释氧量为1212 t〖DK〗·hm-2。采用造林成本法计算得出试区湿地松林平均每年发挥的净固碳释氧效益达9 034元〖DK〗·hm-2。     

Aluminium and fluoride concentrations of three tea varieties growing at Lantau Island,Hong Kong

The present project aims to investigate aluminium (Al) and fluoride (F) contents in teas (Camellia sinensis (L.) O. Kuntze). Three different commercial tea varieties: Assam variety and two China sub-varieties, a large leafed variety and small leafed variety, were collected in two tea gardens of Lantau Island tea plantation of Hong Kong. In general, high concentrations of Al and F were accumulated in the mature leaves (15.3 and of 2.07 g kg^–1 respectively). Among the three varieties, the small leafed variety exhibited the highest Al and F contents followed by the large leafed variety whereas the Assam variety had the lowest Al and F concentrations in its tea bushes. Tea products from a plantation were also analysed and it was noted that black tea had higher Al and F concentrations than green tea. The amount of Al and F released into tea liquor was also tested and the results showed that higher concentrations of Al and F were released into tea liquor under repeated infusion method than continuous infusion method.     

Influence of spruce and pine on the acidity and composition of atmospheric fallout in north taiga forests of an industrially developed region

The ideas concerning the spatial and temporal variation of acidity and composition of atmospheric fallout in forests of the boreal zone are discussed. The role played by the atmospheric component in the functioning of these forests depends on the acidity and composition of fallout and the extent of their transformation by the biocenosis. The most profound transformation of fallout occurs during the growing season. In spaces between crowns, the corresponding changes are atmogenic; in undercrown areas, they are obviously biogenic (autogenic). Spruce transforms the fallout more intensively than pine. Under conditions of industrial pollution, the atmobiogenic character of fallout is supplemented with a technogenic component, as its acidity and concentration of pollutants and other elements sharply increase. Concentrations of principal cations reach high values because of their leaching from the crown by acid precipitation. The traditional concept of atmospheric load on boreal forests should be reconsidered taking into account their spatial structure.     

太湖流域肥料施用策略调整对典型作物系统氮磷流失的影响

太湖流域种植业肥料施用强度普遍较高，且以化学肥料为主要形态.因肥料投入不适宜，种植业氮、磷流失问题显著.2015年以来，各地区积极对种植业肥料施用策略进行调整，但当前工作主要基于粮食作物系统且仍停留在化肥施用总量削减和有机肥施用面积提升层面上，缺少菜地、果园、茶园作物系统的相关数据以及对农业环境问题的响应.对此，以苏州市吴中区为太湖流域典型农区代表，研究2019～2021年稻田、菜地、果园和茶园这4类作物系统肥料策略调整对氮、磷流失的影响.结果表明，肥料源养分投入强度的调控是决定氮、磷流失的关键；适宜的有机肥替代比例有助于降低氮、磷流失风险，但有机肥施用需考虑时机并尽可能搭配农用机械.肥料效率是兼顾农业生产过程环境友好、生产主体经济效益的核心，也是后期肥料施用策略调整的导向.稻田系统的肥料施用策略调整应重视养分中不同元素配比，菜地系统应以种植结构调整为抓手，茶园、果园系统可从复合系统视角制定同时满足茶、果生长的施肥策略，助力构建满足农业绿色发展需求的作物系统.