Litter Productivity and Nutrient Return Characteristics of Three Typical Forest Stands in Golden Mountain

Objective: The paper aims to analyze the dynamic characteristics of litter production and nutrient return of the forest ecosystems in subtropical areas, and provide a theoretical basis for the nutrient cycling study in southwest Hubei Province and carbon sink function of the whole forest ecosystem. Methods: Three typical forest stands (Chinese fir plantation, Cryptomeria fortunei plantation and evergreen and deciduous broad-leaved mixed forest) in Golden Mountain Forest Farm in southwest Hubei Province were investigated and monitored continuously for the litter types and productivity and nutrient return. Results: The annual litter productivity of the three forest stands ranged from 161.77 to 396.26 kg·hm-2;Litters of branches, leaves and reproductive organs accounted for 14.14% - 20.85%, 33.26% - 78.33%, 7.52% - 42.18% of the total, respectively;The litter productivity and total litter productivity of each composition in the three forest stands show unimodal or bimodal changes over months, and the total litter productivity reached the highest value in January, April and October respectively. For different nutrient contents of the three forest stands, the common feature is C > N. The order of nutrient return amount from greatest to least is evergreen and deciduous broad-leaved mixed forest, Cryptomeria fortunei plantation and Chinese fir plantation. For different nutrient return amounts, the common feature is C > N, and the nutrient return amounts are 76.51-180.69 kg·hm-2 and 2.3 - 5.71 kg·hm-2 respectively. Conclusion: The annual litter productivity and nutrient return amount of the evergreen and deciduous broad-leaved mixed forest are the highest among the three forest stands. Therefore, protecting the evergreen and deciduous broad-leaved mixed forest and studying the litter changes of Chinese fir plantation and Cryptomeria fortunei plantation are of far-reaching significance for the development of sustainable forest management in this region and the further improvement of the carbon sequestration function of the whole forest ecosystem.

COMPARATIVE ANALYSES ON THE LITTER IN KOREAN PINE MONGOLIAN SCOTS PINE AND DAHURIAN LARCH PLANTATIONS(Ⅱ)CONTENT AND RETURNING AMOUNT OF NUTRIENT ELEMENTS

Comparative analyses were conducted on the nutrient element content and returning amount of main fractional compositions of litter in Korean pine (KP), Mongolian Scots pine(MSP) and Dahurian larch (DL) plantations in Laoshan Plantation Experiment Station of Maoershan Experiment Forest Farm of Northeast Forestry University. The results are as follows: (1) The nutrient element content and returning amount in litter varies among different fractional compositions and tree species, the total returning amount of all nutrient elements and the returning amount of K, Ca, Mg, N and P are DL>MSP>KP, the returning amount of Cu is DL>KP>MSP, the returning amount of Fe and Mn are MSP>DL>KP, (2) To KP and DL plantations, the main nutrient element returned is dead needles; dead branches, bark scales and dead cones account for a little proportion; whereas to MSP plantation, besides dead needles,dead branches and bark scales also play an important role in the return of nutrient elements; (3)A little deal of dead leaves can provided a great deal of returning amount of nutrient elements.

Litterfall production and nutrient return in different-aged Chinese fir(Cunninghamia lanceolata) plantations in South China

The amounts of litter produced and nutrients returned play a fundamental role in the productivity and biogeochemical and nutrient cycling of forest ecosystems.We monitored annual litterfall production, nutrient return,and monthly dynamics over a one-year period in Chinese fir plantations aged 10, 22, and 34 years. Our objective was to quantify litterfall and nutrient return over a complete harvest rotation of Chinese fir. Annual litterfall production increased with stand age and was recorded as（3,294.6 ± 360.4）,（3,733.9 ± 211.2）, and（4,876.1 ± 212.8） kg ha-1a-1in stands aged 10, 22 and 34 years, respectively. Total litter production was significantly greater in the stand aged34 years than in the stand aged 10 years（p ／ 0.05）. With the exception of miscellaneous components, needle litterfall constituted the highest proportion（27.5–43.6 %）, followed by branches/twigs（9.5–16.6 %）. In all three plantations,annual total nutrient return to soil was in the order of C（1,119.95–2,709.05 kg ha-1a-1） [ N（39.32–62.04 kg ha-1a-1） [ K（15.95–22.44 kg ha-1a-1） [ P（1.30–1.63 kg ha-1a-1）. C, N, K and P input to soil was significantly lower in the 10-year-old stand in comparison to the 22- and34-year-old stands（p ／ 0.05）. Litterfall production and nutrient return（C, N and K） followed similar patterns, and C and N input to soil was significantly related to litterfall production（needle, branch and total litterfall）. C, N, P and K input to soil and total litterfall production were mainly driven by needle litterfall.

