The Alaskan tundra, for instance, has switched from being a net sink of carbon dioxide -- absorbing and storing more carbon from the atmosphere than it releases -- to "being a net source of CO2 (releasing more carbon than is stored) because warmer winters have allowed dead plant matter previously stored in the soil to decompose and release CO2."
1	The	the	DET	DT	Definite=Def|PronType=Art	3	det	3:det	_
2	Alaskan	alaskan	ADJ	JJ	Degree=Pos	3	amod	3:amod	_
3	tundra	tundra	NOUN	NN	Number=Sing	9	nsubj	9:nsubj	SpaceAfter=No
4	,	,	PUNCT	,	_	9	punct	9:punct	_
5	for	for	ADP	IN	_	6	case	6:case	_
6	instance	instance	NOUN	NN	Number=Sing	9	obl	9:obl:for	SpaceAfter=No
7	,	,	PUNCT	,	_	9	punct	9:punct	_
8	has	have	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	9	aux	9:aux	_
9	switched	switch	VERB	VBN	Tense=Past|VerbForm=Part	0	root	0:root	_
10	from	from	SCONJ	IN	_	14	mark	14:mark	_
11	being	be	AUX	VBG	VerbForm=Ger	14	cop	14:cop	_
12	a	a	DET	DT	Definite=Ind|PronType=Art	14	det	14:det	_
13	net	net	NOUN	NN	Number=Sing	14	compound	14:compound	_
14	sink	sink	NOUN	NN	Number=Sing	9	advcl	9:advcl:from	_
15	of	of	ADP	IN	_	17	case	17:case	_
16	carbon	carbon	NOUN	NN	Number=Sing	17	compound	17:compound	_
17	dioxide	dioxide	NOUN	NN	Number=Sing	14	nmod	14:nmod:of	_
18	--	--	PUNCT	,	_	14	punct	14:punct	_
19	absorbing	absorb	VERB	VBG	VerbForm=Ger	14	advcl	14:advcl	_
20	and	and	CCONJ	CC	_	21	cc	21:cc	_
21	storing	store	VERB	VBG	VerbForm=Ger	19	conj	14:advcl|19:conj:and	_
22	more	more	ADJ	JJR	Degree=Cmp	23	amod	23:amod	_
23	carbon	carbon	NOUN	NN	Number=Sing	19	obj	19:obj|21:obj	_
24	from	from	ADP	IN	_	26	case	26:case	_
25	the	the	DET	DT	Definite=Def|PronType=Art	26	det	26:det	_
26	atmosphere	atmosphere	NOUN	NN	Number=Sing	23	nmod	23:nmod:from	_
27	than	than	SCONJ	IN	_	29	mark	29:mark	_
28	it	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	29	nsubj	29:nsubj	_
29	releases	release	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	22	advcl	22:advcl:than	_
30	--	--	PUNCT	,	_	9	punct	9:punct	_
31	to	to	ADP	IN	_	36	mark	36:mark	_
32	"	"	PUNCT	``	_	36	punct	36:punct	SpaceAfter=No
33	being	be	AUX	VBG	VerbForm=Ger	36	cop	36:cop	_
34	a	a	DET	DT	Definite=Ind|PronType=Art	36	det	36:det	_
35	net	net	NOUN	NN	Number=Sing	36	compound	36:compound	_
36	source	source	NOUN	NN	Number=Sing	9	advcl	9:advcl:to	_
37	of	of	ADP	IN	_	38	case	38:case	_
38	CO2	CO2	NOUN	NN	Number=Sing	36	nmod	36:nmod:of	_
39	(	(	PUNCT	-LRB-	_	40	punct	40:punct	SpaceAfter=No
40	releasing	release	VERB	VBG	VerbForm=Ger	36	parataxis	36:parataxis	_
41	more	more	ADJ	JJR	Degree=Cmp	42	amod	42:amod	_
42	carbon	carbon	NOUN	NN	Number=Sing	40	obj	40:obj	_
43	than	than	SCONJ	IN	_	45	mark	45:mark	_
44	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	45	aux:pass	45:aux:pass	_
45	stored	store	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	41	advcl	41:advcl:than	SpaceAfter=No
46	)	)	PUNCT	-RRB-	_	40	punct	40:punct	_
47	because	because	SCONJ	IN	_	51	mark	51:mark	_
48	warmer	warm	ADJ	JJR	Degree=Cmp	49	amod	49:amod	_
49	winters	winter	NOUN	NNS	Number=Plur	51	nsubj	51:nsubj	_
50	have	have	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	51	aux	51:aux	_
51	allowed	allow	VERB	VBN	Tense=Past|VerbForm=Part	9	advcl	9:advcl:because	_
52	dead	dead	ADJ	JJ	Degree=Pos	54	amod	54:amod	_
53	plant	plant	NOUN	NN	Number=Sing	54	compound	54:compound	_
54	matter	matter	NOUN	NN	Number=Sing	51	obj	51:obj|61:nsubj:xsubj|63:nsubj:xsubj	_
55	previously	previously	ADV	RB	_	56	advmod	56:advmod	_
56	stored	store	VERB	VBN	Tense=Past|VerbForm=Part	54	acl	54:acl	_
57	in	in	ADP	IN	_	59	case	59:case	_
58	the	the	DET	DT	Definite=Def|PronType=Art	59	det	59:det	_
59	soil	soil	NOUN	NN	Number=Sing	56	obl	56:obl:in	_
60	to	to	PART	TO	_	61	mark	61:mark	_
61	decompose	decompose	VERB	VB	VerbForm=Inf	51	xcomp	51:xcomp	_
62	and	and	CCONJ	CC	_	63	cc	63:cc	_
63	release	release	VERB	VB	VerbForm=Inf	61	conj	51:xcomp|61:conj:and	_
64	CO2	CO2	NOUN	NN	Number=Sing	63	obj	63:obj	SpaceAfter=No
65	.	.	PUNCT	.	_	9	punct	9:punct	SpaceAfter=No
66	"	"	PUNCT	''	_	9	punct	9:punct	_