Throughfall and stemflow nutrient depositions to soil in asubtropical evergreen broadleaved forest in the Wuyi Mountains

A study concerning the throughfall and stemflow chemistry in the Castanopsis eyrei forest was conducted during 1993—1994. The results showed that the net throughfall nutrient fluxes showed consistent canopy effects on precipitation chemistry. In general, potassium, calcium, magnesium, sodium and sulphur were added to precipitation by foliage, whereas the canopy absorbed nitrogen and phosphorus from precipitation. In stemflow, negative net deposition occurred for phosphorus only, and the rest nutrients were added to precipitation by tree stems and branches. The total net depositions of nutrients in both throughfall and stemflow followed the sequence of potassium>calcium>sodium>magnesium>sulphur, ranging between 2 56—52 54 kg/(hm 2·a). For potassium and calcium, net throughfall was the largest pathway, and the net throughfall contribution to the total yearly nutrient return to the forest soil was 54% and 42% respectively. Although the net stemflow contribution to the total yearly nutrient return was small (between 0 and 13%), stemflow represented the largest pathway of water and nutrient input to the stemflow zone of the forest floor in the C.eyrei forest ecosystem.

Seasonal changes of bioelements in litter and their potential return to green leaves in five species of tropical dry deciduous forest, western India

The Litter nutrient concentrations of N, P, Ca, Mg, K and Na in mature leaves, twigs and reproductive parts and their relationship between senescent and young leaves were investigated in five forest species： Acacia nilotica, Acacia leucophloea. Tectona grandis, Miliusa tomentosa and Butea monosperma in Indian tropical dry deciduous forest in Western India.. Total dry matter of plant species was recorded and analyzed for N, P, Ca, Mg, K and Na. A. nilotica had the highest concentrations of N in leaf, while ,4. leucophloea had the highest concentrations of Ca and Mg in leaf. The highest concentrations of P in leaf were found in A. nilotica, A. leucophloea and B. monosperma where as lowest in T. grandis and M. tomentosa. No significant differences in K and Na were registered among the species. A marked seasonal variability was ob- served in the concentrations of N, P and K, except for Ca and Mg. Potas- sium is the single element that undergoes leaching and mobilization in all species. Resorped N and P can be used for the production of fresh leaf in the following annual cycle. Nutrient resorption and retranslocation from senescent leaves and litter supports the production of new foliage and increase the fertility of soil.

膨化秸秆还田对寒地水稻养分积累、转运、分配及产量的影响

【目的】分析膨化秸秆还田对寒地水稻养分积累、运转、分配及产量的影响,筛选膨化秸秆适宜的还田量,为探索水稻秸秆资源的高效利用提供理论和技术支持。【方法】采用盆栽试验,以水稻品种垦粳8号为试验材料,以秸秆不还田(秸秆用量为0)为对照(CK),设25%、50%、75%和100%(当地常规秸秆还田量7500 kg/ha)4个膨化秸秆还田量处理,分析不同处理间水稻植株氮、磷、钾的吸收、运转、分配及产量差异。【结果】不同水稻秸秆还田处理中,均以25%处理的地上部氮、磷、钾积累量最高或较高,2020和2021年成熟期地上部氮积累量分别较CK提高1.10%和10.53%;2021年磷和钾积累量较CK提高1.30%和3.04%。25%处理能促进茎叶氮、钾向籽粒运转,进而提高氮、钾的转运量、转运率和贡献率,有利于成熟期叶片、茎鞘和穗中氮、钾的积累。从产量及其构成因素来看,膨化秸秆还田通过增加水稻穗粒数和结实率,进而提高水稻产量,其中,25%处理的产量显著高于CK及其他秸秆还田处理,2020和2021年分别较CK提高5.54%和8.93%。【结论】25%膨化秸秆还田量处理能促进寒地水稻的氮、磷、钾积累及植株营养器官氮和钾向籽粒转运,且产量较高,可尝试在寒地水稻生产中推广应用。

不同秸秆还田量对春季稻虾田水质、土壤养分及酶活性的影响

[目的]本文旨在探究稻-小龙虾综合种养模式下合理的秸秆还田方式对稻虾田水质、土壤养分及酶活性的影响。[方法]在2019年通过田间试验,设秸秆不还田不施氮肥(对照,CK)、秸秆还田量为1500 kg·hm-2(S1N1)、秸秆还田量为3500 kg·hm-2(S2N2)以及秸秆还田量为4500 kg·hm-2(S3N3)4种处理,对水体水质、土壤养分及土壤酶活性进行测定。[结果]水体溶氧在未使用增氧机充氧状态下为6.68~14.59 mg·L-1;不同秸秆还田处理相较CK处理增加了水体总磷和活性磷含量;还田95 d,随着秸秆还田量的增加,水体硝态氮含量呈下降趋势;不同处理下水体亚硝态氮、氨氮含量在还田95 d后总体呈下降趋势。秸秆还田后,S3N3处理土壤总磷含量增幅最大为36.86%;不同处理土壤铵态氮含量在还田30 d后达到峰值,土壤硝态氮含量随还田量的增加呈上升趋势;S3N3处理显著增加了土壤有机质含量。3种秸秆还田处理降低了土壤脲酶活性,而增加了土壤碱性磷酸酶活性;还田后CK、S1N1处理土壤蔗糖酶活性增幅较小,S3N3处理土壤蔗糖酶活性增幅最大(118.30%),并显著高于其他处理。[结论]不同秸秆还田处理对水质无不良影响,秸秆还田量为4500 kg·hm-2的处理在土壤养分、酶活性方面优于其他处理。

桉树人工林生态系统养分循环与平衡研究 Ⅳ.桉树林间种山毛豆对生态系统养分循环的作用

桉树人工林间种山毛豆,增加了凋落物量和养分归还量,改善了营养元素的生物小循环。在一个轮伐期内山毛豆归还土壤养分的数量如下:氮528.37 kg/hm2,磷28.06 kg/hm2,钾66.20 kg/hm2,钙184.96 kg/hm2,镁57.21 kg/hm2;而同期刚果W5桉归还土壤养分的数量为:氮85.98 kg/hm2,磷3.94 kg/hm2,钾11.80 kg/hm2,钙36.98 kg/hm2,镁18.30 kg/hm2。由于间种山毛豆增加了生态系统的养分收入,减少了水土流失的养分支出,系统的各种养分出现了盈余的状况。

油菜秸秆还田腐解变化特征及其培肥土壤的作用

为促进油菜秸秆腐解,推进农村作物秸秆的资源化利用,减少秸秆焚烧对环境的负面影响,培养与提高土壤肥力,采用尼龙网袋和田间试验相结合方法,设置了油菜秸秆不同还田量处理和不同还田深度处理,研究了油菜秸秆腐解百分率和腐解速率变化特征,分析了油菜秸秆还田对土壤性质及作物产量的影响。结果表明,油菜秸秆还田的腐解百分率随时间延长而逐渐增大,秸秆腐解速率则早期快后期慢;随秸秆还田量增加,腐解速率降低,表现为全量还田的秸秆腐解速率<2/3量还田秸秆腐解速率<1/2量还田秸秆腐解速率<1/3量还田秸秆腐解速率;在种植水稻条件下油菜秸秆还田深度在10 cm时腐解速度最慢,在表层还田腐解速度最快,20 cm深还田腐解速度居中。相比对照处理来说,油菜秸秆还田降低了土壤容重,增加了土壤有机质含量,一定程度上提高了土壤氮磷钾含量(P<0.05)。油菜秸秆还田对水稻作物有极显著增产作用(P<0.01),增产幅度在6.02%～21.17%之间。本试验对水稻油菜轮作体系下油菜秸秆还田腐解特征进行的研究可为调控油菜秸秆还田腐解速度,改善农业生态环境提供参数依据。

田林老山中山两类森林凋落物研究

田林老山中山两类森林凋落物研究梁宏温（广西农学院林学分院，南宁５３０００１）ＳｔｕｄｉｅｓｏｎｔｈｅＬｉｔｔｅｒｆａｌｌｏｆＴｗｏＦｏｒｅｓｔＴｙｐｃｓｉｎＭｉｄ—ＡｌｔｉｔｕｄｅｏｆＬａｏｓｈａｎＭｏｕｎｔａｉｎｉｎＴｉａｎｌｉｎＣｏｕｎｔｙ．￥Ｌ...

绿肥油菜新品种中油肥1 号的选育与应用

中油肥1号是中国农业科学院油料作物研究所选育的肥油兼用型绿肥油菜新品种,湖北省两年三点试验结果表明,在肥料投入低的情况下,相比对照阳光2009,地上部生物量压青鲜重平均为43560.0 kg/hm^(2),鲜重增加15.81%;植株养分还田量平均分别为氮(N)88.20 kg/hm^(2)、磷(P_(2)O_(5))14.25 kg/hm^(2)、钾(K_(2)O)119.10 kg/hm^(2);植株氮、磷、钾养分还田量分别增加21.2%、12.5%和17.3%。该品种在低氮肥投入条件下菜子产量略高于主栽对照品种,其菜子品质符合国家双低油菜子标准,在正常栽培条件下可以作为兼收菜子型油菜品种进行菜子生产。

紫色土区不同秸秆还田量对土壤酶活性的影响

为了探明长期秸秆不同还田量下紫色土区土壤酶活性及其主要驱动因子,以持续12年的四川紫色土长期定位试验为依托,设置:秸秆不还田(CK)、30%还田(RMW30)、50%还田(RMW50)和100%还田(RMW100)4个处理,测定了土壤各种酶活性以及土壤理化性质。结果显示,与CK处理比较,RMW100处理显著提高土壤有机质、碱解氮和速效钾含量以及pH。秸秆不同还田量处理均降低了β-纤维二糖苷酶(CBH)、纤维素酶(CL)、酚氧化酶(PhOx)和过氧化物酶(Perox)活性,提高了磷酸酶(Phos)、硫酸酯酶(Sul)、β-葡糖苷酶(βG)、α-葡糖苷酶(αG)、β-木糖苷酶(βX)、乙酰氨基葡萄糖苷酶(NAG)和亮氨酸氨基肽酶(LAP)活性。随着秸秆还田量的增加,β-纤维二糖苷酶(CBH)活性呈现降低趋势。冗余分析(RDA)显示土壤pH是土壤酶活性变化的主控因子,解释了方差变异的60.20%,达到显著水平。因此,紫色土区秸秆还田主要是通过土壤pH对土壤酶活性产生影响。秸秆100%还田增加了土壤肥力,提高了土壤pH,是提升紫色土区土壤质量最优的管理措施。

秸秆还田量对小麦-玉米轮作中土壤理化性质及作物产量的影响

[目的]研究秸秆还田量对一年两熟小麦－玉米轮作制度下土壤理化性质的影响。[方法]通过田间试验，研究秸秆不还田，50％小麦、玉米秸秆还田，100％小麦、玉米秸秆还田，150％小麦、玉米秸秆还田对麦－玉轮作体系中土壤容重、有机质和养分含量，以及小麦和玉米产量的影响。[结果]秸秆还田可以降低土壤容重，增加土壤有机质含量，提高土壤养分库容。50％、100％和150％秸秆还田条件下，土壤容重降幅为1．41％～9．15％，土壤有机质含量增加0．02～0．04 g／kg，土壤碱解氮、有效磷、速效钾、全钾含量分别增加6．64～9.00、3.37～4.07、10．33～19．00、40．00～120．00 mg／kg。不同秸秆还田量均能提高小麦、玉米产量，产量增幅分别为7．57％～13．16％、16．29％～26．06％。[结论]秸秆还田量达到150％时，在土壤理化性质及作物产量方面出现转折，建议不超过100％秸秆还田为宜。

神农架常绿落叶阔叶混交林凋落物养分特征

凋落物是联结陆地生态系统植物与土壤养分的重要媒介,了解凋落物养分特征有助于理解陆地生态系统物质循环的机理。该研究于2015年收集了神农架地区常绿落叶阔叶混交林的新鲜凋落物及现存凋落物,测定其不同器官中大量元素(C、N、P、K、Ca、Mg)的含量,据此分析其养分含量、养分归还量、养分储量及化学计量比的特征。结果发现:该常绿落叶阔叶混交林新鲜凋落物的C、K养分含量显著高于现存凋落物,N、P、Ca、Mg养分含量显著低于现存凋落物;其凋落物大量元素的养分归还量及养分储量大小顺序均为C>Ca>N>Mg>K>P,分别为1569.84、52.44、34.82、6.24、5.24、1.30 kg hm^-2 a^-1及1835.29、87.87、51.17、12.12、3.90、1.95 kg hm^-2 a^-1;其新鲜凋落物及现存凋落物的C∶N∶P分别为1307.33∶27.73∶1及976.48∶26.77∶1,新鲜凋落物的C∶N、C∶P显著高于现存凋落物,N∶P无显著区别。研究表明,新鲜凋落物与现存凋落物养分含量之间的差异与不同元素在分解过程中的可淋溶性及生物固持等因素有关。该地区常绿落叶阔叶混交林凋落物养分归还量及养分储量相对于亚热带阔叶林平均水平较低;且显著低于喀斯特地区同类型森林,主要与其凋落物产量、降水量及植被类型有关。该森林生态系统新鲜凋落叶与中国及全球范围内阔叶树种凋落叶相比C∶N较低,C∶P、N∶P较高,这可能是由于该地区N沉降及P限制现象较为严重所致。

滇中亚高山4种典型林分凋落物归还及养分动态变化特征

【目的】通过研究滇中亚高山4种典型林分凋落物归还及养分动态变化特征,得出不同林分类型养分归还变化规律,为开展不同林分林地生产力的维持机制和提高森林生态系统的碳汇功能及其生态恢复提供理论参考。【方法】以滇中亚高山常绿阔叶林、高山栎林、云南松林和华山松林为研究对象,在每个林分随机设置方形凋落物收集器,每月收集凋落枝和叶,烘干至恒质量后计算月和年凋落量,并测定有机碳(C)、全氮(N)、全磷(P)、全钾(K)含量,研究林分凋落物组成、养分含量及养分归还动态变化。【结果】4种林分年凋落物量为396.93~767.32 kg/hm^(2);凋落物组分中凋落叶占86.08%~89.13%,枝仅占10.87%~13.92%;4种林分凋落枝、叶及总量月动态变化呈单峰或双峰型变化规律,凋落物最高值出现在5月,C、N、P和K养分含量无明显变化规律;4种林分养分归还量为常绿阔叶林>云南松林或华山松林>高山栎林,凋落叶养分归还量大于凋落枝,不同养分归还量大小顺序为C>N>K>P,C、N、P和K归还量分别为193.57~359.37、3.18~6.51、0.25~0.49和1.86~3.41 kg/hm^(2);4种林分C、N、P和K归还量月动态变化呈单峰型、双峰型、多峰型或无规则变化规律,受凋落量以及养分含量的共同影响。【结论】常绿阔叶林年凋落物量和养分归还量均较高,周转期短,物种多样性丰富,群落结构稳定,具有较普遍的适应性,较快的凋落物分解周转能更好地进行养分归还,较强地维持土壤肥力。

武夷山六种杉木伴生树种落叶养分归还的研究

本文在福建省几个自然保护区天然杉木混交林群落调查的基础上，对武夷山天然杉木混交林中毛竹、木荷等六种主要杉木伴生树种落叶养分归还的研究结果表明，各伴生树种落叶分解其养分归还量主要取决于落叶量的大小，受养分浓度及分解速率的影响较小．在混交林中，甜储、丝栗栲的落叶量大，分解速度快，具有较强的养分平衡能力，落叶分解的养分归还量分别为３４２．９６４ｋｇ／（ｈｍ２·ａ）和２７４．３７２ｋｇ／（ｈｍ２·ａ）．苦槠和毛竹的养分归还量较低，分别为１０２．８１４ｋｇ／（ｈｍ２·ａ）和１０７．２２４ｋｇ／（ｈｍ２·ａ）．

氮肥调控对浙北地区秸秆全量还田稻田土壤及水稻产量的影响

于2016—2017年连续开展大田定位试验,采用随机区组设计,以嘉优中科6号为材料,设置4种施氮水平(以纯N计:N0,不施氮;N1,225 kg·hm^-2;N2,300 kg·hm^-2;N3,375 kg·hm^-2),研究秸秆全量还田下氮肥调控对浙北地区稻田土壤养分、碳库、微生物,及水稻产量的影响。结果表明,在秸秆全量还田下,随着施氮量的增加,稻田土壤有机质、全氮、速效磷、速效钾、碳库和微生物数量呈先增后减的趋势。与N0相比,N1处理的全氮、铵态氮、硝态氮、易氧化有机碳含量分别显著(P<0.05)增加了7.14%、9.86%、54.74%和21.70%;N2处理的全氮、速效钾、铵态氮、硝态氮、可溶性碳、易氧化有机碳、微生物碳、土壤细菌、真菌和放线菌数量分别显著(P<0.05)增加了32.59%、20.16%、12.12%、58.34%、54.45%、29.57%、56.49%、211.16%、241.61%和96.10%;N3处理的全氮、铵态氮、硝态氮、易氧化有机碳、微生物碳含量和真菌数量分别显著(P<0.05)增加了28.57%、16.84%、61.72%、27.45%、49.79%和231.54%。在产量方面,与N0相比,N1、N2和N3处理分别显著增加37.97%~45.47%、41.85%~53.35%和38.85%~47.57%。在试验设置条件下,秸秆全量还田配施300 kg·hm^-2纯N可以改善土壤养分含量、土壤碳库和土壤微生物活性,增加作物产量。

亚热带10个树种人工幼林凋落物量及养分归还量特征分析

为了评估凋落物在亚热带森林养分循环中的生态作用,选择亚热带10个树种人工幼林为研究对象,分析不同树种间凋落物年产量的差别,以及碳、氮、磷养分归还量的特征和影响因素。结果表明:米老排年凋落物量、碳归还量、磷归还量最高,分别为676.24、416.77、0.27 g·m^(-2);福建柏年凋落物量、碳归还量和磷归还量最低,分别为105.23、53.49、0.03 g·m^(-2);闽粤栲凋落物氮归还量最高,为6.17 g·m^(-2);马尾松凋落物氮归还量最低,为0.73 g·m^(-2)。亚热带人工幼林凋落物碳归还量随着凋落物碳、氮含量的增加而降低;凋落物氮归还量随着凋落物碳、磷含量的增加而降低,随着凋落物氮含量的增加而增加;凋落物磷归还量随着凋落物碳含量的增加而降低。研究显示亚热带人工幼林凋落物碳、氮、磷养分归还量受到凋落物碳、氮、磷养分元素含量的共同调控。

Studies on Material Cycling in Evergreen Broad-Leaved Forest Ecosystem in Hangzhou: Ⅱ . Dynamics and Decomposition Characteristics of Litter

Through the long-term plot study on the litter and its decomposition in the evergreen broad-leaved forest ecosystem in Hangzhou for more than two years,it was resulted that the annual litter production was 5.85 t ha^-1,most of which was the fallen leave (79.5 percent) and the withered branches and fruits were far less (7.1 and 13.4 percents respectively).The dynamics of the fallen litter was shown as a curve of two-peak pattern which appeared in April and September each year.The half-life of the litter was 1.59 years.The decay rate of the litter attenuted as an exponential function.The annual amount of the nutrient returned to the ground through the litter was as large as 223.69kg ha^-1.The total current amount of the litter on the ground was 7.47t ha^-1.The decay rate in the first half of a year was 45.18 percent.This ecosystem remained in the stage of litter increasing with time.

不同秸秆还田量对水稻产量及土壤养分的影响

以水稻品种淮稻5号为供试材料,研究了不同秸秆还田量对水稻产量及土壤养分的影响。结果表明:秸秆全量还田较秸秆半量还田水稻产量有所提升,但差异不显著;2种秸秆还田量,土壤有机质、碱解氮、速效磷含量均有所提升,但秸秆全量还田效果较好,有机质、速效磷含量提升率达10%以上,可有效培肥地力。